Since ancient times solar energy has been harnessed for human use through a range of technologies

Understanding the problems with fossil fuels, the need for the decentralization of power structures and creating self sufficient green economies.

Wood, wind, water, and sun power have been used for cooking, heating, milling, and other tasks for millennia.

Another alternative source that has increased in usage since the 1970s has been geothermal power, which is already cost effective, although the initial capital investment may be high. Geothermal power taps the interior heat of Earth to produce steam or expand compounds such as ammonia (which does not require as high a temperature as steam does). The expanded gases drive turbines to generate power without pollution. By 2000 geothermal power in the United States was already replacing the energy that would require 60,000,000 barrels of oil to produce.

During the Industrial Revolution of the eighteenth and early nineteenth centuries, these forms of renewable energy were replaced by fossil fuels such as coal and petroleum. At various times throughout the nineteenth and twentieth centuries, people believed that fossil fuel reserves would be exhausted and focused their attentions on sources of renewable energy. This led to experiments with solar steam for industry and solid wood, methanol gas, or liquid biofuels for engines. Attention has refocused on renewable energy sources since the 1960s and 1970s, not only because of concern over fossil fuel depletion, but also because of apprehension over acid rain and global warming from the accumulation of carbon dioxide in the atmosphere and wars for oil!

Acid rain is clearly the result of the use of fossil fuels, and most authoritative climatologists also believe that these fuels are contributing to global warming. Many scientists and environmentalists have, therefore, urged a global switch to renewable energy, which derives from the sun or from processes set in motion by the sun. These energy forms include direct use of solar power along with windmills, hydroelectric dams, ocean thermal energy systems, and biomass (solid wood, methane gas, or liquid fuels). Renewable energy thus differs not only from fossil energy sources such as petroleum, gas, and coal, but also from nuclear energy, which usually involves dividing uranium atoms.

In the early 1990s, one-fifth of worldwide energy use was renewable, with by far the largest portion of this coming from fuel wood and biomass. Hydroelectric dams made up most of the rest. More than half the world's population relied on wood for cooking and heating, and although wood is generally considered to be renewable, excessive reliance has long been recognized as a cause of deforestation. Forests disappear faster than they can be renewed by natural processes. Energy "crops" —for example, fast-growing acacia or eucalyptus trees planted for fuel wood in the Third World—and more efficient wood stoves may be useful to poor, wood-reliant nations.

In recent years an academic and public discourse has led to this use of the word sustainability in reference to how long human ecological systems can be expected to be usefully productive. Observers point out that in the past, complex human societies have died out, sometimes as a result of their own growth and associated impacts on ecological support systems. The implication is that modern industrial society, which continues to grow in scale and complexity, might also collapse.

The implied preference would be for systems to be productive indefinitely, or be 'sustainable." For instance, "sustainable agriculture" would require agricultural systems expected to last indefinitely, "sustainable development" would be development of economic systems that last indefinitely, and so on. A side discourse relates the term sustainability to longevity of natural ecosystems and reserves (set aside for other-than-human species), but the greatest emphasis has been on human systems and anthropogenic problems, such as anthropogenic depletion of fossil fuel reserves.

Humankind benefits from a multitude of resources and processes that are supplied by natural ecosystems. Collectively, these benefits are known as ecosystem services and include products like clean drinking water and processes like the decomposition of wastes. Ecosystem services are distinct from other ecosystem products and functions because there is human demand for these natural assets. Services can be subdivided into five categories: provisioning such as the production of food and water; regulating, such as the control of climate and disease; supporting, such as nutrient cycles and crop pollination; cultural, such as spiritual and recreational benefits; and preserving, which includes guarding against uncertainty through the maintenance of diversity.

In macro-economics the term "infrastructure" usually refers to the added-value of a nation-state relative to the raw natural capital of its ecoregions, e.g. dams, roads, ports, canals, sewers, border posts, etc. - although it can also be used to describe firm-specific infrastructure such as factories, private roads, capital equipment, and other such assets. The more generic term physical capital is sometimes used to refer to any combination of either infrastructural capital and natural capital -- recognizing that often an infrastructural improvement, e.g. a dam or road, becomes impossible to differentiate from the natural ecology within which it is embedded.

As human populations grow, so do the resource demand imposed on ecosystems and the impacts of our global footprint. Many people have been plagued with the misconception that these ecosystem services are free, invulnerable and infinitely available. However, the impacts of anthropogenic use and abuse are becoming evermore apparent – air and water quality are increasingly compromised, oceans are being over-fished, pests and diseases are extending beyond their historical boundaries, deforestation is eliminating flood control around human settlements. It has been reported that approximately 40-50% of Earth’s ice-free land surface has been heavily transformed or degraded by anthropogenic activities, 66% of marine fisheries are either overexploited or at their limit, atmospheric CO2 has increased more than 30% since the advent of industrialization, and nearly 25% of Earth’s bird species have gone extinct in the last two thousand years. Consequently, society is coming to realize that ecosystem services are not only threatened and limited, but that the pressure to evaluate trade-offs between immediate and long-term human needs is urgent.

The demand for energy has increased steadily, not only because of the growing population but also because of the greater number of technological goods available and the increased affluence that has brought these goods within the reach of a larger proportion of the population. For example, despite the introduction of more fuel-efficient motor vehicles (average miles per gallon increased by 34% between 1975 and 1990), the consumption of fuel by vehicles in America increased by 20% between 1975 and 1990. The rise in gasoline consumption is attributable to an increase in the number of miles the average vehicle traveled and to a 40% increase in the same period in the number of vehicles on the road. Since 1990 average fuel efficiency has changed relatively little, while the number of vehicles, the number of miles they travel, and the total amount of fuel consumed has continued to increase. At the same time the total profits to the oil cartel has increased in parallel.

Conventional forms of energy, such as fossil fuels and nuclear power, receive more financial support from the federal government than does renewable energy. U.S. government policy toward renewable energy has been a roller coaster of support and neglect. By the end of President Jimmy Carter's administration in 1981, federal contributions to research in solar photovoltaics, solar thermal energy, solar buildings, biofuels, and wind energy research had become almost $500 million, but by 1990 the figure was only $65 million. This is the result of economic domination of the global economy by corporations like standard oil.

Predictions as to what exactly these negative effects will be vary greatly. More optimistic outlooks, delaying the peak of production to the 2020s or 2030s and assuming major investments in alternatives occur before the crisis, show the price at first escalates and then retreats as other types of fuel sources are used as transport fuels and fuel substitution in general occurs. More pessimistic predictions which operate on the thesis that the peak will occur shortly or has already occurred predict a global depression and even the collapse of industrial global civilization as the various feedback mechanisms of the global market cause a disastrous chain reaction. The shortfall will cause demand destruction

Who Killed the Electric Car? is a 2006 documentary film that explores the birth, limited commercialization, and subsequent death of the battery electric vehicle in the United States, specifically the General Motors EV1 of the 1990s. The film explores the roles of automobile manufacturers, the oil industry, the US government, batteries, hydrogen vehicles, and consumers in limiting the development and adoption of this technology. The film deals with the history of the electric car, its development and commercialization, mostly focusing on the General Motors EV1, which was made available for lease in Southern California, after the California Air Resources Board passed the ZEV mandate in 1990, as well as the implications of the events depicted for air pollution, environmentalism, Middle East politics, and global warming. The film details the California Air Resources Board's reversal of the mandate after suits from automobile manufacturers, the oil industry, and the George W. Bush administration. It points out that Bush's chief influences, Dick Cheney, Condoleezza Rice, and Andrew Card, are all former executives and board members of oil and auto companies.

President Bush has issued a call for more oil production, which isn’t necessarily a free-market position but only seems like one given the huge number of restrictions on the market now that inhibit production. A truly free economy would generate as much marketable oil as was economically necessary: no more, no less (over time). The correct energy policy is: allow the market to work.

To what lengths will the Bush administration, which everyone knows is the muscle end of the domestic oil industry, go to pursue its desire for more production? To war, perhaps? Plenty of dissidents out there doubt that the overthrow of the Taliban and the war on terror generally are about justice for terrorists and security for the Americans. Rather, like the War on Iraq before it, this war is really about securing the profits of American oil companies doing business internationally.

Actually, that position is not a stretch. The State doesn’t usually tell the truth about its own motivations. The State doesn’t say: "send us your taxes so that we can enhance our power and pass out dough to our friends." Instead, it says: "taxes are the price you pay for civilization." In the same way, most people understand that the sloganeering of politicians is just eyewash to cover up the desire to get reelected, and that bureaucrats are mainly interested in their own jobs and pay.

It’s the same in foreign policy. In May, Sen. John McCain (R-AZ) also said that he plans to “eliminate our dependence on oil from the Middle East that will prevent us from having ever to send our young men and women into conflict again in the Middle East.” He later backtracked from his comments, denying that he meant to imply that the Iraq war was fought over oil.

In June, Palin told Glenn Beck, "The average Alaskan says again we recognize these reserves being ready to be tapped. … We're ready to contribute more to the U.S. in terms of resources that can lead to a safer nation; and I say this while our nation is at war, while we're fighting, in some sense, over energy supplies."

The alternative is war and famine in slavery to a lying oil cartel in a dying planet.

China and Japan have been locked in a diplomatic battle over access to the big oil fields in Siberia. Japan, which depends entirely on imported oil, is desperately lobbying Moscow for a 2,300-mile pipeline from Siberia to coastal Japan. But fast-growing China, now the world's second-largest oil user, after the United States, sees Russian oil as vital for its own "energy security" and is pushing for a 1,400-mile pipeline south to Daqing.

The petro-rivalry has become so intense that Japan has offered to finance the $5 billion pipeline, invest $7 billion in development of Siberian oil fields and throw in an additional $2 billion for Russian "social projects" -- this despite the certainty that if Japan does win Russia's oil, relations between Tokyo and Beijing may sink to their lowest, potentially most dangerous, levels since World War II.

Asia's undeclared oil war is but the latest reminder that in a global economy dependent largely on a single fuel -- oil -- "energy security" means far more than hardening refineries and pipelines against terrorist attack. At its most basic level, energy security is the ability to keep the global machine humming -- that is, to produce enough fuels and electricity at affordable prices that every nation can keep its economy running, its people fed and its borders defended. A failure of energy security means that the momentum of industrialization and modernity grinds to a halt. And by that measure, we are failing.

In the United States and Europe, new demand for electricity is outpacing the new supply of power and natural gas and raising the specter of more rolling blackouts. In the "emerging" economies, such as Brazil, India and especially China, energy demand is rising so fast it may double by 2020. And this only hints at the energy crisis facing the developing world, where nearly 2 billion people -- a third of the world's population -- have almost no access to electricity or liquid fuels and are thus condemned to a medieval existence that breeds despair, resentment and, ultimately, conflict.

In other words, we are on the cusp of a new kind of war -- between those who have enough energy and those who do not but are increasingly willing to go out and get it. While nations have always competed for oil, it seems more and more likely that the race for a piece of the last big reserves of oil and natural gas will be the dominant geopolitical theme of the 21st century.

Already we can see the outlines. China and Japan are scrapping over Siberia. In the Caspian Sea region, European, Russian, Chinese and American governments and oil companies are battling for a stake in the big oil fields of Kazakhstan and Azerbaijan. In Africa, the United States is building a network of military bases and diplomatic missions whose main goal is to protect American access to oilfields in volatile places such as Nigeria, Cameroon, Chad and tiny Sao Tome -- and, as important, to deny that access to China and other thirsty superpowers.

The diplomatic tussles only hint at what we'll see in the Middle East, where most of the world's remaining oil lies. For all the talk of big new oil discoveries in Russia and Africa -- and of how this gush of crude will "free" America and other big importers from the machinations of OPEC -- the geological facts speak otherwise. Even with the new Russian and African oil, worldwide oil production outside the Middle East is barely keeping pace with demand.

In the run-up to the Iraq war, Russia and France clashed noisily with the United States over whose companies would have access to the oil in post-Saddam Hussein Iraq. Less well known is the way China has sought to build up its own oil alliances in the Middle East -- often over Washington's objections. In 2000 Chinese oil officials visited Iran, a country U.S. companies are forbidden to deal with; China also has a major interest in Iraqi oil.

But China's most controversial oil overture has been made to a country America once regarded as its most trusted oil ally: Saudi Arabia. In recent years, Beijing has been lobbying Riyadh for access to Saudi reserves, the largest in the world. In return, the Chinese have offered the Saudis a foothold in what will be the world's biggest energy market -- and, as a bonus, have thrown in offers of sophisticated Chinese weaponry, including ballistic missiles and other hardware, that the United States and Europe have refused to sell to the Saudis.

Granted, the United States, with its vast economic and military power, would probably win any direct "hot" war for oil. The far more worrisome scenario is that an escalating rivalry among other big consumers will spark new conflicts -- conflicts that might require U.S. intervention and could easily destabilize the world economy upon which American power ultimately rests.

As demand for oil becomes sharper, as global oil production continues to lag (and as producers such as Saudi Arabia and Nigeria grow more unstable) the struggle to maintain access to adequate energy supplies, always a critical mission for any nation, will become even more challenging and uncertain and take up even more resources and political attention.

This escalation will not only drive up the risk of conflict but will make it harder for governments to focus on long-term energy challenges, such as avoiding climate change, developing alternative fuels and alleviating Third World energy poverty -- challenges that are themselves critical to long-term energy security but which, ironically, will be seen as distracting from the current campaign to keep the oil flowing.

This, ultimately, is the real energy-security dilemma. The more obvious it becomes that an oil-dominated energy economy is inherently insecure, the harder it becomes to move on to something beyond oil.

Energy conservation is the practice of decreasing the quantity of energy used. It may be achieved through efficient energy use, in which case energy use is decreased while achieving a similar outcome, or by reduced consumption of energy services. Energy conservation may result in increase of financial capital, environmental value, national security, personal security, and human comfort. Individuals and organizations that are direct consumers of energy may want to conserve energy in order to reduce energy costs and promote economic security. Industrial and commercial users may want to increase efficiency and thus maximize profit. Energy conservation reduces the energy consumption and energy demand per capita, and thus offsets the growth in energy supply needed to keep up with population growth. This reduces the rise in energy costs, and can reduce the need for new power plants, and energy imports. The reduced energy demand can provide more flexibility in choosing the most preferred methods of energy production.

Exploitation of natural resources is an essential condition of the human existence.

This refers primarily to food production, but minerals, timber, and a whole raft of other entities from the natural environment also have been extracted. Often the exploitation of nature has been done in a non-sustainable way, which is causing increasing concern, as a non-sustainable exploitation of natural resources ultimately threatens human existence.

Sustainability is a characteristic of a process or state that can be maintained at a certain level indefinitely. The term, in its environmental usage, refers to the potential longevity of vital human ecological support systems, such as the planet's climatic system, systems of agriculture, industry, forestry, and fisheries, and human communities in general and the various systems on which they depend.

On a larger scale, energy conservation is the most important element of energy policy. In general, energy conservation reduces the energy consumption and energy demand per capita, and thus offsets the growth in energy supply needed to keep up with population growth. This reduces the rise in energy costs, and can reduce the need for new power plants, and energy imports. The reduced energy demand can provide more flexibility in choosing the most preferred methods of energy production.

One of the most important of these fundamental changes necessary to avoid this very bleak future that would also involve devastating consequences for the economy is a shift to vegetarian diets. Vegetarianism is a great investment in a cleaner, more sustainable world, because modern intensive animal agriculture is a significant contributor to soil erosion and depletion, air and water pollution, widespread use of pesticides and other chemicals, the destruction of tropical rain forests and other habitats. Some of the negative effects of animal-based diets are already being felt. Overfishing has caused the collapse of many prime fishing areas. Overgrazing by cattle threatens to convert range land into desert. Rapid deforestation to create additional pastureland results in increased soil erosion which drains the earth of its productivity and causes the rapid extinction of plant and animal species which can eventually result in ecosystem collapse. Widespread irrigation to grow feed crops for farm animals (70 percent of the grain produced in the United States is fed to animals destined for slaughter) depletes aquifers.

If these and other environmental trends related to animal-based agriculture continue unimpeded, they will very likely result in increased food prices as farmers and fishers will be unable to keep up with the demand fueled by rapidly increasing population and affluence. Because of this affluence, countries such as Japan and China are moving up the food chain and eating far more animal products. One result is that China changed in 1995 from a grain exporting country to a major grain importing country. Since China has over 21 percent of the world's people, this is a major factor in future grain availability. Also, for many years, over 70 percent of the grain in the United States has been used to fatten up animals destined for slaughter. According to the highly respected Washington DC-based "Worldwatch Institute" these facts and trends indicate a great threat of severe grain shortages and this can exacerbate already serious environmental threats and lead to political instability in poorer countries, with very negative economic implications.

In summary, animal-based agriculture is very irrational from health, ecological, and resource consumption perspectives, and the high health and ecological costs will put a drag on the economy that can have very negative effects on markets and investments.

With many people in the world suffering from lack of food, we need to maximize our resources so that more people can be fed.

For example, if one were to grow corn and feed it directly to humans, more people could be fed than if the corn were fed to a cow, and then its milk or flesh consumed. For every 3,000 calories in the form of corn that are fed to a cow, only 600 are returned in milk; if the meat is eaten, only 120 calories are available for human use.

For every 10 pounds of corn protein fed to a cow, only one pound is returned in the form of meat. When an acre of land is sown in soybeans, 450 pounds of protein are produced. But only 40 pounds of pork or 45 pounds of beef can be raised on an acre of land. Obviously, more people can be fed when humans use plant food instead of animal products.

Other economic issues are also at stake. For example, meat is six times as expensive as flour, cereal, potatoes, and legumes when considering overall nutritional value. Also, because saturated fats and cholesterol (which are high in meat and in most dairy products) have been associated with heart disease, cancer, and other diseases, we all end up paying indirectly through increased health insurance premiums and taxes. In the final analysis, economic and health issues are economic issues.

Cattle and other ruminant livestock such as sheep and goats graze one-half of the planet's total land area. Ruminants, along with pigs and poultry, also eat feed and fodder raised on one-fourth of the cropland. Ubiquitous and familiar, livestock exert a huge, and largely unrecognized, impact on the global environment. More than 3,000 liters of water are used to produce a kilogram of American beef.

Extensive livestock production, like modern intensive production, has environmental side effects. Many of the world's rangelands, covering one-third of the Earth's land surface, bear the scars of improper livestock management: proliferating weeds, depleted soils, and eroded landscapes. Cattle play a prominent role in global desertification--the reduction of dryland's ecological productivity. The process, however, is far more complex and varied than the word "desertification," conjuring images of sand dunes swallowing the range, implies. Initially, cattle overgraze perennial grasses, allowing annual weeds and tougher shrubs to spread. This shift in species composition is the most prevalent form of range degradation. The new weeds anchor the topsoil poorly, and can leave it vulnerable to trampling hooves and the erosive power of wind and rain. Without the cover of perennial grasses, fires that naturally control bushes lose their tinder, so shrubs expand unchecked. As the variety of plant species dwindles, wildlife species also vanish.

Half of the energy used to make food in the US is spent making animal products - meat, dairy and eggs. Farmers must produce crops to feed the animals that eventually provide humans with animal protein.

In 2004, Pimentel estimated 6 kilograms of plant protein are needed to produce 1 kg of high quality animal protein. He calculates that if Americans maintained their 3747 kcals per day, but switched to a vegetarian diet, the fossil fuel energy required to generate that diet would be cut by one third.

Reducing their meat intake is not the only way Americans can cut the nation's energy bill. change to US eating habits would have the added benefit of cutting the national health bill as well.

Reducing the distance that food is transported could also cut energy costs: food travels 2400 km on average to its consumer in the US. This requires 1.4 times the energy actually contained in the food. Producing food locally would cut the energy expended transporting it by half.

The amount of energy that goes into packaging foods could be halved as well, as could the amount of energy used by agricultural machines.

If these dietary and production measures were implemented, the US food industry would consume half the energy it does.

We do not view the food crisis as an unexpected, sudden emergency of the last year, but as the inevitable consequence of misguided agricultural and food policies over the last 30 years. We will not resolve the problems exposed by this food crisis with more of the same policies and thinking. A wholesale change in the worldwide food system is necessary to address these problems sustainably and equitably.
For more than a century, pundits have confidently predicted the demise of the small farm, labeling it as backward, unproductive, and inefficient -- an obstacle to be overcome in the pursuit of economic development. But this is wrong. Far from being stuck in the past, small-farm agriculture provides a productive, efficient, and ecological vision for the future.

If small farms are worth preserving, then now is the time to educate the world’s policy-makers about the genuine value of small farm agriculture.

Small Farm Productivity

How many times have we heard that large farms are more productive than small farms, and that we need to consolidate land holdings to take advantage of that greater productivity and efficiency? The actual data shows the opposite -- small farms produce far more per acre or hectare than large farms.

One reason for the low levels of production on large farms is that they tend to be monocultures. The highest yield of a single crop is often obtained by planting it alone on a field. But while that may produce a lot of one crop, it generates nothing else of use to the farmer. In fact, the bare ground between crop rows invites weed infestation. The weeds then invest labor in weeding or money in herbicide.

Large farmers tend to plant monocultures because they are the simplest to manage with heavy machinery. Small farmers, especially in the Third World, are much more likely to plant crop mixtures -- intercropping -- where the empty space between the rows is occupied by other crops. They usually combine or rotate crops and livestock, with manure serving to replenish soil fertility.

Such integrated farming systems produce far more per unit area than do monocultures. Though the yield per unit area of one crop -- corn, for example -- may be lower on a small farm than on a large monoculture farm, the total production per unit area, often composed of more than a dozen crops and various animal products, can be far higher.

This holds true whether we are talking about an industrial country like the United States, or any country in the Third World.

Recent history shows that the re-distribution of land to landless and land-poor
rural families can be a very effective way to improve rural well-being. We can examine the outcome of every land reform program carried out in the Third World since World War II, being careful to distinguish between genuine land reforms -— when quality land was really distributed to the poor and the power of the rural oligarchy to distort and "capture" policies was broken -- and "fake land reforms" -- when the poor have been relegated to the poorest, most remote soils. In every case of genuine land reform, real, measurable poverty reduction and improvement in human welfare has invariably been the result.

Feminist economics broadly refers to a developing branch of economics that applies feminist insights and critiques to economics. Research under this heading is often interdisciplinary, critical, or heterodox. It encompasses debates about the relationship between feminism and economics on many levels: from applying mainstream economic methods to under-researched "women's" areas, to questioning how mainstream economics values the reproductive sector, to deeply philosophical critiques of economic epistemology and methodology.

Green economics is an unconventional approach to economics by non-economists. It takes the widest possible view of stakeholders of a transaction to include impacts to nature, non-human species, the planet, earth sciences, and the biosphere. A holistic approach to the subject is typical, so that economic ideas incorporate learning from other disciplines in a true transdisciplinary fashion, and important theories from feminist economics, postmodernism, critical theory, ecology, international relations and peace, deep ecology, animal rights, social and environmental justice, anti-globalisation, energy efficiency, participation and localisation theories. Green Gross Domestic Product (Green GDP) is an index of economic growth with the environmental consequences of that growth factored in.

Organisations practicing sustainable procurement meet their needs for goods, services, utilities and works not on a private cost-benefit analysis, but with a view to maximising net benefits for themselves and the wider world.

The Bottom Lines
"People, Planet and Profit" are used to succinctly describe the triple bottom lines and the goal of sustainability.

"People" (Human Capital) pertains to fair and beneficial business practices toward labor and the community and region in which a corporation conducts its business. A TBL company conceives a reciprocal social structure in which the well being of corporate, labor and other stakeholder interests are interdependent. A triple bottom line enterprise seeks to benefit many constituencies, not exploit or endanger any group of them. The "upstreaming" of a portion of profit from the marketing of finished goods back to the original producer of raw materials, i.e., a farmer in fair trade agricultural practice, is a not unusual feature. In concrete terms, a TBL business would not knowingly use child labor, would pay fair salaries to its workers, would maintain a safe work environment and tolerable working hours, and would not otherwise exploit a community or its labor force. A TBL business also typically seeks to "give back" by contributing to the strength and growth of its community with such things as health care and education. Quantifying this bottom line is relatively new, problematic and often subjective. The Global Reporting Initiative (GRI) has developed guidelines to enable corporations and NGO's alike to comparably report on the social impact of a business.

"Planet" (Natural Capital) refers to sustainable environmental practices. A TBL company endeavors to benefit the natural order as much as possible or at the least do no harm and curtail environmental impact. A TBL endeavor reduces its ecological footprint by, among other things, carefully managing its consumption of energy and non-renewables and reducing manufacturing waste as well as rendering waste less toxic before disposing of it in a safe and legal manner. "Cradle to grave" is uppermost in the thoughts of TBL manufacturing businesses which typically conduct a life cycle assessment of products to determine what the true environmental cost is from the growth and harvesting of raw materials to manufacture to distribution to eventual disposal by the end user. A triple bottom line company does not produce harmful or destructive products such as weapons, toxic chemicals or batteries containing dangerous heavy metals for example. Currently, the cost of disposing of non-degradable or toxic products is borne financially by governments and environmentally by the residents near the disposal site and elsewhere. In TBL thinking, an enterprise which produces and markets a product which will create a waste problem should not be given a free ride by society. It would be more equitable for the business which manufactures and sells a problematic product to bear part of the cost of its ultimate disposal. Ecologically destructive practices, such as overfishing or other endangering depletions of resources are avoided by TBL companies. Often environmental sustainablity is the more profitable course for a business in the long run. Arguments that it costs more to be environmentally sound are often specious when the course of the business is analyzed over a period of time. Generally, sustainability reporting metrics are better quantified and standardized for environmental issues than for social ones. A number of respected reporting institutes and registries exist including the Global Reporting Initiave, CERES, Institute 4 Sustainability and others.

"Profit" is the bottom line shared by all commerce, conscientious or not. In the original concept, within a sustainability framework, the "profit" aspect needs to be seen as the economic benefit enjoyed by the host society. It is the lasting economic impact the organisation has on its economic environment. This is often confused to be limited to the internal profit made by a company or organisation. Therefore, a TBL approach cannot be interpreted as traditional corporate accounting plus social and environmental impact.

The Nature Conservancy Launches “Plant a Billion Trees Campaign” with Planet Green

Today, The Nature Conservancy launched the “Plant a Billion Trees Campaign” at www.plantabillion.org to restore and plant one billion trees by 2015 in Brazil’s Atlantic Forest, one of the greatest repositories of biodiversity on Earth.

“This is an unprecedented effort − nothing on this scale has ever been attempted in a single country in South America,” said Stephanie Meeks, acting president and CEO of The Nature Conservancy. “No tropical forest on Earth has come closer to total destruction than Brazil’s Atlantic Forest, and now we have a real chance to bring this region back from the brink.” Alleviate global poverty by planting a tree now.

You can make a difference. Wise energy use therefore embodies the idea of balancing human comfort with reasonable energy consumption levels by researching and implementing effective and sustainable energy harvesting and utilization measures

Negawatt power is a term coined for an arbitrage way of supplying additional electrical energy to consumers without increased generation capacity by the creation of a market for trading of increased efficiency. The concept was introduced by Amory Lovins in a 1989 speech. While it is related to and utilises consumption efficiencies, it differs in scale and market behaviour from individual company or consumer level efficiencies. Energy consumers may also reduce energy consumption for a few hours to "generate" negawatts - hypothetical tradeable units of saved energy. By shutting off air conditioners energy can be saved over a short period of time. This reduction in consumption is referred to as a negawatt and can be sold in certain specialized markets. This "virtual generation" method can supply growth of supply by increasing efficiencies rather than increasing generation.

Grid energy storage lets electric energy producers send excess electricity over the electricity transmission grid to temporary electricity storage sites that become energy producers when electricity demand is greater, optimizing the production by storing off-peak power for use during peak times. Also, photovoltaic and wind turbine users can avoid the necessity of having battery storage by connecting to the grid, which effectively becomes a giant battery. Photovoltaic operations can store electricity for night time use, and wind power can be stored for calm times.

Grid energy storage is closely related to distributed generation. For distributed generation to function correctly, specialized technical and economic arrangements (such as net metering and vehicle-to-grid power systems) may be needed, and often require regulatory support.

Energy demand management, also known as demand side management (DSM), entails actions that influence the quantity or patterns of use of energy consumed by end users, such as actions targeting reduction of peak demand during periods when energy-supply systems are constrained. Peak demand management does not necessarily decrease total energy consumption but could be expected to reduce the need for investments in networks and/or power plants. Today, demand side management is also known as demand response.

The term DSM was coined in the 1970s when the 1973 energy crisis and 1979 energy crisis suggested that some of the most convenient fossil fuel energy reserves, such as crude oil, were approaching exhaustion

Green Maps are locally created environmentally themed maps which use a universal symbol set and mapmaking resources provided by the non-profit Green Map System. Based on the principles of cartography a Green Map plots the locations of a community's natural, cultural and sustainable resources such as recycling centers, heritage sites, community gardens, toxic waste sites and socially conscious businesses.

Agroforestry combines agriculture and forestry technologies to create more integrated, diverse, productive, profitable, healthy and sustainable land-use systems. -National Agroforestry Center (NAC)

The World Agroforestry Centre (ICRAF) made this definition in 1993: "Agroforestry is a collective name for land use systems and practices in which woody perennials are deliberately integrated with crops and/or animals on the same land management unit. The integration can be either in a spatial mixture or in a temporal sequence. There are normally both ecological and economic interactions between woody and non-woody components in agroforestry". It means that trees are intentionally used within agricultural systems. Knowledge, careful selection of species and good management of trees and crops are needed to maximize the production and positive effects of trees and to minimize negative competitive effects on crops.

Alternatively, agroforestry might be defined as simply: trees on farms [1]. Hence, agroforestry, farm forestry and family forestry can be broadly understood as the commitment of farmers, alone or in partnerships, towards the establishment and management of forests on their land. Where many landholders are involved the result is a diversity of activity that reflects the diversity of aspirations and interests within the community.

Agroforestry is a land-use method that allows trees to grow in crop and livestock areas. It is one way to conserve biodiversity. Human activity and specifically habitat destruction have dramatically increased rates of biodiversity loss. It is extremely important to maintain the proper functioning of ecosystems and society. It is the diversity of life that makes this planet extraordinary. Oil, coal, cement, and limestone are all part of the past biodiversity on which our economies depend. The majority of our medicines and agricultural crops come from the environment. It is also important for providing ecosystem services such as pollination and pest control.

Alley cropping
Agroforestry is a land-use method that allows trees to grow in crop and livestock areas. It is one way to conserve biodiversity. Alley cropping or Intercropping is a strategy used by farmers to combat soil erosion. In this method, several crops are planted together in strips or alleys between trees and shrubs. This design provides shade (reducing water loss from evaporation), ensures retention of soil moisture, and can also produce fruit, fuelwood, fodder, or trimmings to be made into mulch.

Ecoforestry is forestry that emphasizes holistic practices which strive to protect and restore ecosystems1 rather than maximize economic productivity. Practitioners of ecoforestry eschew practices like clearcutting, high grading, and pesticides.2

Ecoforestry is considered by some to be a traditional practice, whereby people tend to an area of forest, helping it to grow sustainably over many years. Practitioners of ecoforestry claim that their techniques promote self-regulating forest ecosytems with a diversity of species and natural habitats in harmony with landscape, weather, soil, water flows, and animals living there.

Ecoforestry has its roots in family homesteads selectively cutting trees for home use.

Green building is the practice of increasing the efficiency of buildings and their use of energy, water, and materials, and reducing building impacts on human health and the environment, through better siting, design, construction, operation, maintenance, and removal — the complete building life cycle.

A similar concept is natural building, which is usually on a smaller scale and tends to focus on the use of natural materials that are available locally.[1] Other commonly used terms include sustainable design and green architecture; however, while good design is essential to green building, the actual operation, maintenance, and ultimate disposal or deconstruction of the building also have very significant effects on buildings' overall environmental impact.

The related concepts of sustainable development and sustainability are integral to green building. Effective green building can lead to 1) reduced operating costs by increasing productivity and using less energy and water, 2) improved public and occupant health due to improved indoor air quality, and 3) reduced environmental impacts by, for example, lessening storm water runoff and the heat island effect. Practitioners of green building often seek to achieve not only ecological but aesthetic harmony between a structure and its surrounding natural and built environment. The sustainable buildings are also environmentaly friendly in the fact that they are built out of materials that are good for the environment.The appearance and style of sustainable homes and buildings can be nearly indistinguishable from their less sustainable counterparts.

Green buildings are scored by rating systems, such as the Leadership in Energy and Environmental Design (LEED) rating system developed by the U.S. Green Building Council, Green Globes from GBI and other locally developed rating systems.

The environmental impact of buildings
Buildings have a profound effect on the environment, which is why green building practices are so important to reduce and perhaps one day eliminate those impacts.

In the United States alone, buildings account for:

39% of total energy use
12% of total water consumption
68% of total electricity consumption
38% of total carbon dioxide emissions

Building materials typically considered to be 'green' include rapidly renewable plant materials like bamboo and straw, lumber from forests certified to be sustainably managed, stone, recycled metal, and other products that are non-toxic, reusable, renewable, and/or recyclable. Building materials should be extracted and manufactured locally to the building site to minimize the energy embedded in their transportation.

Low-impact building materials are used wherever feasible: for example, insulation may be made from low VOC (volatile organic compound)-emitting materials such as recycled denim, rather than the insulation materials that may contain carcinogenic or toxic materials such as formaldehyde. To discourage insect damage, these alternate insulation materials may be treated with boric acid. Organic or milk-based paints may be used.

Architectural salvage and reclaimed materials are used when appropriate as well. When older buildings are demolished, frequently any good wood is reclaimed, renewed, and sold as flooring. Many other parts are reused as well, such as doors, windows, mantels, and hardware, thus reducing the consumption of new goods. When new materials are employed, green designers look for materials that are rapidly replenished, such as bamboo, which can be harvested for commercial use after only 6 years of growth, or cork oak, in which only the outer bark is removed for use, thus preserving the tree. When possible, building materials may be gleaned from the site itself; for example, if a new structure is being constructed in a wooded area, wood from the trees which were cut to make room for the building would be re-used as part of the building itself.

To minimize the energy loads within and on the structure, it is critical to orient the building to take advantage of cooling breezes and sunlight. Daylighting with ample windows will eliminate the need to turn on electric lights during the day (and provide great views outside too). Passive Solar can warm a building in the winter - but care needs to be taken to provide shade in the summer time to prevent overheating. Prevailing breezes and convection currents can passively cool the building in the summer. Thermal mass stores heat gained during the day and releases it at night minimizing the swings in temperature. Thermal mass can both heat the building in winter and cool it during the summer. Insulation is the final step to optimizing the structure. Well-insulated windows, doors, and walls help reduce energy loss, thereby reducing energy usage. These design features don't cost much money to construct and significantly reduce the energy needed to make the building comfortable.

Optimizing the heating and cooling systems through installing energy efficient machinery, commissioning, and heat recovery is the next step. Compared to optimizing the passive heating and cooling features through design, the gains made by engineering are relatively expensive and can add significantly to the projects cost. However, thoughtful integrated design can reduce costs -- for example, once a building has been designed to be more energy-efficient, it may be possible to downsize heating, ventilation and air-conditioning (HVAC) equipment, leading to substantial savings. To further address energy loss hot water heat recycling is used to reduce energy usage for domestic water heating. Ground source heat pumps are more energy efficient then other forms of heating and cooling until you factor in the energy lost during generation and transmission if the project is on the grid.

Finally, onsite generation of renewable energy through solar power, wind power, hydro power, or biomass can significantly reduce the environmental impact of the building. Power generation is the most expensive feature to add to a building.

Good green architecture also reduces waste, of energy, water and materials. During the construction phase, one goal should be to reduce the amount of material going to landfills. Well-designed buildings also help reduce the amount of waste generated by the occupants as well, by providing onsite solutions such as compost bins to reduce matter going to landfills.

To reduce the impact on wells or water treatment plants, several options exist. "Greywater", wastewater from sources such as dishwashing or washing machines, can be used for subsurface irrigation, or if treated, for non-potable purposes, e.g., to flush toilets and wash cars. Rainwater collectors are used for similar purposes.

Green building often emphasizes taking advantage of renewable resources, e.g., using sunlight through passive solar, active solar, and photovoltaic techniques and using plants and trees through green roofs, rain gardens, and for reduction of rainwater run-off.

The Seawater Greenhouse is a unique concept which combines natural processes, simple construction techniques and mathematical computer modelling to provide a low-cost solution to one of the world's greatest needs – fresh water. The Seawater Greenhouse is a new development that offers sustainable solution to the problem of providing water for agriculture in arid, coastal regions.

The process uses seawater to cool and humidify the air that ventilates the greenhouse and sunlight to distil fresh water from seawater. This enables the year round cultivation of high value crops that would otherwise be difficult or impossible to grow in hot, arid regions

Arguments in favor of microgeneration are:

A significant proportion of electrical power is lost during transmission. Microgeneration does not incur this loss.
Microgeneration reduces the transmission capacity requirement of the national grid, avoiding the need for additional grid upgrades.
By curbing the rising demand for grid electricity, microgeneration can avert the need for investment in large new power stations.
The waste-heat byproduct can be used for heating purposes, thus greatly increasing efficiency and offsetting energy total costs. This method is known as combined heat and power (CHP).
Because the electricity does not come from the grid, should the grid fail in a disaster such as an earthquake, the electricity will still be available.

There is considerable resistance to microgeneration from many governments, local authorities and energy companies. Current incentives discourage energy suppliers and grid operators from bringing energy generation to the point of demand.

Policy-makers are accustomed to an energy system based on big, centralised projects like nuclear or gas-fired power stations, and it will require a change of mindsets and incentives to bring microgeneration into the mainstream. Planning regulations may also require streamlining to facilitate the retrofitting of microgenerating facilities onto homes and buildings.

Distributed generation generates electricity from many small energy sources. It has also been called also called on-site generation, dispersed generation, embedded generation, decentralized generation, decentralized energy or distributed energy.Currently, industrial countries generate most of their electricity in large centralized facilities, such as coal power plants, nuclear reactors, hydropower or gas powered plant.

These plants have economies of scale, but usually transmit electricity long distances. Coal plants do so to prevent pollution of the cities. Nuclear reactors are thought too unsafe to be in a city. Dam sites are often both unsafe, and intentionally far from cities. Distributed generation is another approach. It reduces the amount of energy lost in transmitting electricity because the electricity is generated very near where it is used, perhaps even in the same building. This also reduces the size and number of power lines that must be constructed.

Typical distributed power sources have low maintenance, low pollution and high efficiencies. In the past, these traits required dedicated operating engineers, and large, complex plants to pay their salaries and reduce pollution. However, modern embedded systems can provide these traits with automated operation and clean fuels, such as sunlight, wind and natural gas. This reduces the size of power plant that can show a profit.

A sustainable community energy system is an integrated approach to supplying a local community with its energy requirements from renewable energy or high-efficiency co-generation energy sources. The approach can be seen as a development of the distributed generation concept.

Stanford researchers have found a way to use silicon nanowires to reinvent the rechargeable lithium-ion batteries that power laptops, iPods, video cameras, cell phones, and countless other devices.

The new technology, developed through research led by Yi Cui, assistant professor of materials science and engineering, produces 10 times the amount of electricity of existing lithium-ion, known as Li-ion, batteries. A laptop that now runs on battery for two hours could operate for 20 hours, a boon to ocean-hopping business travelers.

"It's not a small improvement," Cui said. "It's a revolutionary development.
"

The breakthrough is described in a paper, "High-performance lithium battery anodes using silicon nanowires," published online Dec. 16 in Nature Nanotechnology, written by Cui, his graduate chemistry student Candace Chan and five others.

The greatly expanded storage capacity could make Li-ion batteries attractive to electric car manufacturers. Cui suggested that they could also be used in homes or offices to store electricity generated by rooftop solar panels.

"Given the mature infrastructure behind silicon, this new technology can be pushed to real life quickly," Cui said.

The electrical storage capacity of a Li-ion battery is limited by how much lithium can be held in the battery's anode, which is typically made of carbon. Silicon has a much higher capacity than carbon, but also has a drawback.

Silicon placed in a battery swells as it absorbs positively charged lithium atoms during charging, then shrinks during use (i.e., when playing your iPod) as the lithium is drawn out of the silicon. This expand/shrink cycle typically causes the silicon (often in the form of particles or a thin film) to pulverize, degrading the performance of the battery.

Cui's battery gets around this problem with nanotechnology. The lithium is stored in a forest of tiny silicon nanowires, each with a diameter one-thousandth the thickness of a sheet of paper. The nanowires inflate four times their normal size as they soak up lithium. But, unlike other silicon shapes, they do not fracture.

Research on silicon in batteries began three decades ago. Chan explained: "The people kind of gave up on it because the capacity wasn't high enough and the cycle life wasn't good enough. And it was just because of the shape they were using. It was just too big, and they couldn't undergo the volume changes.
"

Then, along came silicon nanowires. "We just kind of put them together," Chan said.

For their experiments, Chan grew the nanowires on a stainless steel substrate, providing an excellent electrical connection. "It was a fantastic moment when Candace told me it was working," Cui said.

Cui said that a patent application has been filed. He is considering formation of a company or an agreement with a battery manufacturer. Manufacturing the nanowire batteries would require "one or two different steps, but the process can certainly be scaled up," he added. "It's a well understood process.
"

Thermal energy storage can refer to a number of technologies that store energy in a thermal reservoir for later reuse. They can be employed to balance energy demand between day time and night time. The thermal reservoir may be maintained at a temperature above (hotter) or below (colder) than that of the ambient environment.

The principal application today is the production of ice, chilled water, or eutectic solution at night, which is then used to cool environments during the day.

Thermal energy storage technologies store heat, usually from active solar collectors, in an insulated repository for later use in space heating, domestic or process hot water, or to generate electricity. Most practical active solar heating systems have storage for a few hours to a day's worth of heat collected. There are also a small but growing number of seasonal thermal stores, used to store summer heat for use during winter.

Molten salt has been proposed as a means to retain a high temperature thermal store for later use in electricity generation.

Economics
High peak summertime loads drive the capital expenditures of the electricity generation industry. The industry meets these peak loads with low-efficiency peaking power plants, usually gas turbines, which have lower capital costs but higher fuel costs. A kilowatt-hour of electricity consumed at night can be produced at much lower marginal cost. Utilities have begun to pass these lower costs to consumers, in the form of Time of Use (TOU) rates, or Real Time Pricing (RTP) Rates.

Water based technology
Thermal energy storage is made practical by the large heat of fusion of water. One metric ton of water, just one cubic meter, can store 334 MJ (317 k BTUs, 93kWh or 26.4 ton-hours). In fact, ice was originally transported from mountains to cities for use as a coolant, and the original definition of a "ton" of cooling capacity (heat flow) was the heat to melt one ton of ice every 24 hours. This is the heat flow one would expect in a 3,000 square foot house in Boston in the summer. This definition has since been replaced by less archaic units: one ton HVAC capacity = 12,000 BTU/hour. Either way, an agreeably small storage facility can hold enough ice to cool a large building for a day or a week, whether that ice is produced by anhydrous ammonia chillers or hauled in by horse-drawn carts.

New materials for energy conservation and energy conversion" links a number of topics and areas of technology, along with various groups of materials.

The development and implementation of technologies that are energy efficient are necessary components of any responsible energy plan. Research and experience in industrialised countries suggest that efficient technologies can play a vital role in improving industrial productivity and sustaining high rates of economic growth. They are also less costly and more environmentally benign than an exclusively supply-oriented strategy.

Carbon Composites.. A carbon fiber is a long, thin strand of material about 0.0002-0.0004 in (0.005-0.010 mm) in diameter and composed mostly of carbon atoms. The carbon atoms are bonded together in microscopic crystals that are more or less aligned parallel to the long axis of the fiber. The crystal alignment makes the fiber incredibly strong for its size. Several thousand carbon fibers are twisted together to form a yarn, which may be used by itself or woven into a fabric. The yarn or fabric is combined with epoxy and wound or molded into shape to form various composite materials. Carbon fiber-reinforced composite materials are used to make aircraft and spacecraft parts, racing car bodies, golf club shafts, bicycle frames, fishing rods, automobile springs, sailboat masts, and many other components where light weight and high strength are needed.

Carbon fibers were developed in the 1950s as a reinforcement for high-temperature molded plastic components on missiles. The first fibers were manufactured by heating strands of rayon until they carbonized. This process proved to be inefficient, as the resulting fibers contained only about 20% carbon and had low strength and stiffness properties. In the early 1960s, a process was developed using polyacrylonitrile as a raw material. This produced a carbon fiber that contained about 55% carbon and had much better properties. The polyacrylonitrile conversion process quickly became the primary method for producing carbon fibers.

During the 1970s, experimental work to find alternative raw materials led to the introduction of carbon fibers made from a petroleum pitch derived from oil processing. These fibers contained about 85% carbon and had excellent flexural strength. Unfortunately, they had only limited compression strength and were not widely accepted.

Today, carbon fibers are an important part of many products, and new applications are being developed every year. The United States, Japan, and Western Europe are the leading producers of carbon fibers.The latest development in carbon fiber technology is tiny carbon tubes called nanotubes.

These hollow tubes, some as small as 0.00004 in (0.001 mm) in diameter, have unique mechanical and electrical properties that may be useful in making new high-strength fibers, submicroscopic test tubes, or possibly new semiconductor materials for integrated circuits.

Three selected areas of application for new materials, where some of the areas already have individual applications and some are still in the research stage:

The common element is their shared goal of generating, transporting, storing or using (electrical) power in an efficient, low-cost manner which also spares the environment and conserves nature. A large number of approaches are being followed:

The current state of knowledge in materials development is increasingly permitting customised production or improvement of materials. Here, the properties of the material no longer dictate its use: instead, the development goals are derived from the desired functions of the systems or products. Based on the definition of a desired technological service, a use profile is elaborated which defines the requirements for the materials used together with the development goal. Customised materials accordingly reflect a substantial qualitative advance in the materials field.

The use of solar energy for photovoltaic and solar thermal installations is now state-of-the-art. A breakthrough in the energy sector – particularly for photovoltaic generation – has so far been held up by the relatively high manufacturing costs of photovoltaic solar cells and their low level of efficiency together with the complicated techniques needed to integrate them into a system. Photovoltaic use in stand-alone installations is the only case which has proved cost-effective to date. Besides work on improving the solar cell concept based on the "classic" material silicon, there is accordingly a worldwide search for new materials for photovoltaic cells. The search is for materials which will make possible solar cells which are cheap to manufacture, have a high degree of efficiency and long useful life and cause little pollution in manufacture, use and disposal (recycling).

Gas turbines are very flexible in terms of low cost, range of fuels and rapid availability, and are currently on a rising trend. Even if there are limits to improving their efficiency, further progress towards the thermodynamic limits is still possible. A further increase in efficiency is desirable because more efficient utilisation of fuel conserves natural resources and reduces the release of pollution into the environment.

In achieving an increase in efficiency new and improved materials have a major role to play. The focus is on four classes of materials: metallic materials (superalloys and intermetallics), ceramic materials (structural ceramics), composite materials with a ceramic matrix (carbon fibre reinforced carbon) and surface coatings (heat insulation layers). New high-temperature materials are expected to show characteristics which are at least as good as and probably significantly better than conventional materials, attainable at low cost if at all possible. A striking feature is the large number of individual questions currently being studied in new high-temperature materials. Major improvements have been achieved in individual application and production characteristics (where material developments in gas turbine construction have so far profited mainly from developments in aviation turbine construction), but superiority over the entire characteristics profile has yet to be demonstrated.

With oriented or single-crystal superalloys surface temperatures of c. 1,000°C have already been achieved. An increase in surface temperature to c. 1,100°C will be attainable with metallic components such as improved or oxide-dispersion-strengthened (ODS) superalloys. A significant increase in surface temperatures to c. 1,400°C will require the development of ceramic structural materials. A further increase in temperature will mean a switch towards composites (e.g. carbon fibre reinforced carbon). Allowing for a time dimension in development, this means:

Surface coatings applied as heat insulation play a supplementary role in almost every high-temperature material, mostly compensating for corrosive conditions and accordingly with a stabilising function. This makes it possible to raise the temperature in use of individual components by up to 100°C. Problems affecting practical use such as stability and adhesion of coatings, for example in multilayer systems, seem to be soluble in the medium term.

For the high-temperature materials for gas turbines under consideration here these relatively high expectations for new materials are offset by extensive need for R&D, e.g. in the following areas:

Superconductors can (theoretically) be used at all levels of production in the electricity industry (conversion, transport and distribution). For some time, energy technology has been seen as a major area of application for superconducting materials. Besides improvements in known technological systems (superconducting generators, transformers, cable) where low electrical losses with superconductors make possible achievement of higher efficiency and the high power density means reduced volume and weight, there are also new concepts under discussion (e.g. fault current limiters using superconducting materials and the use of superconducting magnetic energy storage). However, complex technologies are requires, particularly for cooling the superconductors, and the energy consumed by these reduces or outweighs the advantages of the low-loss conductors. In addition, production of wires is considerably more difficult and elaborate, compared with conventional copper wires, and the systems themselves are frequently more complicated, so that major efforts are needed to achieve the same reliability and availability as with the conventional alternatives now available. This in turn leads to higher system costs.

The discovering of high-temperature superconducting materials in the mid-Eighties gave new life to old expectations for superconducting technology in the electricity industry. The new materials and their energy sector applications do not involve any fundamental change in the underlying physical and technical principles or the environment in which they are used. The use of a "higher" temperature range for cooling could, however, mean that simpler and cheaper cooling systems can be used, and the expense on thermal insulation could also be reduced. On the other hand, the characteristics of the new materials had first to be investigated and understood, and processes for manufacturing conductors suitable for the various applications had to be developed.

For the "classic" high-temperature superconductors, we need to develop new concepts and manufacturing processes and improve existing ones for producing conductors which are suitable for energy industry applications.

The "controllability" of a material is a fundamental factor in practical use. In the case of high-temperature superconductors, numerous advances have been made in the past ten years, and our understanding of the main materials is now adequate. There is, however, no sign of an accepted physical theory of high-temperature superconductivity, despite widespread efforts and numerous original and stimulating ideas. More fundamental research seems required here.

In recent years, numerous processes have been developed for producing conductors using high-temperature superconducting materials. Each of these has specific strengths and weaknesses. For the implementation of the processes in industrial-scale manufacture the key principle that seems to be emerging (for both physical-technological and economic reasons) is the need to keep these processes as flexible and simple as possible, and only use as many process stages as are needed to reach the required parameters. It is hoped that new technologies will make it possible to maintain superconductivity at "higher" temperatures and/or with stronger magnetic fields. Very promising results have already been achieved with short wires, but it remains to be seen whether these techniques are practical and economical for longer conductors.

Although over 100 compounds which can be described as high-temperature superconductors are already known, the search for further materials should be continued. The emphasis should be less on materials with higher critical temperatures: for most energy industry applications it will be more important to find superconductors which:

The empirical search for new materials will continue to play the central role here, although in future a suitable theoretical explanation of the mechanism of high-temperature superconductivity should be found.

Superconducting components for applications in the electrical industry permit (irrespective at this point of the superconductor actually used) either entirely new technological systems or will replace conventional systems because of their more favourable technological and economic parameters. The decisive breakthrough for energy industry HTS applications at 77K will only be possible if the HTS can be manufactured with suitable technical configurations. It is not clear what the electrical parameters and costs will be for manufacturing suitable technical HTS on an industrial scale. It is, however, clear that there will be no single "all-purpose" superconductor for energy industry use: instead, technical and economic optimisation will lead to a wide range of concepts in the selection of the superconducting material and also the conductor configuration.

In the light of our present knowledge, the possible uses for the individual applications (assuming availability of suitable and "affordable" conductors) can be summarised as follows.

For the evaluation of the long-term prospects of superconducting energy technologies it will not be sufficient to compare these with their conventional alternatives. It would be interesting to design a "superconductor-based" electricity supply system and put this into a macroeconomic framework for comparison with the current systems and systems evolving in the new environments.

At present, ecological evaluation of the use of new materials in energy technology is only possible in rudimentary form. On the one hand, for example, the use of high-temperature materials in gas turbines promise an increase in efficiency, with resulting reduced energy consumption and pollution. The desired – and achieved – high resistance of these materials to thermal and chemical influences could, however, reduce their recycling capability. Materials for solar cells are a contribution to electricity generation which is pollution-free in operation, but their manufacture requires substantial energy input. .Generally, it can be said that (with a few exceptions) we lack the research results and assembled information to reach a satisfactory evaluation of the ecological consequences of the use of new materials. Many companies (particularly SMEs) lack the data on conventional and (particularly) new materials to draw up ecological balance sheets, and frequently also lack the personnel. It would be desirable to pay greater attention in future R&D activities to aspects of ecological evaluation in materials development.

Flywheel Energy Storage (FES) works by accelerating a rotor (flywheel) to a very high speed and maintaining the energy in the system as rotational energy. The energy is converted back by slowing down the flywheel.

Most FES systems use electricity to accelerate and decelerate the flywheel, but devices that directly use mechanical energy are being developed.[1]

Advanced FES systems have rotors made of high strength carbon-composite filaments that spin at speeds from 20,000 to over 50,000 rpm [2] in a vacuum enclosure and use magnetic bearings. Such flywheels come up to speed in a matter of minutes, rather than the hours needed to recharge a battery.[2]

Main components
A typical system consists of a rotor suspended by bearings inside a vacuum chamber to reduce friction, connected to a combination electric motor/electric generator.

Rotor
First generation flywheel energy storage systems use a large steel flywheel rotating on mechanical bearings. Newer systems use carbon-fiber composite rotors that have a higher tensile strength than steel and are an order of magnitude lighter.

Bearings
Magnetic bearings are necessary; in conventional mechanical bearings, friction is directly proportional to speed, and at such speeds, too much energy would be lost to friction.

The expense of refrigeration led to the early dismissal of low temperature superconductors for use in magnetic bearings. High-temperature superconductor (HTSC) bearings however may be economical and could possibly extend the time energy could be stored economically. Hybrid bearing systems are most likely to see use first. HTSC bearings have historically had problems providing the lifting forces necessary for the larger designs, but can easily provide a stabilizing force. Therefore, in hybrid bearings, permanent magnets support the load and HTSC are used to stabilize it. The reason superconductors can work well stabilizing the load is because they are good diamagnets. In hybrid-bearing systems, a conventional magnet levitates the rotor, but the high temperature superconductor keeps it stable. If the rotor tries to drift off center, a restoring force due to flux pinning restores it. This is known as the magnetic stiffness of the bearing. Rotational axis vibration can occur due to low stiffness and damping, which are inherent problems of superconducting magnets, preventing the use of completely superconducting magnetic bearings for flywheel applications.

Since flux pinning is the important factor for providing the stabilizing and lifting force, the HTSC can be made much more easily for FES than for other uses. HTSC powders can be formed into arbitrary shapes so long as flux pinning is strong. An ongoing challenge that has to be overcome before superconductors can provide the full lifting force for a FES system is finding a way to suppress the decrease of levitation force and the gradual fall of rotor during operation caused by the flux creep of SC material.

Parasitic losses such as friction, hysteresis, and eddy currents of both magnetic and conventional bearings in addition to refrigerant costs can limit the economical energy storage time for flywheels. However, further improvements in superconductors may help eliminate eddy current losses in existing magnetic bearing designs as well as raise overall operating temperatures. Even without such improvements, however, modern flywheels can have a zero-load rundown time measurable in years. (The 'zero-load rundown time' measures how long it takes for the device to come to a standstill when it is not connected to any other devices.)

Physical characteristics
For the basic physics of a flywheel, see Flywheel#Physics.

Compared with other ways of storing electricity, FES systems have long lifetimes (lasting decades with little or no maintenance[2]; full-cycle lifetimes quoted for flywheels range from in excess of 105, up to 107)[3], high energy densities (~ 130 W·h/kg, or ~ 500 kJ/kg), and large maximum power outputs. The energy efficiency (ratio of energy out per energy in) of flywheels can be as high as 90%. Typical capacities range from 3 kWh to 133 kWh.[2] Rapid charging of a system occurs in less than 15 minutes.[4]

Applications

Transportation
In the 1950s flywheel-powered buses, known as gyrobuses, were used in Yverdon, Switzerland, and there is ongoing research to make flywheel systems that are smaller, lighter, cheaper, and have a greater capacity. It is hoped that flywheel systems can replace conventional chemical batteries for mobile applications, such as for electric vehicles. Proposed flywheel systems would eliminate many of the disadvantages of existing battery power systems, such as low capacity, long charge times, heavy weight, and short usable lifetimes. In Vancouver, BC, flywheels were used in buses to retain their electric power when disconnected from overhead lines [5]; they may also have been used in the experimental Chrysler Patriot, though that has been disputed [6].

Recently, there has been a new incentive to develop continuously variable transmissions (CVTs) for use in the new kinetic energy recovery systems (KERS) proposed for Formula One motor racing. (In 2009, F1 is introducing new rules that will lower the environmental impact of the sport. Part of this is to recover deceleration energy that can be stored for acceleration.)[1]

Flywheel systems have also been used experimentally in small electric locomotives for shunting or switching, e.g. the Sentinel-Oerlikon Gyro Locomotive. Larger electric locomotives, e.g. British Rail Class 70, have sometimes been fitted with flywheel boosters to carry them over gaps in the third rail. Advanced flywheels, such as the 133 kWh pack of the University of Texas at Austin, can take a train from a standing start up to cruising speed.[2]

Uninterruptible power supply
Flywheel power storage systems in current production (2001) have storage capacities comparable to batteries and faster discharge rates. They are mainly used to provide load leveling for large battery systems, such as an uninterruptible power supply and for maintaining power quality in renewable energy systems. Developers of such flywheel energy storage systems include Hitec Power Protection, Active Power, AFS Trinity, Beacon Power, Piller, Powercorp and Pentadyne.

Flywheel maintenance in general runs about one-half the cost of traditional battery UPS systems. The only maintenance is a basic annual preventive maintenance routine and replacing the bearings every three years, which takes about four hours.[4]

Laboratories
A long-standing niche market for flywheel power systems are facilities where circuit-breakers and similar devices are tested: even a small household circuit-breaker may be rated to interrupt a current of 10,000 or more amperes, and larger units may be have interrupting ratings of 100,000 or 1,000,000 amperes. Obviously the enormous transient loads produced by deliberately forcing such devices to demonstrate their ability to interrupt simulated short circuits would have unacceptable effects on the local grid if these tests were done directly off building power. So typically such a laboratory will have several large motor-generator sets, which can be spun-up to speed over some minutes; then the motor is disconnected before a circuit-breaker is tested. Other similar applications are in tokamak and laser experiments, where very high currents are also used for very brief intervals.

Amusement Ride
The Incredible Hulk roller coaster at Universal Studio's Islands of Adventure features a rapidly accelerating uphill launch as opposed to the typical gravity drop. This is achieved through powerful traction motors that throw the car up the track. To achieve the brief very high current required to accelerate a full coaster train to full speed uphill the park utilizes several motor generator sets with large flywheels. Without these stored energy units the park would have had to invest in a new substation and risked browning out the local energy grid every time the ride launched.

Pulse power
Since FES can store and release energy quickly, they have found a niche providing pulsed power (see compulsator).

Advantages and disadvantages
Flywheels are not affected by temperature changes as are chemical rechargeable batteries, nor do they suffer from memory effect. They are also less potentially damaging to the environment, being made of largely inert or benign materials. Another advantage of flywheels is that by a simple measurement of the rotation speed it is possible to know the exact amount of energy stored.

A magnetic bearing is a bearing which supports a load using magnetic levitation. Magnetic bearings support moving machinery without physical contact, for example, they can levitate a rotating shaft and permit relative motion without friction or wear. They are in service in such industrial applications as electric power generation, petroleum refining, machine tool operation and natural gas pipelines. They are also used in the Zippe-type centrifuge [1] used for uranium enrichment.

Description
It is difficult to build a magnetic bearing using permanent magnets due to the limitations imposed by Earnshaw's theorem, and techniques using diamagnetic materials are relatively undeveloped. As a result, most magnetic bearings require continuous power input and an active control system to hold the load stable. Because of this complexity, the magnetic bearings also typically require some kind of back-up bearing in case of power or control system failure.

However with the use of an induction based levitation system present in cutting edge MAGLEV technologies, magnetic bearings could do away with complex control systems by using Halbach Arrays and simple closed loop coils.

Basic Operation
Basic Operation for a Single AxisAn active magnetic bearing (AMB) consists of an electromagnet assembly, a set of power amplifiers which supply current to the electromagnets, a controller, and gap sensors with associated electronics to provide the feedback required to control the position of the rotor within the gap. These elements are shown in the diagram. The power amplifiers supply equal bias current to two pairs of electromagnets on opposite sides of a rotor. This constant tug-of-war is mediated by the controller which offsets the bias current by equal but opposite perturbations of current as the rotor deviates by a small amount from its center position.

The gap sensors are usually inductive in nature and sense in a differential mode. The power amplifiers in a modern commercial application are solid state devices which operate in a pulse width modulation (PWM) configuration. The controller is usually a microprocessor or DSP.

Applications
Magnetic bearing advantages include very low and predictable friction, ability to run without lubrication and in a vacuum. Magnetic bearings are increasingly used in industrial machines such as compressors, turbines, pumps, motors and generators. Magnetic bearings are commonly used in watt-hour meters by electric utilities to measure home power consumption. Magnetic bearings are also used in high-precision instruments and to support equipment in a vacuum, for example in flywheel energy storage systems.

Magnetic levitation transport, or maglev, is a form of transportation that suspends, guides and propels vehicles (especially trains) using electromagnetic force. This method can be faster than wheeled mass transit systems, potentially reaching velocities comparable to turboprop and jet aircraft (900 km/h, 600 mph). The highest recorded speed of a maglev train is 581 km/h (361 mph), achieved in Japan in 2003, which is 4 mph more than the conventional TGV speed record.

Maglev research in the 1960s in the United States was short-lived. In the 1970s, Germany and Japan began research and after some failures both nations developed mature technologies in the 1990s. While high-speed maglevs are expensive to build, they are less expensive to operate and maintain than traditional high-speed trains, planes or intercity buses.

Batteries.. Rechargeable
A rechargeable lithium polymer Nokia mobile phone battery.Main articles: Rechargeable battery and Battery charger
Also known as secondary batteries or accumulators. The National Electrical Manufacturers Association has estimated that U.S. demand for rechargeables is growing twice as fast as demand for non-rechargeables. There are a few main types:

Nickel-cadmium battery (NiCd): Best used for motorized equipment and other high-discharge, short-term devices. NiCd batteries can withstand even more drain than NiMH; however, the mAh rating is not high enough to keep a device running for very long, and the memory effect is far more severe.
Nickel-metal hydride battery (NiMH): Best used for high-tech devices. NiMH batteries can last up to four times longer than alkaline batteries because NiMH can withstand high current for a long while.[28]
Rechargeable alkaline battery: use similar chemistry to non-rechargeable alkaline batteries and best suited for similar applications, but hold their charge for years, unlike NiCd and NiMH batteries.

Flow batteries
Flow batteries are a special class of rechargeable battery where additional quantities of electrolyte are stored outside the main power cell of the battery, and circulated through it by pumps or by movement. Flow batteries can have extremely large capacities and are used in marine applications and are gaining popularity in grid energy storage applications.

Zinc-bromine and vanadium redox batteries are typical examples of commercially available flow batteries.

Homemade cells
Almost any liquid or moist object that has enough ions to be electrically conductive can serve as the electrolyte for a cell. As a novelty or science demonstration, it is possible to insert two electrodes made of different metals into a lemon, potato, et cetera and generate small amounts of electricity. "Two-potato clocks" are also widely available in hobby and toy stores; they consist of a pair of cells, each consisting of a potato (lemon, et cetera) with two electrodes inserted into it, wired in series to form a battery with enough voltage to power a digital clock. Homemade cells of this kind are of no real practical use, because they produce far less current—and cost far more per unit of energy generated—than commercial cells, due to the need for frequent replacement of the fruit or vegetable. In addition, one can make a voltaic pile from two coins (such as a nickel and a penny) and a piece of paper towel dipped in salt water. Such a pile would make very little voltage itself, but when many of them are stacked together in series, they can replace normal batteries for a short amount of time.

Sony has developed a biologically friendly battery that generates electricity from sugar in a way that's similar to what's found in living organisms. The battery generates electricity through the use of enzymes that break down carbohydrates, which are essentially sugar.

An electrochemical cell in which the energy of a reaction between a fuel, such as liquid hydrogen, and an oxidant, such as liquid oxygen, is converted directly and continuously into electrical energy.

Functioning similar to a battery, which uses electrochemical conversion, fuel cells take in hydrogen-rich fuel and oxygen and turn them into electricity and heat. The waste product is water. The hydrogen can be derived from gasoline, natural gas, propane or methanol.

The hydrogen, which comes into the anode side of the fuel cell, is converted into electrons and hydrogen ions. The electrons are repelled by the anode and flow to the cathode. The cathode accepts the electrons as well as oxygen, which combine with the hydrogen ions from the anode, and converts them into water.

Some predict this will be the largest, new industry of the 21st century, although there are many obstacles to overcome. It depends on which sources for hydrogen ultimately make sense. Currently, Ballard Power Systems, Inc., Burnaby, British Columbia www.ballard.com.is the largest company making fuel cells.

The term alternative propulsion or "alternate methods of propulsion" includes both

alternative fuels used in standard or modified internal combustion engines (e.g. combustion hydrogen).
alternative propulsion systems, that is to say, those not based on internal combustion, such as those based on electricity (for example, electric or hybrid vehicles) , compressed air, or fuel cells (e.g. hydrogen fuel cells). Under certain conditions they can be more efficient than petroleum propulsion.

A motorised bicycle is a bicycle with an attached motor used to assist with pedalling. Generally considered to be a vehicle, sometimes as a motor vehicle or a class of hybrid vehicle, motorized bicycles are usually powered by electric motors or small internal combustion engines. Some can be propelled by the motor alone if the rider chooses not to pedal, while in others the motor will only run if the rider pedals. Different regulatory authorities use a variety of names and classifications.[3]

Some early motorized bicycles were powered by internal combustion engines whereas some utilized electric motors. With lighter batteries and better storage density, the electric motor has recently seen an increase in popularity.

Motorized bicycles are distinguished from motorcycles by being capable of being powered by pedals alone if required. The actual usage of the pedals varies widely according to the type of vehicle. Those known as mopeds mostly have pedals for emergency use or because of legal requirements and these are not normally used. Those known as power-assist bikes have the pedals as the main form of propulsion with the motor used to give a bit of extra speed, especially uphill. Many motorized bicycles are based on standard bicycle frame designs and technologies, although the modifications to the design to support motorization may be extensive.

In countries where there is a strong bicycle culture (notably in Asia), the motorized bicycle is particularly popular; in 1996 Shanghai had 370,000 motorized bicycles and 470,000 other vehicles.

A low-energy vehicle is any type of vehicle that uses less energy than a regular vehicle. The higher efficiency is achieved by a different vehicle design not only power train modifications. The biggest influence on the efficiency however is not the engineering quality but the vehicle specification (top speed, safety reserves, load capacity...)

A hydrogen vehicle is a vehicle that uses hydrogen as its on-board fuel for motive power. The term may refer to a personal transportation vehicle, such as an automobile, or any other vehicle that use hydrogen in a similar fashion, such as an aircraft. The power plants of such vehicles convert the chemical energy of hydrogen to mechanical energy (torque) in one of two methods: electrochemical conversion in a fuel-cell, or combustion :

In combustion, the hydrogen is burned in engines in fundamentally the same method as traditional gasoline cars.
In fuel-cell conversion, the hydrogen is reacted with oxygen to produce water and electricity, the latter of which is used to power an electric traction motor.
The molecular hydrogen needed as an on-board fuel for hydrogen vehicles can be obtained through various thermochemical methods utilizing natural gas, coal (by a process known as coal gasification), liquefied petroleum gas, biomass (biomass gasification), by a process called thermolysis, or as a microbial waste product called biohydrogen or Biological hydrogen production. Hydrogen can also be produced from water by electrolysis. If the electricity used for the electrolysis is produced using renewable energy, the production of the hydrogen would (in principle) result in no net carbon dioxide emissions.

BEVs (battery electric vehicle) were among the earliest automobiles, and are more energy-efficient than internal combustion, fuel cell, and most other types of vehicles.

BEVs produce no exhaust fumes, and minimal pollution if charged from most forms of renewable energy. Many are capable of acceleration exceeding that of conventional vehicles, are quiet, and do not produce noxious fumes. For equivalent production volumes battery EVs should be cheaper than internal combustion engine vehicles because they have many fewer parts. This also means they are cheaper to maintain. They are less expensive to operate by a factor of ten over gasoline. Using regenerative braking, a feature which is standard on electric cars, allows hybrids to get about double the fuel efficiency of regular cars. In general terms a battery electric vehicle is a rechargeable electric vehicle. Other examples of rechargeable electric vehicles are ones that store electricity in ultracapacitors, or in a flywheel.

Electric vehicles can also utilize a direct motor-to-wheel configuration which increases the amount of available power. Having multiple motors connected directly to the wheels allows for each of the wheels to be used for both propulsion and as braking systems, thereby increasing traction. In some cases, the motor can be housed directly in the wheel, such as in the Whispering Wheel design, which lowers the vehicle's center of gravity and reduces the number of moving parts. When not fitted with an axle, differential, or transmission, electric vehicles have less drivetrain rotational inertia.

A gearless or single gear design in some BEVs eliminates the need for gear shifting, giving such vehicles both smoother acceleration and smoother braking. Because the torque of an electric motor is a function of current, not rotational speed, electric vehicles have a high torque over a larger range of speeds during acceleration, as compared to an internal combustion engine. As there is no delay in developing torque in an EV, EV drivers report generally high satisfaction with acceleration.

A plug-in hybrid electric vehicle (PHEV) is a hybrid vehicle with batteries that can be recharged by connecting a plug to an electric power source. It shares the characteristics of both conventional hybrid electric vehicles, having an electric motor and a backup internal combustion engine (ICE) for power, and of battery electric vehicles, also having a plug to connect to the electric grid. Most PHEVs on the road today are passenger cars, but there are also PHEV versions of commercial passenger vans, utility trucks, school buses, motorcycles, scooters, and military vehicles. PHEVs are sometimes called grid-connected hybrids, gas-optional hybrids, or GO-HEVs.

The cost for electricity to power plug-in hybrids for all-electric operation has been estimated at less than one quarter of the cost of gasoline.[1] Compared to conventional vehicles, PHEVs can reduce air pollution and dependence on petroleum, and lessen greenhouse gas emissions that contribute to global warming. Plug-in hybrids use no fossil fuel during their all-electric range if their batteries are charged from nuclear or renewable energy sources. Other benefits include improved national energy security, fewer fill-ups at the filling station, the convenience of home recharging, opportunities to provide emergency backup power in the home, and vehicle to grid applications.

Hydrogen is now being researched as a fuel for vehicles because of its abundance and its ability to be regenerated. The burning of hydrogen fuel also produces no polluting emissions which makes it very environmentally friendly. BMW has been the leader in consistent research to develop cars that use hydrogen. Hydrogen can be used in fuel cells that produce electricity to power the vehicle or in combustion engines. BMW has developed a bivalent internal combustion engine that can switch between petroleum and liquid hydrogen fuels. Liquid hydrogen has almost three times as much energy as gasoline in terms of density per unit volume. The liquid hydrogen can be produced in many different ways but many of these methods produce carbon dioxide in the process. The most promising method of hydrogen production is through a process known as electrolysis. There are two fuel tanks in the vehicle and it can run on either type of fuel if one is not available. Safety of the hydrogen storage tanks has been investigated in the event of an accident and various tests show that the storage tanks used do not present any problems.[1] The engine itself is similar to a regular gasoline combustion engine with an exception to the fuel injection system. As seen in BMW's Hydrogen 7, when the vehicle is running in gasoline mode the fuel is injected directly into the cylinders, and when the vehicle is running on hydrogen the fuel is injected into the intake manifold. Hydrogen when used as a fuel has a wide range of flammability, and has a low ignition energy. These properties allow hydrogen to be combusted over a wide range of air-fuel mixtures

The hydrogen economy is a proposed method of deriving the energy needed for motive power (cars, boats, airplanes), buildings or portable electronics, by reacting hydrogen (H2) with oxygen, the hydrogen having been generated by a number of possible methods, including the electrolysis of water. If the energy used to split the water were obtained from renewable or nuclear power sources, and not from burning carbon-based fossil fuels, a hydrogen economy would greatly reduce the emissions. Countries without oil, but with renewable energy resources, could use a combination of renewable energy and hydrogen instead of fuels derived from petroleum, to achieve energy independence.

In the context of a hydrogen economy, hydrogen is an energy carrier, not a primary energy source (see nuclear fusion for an entirely separate discussion of using hydrogen isotopes as an atomic energy source). Nevertheless, controversy over the usefulness of a hydrogen economy has been confused by issues of energy sourcing, including fossil fuel use, acid rain, and sustainable energy generation. These are all separate issues, although the hydrogen economy affects them all.

Proponents of a world-scale hydrogen economy show that hydrogen can be an environmentally cleaner source of energy to end-users, particularly in transportation applications, without release of pollutants (such as particulate matter) or greenhouse gases at the point of end use. Analyses have concluded that "most of the hydrogen supply chain pathways would release significantly less carbon dioxide into the atmosphere than would gasoline used in hybrid electric vehicles" and that significant reductions in carbon dioxide emissions would be possible if carbon capture or carbon sequestration methods were utilized at the site of energy or hydrogen production.

Hydrogen has a high energy density by weight. The fuel cell is also more efficient than an internal combustion engine . The internal combustion engine is said to be 20–30% efficient, while the fuel cell is 2-3 times more efficient than an internal combustion engine depending on the fuel cell.

One of the main offerings of a hydrogen economy is that fuel cells can replace internal combustion engines and turbines as the primary way to convert chemical energy into kinetic or electrical energy. The reason to expect this changeover is that fuel cells, being electrochemical, are usually (and theoretically) more efficient than heat engines. Currently, fuel cells are more expensive to produce than common internal combustion engines, but are becoming cheaper as new technologies and production systems develop.

Some types of fuel cells work with hydrocarbon fuels while all can be operated on pure hydrogen. In the event that fuel cells become price-competitive with internal combustion engines and turbines, large gas-fired power plants could adopt this technology. Such commercialization would be an important step in driving down the cost of fuel cell technology.

Much of the interest in the hydrogen economy concept is focused on the use of fuel cells in cars. The cells can have a superior power-to-weight ratio, are much more efficient than internal combustion engines, and produce no harmful emissions. If a practical and engineer-able method to store and carry hydrogen is introduced and fuel cells become cheaper, they can be economically viable to power hybrid fuel cell/battery vehicles, or purely fuel cell-driven ones. The economic viability of fuel cell powered vehicles will improve as the hydrocarbon fuels used in internal combustion engines become more expensive, due to the depletion of easily accessible reserves or economic accounting of environmental impact through such measures as carbon taxes.

In a future (full) hydrogen economy, primary energy sources and feedstock would be used to produce hydrogen gas as stored energy for use in various sectors of the economy. Producing hydrogen from primary energy sources other than coal, oil, and natural gas, would result in lower production of the greenhouse gases characteristic of the combustion of these fossil energy resources.

One key feature of a hydrogen economy is that in mobile applications (primarily vehicular transport) energy generation and use is decoupled. The primary energy source need no longer travel with the vehicle, as it currently does with hydrocarbon fuels. Instead of tailpipes creating dispersed emissions, the energy (and pollution) can be generated from point sources such as large-scale, centralized facilities with improved efficiency. This allows the possibility of technologies such as carbon sequestration, which are otherwise impossible for mobile applications. Alternatively, distributed energy generation schemes (such as small scale renewable energy sources) can be used, possibly associated with hydrogen stations.

Aside from the energy generation, hydrogen production could be centralized, distributed or a mixture of both. While generating hydrogen at centralized primary energy plants promises higher hydrogen production efficiency, difficulties in high-volume, long range hydrogen transportation (due to factors such as hydrogen damage and the ease of hydrogen diffusion through solid materials) makes electrical energy distribution attractive within a hydrogen economy. In such a scenario, small regional plants or even local filling stations could generate hydrogen using energy provided through the electrical distribution grid. While hydrogen generation efficiency is likely to be lower than for centralized hydrogen generation, losses in hydrogen transport can make such a scheme more efficient in terms of the primary energy used per kilogram of hydrogen delivered to the end user.

The proper balance between hydrogen distribution and long-distance electrical distribution is one of the primary questions that arises in the hydrogen economy.

Again the dilemas of production sources and transportation of hydrogen can now be overcome using on site (home, business, or fuel station) generation of hydrogen from off grid renewable sources. This clean fuel could make obsolete our big-scale, polluting oil network through a locally based system. The first thing to keep in mind is that with distributed generation, every family, business, neighborhood and community is potentially consumer, producer and vendor of hydrogen and electricity. Because fuel cells are located physically at the sites where the hydrogen and electricity are going to be produced and partially consumed, with surplus hydrogen sold as fuel and surplus electricity sent back onto the energy network, the ability to aggregate large numbers of producer/users into associations is critical to energy empowerment and the advancing of the vision of democratic energy.

Empowering people and democratizing energy will require that public institutions and nonprofit organizations—local governments, cooperatives, community development corporations, credit unions and the like—jump in at the beginning of the new energy revolution and help establish distributed generation associations in every country.

Eventually, the end users’ combined generating power via the energy web will exceed the power generated by the utility companies at their own central plants. When that happens, it will constitute a revolution in the way energy is produced and distributed. Once the customer, the end user, becomes the producer and supplier of energy, power companies around the world will be forced to redefine their role if they are to survive.

Hydrogen storage is the main technological problem of a viable hydrogen economy. Some attention has been given to the role of hydrogen to provide grid energy storage for unpredictable energy sources, like wind power, but most research into hydrogen storage is focused on storing hydrogen in a lightweight, compact manner for mobile applications.

Ammonia storage
Ammonia (NH3) can be used to store hydrogen chemically and then release it in a catalytic reformer. Ammonia provides exceptionally high hydrogen storage densities as a liquid with mild pressurization and cryogenic constraints. It can also be stored as a liquid at room temperature and pressure when mixed with water. Ammonia is the second most commonly produced chemical in the world and a large infrastructure for making, transporting and distributing ammonia already exists. Ammonia can be reformed to produce hydrogen with no harmful waste, or can mix with existing fuels and burn efficiently. Pure ammonia burns poorly at the atmospheric pressures found in natural gas fired water heaters and stoves. Under compression in an automobile engine it is a suitable fuel for slightly modified gasoline engines.

Iceland is embarking on a radical plan to abolish the burning of fossil fuels altogether - by transforming itself into the world's first "hydrogen economy". It aims to run all its transport and even its huge fishing fleet on hydrogen produced in Iceland itself.

Iceland has a driving ambition, to run these and every vehicle on its roads with clean hydrogen fuel. In Iceland's bubbling volcanic landscape, what once sounded like a science fiction fantasy is now taking shape. Iceland is full of natural energy and by harnessing these resources, its waterfalls and hot springs, it wants to become the world's first hydrogen economy.

Over the next 30 years, it aims to do away with polluting fossil fuels like petrol and diesel altogether and replace them with what could be the cleanest fuel on earth. .

To make hydrogen you need water and electricity. Iceland has plenty of water. It can also produce electricity cheaply and cleanly, hydropower from its glacial rivers and waterfalls. From its craters and crevices, huge stores of underground heat. Only 5% of geothermal power has been tapped so far. One day, Iceland thinks it could use it to provide enough green electricity to make hydrogen for itself and to export to other parts of the world.

Sustainable energy sources are energy sources which are not expected to be depleted in a timeframe relevant to the human race, and which therefore contribute to the sustainability of all species. This concept is termed sustainability. An additional criterion for strict sustainability, useful for short- and medium-term decisions is social and political sustainability of an energy technology.

Sustainable energy sources are most often regarded as including all renewable sources, such as solar power, wind power, wave power, geothermal power, tidal power, and others. Renewable energy resources are cleaner and far more abundant than fossil resources, however, they tend to be dispersed and so are usually more expensive to collect. Many of them, such as wind and solar energy, are intermittent in nature, making energy storage or distributed production systems necessary. Therefore, currently the direct cost of renewable energy is generally higher than the direct cost of fossil fuels. At the same time, fossil fuels have very significant indirect or external costs, such as pollution, acid rain, and global warming. On the other hand renewable energy systems start to pay back a surplus into the general economy and in the long run they are money producers!

Mostly thanks to the Sun, the world also has a renewable usable energy flux that exceeds 120 PW (8,000 times 2004 total usage), or 3.8 YJ/yr, dwarfing all non-renewable resources. Even that amount is also only a minute amount of the sun's total energy output, due to the small solid angle the earth's outline makes with the sun.

Since ancient times solar energy has been harnessed for human use through a range of technologies. Solar radiation along with secondary solar resources such as wind and wave power, hydroelectricity and biomass account for most of the available flow of renewable energy on Earth.

Solar energy technologies can provide electrical generation by heat engine or photovoltaic means, day lighting and space heating in passive solar and active solar buildings, potable water via distillation and disinfection, hot water, space cooling by absorption or vapor-compression refrigeration, thermal energy for cooking, and high temperature process heat for industrial purposes.

Solar technologies are broadly characterized as either passive or active depending on the way they capture, convert and distribute sunlight. Active solar techniques use photovoltaic panels, pumps, and fans to convert sunlight into useful outputs. Passive solar techniques include selecting materials with favorable thermal properties, designing spaces that naturally circulate air, and referencing the position of a building to the Sun. Active solar technologies increase the supply of energy

The common features of passive solar architecture are orientation relative to the Sun, compact proportion (a low surface area to volume ratio), selective shading (overhangs) and thermal mass. When these features are tailored to the local climate and environment they can produce well-lit spaces that stay in a comfortable temperature range. The most recent approaches to solar design use computer modeling tying together solar lighting, heating and ventilation systems in an integrated solar design package. Active solar equipment such as pumps, fans and switchable windows can complement passive design and improve system performance.

Day lighting systems collect and distribute sunlight to provide interior illumination. This passive technology directly offsets energy use by replacing artificial lighting, and indirectly offsets non-solar energy use by reducing the need for air-conditioning Although difficult to quantify, the use of natural lighting also offers physiological and psychological benefits compared to artificial lighting.[

Solar hot water systems use sunlight to heat water. In low geographical latitudes (below 40 degrees) from 70 to 80% of the domestic hot water use with temperatures up to 60 °C can be provided by solar heating systems

The earliest significant application of solar cells was as a back-up power source to the Vanguard I satellite, which allowed it to continue transmitting for over a year after its chemical battery was exhausted.The successful operation of solar cells on this mission was duplicated in many other Soviet and American satellites, and by the late 1960s, PV had become the established source of power for them. Photovoltaics went on to play an essential part in the success of early commercial satellites such as Telstar, and they remain vital to the telecommunications infrastructure today.

The high cost of solar cells limited terrestrial uses throughout the 1960s. This changed in the early 1970s when prices reached levels that made PV generation competitive in remote areas without grid access. Early terrestrial uses included powering telecommunication stations, off-shore oil rigs, navigational buoys and railroad crossings. These off-grid applications have proven very successful

Solar shingles (or photovoltaic shingles) are a new type of solar energy system that, at first glance, look like regular asphalt shingles but are actually photovoltaic cells (PV). They are manufactured by only a few companies worldwide including SunPower Corporation, United Solar Ovonics (Uni-Solar) and Atlantis Energy Systems.

A solar chimney — often referred to as a thermal chimney — is a way of improving the natural ventilation of buildings by using convection of air heated by passive solar energy. A simple description of a solar chimney is that of a vertical shaft utilizing solar energy to enhance the natural stack ventilation through a building. The solar chimney has been in use for centuries, particularly in the Middle east, as well as by the Romans. Solar chimney and sustainable architecture
This solar chimney draws air through a geothermal heat exchange to provide passive home cooling.[2]Air conditioning and mechanical ventilation have been for decades the standard method of environmental control in many building types especially offices. Global warming, pollution and dwindling energy supplies have lead to a new environmental approach in building design. Innovative technologies along with bioclimatic principles and traditional design strategies are often combined to create new and potentially successful design solutions. The solar chimney is one of these concepts currently explored by scientists as well as designers, mostly through research and experimentation.

A Solar chimney can serve many purposes. Direct gain warms air inside the chimney causing it to rise out the top and drawing air in from the bottom. This drawing of air can be used to ventilate a home or office, to draw air through a geothermal heat exchange, or to ventilate only a specific area such as a composting toilet.

Natural ventilation can be created by providing vents in the upper level of a building to allow warm air to rise by convection and escape to the outside. At the same time cooler air can be drawn in through vents at the lower level. Trees may be planted on that side of the building to provide shade for cooler outside air.

This natural ventilation process can be augmented by a solar chimney. The chimney has to be higher than the roof level, and has to be constructed on the wall facing the direction of the sun. Absorption of heat from the sun can be increased by using a glazed surface on the side facing the sun. Heat absorbing material can be used on the opposing side. The size of the heat-absorbing surface is more important than the diameter of the chimney. A large surface area allows for more effective heat exchange with the air necessary for heating by solar radiation. Heating of the air within the chimney will enhance convection, and hence airflow through the chimney. Openings of the vents in the chimney should face away from the direction of the prevailing wind.

To further maximize the cooling effect, the incoming air may be led through underground ducts before it is allowed to enter the building. The solar chimney can be improved by integrating it with a trombe wall. The added advantage of this design is that the system may be reversed during the cold season, providing solar heating instead.

A variation of the solar chimney concept is the solar attic. In a hot sunny climate the attic space is often blazingly hot in the summer. In a conventional building this presents a problem as it leads to the need for increased air conditioning. By integrating the attic space with a solar chimney, the hot air in the attic can be put to work. It can help the convection in the chimney, improving ventilation

A solar updraft tower (also known as a solar chimney or solar tower) consists of a large greenhouse that funnels into a central tower. As sunlight shines on the greenhouse, the air inside is heated, and expands. The expanding air flows toward the central tower, where a turbine converts the air flow into electricity. A 50 kW prototype was constructed in Ciudad Real, Spain and operated for eight years before decommissioning in 1989

A solar pond is a pool of salt water (usually 1–2 m deep) that collects and stores solar energy. Solar ponds were first proposed by Dr. Rudolph Bloch in 1948 after he came across reports of a lake in Hungary in which the temperature increased with depth. This effect was due to salts in the lake's water, which created a "density gradient" that prevented convection currents. A prototype was constructed in 1958 on the shores of the Dead Sea near Jerusalem. The pond consisted of layers of water that successively increased from a weak salt solution at the top to a high salt solution at the bottom. This solar pond was capable of producing temperatures of 90 °C in its bottom layer.

Thermoelectric, or "thermovoltaic" devices convert a temperature difference between dissimilar materials into an electric current. First proposed as a method to store solar energy by solar pioneer Mouchout in the 1800s, thermoelectrics reemerged in the Soviet Union during the 1930s. Under the direction of Soviet scientist Abram Ioffe a concentrating system was used to thermoelectrically generate power for a 1 hp engine. Thermogenerators were later used in the US space program as an energy conversion technology for powering deep space missions such as Cassini, Galileo and Viking. Research in this area is focused on raising the efficiency of these devices from 10% to 20%.

Solar chemical
Main article: Solar chemical
Solar chemical processes use solar energy to drive chemical reactions. These processes offset energy that would otherwise come from an alternate source and can convert solar energy into storable and transportable fuels. Solar induced chemical reactions can be divided into thermochemical or photochemical.

Hydrogen production technologies been a significant area of solar chemical research since the 1970s. Aside from electrolysis driven by photovoltaic or photochemical cells, several thermochemical processes have also been explored. One such route uses concentrators to split water into oxygen and hydrogen at high temperatures (2300-2600 °C). Another approach uses the heat from solar concentrators to drive the steam reformation of natural gas thereby increasing the overall hydrogen yield compared to conventional reforming methods. Thermochemical cycles characterized by the decomposition and regeneration of reactants present another avenue for hydrogen production. The Solzinc process under development at the Weizmann Institute uses a 1 MW solar furnace to decompose zinc oxide (ZnO) at temperatures above 1200 °C. This initial reaction produces pure zinc, which can subsequently be reacted with water to produce hydrogen.

Sandia's Sunshine to Petrol (S2P) technology uses the high temperatures generated by concentrating sunlight along with a zirconia/ferrite catalyst to break down atmospheric carbon dioxide into oxygen and carbon monoxide (CO). The carbon monoxide can then be used to synthesize conventional fuels such as methanol, gasoline and jet fuel.

A photogalvanic device is a type of battery in which the cell solution (or equivalent) forms energy-rich chemical intermediates when illuminated. These energy-rich intermediates can potentially be stored and subsequently reacted at the electrodes to produce an electric potential. The ferric-thionine chemical cell is an example of this technology.

Photoelectrochemical cells or PECs consist of a semiconductor, typically titanium dioxide or related titanates, immersed in an electrolyte. When the semiconductor is illuminated an electrical potential develops. There are two types of photoelectrochemical cells: photoelectric cells that convert light into electricity and photochemical cells that use light to drive chemical reactions such as electrolysis.

Solar vehicle, Electric boat, and Solar balloon

Australia hosts the World Solar Challenge where solar cars like the Nuna3 race through a 3,021 km (1,877 mi) course from Darwin to Adelaide. Development of a solar powered car has been an engineering goal since the 1980s. The World Solar Challenge is a biannual solar-powered car race, where teams from universities and enterprises compete over 3,021 kilometres (1,877 mi) across central Australia from Darwin to Adelaide. In 1987, when it was founded, the winner's average speed was 67 kilometres per hour (42 mph) and by 2007 the winner's average speed had improved to 90.87 kilometres per hour (56.46 mph).[108] The North American Solar Challenge and the planned South African Solar Challenge are comparable competitions that reflect an international interest in the engineering and development of solar powered vehicles.

Some vehicles use solar panels for auxiliary power, such as for air conditioning, to keep the interior cool, thus reducing fuel consumption.

In 1975, the first practical solar boat was constructed in England. By 1995, passenger boats incorporating PV panels began appearing and are now used extensively.In 1996, Kenichi Horie made the first solar powered crossing of the Pacific Ocean, and the sun21 catamaran made the first solar powered crossing of the Atlantic Ocean in the winter of 2006–2007.There are plans to circumnavigate the globe in 2010.

Helios UAV in solar powered flightI n 1974, the unmanned Sunrise II plane made the first solar flight. On 29 April 1979, the Solar Riser made the first flight in a solar powered, fully controlled, man carrying flying machine, reaching an altitude of 40 feet (12 m). In 1980, the Gossamer Penguin made the first piloted flights powered solely by photovoltaics. This was quickly followed by the Solar Challenger which crossed the English Channel in July 1981. In 1990 Eric Raymond in 21 hops flew from California to North Carolina using solar power. Developments then turned back to unmanned aerial vehicles (UAV) with the Pathfinder (1997) and subsequent designs, culminating in the Helios which set the altitude record for a non-rocket-propelled aircraft at 29,524 metres (96,860 ft) in 2001. The Zephyr, developed by BAE Systems, is the latest in a line of record-breaking solar aircraft, making a 54-hour flight in 2007, and month-long flights are envisioned by 2010.

A solar balloon is a black balloon that is filled with ordinary air. As sunlight shines on the balloon, the air inside is heated and expands causing an upward buoyancy force, much like an artificially-heated hot air balloon. Some solar balloons are large enough for human flight, but usage is generally limited to the toy market as the surface-area to payload-weight ratio is relatively high.

Solar sails are a proposed form of spacecraft propulsion using large membrane mirrors to exploit radiation pressure from the Sun. Unlike rockets, solar sails require no fuel. Although the thrust is small compared to rockets, it continues as long as the Sun shines onto the deployed sail and in the vacuum of space significant speeds can eventually be achieved.

The High-altitude airship (HAA) is an unmanned, long-duration, lighter-than-air vehicle using helium gas for lift, and thin-film solar cells for power. The United States Department of Defense Missile Defense Agency has contracted Lockheed Martin to construct it to enhance the Ballistic Missile Defense System (BMDS).Airships have some advantages for solar-powered flight: they do not require power to remain aloft, and an airship's envelope presents a large area to the Sun.

Energy storage methods
Main articles: Thermal mass, Thermal energy storage, Phase change material, Grid energy storage, and V2G

Solar Two's thermal storage system generated electricity during cloudy weather and at night. Storage is an important issue in the development of solar energy because modern energy systems usually assume continuous availability of energy. Solar energy is not available at night, and the performance of solar power systems is affected by unpredictable weather patterns; therefore, storage media or back-up power systems must be used.

Thermal mass systems can store solar energy in the form of heat at domestically useful temperatures for daily or seasonal durations. Thermal storage systems generally use readily available materials with high specific heat capacities such as water, earth and stone. Well-designed systems can lower peak demand, shift time-of-use to off-peak hours and reduce overall heating and cooling requirements.

Phase change materials such as paraffin wax and Glauber's salt are another thermal storage media. These materials are inexpensive, readily available, and can deliver domestically useful temperatures (approximately 64 °C). The "Dover House" (in Dover, Massachusetts) was the first to use a Glauber's salt heating system, in 1948.

Solar energy can be stored at high temperatures using molten salts. Salts are an effective storage medium because they are low-cost, have a high specific heat capacity and can deliver heat at temperatures compatible with conventional power systems. The Solar Two used this method of energy storage, allowing it to store 1.44 TJ in its 68 m³ storage tank with an annual storage efficiency of about 99%.

Off-grid PV systems have traditionally used rechargeable batteries to store excess electricity. With grid-tied systems, excess electricity can be sent to the transmission grid. Net metering programs give these systems a credit for the electricity they deliver to the grid. This credit offsets electricity provided from the grid when the system cannot meet demand, effectively using the grid as a storage mechanism.

Pumped-storage hydroelectricity stores energy in the form of water pumped when energy is available from a lower elevation reservoir to a higher elevation one. The energy is recovered when demand is high by releasing the water to run through a hydroelectric power generator

Compressed Air Energy Storage (CAES) refers to the compression of air to be used later as energy source. At utility scale, it can be stored during periods of low energy demand (off-peak), for use in meeting periods of higher demand (peak load). Alternatively it can be used to power tools, or even vehicles. Compressed air energy storage can be done adiabatically, diabatically, or isothermally:

With Adiabatic storage, the heat that appears during compression is also stored, then returned to the air when the air is expanded. This is a subject of ongoing study, but no utility scale plants of this type have been built. The theoretical efficiency of adiabatic energy storage approaches 100% for large and/or rapidly cycled devices and/or perfect thermal insulation, but in practice round trip efficiency is expected to be 70%[1]. Heat can be stored in a solid such as concrete or stone, or more likely in a fluid such as hot oil (up to 300C) or a molten-salt (600C).
With Diabatic storage, the extra heat is removed from the air with inter coolers following compression (thus approaching isothermal compression), and is dissipated into the atmosphere as waste. Upon removal from storage, the air must be re-heated (usually in a natural gas fired burner for utility grade storage or with a heated metal mass for large Uninterruptible Power Supplies) prior to expansion in the turbine to power a generator. The heat discarded in the intercoolers degrades efficiency, but the system is simpler than the adiabatic one, and thus far is the only system which has been implemented commercially. The McIntosh CAES plant requires 0.69kWh of electricity and 1.17kWh of gas for each 1.0kWh of electrical output [1](a non-CAES natural gas plant can be up to 60% efficient therefore uses 1.67kWh of gas per kWh generated).
Isothermal compression and expansion (which attempts constant temperature operation by constant heat exchange to the environment) approaches is only practical for rather low power levels, unless very effective heat exchangers can be incorporated. The theoretical efficiency of isothermal energy storage approaches 100% for small and/or slowly cycled devices and/or perfect heat transfer to the environment.
In practice neither of these perfect thermodynamic cycles are obtainable, as some heat losses are unavoidable.

A highly efficient arrangement, which fits neatly into none of the above categories, uses high, medium and low pressure pistons in series, with each stage followed by an airblast venturi that draws ambient air (or seawater as in early compressed air torpedo designs) over an air-to-air (or air-to-seawater) heat exchanger between each expansion stage. This warms the exhaust of the preceding stage and admits this preheated air to the following stage. This practice was widely practiced on various compressed air vehicles such as H. K. Porter, Inc in mining locomotives (see CHARLES HODGES AND THE PORTER COMPOUND AIR LOCOMOTIVES ) and trams.

Here the heat of compression is effectively stored in the atmosphere (or sea) and returned later on, but interestingly it is not not the "same" heat.

Compression can be done with electrically powered turbo-compressors, expansion with turbo 'expanders' driving electrical generators or air engines (generator) to produce electricity. Air is stored in mass quantity in underground in a cavern created by solution mining (salt is dissolved away) or an abandoned mine. Plants are designed to operate on a daily cycle, charging at night and discharging during the day.

Compressed air energy storage can also be used to describe technology on a smaller scale such as exploited by air cars or wind farms in steel or carbon-fiber tanks.

An air engine or air motor is a device for converting potential energy from compressed air into kinetic energy to drive other machines. As in a steam engine, expansion of externally supplied pressurized gas performs work against one or more pistons or rotors to move wheels or other tools.

The most recent development uses pressurized air as fuel in an engine invented by Guy Nègre, a French engineer. A similar concept is currently being developed by Uruguayan engineer Armando Regusci, Australian Angelo Di Pietro, South Korea Chul-Seung Cho, and more recently, Kernelys' K'Airmobiles Compressed air vehicles. Despite interest in the technology, no company has yet put a vehicle using this technology into mass production. A successful vehicle would offer many of the advantages of a battery electric vehicle without the need for heavy and potentially toxic batteries, which take hours to recharge instead of the few minutes required to refill the tanks for an air engine.

History
The air engine and its idea of using air as an energy carrier is not new. Air has been used since the 19th century to power mine locomotives, and has been the basis of naval torpedo propulsion since 1866. Compressed air is still currently used in racecars to provide the initial energy needed to start the car's main power plant, the internal combustion engine (ICE).

In 1991 the inventor Guy Nègre started MDI, and invented a dual-energy engine, capable of running on both compressed air and regular fuel. From this moment on he managed to create a compressed air only-engine, and improved his design to make it more powerful. In the 15 years he's been working on this engine, considerable progress has been made: the engine is now claimed to be competitive with modern ICEs. It is probably still not as powerful as an ICE (although depending on which model of air engine vs model ICE). Proponents claim that this is of little importance since the car can simply be made lighter, or the tanks be put on a higher pressure, pushing the engine to above a comparable ICE-engine.

Other people that have been working on the idea of compressed air vehicles, among them Armando Regusci, Angelo Di Pietro, Tony Salvino, and Chul-Seung Cho. They too have companies, Regusci's RegusciAir, Di Pietro's EngineAir and Chul-Seung Cho's Energine, selling their engines. Tony Salvino, however is a high school student who is pursuing a more efficient engine.

In 2008 Tata Motors plan on producing CityCAT that is powered by an air engine.

Also since 2007, K'Airmobiles looks at commercialing some urban and leisure VPP vehicles (Vehicles with Pneumatic Propulsion) and tries to gain partnerships and sponsors. Their goals appears to be individual transport and taxi-bikes as the projects proposed on the site are mainly made of a motor-bike and trikes (with 1 to 3 seats).

Engine design
It uses the expansion of compressed air to drive the pistons in a modified piston engine. Efficiency of operation is gained through the use of environmental heat at normal temperature to warm the otherwise cold expanded air from the storage tank. This non-adiabatic expansion has the potential to greatly increase the efficiency of the machine. The only exhaust gas is cold air (−15 °C), which may also be used for air conditioning in a car. The source for air is a pressurized carbon-fiber tank holding air at around 20 MPa (3,000 psi, 200 bar). Air is delivered to the engine via a rather conventional injection system. Unique crank design within the engine increases the time during which the air charge is warmed from ambient sources and a two stage process allows improved heat transfer rates.

Armando Regusci's version of the air engine has several advantages over the original Nègre design. In the original Nègre air engine, one piston compresses air from the atmosphere, holding it on a small container that feeds the high pressure air tanks with a small amount of air. Then that portion of the air is sent to the second piston where it works. During compression for heating it up, there is a loss of energy due to the fact that it cannot receive energy from the atmosphere as the atmosphere is less warm than it. Also, it has to expand as it has the crank. Nègre's engine works with constant torque, and the only way to change the torque to the wheels is to use a pulley transmission of constant variation, losing some efficiency. In Regusci's version, the transmission system is direct to the wheel, and has variable torque from zero to the maximum, enhancing efficiency. When vehicle is stopped, Guy Nègre's engine has to be on and working, losing energy, while the Regusci's version need not.

The principle advantages for an air powered vehicle are:

Fast recharge time
Very low self-discharge (most batteries will deplete their charge without external load at a rate determined by the chemistry, design, and size, while compressed gas storage will have an extremely low leakage rate)
Long storage lifetime device (electric vehicle batteries have a limited useful number of cycles, and sometimes a limited calendar lifetime, irrespective of use). This means that batteries are in operation much more expensive than compressed air engines, and are more pollutant because of the fact that a lot more pollutant material needs to be used (typical car batteries are made from sulphuric acids and lead).
Potentially lower initial cost than battery electric vehicles when mass produced.
Expansion of the compressed air reduces its temperature and heat from the passenger compartment may be cooled using a heat exchanger, providing both hot weather air conditioning and increased efficiency.
Zero pollutant emissions from the vehicle itself.

Wind Power is the conversion of wind energy into a useful form, such as electricity, using wind turbines. At the end of 2007, worldwide capacity of wind-powered generators was 94.1 gigawatts. Although wind produces about 1% of world-wide electricity use, it accounts for approximately 19% of electricity production in Denmark, 9% in Spain and Portugal, and 6% in Germany and the Republic of Ireland (2007 data). Globally, wind power generation increased more than fivefold between 2000 and 2007.[1]

The principle application of wind power is to generate electricity. Large scale wind farms are connected to electrical grids. Individual turbines can provide electricity to isolated locations. In the case of windmills, wind energy is used directly as mechanical energy for pumping water or grinding grain.

Wind energy is plentiful, renewable, widely distributed, clean, and reduces greenhouse gas emissions when it displaces fossil-fuel-derived electricity. Therefore, it is considered by experts to be more environmentally friendly than many other energy sources. The intermittency of wind seldom creates problems when using wind power to supply a low proportion of total demand. Where wind is to be used for a moderate fraction of demand, additional costs for compensation of intermittency are considered to be modest.

Wind farms have sprung up all over the United States, most notably in California. Wind farms are huge arrays of wind turbines set in areas of favorable wind production. The great number of interconnected wind turbines is necessary in order to produce enough electricity to meet the needs of a sizable population. Currently, 17,000 wind turbines on wind farms owned by several wind energy companies produce 3.7 billion kilowatt-hours of electricity annually, enough to meet the energy needs of 500,000 homes.

A windcatcher (Bâdgir; بادگیر) is a traditional Persian architectural device used for many centuries to create natural ventilation in buildings. It is not known who first invented the windcatcher, but it still can be seen in many countries today. Windcatchers come in various designs, such as the uni-directional, bi-directional, and multi-directional.

Image:Wind-Tower-and-Qanat-Cooling-1.jpg

Background
Central Iran has a very large day-night temperature difference, ranging from cool to extremely hot, and the air tends to be very dry all day long. Most buildings are constructed of very thick ceramics with extremely high insulation values. Furthermore, towns centered on desert oases tend to be packed very closely together with high walls and ceilings relative to Western architecture, maximizing shade at ground level. The heat of direct sunlight is minimized with small windows that don't face the sun.

Function
Illustration of use of windcatcher and qanat for cooling.The windcatcher functions on several principles:

First, a windcatcher is capped and has several directional ports at the top (Traditionally four). By closing all but the one facing away from the incoming wind, air is drawn upwards using the Coanda effect, similar to how opening the one facing the wind would push air down the shaft. This generates significant cooling ventilation within the structure below, but is not enough to bring the temperature below ambient alone - it would simply draw hot air in through any cracks or windows in the structure below.

Therefore, the key to generating frigid temperatures seems to be that there are very few cracks at the base of the thick structure below, but there is a significant air gap above the qanat. A qanat has quite a lot of water inside, because there are frequent well-like reservoirs along its path. Completely shaded from the sun, a qanat also aggregates the cold, sinking air of the night, which is then trapped within, unable to rise up to the less dense surface air. A windcatcher, however, can create a pressure gradient which sucks at least a small amount of air upwards through a house. This cool, dry night air, being pulled over a long passage of water, evaporates some of it and is cooled down further.

Finally, in a windless environment or waterless house, a windcatcher functions as a stack effect aggregator of hot air. It creates a pressure gradient which allows less dense hot air to travel upwards and escape out the top. This is also compounded significantly by the day-night cycle mentioned above, trapping cool air below. The temperature in such an environment can't drop below the nightly low temperature. These last two functions have gained some ground in Western architecture, and there are several commercial products using the name windcatcher.

When coupled with thick adobe that exhibits high heat transmission resistance qualities (R-value), the windcatcher is able to chill lower level spaces in mosques and houses (e.g. shabestan) in the middle of the day to frigid temperatures.

So effective has been the windcatcher in Persian architecture that it has been routinely used as a refrigerating device (yakhchal) for ages. Many traditional water reservoirs (ab anbars) are built with windcatchers that are capable of storing water at near freezing temperatures for months in summer. High humidity environments destroy the evaporative cooling effect enjoyed in the dry conditions seen on the Iranian plateau; Hence the ubiquitous use of these devices in drier areas such as Yazd, Kashan, Nain, and Bam. This is especially visible in ab anbars that use windcatchers.

A small windcatcher (badgir) is called a "shish-khan" in traditional Persian architecture. Shish-khans can still be seen on top of ab anbars in Qazvin, and other northern cities in Iran. These seem to be more designed as a pure ventilating device, as opposed to temperature regulators, as their larger cousins in the central deserts of Iran are.

Penetration

Wind energy "penetration" refers to the fraction of energy produced by wind compared with the total available generation capacity. There is no generally accepted "maximum" level of wind penetration. The limit for a particular grid will depend on the existing generating plants, pricing mechanisms, capacity for storage or demand management, and other factors. An interconnected electricity grid will already include reserve generating and transmission capacity to allow for equipment failures; this reserve capacity can also serve to regulate for the varying power generation by wind plants. Studies have indicated that 20% of the total electrical energy consumption may be incorporated with minimal difficulty.

Blade design... Many different models of wind turbines exist, the most striking being the vertical-axis Darrieus, which is shaped like an egg beater. The model most supported by commercial manufacturers, however, is a horizontal-axis turbine, with a capacity of around 100 kilowatts and three blades not more than 33 yards (30 meters) in length. Wind turbines with three blades spin more smoothly and are easier to balance than those with two blades. Also, while larger wind turbines produce more energy, the smaller models are less likely to undergo major mechanical failure, and thus are more economical to maintain.

A Laddermill is a kind of windmill, an "Airborne wind turbine", that consists of a "ladder", a long string or loop of "kites". The loop or string of kites on the ladder is launched in the air by the lifting force of the kites, until it is fully enrolled, and the top reaches a height of about 30.000 feet.

Operating modes
There are currently two operating modes considered:

The kites pull up the long string on which they are tethered, and the resulting energy is then used to drive an electric generator. When the end of the string is reached the pull force of the kites is reduced by changing the angle of attack of the kites "wing shape", and the string is then rewound with the electric generator acting as a motor, or by other means. If the string is reduced to its minimum length the next energy generating cycle is started by restoring the angle of attack of the kites to maximum lift.
Kites on one side of a wire loop generate lift while the ones on the other side do not because the Angle of attack of the kites "wing shape" changes when the kite passes the top of the loop. So the kites pull up only one end of an endless loop, causing the loop to start to rotate, and the resulting released energy is then used to drive an electric generator. The "rotating loop" "LadderMill" project is designed and developed by the Dutch ex astronaut and Physicist Wubbo Ockels. The LadderMill is the response to the challenge for exploiting the gigantic energy source contained in the airspace up to high altitudes of 10 km. The concept has been developed with the aim to convert wind energy at altitude in electricity on the ground in an environmental and cost effective manner.

Hydroelectricity is electricity generated by hydropower, i.e., the production of power through use of the gravitational force of falling water. It is the most widely used form of renewable energy. Once a hydroelectric complex is constructed, the project produces no direct waste, and has a considerably different output level of the greenhouse gas carbon dioxide (CO2) than fossil fuel powered energy plants. Worldwide, hydroelectricity suppled an estimated 715,000 MWe in 2005. This was aproximately 19% of the world's electricity (up from 16% in 2003), and accounted for over 63% of electricity from renewable sources. Some jurisdictions do not consider large hydro projects to be a sustainable energy source, due to the human, economic and environmental impacts of dam construction and maintenance.

Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator. In this case the energy extracted from the water depends on the volume and on the difference in height between the source and the water's outflow. This height difference is called the head. The amount of potential energy in water is proportional to the head. To obtain very high head, water for a hydraulic turbine may be run through a large pipe called a penstock.

Pumped storage hydroelectricity produces electricity to supply high peak demands by moving water between reservoirs at different elevations. At times of low electrical demand, excess generation capacity is used to pump water into the higher reservoir. When there is higher demand, water is released back into the lower reservoir through a turbine. Pumped storage schemes currently provide the only commercially important means of large-scale grid energy storage and improve the daily load factor of the generation system. Hydroelectric plants with no reservoir capacity are called run-of-the-river plants, since it is not then possible to store water. A tidal power plant makes use of the daily rise and fall of water due to tides; such sources are highly predictable, and if conditions permit construction of reservoirs, can also be dispatchable to generate power during high demand periods.

Less common types of hydro schemes use water's kinetic energy or undammed sources such as undershot waterwheels.

A simple formula for approximating electric power production at a hydroelectric plant is: P = hrk, where P is Power in watts, h is height in meters, r is flow rate in cubic meters per second, and k is a conversion factor of 7500 watts (assuming an efficiency factor of about 76.5 percent and acceleration due to gravity of 9.81 m/s2, and fresh water with a density of 1000 kg per cubic metre. Efficiency is often higher with larger modern turbines and may be lower with very old or small installations due to proportionately higher friction losses).

Annual electric energy production depends on the available water supply. In some installations the water flow rate can vary by a factor of 10:1 over the course of a year.
Although large hydroelectric installations generate most of the world's hydroelectricity, some situations require small hydro plants. These are defined as plants producing up to 10 megawatts, or projects up to 30 megawatts in North America. A small hydro plant may be connected to a distribution grid or may provide power only to an isolated community or a single home. Small hydro projects generally do not require the protracted economic, engineering and environmental studies associated with large projects, and often can be completed much more quickly. A small hydro development may be installed along with a project for flood control, irrigation or other purposes, providing extra revenue for project costs. In areas that formerly used waterwheels for milling and other purposes, often the site can be redeveloped for electric power production, possibly eliminating the new environmental impact of any demolition operation. Small hydro can be further divided into mini-hydro, units around 1 MW in size, and micro hydro with units as large as 100 kW down to a couple of kW rating.

Small hydro schemes are particularly popular in China, which has over 50% of world small hydro capacity

Small hydro units in the range 1 MW to about 30 MW are often available from multiple manufacturers using standardized "water to wire" packages; a single contractor can provide all the major mechanical and electrical equipment (turbine, generator, controls, switchgear), selecting from several standard designs to fit the site conditions. Micro hydro projects use a diverse range of equipment; in the smaller sizes industrial centrifugal pumps can be used as turbines, with comparatively low purchase cost compared to purpose-built turbines.

Micro Hydro is a term used for hydroelectric power installations that typically produce up to 100 kW of power. They are often used in water rich areas as a Remote Area Power Supply (RAPS). There are many of these installations around the world, including several delivering around 50 kW in the Solomon Islands, supplying energy for small communities.

Micro hydro is frequently accomplished with a pelton wheel for high head, low flow water supply. The installation is often just a small dammed pool, at the top of a waterfall, with several hundred feet of pipe leading to a small generator housing.

In low-head installations, maintenance and mechanism costs often become important. A low-head system moves larger amounts of water, and is more likely to encounter surface debris. For this reason a Banki turbine, a pressurized self-cleaning crossflow waterwheel, is often preferred for low-head microhydropower systems. Though less efficient, its simpler structure is less expensive than other low-head turbines of the same capacity. Since the water flows in, then out of it, it cleans itself and is less prone to jam with debris.

Micro hydro systems complement photovoltaic solar energy systems because in many areas, water flow, and thus available hydro power, is highest in the winter when solar energy is at a minimum.

Damless hydro or Damless hydro-electric is a renewable technology based on capturing the kinetic energy of rivers, channels of chutes, spillways, irrigation systems, tides and oceans without the use of dams Run-of-the-river hydroelectricity is a type of hydroelectric generation whereby the natural flow and elevation drop of a river are used to generate electricity. Power stations of this type are built on rivers with a consistent and steady flow, either natural or through the use of a large reservoir at the head of the river (such as the Gouin Reservoir for the Saint-Maurice River in Quebec, Canada).

Power stations on rivers with great seasonal fluctuations require a large reservoir in order to operate during the dry season, resulting in the necessity to impound and flood large tracks of land. In contrast, run of river projects do not require impoundment of water. Instead, some of the water is diverted from a river, and sent into a pipe called a penstock. The penstock feeds the water downhill to the power station's turbines. The natural force of gravity creates the energy required to spin the turbines that in turn generate electricity. The water leaves the generating station and is returned to the river without altering the existing flow or water levels.

Most run-of-river power plants will have a dam across the full width of the river in order to utilize all the river's water for electricity generation. Such installations will have a reservoir behind the dam but since flooding is minimal, they can be considered "run-of-river".

Pico hydro is a term used for hydroelectric power generation of under 5kW. It is useful in small, remote communities that require only a small amount of electricity - for example, to power one or two lightbulbs in a house, or a radio, for part of the day.

Frequency stability
The frequency of the alternating current generated needs to match the local standard utility frequency. Typically, the controller valves the water supply to generate a constant frequency for motors and clocks. The normal controller is a small programmable logic controller with a custom program that uses a deadband to minimize valve motion so the valve wears out as slowly as possible, while conserving water.

A grid-linked system slaves its generator to the grid by measuring current, to assure that the power is always output, so the grid never drives the turbine. The usual scheme is to measure voltage across a shunt resistor on one of the phases. The external utility's grid controller provides precision frequency controls.

An independent system usually governs its long-term frequency from an external time standard. The hydropower's AC time may vary by several seconds per hour, but over many days, it doesn't vary at all. Traditionally a caretaker would compare a simple AC clock driven by the hydropower system to a shortwave clock broadcast and adjust the mechanical governor on the hydropower system until the AC clock read the same as the broadcast for a few minutes. Over time, the result would be good. With a modern PLC-based system, the caretaker can just set the PLC's clock periodically from a radio clock, say once per week. Some more-professional systems automatically set the controller's clock from a radio clock.

Biomass refers to living and recently dead biological material that can be used as fuel or for industrial production. Most commonly, biomass refers to plant matter grown to generate electricity or produce biofuel, but it also includes plant or animal matter used for production of fibers, chemicals or heat. Biomass may also include biodegradable wastes that can be burnt as fuel. It excludes organic material which has been transformed by geological processes into substances such as coal or petroleum.

Biomass energy involves a wide range of low and high technologies, from wood burning to use of manure, sea kelp, and farm crops to make gas and liquid biofuels. Brazil leads the world in use of pure ethyl alcohol derived from sugarcane as a replacement for petroleum. A common fuel in the United States is corn-derived ethyl alcohol, which is used as a low-pollution octane booster in a 10-percent blend with gasoline called "gasohol." Another form of renewable energy used in the rural Third World is the gas-producing biogas digester. Human and animal wastes are mixed with straw and water in an airless underground tank made of brick or cement. Methane gas is siphoned from the tank to a cooking stove. Meanwhile, the tank gets hot enough to kill disease-causing bacteria, which is an important sanitary improvement in many countries. Over the past few decades, 5 million biogas tanks have been built in China and half a million in India.

Industrial biomass can be grown from numerous types of plants, including miscanthus, switchgrass, hemp, corn, poplar, willow, sorghum, sugarcane, and a variety of tree species, ranging from eucalyptus to oil palm (palm oil). The particular plant used is usually not very important to the end products, but it does affect the processing of the raw material. Production of biomass is a growing industry as interest in sustainable fuel sources is growing.

Vegetable oil is generated from sunlight and CO2 by plants. It is safer to use and store than gasoline or diesel as it has a higher flash point. Straight vegetable oil works in diesel engines if it is heated first. Vegetable oil can also be transesterified to make biodiesel which burns like normal diesel.

Pros
Biomass production can be used to burn organic waste products resulting from agriculture. This type of recycling encourages the philosophy that nothing on this Earth should be wasted. The result is less demand on the Earth's resources, and a higher carrying capacity for Earth because non-renewable fossil fuels are not consumed.
Biomass is abundant on Earth and is generally renewable. In theory, we will never run out of organic waste products as fuel, because we are continuously producing them. In addition, biomass is found throughout the world, a fact that should alleviate energy pressures in third world nations.
When methods of biomass production other than direct combustion of plant mass, such as fermentation and pyrolysis, are used, there is little effect on the environment. Alcohols and other fuels produced by these alternative methods are clean burning and are feasible replacements to fossil fuels.
Since CO2 is first taken out of the atmosphere to make the vegetable oil and then put back after it is burned in the engine, there is no net increase in CO2. So vegetable oil does not contribute to the problem of greenhouse gas.
It has a high flash point and is safer than most fuels.
Transitioning to vegetable oil could be relatively easy as biodiesel works where diesel works, and straight vegetable oil takes relatively minor modifications.
The World already produces more than 100 billion gallons a year for food industry, so we have experience making it.
Algaculture has the potential to produce far more vegetable oil per acre than current plants.
Infrastructure for biodiesel around the World is significant and growing.

Plastics from biomass, like some recently developed to dissolve in seawater, are made the same way as petroleum-based plastics, are actually cheaper to manufacture and meet or exceed most performance standards. But they lack the same water resistance or longevity as conventional plastics

Biomass which is not simply burned as fuel may be processed in other ways :

Low tech processes include:

composting (to make soil conditioners and fertilizers)
anaerobic digestion (decaying biomass to produce methane gas and sludge as a fertilizer)
fermentation and distillation (both produce ethyl alcohol)
More high-tech processes are:

Acid hydrolysis (treatment of wood wastes to produce sugars, which can be distilled)
Destructive distillation (produces methyl alcohol from high cellulose organic wastes).
Hydrogasification (produces methane and ethane)
Hydrogenation (converts biomass to oil using carbon monoxide and steam under high pressures and temperatures)
Pyrolysis (heating organic wastes in the absence of air to produce gas and char. Both are combustible.)
Thermal depolymerization (uses hydrous pyrolysis to convert biomass into liquid hydrocarbons, carbon solids, and methane)
Burning biomass, or the fuel products produced from it, may be used for heat or electricity production.

Electrification using the combustion of biomass to produce heat. This heat can be converted into electricity on a large scale with the water steam cycle. For smaller power plants with a power output up to 2 MWel the ORC-process Organic Rankine Cycle has to be used.[4]
Other uses of biomass, besides fuel and compost include:

Building materials
Biodegradable plastics and paper (using cellulose fibres)

Biofuel is defined as solid, liquid or gas fuel derived from recently dead biological material and is distinguished from fossil fuels, which are derived from long dead biological material. Theoretically, biofuels can be produced from any (biological) carbon source; although, the most common sources are photosynthetic plants. Various plants and plant-derived materials are used for biofuel manufacturing. Globally, biofuels are most commonly used to power vehicles, heating homes cornstoves and cooking stoves. Biofuel industries are expanding in Europe, Asia and the Americas.

There are two common strategies of producing biofuels. One is to grow crops high in sugar (sugar cane, sugar beet, and sweet sorghum) or starch (corn/maize), and then use yeast fermentation to produce ethyl alcohol (ethanol). The second is to grow plants that contain high amounts of vegetable oil, such as oil palm, soybean, algae, or jatropha. When these oils are heated, their viscosity is reduced, and they can be burned directly in a diesel engine, or they can be chemically processed to produce fuels such as biodiesel. Wood and its byproducts can also be converted into biofuels such as woodgas, methanol or ethanol fuel. It is also possible to make cellulosic ethanol from non-edible plant parts, but this can be difficult to accomplish economically.

Biofuels are discussed as having significant roles in a variety of international issues, including: mitigation of carbon emissions levels and oil prices, the "food vs fuel" debate, deforestation and soil erosion, impact on water resources, and energy balance and efficiency.

Biodiesel is the most common biofuel in Europe. It is produced from oils or fats using transesterification and is a liquid similar in composition to fossil/mineral diesel. Its chemical name is fatty acid methyl (or ethyl) ester (FAME). Oils are mixed with sodium hydroxide and methanol (or ethanol) and the chemical reaction produces biodiesel (FAME) and glycerol. One part glycerol is produced for every 10 parts biodiesel. Feedstocks for biodiesel include animal fats, vegetable oils, soy, rapeseed, jatropha, mahua, mustard, flax, sunflower, palm oil, hemp, field pennycress, and algae. Pure biodiesel (B100) is by far the lowest emission diesel fuel. Although liquefied petroleum gas and hydrogen have cleaner combustion, they are used to fuel much less efficient petrol engines and are not as widely available.Biologically produced alcohols, most commonly ethanol, and less commonly propanol and butanol, are produced by the action of microorganisms and enzymes through the fermentation of sugars or starches (easiest), or cellulose (which is more difficult). Biobutanol (also called biogasoline) is often claimed to provide a direct replacement for gasoline, because it can be used directly in a gasoline engine (in a similar way to biodiesel in diesel engines).

Although the Jatropha tree is already widely recognized in many countries as one of the lowest capital-cost BioDiesel feedstock plants available today, JatrophaTech's proprietary process to facilitate Jatropha Oil production could provide even greater plant survival rates, yields and thus income potential.

With its numerous inherent advantages, and the advances achieved through our unique technology, JatrophaTech is well-positioned to become a key contributor to profitable feedstock and Jatropha Oil production worldwide.

JatrophaTech does not plant on land that could be used for growing food. We work only with local farmers and land owners to ensure that there is never a food versus fuel debate where we work. We are ethical and pay our farmers well.

Butanol is formed by ABE fermentation (acetone, butanol, ethanol) and experimental modifications of the process show potentially high net energy gains with butanol as the only liquid product. Butanol will produce more energy and allegedly can be burned "straight" in existing gasoline engines (without modification to the engine or car),[14] and is less corrosive and less water soluble than ethanol, and could be distributed via existing infrastructures. DuPont and BP are working together to help develop Butanol.

Ethanol fuel is the most common biofuel worldwide, particularly in Brazil. Alcohol fuels are produced by fermentation of sugars derived from wheat, corn, sugar beets, sugar cane, molasses and any sugar or starch that alcoholic beverages can be made from (like potato and fruit waste, etc.). The ethanol production methods used are enzyme digestion (to release sugars from stored starches, fermentation of the sugars, distillation and drying. The distillation process requires significant energy input for heat (often unsustainable natural gas fossil fuel, but cellulosic biomass such as bagasse, the waste left after sugar cane is pressed to extract its juice, can also be used more sustainably).

Ethanol can be used in petrol engines as a replacement for gasoline; it can be mixed with gasoline to any percentage. Most existing automobile petrol engines can run on blends of up to 15% bioethanol with petroleum/gasoline. Gasoline with ethanol added has higher octane, which means that your engine can typically burn hotter and more efficiently. In high altitude (thin air) locations, some states mandate a mix of gasoline and ethanol as a winter oxidizer to reduce atmospheric pollution emissions.

Biogas is produced by the process of anaerobic digestion of organic material by anaerobes. It can be produced either from biodegradable waste materials or by the use of energy crops fed into anaerobic digesters to supplement gas yields. The solid byproduct, digestate, can be used as a biofuel or a fertilizer. In the UK, the National Coal Board experimented with microorganisms that digested coal in situ converting it directly to gases such as methane.

Biogas contains methane and can be recovered from industrial anaerobic digesters and mechanical biological treatment systems. Landfill gas is a less clean form of biogas which is produced in landfills through naturally occurring anaerobic digestion. If it escapes into the atmosphere it is a potent greenhouse gas.

Oils and gases can be produced from various biological wastes:

Thermal depolymerization of waste can extract methane and other oils similar to petroleum.
GreenFuel Technologies Corporation developed a patented bioreactor system that uses nontoxic photosynthetic algae to take in smokestacks flue gases and produce biofuels such as biodiesel, biogas and a dry fuel comparable to coal.[22]

Solid biofuels
Examples include wood, sawdust, grass cuttings, domestic refuse, charcoal, agricultural waste, non-food energy crops, and dried manure. When raw biomass is already in a suitable form (such as firewood), it can burn directly in a stove or furnace to provide heat or raise steam. When raw biomass is in an inconvenient form (such as sawdust, wood chips, grass, agricultural wastes), another option is to pelletize the biomass with a pellet mill. The resulting fuel pellets are easier to burn in a pellet stove.

Supporters of biofuels claim that a more viable solution is to increase political and industrial support for, and rapidity of, second-generation biofuel implementation from non food crops, including cellulosic biofuels.[23] Second-generation biofuel production processes can use a variety of non food crops. These include waste biomass, the stalks of wheat, corn, wood, and special-energy-or-biomass crops (e.g. Miscanthus). Second generation (2G) biofuels use biomass to liquid technology, including cellulosic biofuels from non food crops.[24] Many second generation biofuels are under development such as biohydrogen, biomethanol, DMF, Bio-DME, Fischer-Tropsch diesel, biohydrogen diesel, mixed alcohols and wood diesel.

Cellulosic ethanol production uses non food crops or inedible waste products and does not divert food away from the animal or human food chain. Lignocellulose is the "woody" structural material of plants. This feedstock is abundant and diverse, and in some cases (like citrus peels or sawdust) it is a significant disposal problem.

Producing ethanol from cellulose is a difficult technical problem to solve. In nature, ruminant livestock (like cattle) eats grass and then use slow enzymatic digestive processes to break it into glucose (sugar). In cellulosic ethanol laboratories, various experimental processes are being developed to do the same thing, and then the sugars released can be fermented to make ethanol fuel.

Third generation biofuels
Main article: Algae fuel
Algae fuel, also called oilgae or third generation biofuel, is a biofuel from algae. Algae are low-input, high-yield feedstocks to produce biofuels. It produces 30 times more energy per acre than land crops such as soybeans.[25] With the higher prices of fossil fuels (petroleum), there is much interest in algaculture (farming algae). One advantage of many biofuels over most other fuel types is that they are biodegradable, and so relatively harmless to the environment if spilled.[26][27][28]

The United States Department of Energy estimates that if algae fuel replaced all the petroleum fuel in the United States, it would require 15,000 square miles (38,849 square kilometers), which is roughly the size of Maryland.[25]

Second and third generation biofuels are also called advanced biofuels.

Algae biodiesel looks better all the time.

A newfound fungus living in rainforest trees makes biofuel more efficiently than any other known method, researchers say.

In fact, it's so good at turning plant matter into fuel that researchers say their discovery calls into question the whole theory of how crude oil was made by nature in the first place.

While many crops and microbes can be combined to make biofuels — including the fungi that became infamous as jungle rot during WWII — the newfound fungus could greatly simplify the process, its discoverers claim. Researchers have suggested that billions of acres of fallow farmland could be used to grow the raw material of biofuels. But turning corn stalks or switchgrass into fuel is a painstaking process and the end product is expensive and not entirely friendly to the environment.

The fungus, which has been named Gliocladium roseum, stands out in the crowd. "This is the only organism that has ever been shown to produce such an important combination of fuel substances," said researcher Gary Strobel from Montana State University. "The fungus can even make these diesel compounds from cellulose, which would make it a better source of biofuel than anything we use at the moment." The fungus grows inside the Ulmo tree in the Patagonian rainforest in South America. "When we examined the gas composition of G. roseum, we were totally surprised to learn that it was making a plethora of hydrocarbons and hydrocarbon derivatives. The fuel it produces has been dubbed "myco-diesel."

Anaerobic digestion (AD) is the natural process of biological degradation of organic material in the absence of air. An anaerobic digester is a man-made system that harnesses this process to treat waste and produce biogas and anaerobic digestate, a soil-improving material. The biogas can then be converted into heat and electricity. Anaerobic digestion is widely used as a stabilisation process for the treatment of wastewater sludges and organic wastes. The process provides volume and mass reduction of the input material, whilst delivering valuable renewable energy. A biogas plant is an anaerobic digestion system that is designed and operated specifically for the purpose of producing biogas. Methane produce in anaerobic digestion facilities can be utilised to replace methane derived from fossil fuels. The carbon in biodegradable waste is part of a carbon cycle, as such the carbon released from the combustion of biogas can be thought of as having been removed by plants in the recent past, for instance within the last decade, but typically within the last growing season. If these plants are re-grown, as is the case with crops, it can be argued that the systems can be considered to be carbon neutral.

Raw natural gas is composed of several gases. The main component is methane. Other components include ethane, propane, butane, and many other combustible hydrocarbons. Raw natural gas may also contain water vapor, hydrogen sulfide, carbon dioxide, nitrogen, and helium. During processing, many of these components may be removed. Some—such as ethane, propane, butane, hydrogen sulfide, and helium—may be partially or completely removed to be processed and sold as separate commodities. Other components—such as water vapor, carbon dioxide, and nitrogen—may be removed to improve the quality of the natural gas or to make it easier to move the gas over great distances through pipelines. As an alternative fuel for motor vehicles. Compressed natural gas (CNG) cars and trucks are already on the road in many areas. Companies using industrial processes that require high temperatures are also turning to natural gas instead of other fuels in order to reduce the air pollution emitted by their plants. This includes companies involved in manufacturing steel, glass, ceramics, cement, paper, chemicals, aluminum, and processed foods.

Compressed Natural Gas (CNG) is a substitute for gasoline (petrol) or diesel fuel. It is considered to be an environmentally "clean" alternative to those fuels. It is made by compressing natural gas (which is mainly composed by methane (CH4), in a percantage range of 70% to 98%). It is stored and distributed in hard containers, at a normal pressure of 200/220 bar, usually in cylindrical or spherical shapes to maintain equal pressure on the walls of the containers. In response to high fuel prices and environmental concerns, compressed natural gas is starting to be used in light-duty passenger vehicles and pickup trucks, medium-duty delivery trucks, and in transit and school buses. CNG has grown into one of the major fuel sources used in car engines in Pakistan, Bangladesh and India. The use of CNG is mandated for the public transport system of India's capital New Delhi as well as for the city of Ahmedabad in the state of Gujarat. The Delhi Transport Corporation operates the world's largest fleet of CNG buses. Today many rickshaws as well as personal vehicles in India and Bangladesh are being converted to CNG powered technology, the cost of which is in the range of $800-$1000. In the Bangladesh capital of Dhaka not a single auto rickshaw without CNG has been permitted since 2003 . The Cost saving is immense along with reduced Emissions and Environment friendly cars.

Two other technologies that are revolutionizing the natural gas industry include the increased use of liquefied natural gas, and natural gas fuel cells. These technologies are discussed below.

Cooling natural gas to about -260°F at normal pressure results in the condensation of the gas into liquid form, known as Liquefied Natural Gas (LNG). LNG can be very useful, particularly for the transportation of natural gas, since LNG takes up about one six hundredth the volume of gaseous natural gas. While LNG is reasonably costly to produce, advances in technology are reducing the costs associated with the liquification and regasification of LNG. Because it is easy to transport, LNG can serve to make economical those stranded natural gas deposits for which the construction of pipelines is uneconomical.

LNG, when vaporized to gaseous form, will only burn in concentrations of between 5 and 15 percent mixed with air. In addition, LNG, or any vapor associated with LNG, will not explode in an unconfined environment. Thus, in the unlikely event of an LNG spill, the natural gas has little chance of igniting an explosion. Liquification also has the advantage of removing oxygen, carbon dioxide, sulfur, and water from the natural gas, resulting in LNG that is almost pure methane.

LNG is typically transported by specialized tanker with insulated walls, and is kept in liquid form by autorefrigeration, a process in which the LNG is kept at its boiling point, so that any heat additions are countered by the energy lost from LNG vapor that is vented out of storage and used to power the vessel.

The increased use of LNG is allowing for the production and marketing of natural gas deposits that were previously economically unrecoverable. Although it currently accounts for only about 1 percent of natural gas used in the United States, it is expected that LNG imports will provide a steady, dependable source of natural gas.

Fuel cells powered by natural gas are an extremely exciting and promising new technology for the clean and efficient generation of electricity. Fuel cells have the ability to generate electricity using electrochemical reactions as opposed to combustion of fossil fuels to generate electricity. Essentially, a fuel cell works by passing streams of fuel (usually hydrogen) and oxidants over electrodes that are separated by an electrolyte. This produces a chemical reaction that generates electricity without requiring the combustion of fuel, or the addition of heat as is common in the traditional generation of electricity. When pure hydrogen is used as fuel, and pure oxygen is used as the oxidant, the reaction that takes place within a fuel cell produces only water, heat, and electricity. In practice, fuel cells result in very low emission of harmful pollutants, and the generation of high-quality, reliable electricity. The use of natural gas powered fuel cells has a number of benefits, including:

Methanol is the most versatile and cheapest liquid fuel that can be made. It is also less flammable than gasoline; accidental fires are extinguished with water instead of being spread as flaming films. When it combusts, it yields neither particulates (soot) nor sulfur oxides, and yields lower quantities of nitrogen oxides than any other fuel. When produced from natural gas or solid fuel, methanol can always be regasified to give substitute natural gas (SNG) with only a small loss of energy. Even when expensive chemical-grade methanol is used in automobiles with relatively insignificant changes, the mileage costs are less for these vehicles than when they use gasoline as a fuel. See also Methanol.

Hydrogen can be generated from natural gas with approximately 80% efficiency, or other hydrocarbons to a varying degree of efficiency. The hydrocarbon conversion method releases greenhouse gases. Since the production is concentrated in one facility, it is possible to separate the gases and dispose of them properly, for example by injecting them in an oil or gas reservoir (see carbon capture), although this is not currently done in most cases. A carbon dioxide injection project has been started by Norwegian company Statoil in the North Sea, at the Sleipner field.

Hydrogen production is commonly completed from hydrocarbon fossil fuels via a chemical path. Hydrogen may also be extracted from water via biological production in an algae bioreactor, or using electricity (by electrolysis) or heat (by thermolysis); because of our oil based economy these methods are presently not cost effective for bulk generation in comparison to chemical paths derived from hydrocarbons. Cheap bulk production of hydrogen is a requirement for a healthy hydrogen economy.

Popular Mechanics magazine has awarded GE Global Research (of the General Electric Company) its 2006 Breakthrough Award. The award was given in recognition of GE's development of an advanced hydrogen electrolyzer. The Electrolyzer has the potential to lower the cost of producing hydrogen energy through the water electrolysis process. High-tech plastic parts are used in place of metal parts to lower the cost of producing high performance electrodes, which improves the technology's market competitiveness.

A hydrogen vehicle is a vehicle that uses hydrogen as its on-board fuel for motive power. The term may refer to a personal transportation vehicle, such as an automobile, or any other vehicle that uses hydrogen in a similar fashion, such as an aircraft. The power plants of such vehicles convert the chemical energy of hydrogen to mechanical energy (torque) in one of two methods: combustion, or electrochemical conversion in a fuel-cell:

In combustion, the hydrogen is burned in engines in fundamentally the same method as traditional gasoline (petrol) cars.
In fuel-cell conversion, the hydrogen is reacted with oxygen to produce water and electricity, the latter of which is used to power an electric traction motor.
Automakers rapidly are closing in on making hydrogen fuel cell vehicles an everyday fact of life, with several test models set to debut over the next few years. Hydrogen fuel cells to power vehicles is desirable, experts say, because hydrogen is a renewable fuel that can be used to create electricity to run cars. A chemical reaction between oxygen and hydrogen produces the electric power, and when pure hydrogen is used, the only emission from the tailpipe is harmless water vapor.

Hydrogen does not come as a pre-existing source of energy like fossil fuels, but rather as a carrier, much like a battery. It can be made from both renewable and non-renewable energy sources. The common internal combustion engine, usually fueled with gasoline (petrol) or diesel liquids, can be converted to run on gaseous hydrogen. However, the more energy efficient use of hydrogen involves the use of fuel cells and electric motors. Hydrogen reacts with oxygen inside the fuel cells, which produces electricity to power the motors. A primary area of research is hydrogen storage, to try to increase the range of hydrogen vehicles, while reducing the weight, energy consumption, and complexity of the storage systems. Two primary methods of storage are metal hydrides and compression.

The advantage of hydrogen is that it can be produced and consumed continuously, using solar, water, wind and geothermal power sources.

Trees are necessary for our survival. They produce large amounts of oxygen and absorb large amounts of carbon dioxide, helping regulate the gases in Earth's atmosphere. Through photosynthesis trees produce the all important gas we cannot live without: oxygen (O2). As we breathe in, our bodies take in oxygen and when we breathe out, we release carbon dioxide (CO2). Trees do the opposite. They take in CO2 and release O2. This cleans the air by removing poisonous CO2 so that people and animals can breathe. Trees produce oxygen and store carbon dioxide and they do it day after day and year after year. As a tree grows it removes carbon dioxide from the atmosphere and stores it as wood fiber. It then converts that carbon dioxide into clean water and oxygen and releases it back into the atmosphere. A single tree can store over 70kg of carbon over its lifetime.
In addition to cycling carbon dioxide and oxygen, trees have the added effect that they provide many other benefits to the ecosystem. Not only do they release clean air and water they also provide habitat for birds and wildlife, prevent soil erosion, and provide recreation opportunities.

We rely upon Trees, Plants and Algae to produce the Oxygen which we breathe.

Since 1492 Human Civilization has cleared nearly 10 Billion Acres of Trees. We've cut down many more, but many have re-grown. That means we have about 54% less trees and plants on Earth today. The clearing was done mainly by civilization's expansion and fires. Logging and Wood Industries are generally respectful of the forests and replant forest areas they perform logging activities in so that new growth will eventually become wood products (with some noteworthy exceptions). Civilization has also cleared plant life in corresponding amounts.

Trees, Plants and Algae, through Photosynthesis, use the Sun's energy to metabolize nutrients, where certain key gasses they "inhale" and "exhale" convert Carbon Dioxide (CO2) to Oxygen (O2). Without plants, trees and algae, we'd be doomed... Without CO2, plants, trees and algae would be doomed. Such represents an ageless symbiotic biological partnership which hangs in the balance. If we keep cutting down trees and plants, the Atmosphere could become tragically damaged, leading to our extinction for LACK OF SUFFICIENT SUSTAINABLE O2 in the AIR FOR US ALL TO BREATHE! The true threat is the ongoing disruption of the environmental chain that produces Oxygen which are far more at risk! Humanity, and all life that breathes Oxygen (O2), are at risk of becoming extinct.

We've already caused the atmosphere to have a greatly lengthened cycle of Oxygen exchange (the time it takes to exchange all the Oxygen from CO2 and NO). The rate was much faster when there were more trees: 500 years was needed to completely replace all oxygen. As a result of deforestation it is taking place at a slower rate, relying upon Algae more than Trees and Plants versus 1492. It has expanded fourfold, exchanging the oxygen at what is approaching a dangerously slow rate, causing a net decrease in the amount of oxygen (the atmosphere's ratio of oxygen to nitrogen has remained the same, so a corresponding decline in the volume of nitrogen has also taken place). It is now 2000 years (in 1492 it was more like 500 years) for a complete "change of air". Tree clearing, plant clearing, plant decomp and mankind's use of combustion, along with uncontrolled fires, have taken their toll, alarmingly so.
To give you an idea of how humanity has underestimated the quantum degree of action need to save our world and repair our atmosphere: while the US Forestry Service has replanted 10 million trees since 1990. In spite of their well intentions, that represents only 100,000 acres. To plant 8.5 billion acres of trees (the minimum net requirement to equal the oxygen/carbon cycle and capacity of our planet as it was in 1492) would require a "net" (after logging and clearing planet wide) of 85 Billion trees, 8500 times as much as the effort that has been undertaken by the USFS. While of an extraordinary magnitude, the paramount importance of shifting the oxygen / carbon cycle to Trees and away from Sea Algae is enormous. The burden on the oceans' infrastructure is destroying the underlying lifecycles of our Seas, Rivers and Lakes, killing or altering the populations of fish, water creatures and water plants, leading to undermining of the planet's Algae. To process as much CO2 as it needs to to maintain the atmosphere, Algae is overgrowing and consuming nutrients from the oceans, rivers and lakes at beyond record rates. That is undermining the source of nutrients and leaving Algae exposed to disease, with humanity counting on it's oxygen production ability, putting all its eggs in the one basket. If it, the Oceanic, River and Lake Algae, dies off, which could be very likely within 50-100 years - if we don't subdivide the burden of the CO2 to Oxygen processing cycle by replanting the volume of Trees (and Plants) to 1492 levels: repopulation of the earth's Trees to a minimum of 17 Billion Acres, HUMANITY SHALL DIE WITH THE ALGAE. Pollutants that kill the Algae or damage them, are worsening the problem.

Living Machines are a form of biological wastewater treatment designed to mimic the cleansing functions of wetlands. They are intensive bioremediation systems that can also produce beneficial by-products such as methane gas, edible and ornamental plants, and fish. Aquatic and wetland plants, bacteria, algae, protozoa, plankton, snails, clams, fish and other organisms are used in the system to provide specific cleansing or trophic functions. In temperate climates, the system of tanks, pipes and filters is housed in a greenhouse to raise the temperature, and thus the rate of biological activity. The initial development of living machines is generally credited to John Todd, and evolved out of the bioshelter concept developed at the now-defunct New Alchemy Institute. Living Machine is a trademarked term held by Living Designs Group, LLC of Taos, New Mexico. Living machines fall within the emerging discipline of ecological engineering, and many similar systems are built in Europe without being dubbed “Living Machines.”

Design theory
The scale of living machines ranges from the backyard experiment to dependable public works. Some living machines treat domestic wastewater in small, ecologically-conscious villages, such as Findhorn Community in Scotland [1], and some treat the mixed municipal wastewater for semi-urban areas, such as South Burlington, Vermont.[2]

Each system is designed to handle a certain volume of water per day, but the system is also tailored for the qualities of the specific influent. For example, if the influent contains high levels of heavy metals, the living machine must be designed to include the proper biota to accumulate the metals. [3] During the “spring cleaning” season, there may be high levels of bleach in the water. This sudden concentration of a toxin is an example of a steep gradient.

Steep gradients are drastic changes in conditions throughout the system that challenge the ecosystem to become resilient and stable. [4] A well-designed living machine requires little management, so managers may intentionally create abrupt environmental or biochemical changes to promote ecosystem self-regulation. This mimics nature’s power and trains the ecosystem to adapt to influent variations.
Designers seek to increase the surface area of contact that biota have with the sewage to promote high reaction rates. When organisms have ready access to the sewage, they can treat it more thoroughly.
The living machine is cellular, as opposed to monolithic, in design. If influent volume or makeup changes, new cells can be added or omitted without halting or disturbing the ecosystem.
Photosynthetic plants and algae are important for oxygenating water, providing a medium for biofilms, sequestering heavy metals and many other services.
Species diversity is a design goal that promotes complexity and resiliency in an ecosystem. Functional redundancy (the presence of multiple species that provide the same function) is an important example of the need for biodiversity. Snails and fish filter sludge and act as diagnostics; when a toxic load enters, snails will rise above the water level on the wall of the tank.

The micro-ecosystem of the living machine can be integrated with the macro-ecosystem just as ecosystems fade into one another naturally. This connection is commonly made with an outdoor constructed or natural wetland into which the effluent flows. Some living machines are partially or completely open to the outdoors, and this promotes interaction with the surrounding environment.

Built components
In warm climates, living machines can be outdoors, as the temperature will sustain sufficient biological activity throughout the winter. In temperate climates, a greenhouse is used to keep water temperatures warm so that plants do not winterize. In cold climates supplemental heating may also be necessary.

Living machines use screens, biofilters, plumbing, large plastic tanks, reed beds, rocks, fans, pumps and other mechanical devices. Every system is tailored to the volume and makeup of the sewage. Some are stand-alone greenhouses, while others are built into larger buildings.

John Todd and James Shaw have a patent on a device called an "ecological fluidized bed" which is essentially a pumice-filled tank with a concentric inner tank that contains wetland plants. Pumps rapidly recirculate water to maximize the filtration rate of this device. [10]

Biological processes
The first step of the process is an anaerobic settling tank. This closed anaerobic tank serves as a pre-treatment to allow solids to fall out of suspension and precipitate to the bottom of the reactor to reduce the turbidity of the water. A variety of anaerobic bacteria are present in this tank; they generate acids and ferment methane. This step may be unnecessary if the influent has low levels of solids.
Next, the sewage flows through a biofilter of bark and humic materials. This gives the influent its first filtration and reduces the odors prevalent in anaerobic conditions.
The mixture then moves into a series of aerobic tanks. The first tank is a dark, closed-top aerobic reactor that serves as a transitional step. The next tank is an open-top, aerobic reactor that contains photosynthetic algae that fix oxygen back into the formerly anoxic, turbid water. This provides oxygen and organic food (dead algae) for biological metabolism and respiration. Microbial communities proliferate, and eventually must consume all of the photosynthetic algae so that the algae do not choke out macrophytes in later steps.
Many types of bacteria immobilize pollutant minerals, but certain species of bacteria are crucial to nutrient conversion. Specifically, Nitrosomonas and Nitrobacter work in steps to nitrify ammonia, making it into nitrates, which are available for plant and microbial uptake. These bacteria need calcium carbonate to catalyze this reaction, so managers must maintain sufficient calcium levels in the water. Denitrifying bacteria such as Pseudomonas fluorescens convert nitrates into gaseous nitrogen, which is volatilized in these open aerobic tanks. Denitrification is the most desirable sink for nitrogen in living machines. Protozoa have been shown to be capable of coliform and pathogen suppression. Microbial breakdown is the primary biological treatment of both the conventional activated sludge process as well as these aquatic ecosystem sludge reactors.
Higher plants are grown hydroponically in the aerobic tanks and provide multiple services. The most common plant used is water hyacinth (Eicchornia crassipies), which has filamentous aquatic roots with a high specific area. These feather-like roots provide a stable habitat for microbes, and over time a bacterial biofilm builds up around the roots. Water hyacinth, bulrush and other macrophytes sequester heavy metals. The bodies of these plants can be harvested and burned, and the heavy metals can be chemically isolated to take them out of the environment. Brassica juncea growing in waste streams has been found to contain 60% of its dry weight in lead.
Plankton carries out multiple functions in the system with varying efficacy. Zooplankton feed on extremely small (<25µm) particles. In juvenile stages they feed on particles smaller than 1 µm. Conventional waste treatment cannot process these fine suspended solids. Although zooplankton do consume these fine particles, which are difficult for conventional treatment systems to process, the placement of plankton in the system is more valuable as a trophic link. Plankton can eat microbes, which are abundant in the system, and the plankton is an ideal food for filter feeding fish and mollusks. This food chain transfers biomass to higher trophic levels and increases the diversity and complexity of the ecosystem. John Todd thinks that “Since zooplankton can exchange the volume of a natural body of water several times per day it is difficult to overstate their importance in ecological engineering.”
According to Björn Guterstam, another one of the most well-published and experienced ecological engineers, this theoretical role has not been as successful in practice. He concedes that phytoplankton populations have been limited by toxic and somewhat deoxidized water at the bottom of tanks, as well as light limitations. Phytoplankton are primary producers, which provide food for larger zooplankton species, so the zooplankton population drops with its photosynthetic counterpart. Because these principles have been implemented only on a small scale, these systems have a lowered buffering capacity due to issues of scale and separation from the macroecosystem, even though genetic and functional diversity is encouraged.
Aquaculture can take place in more dilute tanks downstream after the eutrophication-causing contaminants have been ameliorated. Snails slide along the tank walls and graze on slime and sludge buildup, cleaning the tank. This self-regulation improves light penetration, which stimulates photosynthetic forms of algae, bacteria and plankton. Filter feeders sift through large volumes of water each day and consume the bacteria and plankton that are small enough to pass through. Mollusks such as mussels and snails, as well as some fish, are filter feeders. Detritus-feeding fish consume larger particles of suspended biosolids. Herbivorous fish are excluded from tanks where macrophytes carry out useful functions (such as biofilm hosting), but when plants are eventually harvested from the system, this plant tissue can be fed to a tank of herbivorous fish for aquaculture production.
A single Anodonta freshwater clam can filter as much as 40 litres/day of water, absorbing colloidal materials and other suspended solids at a removal rate of 99.5%. Many freshwater clams are in danger of extinction, in part because some have gills that perform poorly in polluted environments. Since some of these clams can sequester colloids from streams or lakes, this provides an ecosystem service by slowing the erosion of soil colloids. Do clams aid in nutrient retention of their home streambeds? Humans can strike up a symbiotic relationship with the clam genera Unlo and Anodonta by providing a clean habitat (when the water reaches the clam tank it is cleaner than some of their wild habitats). In exchange for a good home, the clams could aid humans by filtering colloids and suspended solids out of our wastewater. It is yet to be determined if the clams break up these colloids at all or if it is feasible to recycle clam compost back into field (which increases cation exchange capacity—-an agricultural benefit). Ecological engineering supports symbiotic relations between different species to serve the needs of humans as well as promoting the health of the ecosystem.

Mycoremediation is a form of bioremediation, the process of using mushrooms to return an environment (usually soil) contaminated by pollutants to a less contaminated state. The term mycoremediation was coined by Paul Stamets and refers specifically to the use of fungal mycelia in bioremediation.

One of the primary roles of fungi in the ecosystem is decomposition, which is performed by the mycelium. The mycelium secretes extracellular enzymes and acids that break down lignin and cellulose, the two main building blocks of plant fiber. These are organic compounds composed of long chains of carbon and hydrogen, structurally similar to many organic pollutants. The key to mycoremediation is determining the right fungal species to target a specific pollutant. Certain strains have been reported to successfully degrade the nerve gases VX and sarin.

In an experiment conducted in conjunction with Battelle, a major contributor in the bioremediation industry, a plot of soil contaminated with diesel oil was inoculated with mycelia of oyster mushrooms; traditional bioremediation techniques (bacteria) were used on control plots. After four weeks, more than 95% of many of the PAH (polycyclic aromatic hydrocarbons) had been reduced to non-toxic components in the mycelial-inoculated plots. It appears that the natural microbial community participates with the fungi to break down contaminants, eventually into carbon dioxide and water. Wood-degrading fungi are particularly effective in breaking down aromatic pollutants (toxic components of petroleum), as well as chlorinated compounds (certain persistent pesticides; Battelle, 2000).

Mycofiltration is a similar or same process, using fungal mycelia to filter toxic waste and microorganisms from water in soil.

We need the development of a natural gas to hydrogen, carbon to oxygen, 'transitional economy' plan

Wave power refers to the energy of ocean surface waves and the capture of that energy to do useful work — including electricity generation, desalination, and the pumping of water (into reservoirs).

Though often co-mingled, wave power is distinct from the diurnal flux of tidal power and the steady gyre of ocean currents. Wave power generation is not currently a widely employed commercial technology although there have been attempts at using it since at least 1890.The world's first commercial wave farm based in Portugal, at the Aguçadora Wave Park, consists of three 750 kilowatt Pelamis devices.

Wave power devices are generally categorized by the method used to capture the energy of the waves. They can also be categorized by location and power take-off system. Method types are point absorber or buoy; surfacing following or attenuator; terminator, lining perpendicular to wave propagation; oscillating water column; and overtopping. Locations are shoreline, near shore and offshore. Types of power take-off include: hydraulic ram, elastomeric hose pump, pump-to-shore, hydroelectric turbine, air turbine,[11] and linear electrical generator. Some of these designs incorporate parabolic reflectors as a means of increasing the wave energy at the point of capture.

Tidal power, sometimes called tidal energy, is a form of hydropower that converts the energy of tides into electricity or other useful forms of power.

Although not yet widely used, tidal power has potential for future electricity generation. Tides are more predictable than wind energy and solar power. Historically, tide mills have been used, both in Europe and on the Atlantic coast of the USA. The earliest occurrences date from the Middle Ages, or even from Roman times

1. Horizontal axis turbines. These are close in concept to traditional windmills operating under the sea and have the most prototypes currently operating. These include:

2. Vertical axis turbines. The Gorlov turbine is an improved helical design which is being prototyped on a large scale in S. Korea.[13] Neptune Renewable Energy has developed Proteus which uses a barrage of vertical axis crossflow turbines for use mainly in estuaries.

3. Oscillating devices. These don't use rotary devices at all but rather aerofoil sections which are pushed sideways by the flow.
Oscillating stream power extraction was proven with the omni or bi-directional Wing'd Pump windmill
During 2003 a 150kW oscillating hydroplane device, the Stingray, was tested off the Scottish coast.

4. Venturi effect. This uses a shroud to increase the flow rate through the turbine. These can be mounted horizontally or vertically.
Australian company Tidal Energy Pty Ltd undertook successful commercial trials of highly efficient shrouded tidal turbines on the Gold Coast,

Considerable commercial interest has been shown in recent times in shrouded tidal stream turbines as it allows a smaller turbine to be used at sites where large turbines are restricted. Arrayed across a seaway or in fast flowing rivers shrouded tidal stream turbines are easily cabled to a terrestrial base and connected to a grid or remote community. Alternatively the property of the shroud that produces an accelerated flow velocity across the turbine allows tidal flows formerly too slow for commercial use to be utilised for commercial energy production.

While the shroud may not be practical in wind, as the next generation of tidal stream turbine design it is gaining more popularity and commercial use. A shrouded tidal turbine is mono directional and constantly needs to face upstream in order to operate. It can be floated under a pontoon on a swing mooring, fixed to the seabed on a mono pile and yawed like a wind sock to continually face upstream. A shroud can also be built into a tidal fence or barrage increasing the performance of the turbines.

Cabled to the mainland they can be grid connected or can provide energy to remote communities where large civil infrastructures are not viable. Describe as eco benign the slow R.P.M. of tidal stream open turbines does not interfere with marine life or the environment and have little if any visual amenity impact. They are ideal for remote communities that are far from grid connected infrastructure such as islands and rivers.

Geothermal power (from the Greek roots geo, meaning earth, and therme, meaning heat) is energy generated by heat stored in the earth, or the collection of absorbed heat derived from underground, in the atmosphere and oceans. Prince Piero Ginori Conti tested the first geothermal generator on 4 July 1904, at the Larderello dry steam field in Italy. The largest group of geothermal power plants in the world is located in The Geysers, a geothermal field in California. As of 2008, geothermal power supplies less than 1% of the world's energy.

The Earth can be divided into three large sections: the mantle, inner core, and outer core. The inner core is at the center of the earth. The pressure and temperature of the earth increases as one moves closer to the center. First comes the mantle, this is a layer that is bellow the crust of the earth. This is said to go down 2,900 kilometers; it's temperature is about 870 degrees Celsius. The outer core has a very high temperature and ranges from about 4,400 degrees Celsius to about 6,100 degrees Celsius. The outer core beginnings where the mantle stops and it extends further down to the center 2,250 kilometers. The inner core is about 6,400 kilometers below the earths surface. the temperature at the inner core of the earth is at the high is about 7,000 degrees Celsius. Radioactive potassium, uranium and thorium are thought to be the three main sources of heat in the Earth's interior, aside from that generated by the formation of the planet. The Earth's core is mainly made by iron, and as it happens the very interior of the core is solid, surrounded by a shell of liquid iron which extends roughly half way up towards the surface of the planet. But compared with the sun the earth's temperature at the center of the earth is about the outer reign of the sun.

"Geothermal" can generally refer to any heat contained in the ground.

Geothermal resources range from shallow ground to hot water and rock several miles below the Earth's surface, and even further down to the extremely hot molten rock called magma. Wells over a mile deep can be drilled into underground reservoirs to tap steam and very hot water that can be brought to the surface for use in a variety of applications.

Geothermal technologies include:

Geothermal heat pump: Almost everywhere, the upper 10 feet of Earth's surface maintains a nearly constant temperature between 50 and 60°F (10 and 16°C). A geothermal heat pump system consists of pipes buried in the shallow ground near the building, a heat exchanger, and ductwork into the building. In winter, heat from the relatively warmer ground goes through the heat exchanger into the house. In summer, hot air from the house is pulled through the heat exchanger into the relatively cooler ground. Heat removed during the summer can be used as no-cost energy to heat water.
Direct exchange geothermal heat pump: A heat pump without a heat exchanger, which circulates the working fluid through pipes in the ground.
Hot water near Earth's surface can be piped directly into facilities and used to heat buildings, grow plants in greenhouses, dehydrate onions and garlic, heat water for fish farming, and pasteurize milk. Some cities pipe the hot water under roads and sidewalks to melt snow. District heating applications use networks of piped hot water to heat buildings in whole communities.
Hot dry rock geothermal energy: Using deep wells into hot rock, a fluid is heated and used to generate power:
Dry steam plants, which directly use geothermal steam to turn turbines;
Flash steam plants, which pull deep, high-pressure hot water into lower-pressure tanks and use the resulting flashed steam to drive turbines; and
Binary-cycle plants, which pass moderately hot geothermal water by a secondary fluid with a much lower boiling point than water. This causes the secondary fluid to flash to vapor, which then drives the turbines.

Geothermal energy offers a number of advantages over traditional fossil fuel based sources, primarily that the heat source requires no purchase of fuel. From an environmental standpoint, emissions of undesirable substances are small. It is also nearly sustainable because the heat extraction is small compared to the size of the heat reservoir, which may also receive some heat replenishment from greater depths. In addition, geothermal power plants are unaffected by changing weather conditions. Geothermal power plants work continuously, day and night, making them base load power plants. From an economic view, geothermal energy is extremely price competitive in some areas and reduces reliance on fossil fuels and their inherent price unpredictability. It also offers a degree of scalability: a large geothermal plant can power entire cities while smaller power plants can supply more remote sites such as rural villages.

Seasonal thermal store (also known as a seasonal heat store or inter-seasonal thermal store) is a store designed to retain heat deposited during the hot summer months for use during colder winter weather. The heat is typically captured using solar collectors, although other energy sources are sometime used separately or in parallel.

Types of seasonal thermal storage system
Seasonal (or "annualized") thermal storage can be divided into two broad categories:

Low-temperature systems use the soil adjoining the building as a low-temperature seasonal heat store (reaching temperatures similar to average annual air temperature), drawing upon the stored heat for space heating. Such systems can also be seen as an extension to the building design (normally passive solar building design), as the design involves some simple but significant differences when compared to 'traditional' buildings.
High-temperature seasonal heat stores are essentially an extension of the building's HVAC and water heating systems. Water is normally the storage medium, stored in tanks at temperatures that can approach boiling point. Phase change materials (which are expensive but which require much smaller tanks) and high-tech soil heating systems (remote from the building) are occasionally used instead. For systems installed in individual buildings, additional space is required to accommodate the size of the storage tanks.
In both cases, very effective above-ground insulation / superinsulation of the building structure is required to minimise heat-loss from the building, and hence the amount of heat that needs to be stored and used for space heating.

Despite the differences in design that they involve, low-temperature systems tend to offer simple and relatively inexpensive implementations which are less vulnerable to equipment failure. They do, however, require the site of the building to be clear of the water table, bedrock and existing buildings, and are limited to temperate (or warmer) climate zones and to space heating only. High-temperature systems share the same vulnerabilities as conventional space and water heating systems due to their 'active' mechanical and electrical components, as well as their advantage of enabling greater control. They can also be employed in colder climates.

Deep lake water cooling uses cold water pumped from the bottom of a lake as a heat sink for climate control systems. Because heat pump efficiency improves as the heat sink gets colder, deep lake water cooling can reduce the electrical demands of large cooling systems where it is available. It is similar in concept to modern geothermal sinks, but generally simpler to construct given a suitable water source.

Basic concept
Water is most dense at 3.98 °C at standard atmospheric pressure. Thus as water cools below 3.98 °C it lowers in density and will rise, the most obvious example being that ice floats. As the temperature climbs above 3.98 °C, water density also decreases and causes the water to rise, which is why lakes are warmer on the surface during the summer. The combination of these two effects means that the bottom of most deep bodies of water located well away from the equatorial regions is at a constant 3.98 °C. [citation needed]

Air conditioners are heat pumps. During the summer, when outside air temperatures are higher than the thermostat set temperature inside a building, air conditioners use electricity to pump heat uphill, from the cooler interior of the building to the warmer exterior ambient. This process is expensive because large buildings collect an enormous amount of solar thermal energy (at noon, about one kilowatt per square meter facing the sun), and require lots of electrical energy to pump out all that heat.

Unlike residential air conditioners, most modern commercial air conditioning systems do not pump heat directly into the exterior air. Instead, water is brought down to the wet-bulb temperature by partial evaporation in a cooling tower. This cold water then acts as the heat sink for the heat pump. The improvement in heat pump efficiency saves so much energy that cooling towers have become ubiquitous on the rooftops and mechanical floors of skyscrapers.

Deep lake water cooling goes even further. Except in the driest of summer conditions, deep lake water will be cooler than the ambient wet bulb temperature. Because it is a colder heat sink it saves still more electricity. For many buildings, the sink should be sufficiently cold that the heat pumps can be shut down and the building can use free cooling, allowing interior heat to conduct directly to the heat sink. "Free cooling" is not actually free, since pumps and fans still must be run to circulate the heat sink water and building air.

One added attraction of deep lake water cooling is that it saves energy during peak load times–summer afternoons when a sizable amount of the total electrical grid load is air conditioning.

Using the same technologies developed for the oil industry, Geothermal energy is one 'solution' for electric bulk power generation.

A heat pump is a machine or device that moves heat from one location (the 'source') to another location (the 'sink' or 'heat sink') using work. Most heat pump technology moves heat from a low temperature heat source to a higher temperature heat sink. Common examples are food refrigerators and freezers, air conditioners, and reversible-cycle heat pumps for providing thermal comfort. Heat pumps can also operate in reverse, producing heat. This produces an efficient way of drying, and manufacturers such as AEG and Miele have released tumble dryers that utilise this method. It is claimed to be more energy saving and quicker than conventional drying.

Heat pumps can be thought of as a heat engine which is operating in reverse. One common type of heat pump works by exploiting the physical properties of an evaporating and condensing fluid known as a refrigerant. In heating, ventilation, and cooling (HVAC) applications, a heat pump normally refers to a vapor-compression refrigeration device that includes a reversing valve and optimized heat exchangers so that the direction of heat flow may be reversed. Most commonly, heat pumps draw heat from the air or from the ground. Air-source heat pumps with a coefficient of performance (COP) 3 are developed in Japan at −20 °C.

A simple stylized diagram of a heat pump's vapor-compression refrigeration cycle: 1) condenser, 2) expansion valve, 3) evaporator, 4) compressor.

Heat pumps differ in how they apply this work to move heat, but they can essentially be thought of as heat engines operating in reverse. A heat engine allows energy to flow from a hot 'source' to a cold heat 'sink', extracting a fraction of it as work in the process. Conversely, a heat pump requires work to move thermal energy from a cold source to a warmer heat sink.

Since the heat pump uses a certain amount of work to move the heat, the amount of energy deposited at the hot side is greater than the energy taken from the cold side by an amount equal to the work required. Conversely, for a heat engine, the amount of energy taken from the hot side is greater than the amount of energy deposited in the cold heat sink since some of the heat has been converted to work.

One common type of heat pump works by exploiting the physical properties of an evaporating and condensing fluid known as a refrigerant.

A simple stylized diagram of a heat pump's vapor-compression refrigeration cycle: 1) condenser, 2) expansion valve, 3) evaporator, 4) compressor.The working fluid, in its gaseous state, is pressurized and circulated through the system by a compressor. On the discharge side of the compressor, the now hot and highly pressurized gas is cooled in a heat exchanger, called a condenser, until it condenses into a high pressure, moderate temperature liquid. The condensed refrigerant then passes through a pressure-lowering device like an expansion valve, capillary tube, or possibly a work-extracting device such as a turbine. This device then passes the low pressure, (almost) liquid refrigerant to another heat exchanger, the evaporator where the refrigerant evaporates into a gas via heat absorption. The refrigerant then returns to the compressor and the cycle is repeated.

In such a system it is essential that the refrigerant reaches a sufficiently high temperature when compressed, since the second law of thermodynamics prevents heat from flowing from a cold fluid to a hot heat sink. Similarly, the fluid must reach a sufficiently low temperature when allowed to expand, or heat cannot flow from the cold region into the fluid. In particular, the pressure difference must be great enough for the fluid to condense at the hot side and still evaporate in the lower pressure region at the cold side. The greater the temperature difference, the greater the required pressure difference, and consequently more energy is needed to compress the fluid. Thus as with all heat pumps, the energy efficiency (amount of heat moved per unit of input work required) decreases with increasing temperature difference.

Due to the variations required in temperatures and pressures, many different refrigerants are available. Refrigerators, air conditioners, and some heating systems are common applications that use this technology.

A HVAC heat pump systemIn HVAC applications, a heat pump normally refers to a vapor-compression refrigeration device that includes a reversing valve and optimized heat exchangers so that the direction of heat flow may be reversed. The reversing valve switches the direction of refrigerant through the cycle and therefore the heat pump may deliver either heating or cooling to a building. In the cooler climates the default setting of the reversing valve is heating. The default setting in warmer climates is cooling. Because the two heat exchangers, the condenser and evaporator, must swap functions, they are optimized to perform adequately in both modes. As such, the efficiency of a reversible heat pump is typically slightly less than two separately-optimized machines.

The heat pump can also be used to heat water (thus in solar hot water systems); heat pumps may also be used to cool the house (eg in summer).

In plumbing applications, a heat pump is sometimes used to heat or preheat water for swimming pools or domestic water heaters.

In somewhat rare applications, both the heat extraction and addition capabilities of a single heat pump can be useful, and typically results in very effective use of the input energy. For example, when an air cooling need can be matched to a water heating load, a single heat pump can serve two useful purposes.

Types of heat pumps
A number of sources have been used for the heat source for heating private and communal buildings. The two main types of heat pumps are compression heat pumps and absorption heat pumps. Compression heat pumps always operate on mechanical energy (through electricity), while absorption heat pumps may also run on heat as an energy source (through electricity or burnable fuels).

Air-source heat pumps
Air source heat pumps are relatively easy (and inexpensive) to install and have therefore historically been the most widely used heat pump type. However, they suffer limitations due to their use of the outside air as a heat source or sink. The higher temperature differential during periods of extreme cold or heat leads to a lower efficiency, as explained above. In mild weather, COP may be around 3.5, while at temperatures below around −5°C (23°F) an air-source heat pump's COP will drop below 2. But Air-source heat pumps with a COP 3 are developed in Japan at −20 °C. The average COP over seasonal variation is typically 2.5-2.8,high efficiency model in Japan over 6.0(2.8kW). Domestic air-source heat pump water heater called Eco-cute was developed in 2001.

Solid state heat pumps
Main article: Magnetic refrigeration
In 1881, the German physicist Emil Warburg put a block of iron into a strong magnetic field and found that it increased very slightly in temperature. Some commercial ventures to implement this technology are underway, claiming to cut energy consumption by 40% compared to current domestic refrigerators The process works as follows: Powdered gadolinium is moved into a magnetic field, heating the material by 2 to 5 °C. The heat is removed by a circulating fluid. The material is then moved out of the magnetic field, reducing its temperature below its starting temperature.

Earth cooling tubes or earth warming tubes (also known as ground-coupled heat exchangers) utilize the earth's near constant subterranean temperature to warm or cool air for residential, agricultural or industrial uses. They are often a viable and economical alternative to conventional heating, cooling or heat pump systems since there are no compressors, chemicals or burners and only blowers are required to move the air. Earth tubes are regularly used in Europe to pre-heat (or pre-cool) air for the whole-building heat recovery ventilation systems that are used in buildings designed to the German Passive House standard.

Geothermal heat pumps
Geothermal heat pumps typically have higher efficiencies than air-source heat pumps. This is because they draw heat from the ground or groundwater which is at a relatively constant temperature all year round below a depth of about eight feet (2.5 m). This means that the temperature differential is lower, leading to higher efficiency. Ground-source heat pumps typically have COPs of 3.5-4.0 with little seasonal variation. The tradeoff for this improved performance is that a ground-source heat pump is more expensive to install due to the need for the digging of wells or trenches in which to place the pipes that carry the heat exchange fluid. When compared versus each other, groundwater heat pumps are generally more efficient than heat pumps using heat from the soil.

Heat pumps move heat from a source to a sink. With GSHPs, the source is the ground, and the sink is the house or other object to which the heat is being transferred. They use the same basic system as a refrigerator, which tranfers heat from the inside of the refrigerator (the 'source') to the outside (the 'sink').

Heat pumps are characterised by two loops, the 'source' or external (ground) loop, and the 'sink' or internal (building) loop, each containing refrigerant. These loops can deliver heating and cooling directly to ground or building or, via heat exchangers, through secondary loops containing water (or an antifreeze mixture with water and propylene glycol, denatured alcohol or methanol). Secondary loops are popular for ground use because they are not pressurized, so cheap plastic tubing can be used, and because they reduce the amount of expensive refrigerant required.

Heat transfer
After the heat has been absorbed from the source (air or ground), the heat is transferred and used in the home or building (for space heating. This is generally done by pipes in the floor, wall or ceiling.

Solar Heat Pump Electrical Generation System (SHPEGS) utilizes a solar or geothermal powered absorption heat pump to improve the efficiency and location independence of SEGS/CSP solar thermal systems. The idea is to leverage an available heat source to transfer much larger amounts of heat between the ambient air and the ground using a heat pump system. This heat source could be solar thermal, geothermal, or other heat sources. A convection tower (bi-directional chimney) allows the large quantities of air to move across the heat exchangers without expending energy as in a forced air system. A large subterranean heat storage system (water, sand, stone or earth, either natural or man-made) is used to store both the heat from the air and the heat collected from the solar/geothermal source until the air is cooler (either day/night cycle or seasonal). This stored heat is relatively close to the system (as compared to deep geothermal) and the energy to pump the heat is relatively low.

The system uses both a low boiling point fluid steam turbine and wind turbines in the tower to generate electricity.

This is an amalgamation of the SEGS, OTEC, Solar Tower, Water Spray Down Draft Tower, Low Temperature Geothermal and Shallow Thermal Storage ideas and has several fundamental improvements in efficiency, location independence and reliability over these systems when deployed separately. See the background page for more information on existing systems.

A tower is built to allow large quantities of air to move across heat exchangers by natural convection without expending energy.
Solar thermal or deep geothermal heat is used to power a heat pump which moves a much larger amount of heat from the air.
Both the heat from the air and the heat powering the heat pump are stored in shallow heat storage and this is used to exploit the difference in temperature changes due to day time heating between the air and shallow underground, either day/night or seasonally. In effect this creates a local geothermal source and the low media transfer energy allows for an efficient geothermal power generation system. This source is reliable and may be used for base load electrical generation and structure heating.

Geothermal power, Solar Heat Pump Generation, is one 'solution' for electric bulk power generation.

Ocean thermal energy conversion (OTEC) is an energy technology that converts solar radiation to electric power which uses the temperature difference that exists between deep and shallow waters to run a heat engine. As with any heat engine, the greatest efficiency and power is produced with the largest temperature difference. This temperature difference generally increases with decreasing latitude, i.e. near the equator, in the tropics. However, evaporation prevents the surface temperature from exceeding 27 deg.C (80 deg.F). Also the subsurface water rarely falls below 5 deg.C. Historically, the main technical challenge of OTEC was to generate significant amounts of power, efficiently, from this very small temperature ratio. Changes in efficiency of heat exchange in modern designs allow performance approaching the theoretical maximum efficiency.

OTEC systems use the ocean's natural thermal gradient—the fact that the ocean's layers of water have different temperatures—to drive a power-producing cycle. As long as the temperature between the warm surface water and the cold deep water differs by about 20°C (36°F), an OTEC system can produce a significant amount of power, with little impact on the surrounding environment. The oceans are thus a vast renewable resource, with the potential to help us produce billions of watts of electric power. This potential is estimated to be about 10 13 watts of baseload power generation, according to some experts.
The distinctive feature of OTEC energy systems is that the end products include not only energy in the form of electricity, but several other synergistic products.

Fresh Water
The first by-product is fresh water. A small 1 MW OTEC is capable of producing some 4,500 cubic meters of fresh water per day, enough to supply a population of 20,000 with fresh water. OTEC-produced fresh water compares very favourably with standard desalination plants, in terms of both quality and production costs.

Food
A further by-product is nutrient rich cold water from the deep ocean. The cold "waste" water from the OTEC is utilised in two ways. Primarily the cold water is discharged into large contained ponds, near shore or on land, where the water can be used for multi-species mariculture producing harvest yields which far surpass naturally occurring cold water upwelling zones, just like agriculture on land.

Cooling
The cold water is also available as chilled water for cooling greenhouses, such as the Seawater Greenhouse or for cold bed agriculture. The cold water can also be used for air conditioning systems or more importantly for refrigeration systems, most likely linked with creating cold storage facilities for preserving food. When the cold water has been used it is released to the deep ocean.

The Earth's oceans are continually heated by the sun and cover nearly 70% of the Earth's surface; this temperature difference contains a vast amount of solar energy which can potentially be harnessed for human use. If this extraction could be made cost effective on a large scale, it could provide a source of renewable energy needed to deal with energy shortages, and other energy problems. The total energy available is one or two orders of magnitude higher than other ocean energy options such as wave power, but the small magnitude of the temperature difference makes energy extraction comparatively difficult and expensive, due to low thermal efficiency. Current designs under review will operate closer to the theoretical maximum efficiency. The energy carrier, seawater, is free, although it has an access cost associated with the pumping materials and pump energy costs. Although an OTEC plant operates at a low overall efficiency, it can be configured to operate continuously as a Base load power generation system. Any thorough Cost-benefit analysis should include these factors to provide an accurate assessment of performance, efficiency, operational and construction costs and returns on investment.

The concept of a heat engine is very common in thermodynamics engineering, and much of the energy used by humans passes through a heat engine. A heat engine is a thermodynamic device placed between a high temperature reservoir and a low temperature reservoir. As heat flows from one to the other, the engine converts some of the heat energy to work energy. This principle is used in steam turbines and internal combustion engines, while refrigerators reverse the direction of flow of both the heat and work energy. Rather than using heat energy from the burning of fuel, OTEC power draws on temperature differences caused by the sun's warming of the ocean surface. Perhaps the largest source of waters, in which sufficient temperature differentials exist, are tropical ocean waters where temperature differences between the warm surface water and the cold deep ocean water, several thousand feet below the ocean surface, are often as high as 40° to 45° F.

OTEC could produce gigawatts of electrical power. However, OTEC plants usually require a large diameter intake pipe, which is submerged a kilometre or more into the ocean's depths, to bring very cold water to the surface.

Left: Pipes used for OTEC.
Right: Floating OTEC plant constructed in India in 2000
Depending on the location
Land based plant
Shelf based plant
Floating plant

Depending on the cycle used
Open cycle
Closed cycle
Hybrid cycle
This cold seawater is an integral part of each of the three types of OTEC systems: closed-cycle, open-cycle, and hybrid. To operate, the cold seawater must be brought to the surface. This can be accomplished through direct pumping. A second method is to desalinate the seawater near the sea floor; this lowers its density, which will cause it to "float" up through a pipe to the surface.

Closed-cycle

Diagram of a closed cycle OTEC plantClosed-cycle systems use fluid with a low boiling point, such as ammonia, to rotate a turbine to generate electricity. Warm surface seawater is pumped through a heat exchanger where the low-boiling-point fluid is vaporized. The expanding vapor turns the turbo-generator. Then, cold, deep seawater—pumped through a second heat exchanger—condenses the vapor back into a liquid, which is then recycled through the system.

In 1979, the Natural Energy Laboratory and several private-sector partners developed the mini OTEC experiment, which achieved the first successful at-sea production of net electrical power from closed-cycle OTEC. The mini OTEC vessel was moored 1.5 miles (2.4 km) off the Hawaiian coast and produced enough net electricity to illuminate the ship's light bulbs, and run its computers and televisions.

Then, the Natural Energy Laboratory in 1999 tested a 250 kW pilot closed-cycle plant, the largest of its kind ever put into operation. Since then, there have been no tests of OTEC technology in the United States, largely because the economics of energy production today have delayed the financing of a permanent, continuously operating plant.

Outside the United States, the government of India has taken an active interest in OTEC technology. India has built and plans to test a 1 MW, closed-cycle, floating OTEC plant.

Open-cycle
Open-cycle OTEC uses the tropical oceans' warm surface water to make electricity. When warm seawater is placed in a low-pressure container, it boils. The expanding steam drives a low-pressure turbine attached to an electrical generator. The steam, which has left its salt and contaminants behind in the low-pressure container, is pure fresh water. It is condensed back into a liquid by exposure to cold temperatures from deep-ocean water. This method has the advantage of producing desalinized fresh water, suitable for drinking water or irrigation.

In 1984, the Solar Energy Research Institute (now the National Renewable Energy Laboratory) developed a vertical-spout evaporator to convert warm seawater into low-pressure steam for open-cycle plants. Energy conversion efficiencies as high as 97% were achieved for the seawater to steam conversion process (overall efficiency of an OTEC system using a vertical-spout evaporator would still only be a few per cent). In May 1993, an open-cycle OTEC plant at Keahole Point, Hawaii, produced 50,000 watts of electricity during a net power-producing experiment. This broke the record of 40,000 watts set by a Japanese system in 1982.

Hybrid
A hybrid cycle combines the features of both the closed-cycle and open-cycle systems. In a hybrid OTEC system, warm seawater enters a vacuum chamber where it is flash-evaporated into steam, similar to the open-cycle evaporation process. The steam vaporizes the ammonia working fluid of a closed-cycle loop on the other side of an ammonia vaporizer. The vaporized fluid then drives a turbine to produce electricity. The steam condenses within the heat exchanger and provides desalinated water. (see heat pipe)

The electricity produced by the system can be delivered to a utility grid or used to manufacture methanol, hydrogen, refined metals, ammonia, and similar products.

OTEC has important benefits other than power production.

Air conditioning
The cold [5°C (41ºF)] seawater made available by an OTEC system creates an opportunity to provide large amounts of cooling to operations that are related to or close to the plant. Salmon, lobster, abalone, trout, oysters, and clams are not indigenous to tropical waters, but they can be raised in pools created by OTEC-pumped water; this will extend the variety of seafood products for nearby markets. Likewise, the low-cost refrigeration provided by the cold seawater can be used to upgrade or maintain the quality of indigenous fish, which tend to deteriorate quickly in warm tropical regions.

The cold seawater delivered to an OTEC plant can be used in chilled-water coils to provide air-conditioning for buildings. It is estimated that a pipe 0.3-meters in diameter can deliver 0.08 cubic meters of water per second. If 6°C water is received through such a pipe, it could provide more than enough air-conditioning for a large building. If this system operates 8000 hours per year and local electricity sells for 5¢-10¢ per kilowatt-hour, it would save $200,000-$400,000 in energy bills annually (U.S. Department of Energy, 1989).

The InterContinental Resort and Thalasso-Spa on the island of Bora Bora uses an OTEC system to air-condition its buildings.[1]

Chilled-soil agriculture
OTEC technology also supports chilled-soil agriculture. When cold seawater flows through underground pipes, it chills the surrounding soil. The temperature difference between plant roots in the cool soil and plant leaves in the warm air allows many plants that evolved in temperate climates to be grown in the subtropics. The Natural Energy Laboratory maintains a demonstration garden near its OTEC plant with more than 100 different fruits and vegetables, many of which would not normally survive in Hawaii.

Aquaculture
Aquaculture is perhaps the most well-known byproduct of OTEC. Cold-water delicacies, such as salmon and lobster, thrive in the nutrient-rich, deep, seawater from the OTEC process. Microalgae such as Spirulina, a health food supplement, also can be cultivated in the deep-ocean water.

Desalination
Desalinated water can be produced in open- or hybrid-cycle plants using surface condensers. In a surface condenser, the spent steam is condensed by indirect contact with the cold seawater. This condensate is relatively free of impurities and can be collected and sold to local communities where natural freshwater supplies for agriculture or drinking are limited. System analysis indicates that a 2-megawatt (electric) (net) plant could produce about 4300 cubic meters of desalinated water each day (Block and Lalenzuela 1985).

Hydrogen Production
Hydrogen can be generated via the process of electrolysis. Electrolysis can be powered via the OTEC process and the resultant condensate can be used as a relatively pure medium with electrolyzing agents added to improve overall efficiency.

Mineral extraction
Not yet exploited to its full potential is the opportunity OTEC could provide to mine ocean water for its 57 elements dissolved in solution. In the past, most economic analyses showed that mining the ocean for trace elements dissolved in solution would be unprofitable because so much energy is required to pump the large volume of water needed and because it is so expensive to separate the minerals from seawater. However, because OTEC plants will already be pumping the water economically, the only problem to solve is the cost of the extraction process. The Japanese recently began investigating the concept of combining the extraction of uranium dissolved in seawater with wave-energy technology. They found that developments in other technologies (especially materials sciences) were improving the viability of mineral extraction processes that employ ocean energy.

The ocean as a battery ; electrical energy or electricity can be made from air and saltwater. After all, both the air and the saltwater are freely available everywhere. These are the two things that we have plenty of them.

An experimental sea-water battery
We have seen how a pair of electrodes can produce a voltage when immersed in an electrolyte. In the following experiments we use of galvanised (zinc- plated) screws and carbon rods as the electrodes and salt water as the electrolyte. While carbon is a good conductor of electricity, the chemistry that takes place at the carbon electrode is more complicated than would be the case when simply using metals. However, larger potentials are produced with carbon and zinc than with copper and zinc, so it is worth the complication. Carbon is a good conductor of electricity. In these cells the metal (zinc) electrode is negative (-) while the carbon becomes positive (+).

To get round the limited voltage and current of such a simple cell, we can join up cells to make a battery of cells - thereby increasing the power.

Making the battery; Household ice- cube trays are used to hold the electrolyte, and wood supports the multiple pairs of electrodes, a set for each ice cube tray.
Each of the ice cube trays is 3/4 filled with a salt solution (sea water or a solution of table salt in water). Galvanised screws can be purchased from any hardware store. Pencil leads can be used for the carbon rods or, better still, they can be salvaged from carefully dismantled old ('flat') batteries. Then the electrode pairs are lowered into their respective ice cube tray solutions to create the 12 cells. They are then wired-up on the top side of the wooden support to form the battery.

Wiring the the cells up in series or parallel?
So what is the best way to wire up the 12 cells to get useful power from the battery? Consider a single cell; it can produce a voltage of V volts and a maximum current of say I amps. Wiring a number (n) of these cells in series (one after the other in a sort of daisy chain) will multiply the voltage giving n x V volts. However, the maximum current produced by this arrangement will be the same as that of a single cell - I. On the other hand wiring all the cells in parallel will increase the curent n-fold but maintain the voltage equivalent to that of a single cell (i.e. V). Combinations of series and parallel cells with produce combination of possible total V and I.

The ice cube tray used in these experiments had 12 compartments (ice cubes) and so to get useful power from the battery two combinations of wiring were chosen (see Figure 2): The first a) consists of two sets of six cells wired in series and these two sets then wired in parallel - giving a total of 6 x V and 2 x I. b) consisted of two sets of six parallel parallel cells which were wired in series - giving a total of 2 x V and 6 x I.

Figure 1. two of the many possible circuit arrangements for making a battery from 12 sea water cells
Parts list:
Table 1) Salt (NaCl)
2) Ice- cube trays
3) Wood for electrode support
4) galvanised screws ( ca. 5 cm long) for each battery
5) 12 pencil leads (2B or softer), or better still, school lab carbon rods or ones salvaged from old worn out batteries
6) Tinned copper wire

This is the 'high' voltage, 'low' current version. The ice cube trays hold the electrolyte for each cell. The cells are wired up above the board.
A sea water power plant (!)
The first battery circuit provides a relatively higher voltage than the second and so it can therefore be used to power devises devices that need 'higher voltages' but low currents. A pocket LCD calculator, an LED (and series resistor), and possibly a pocket radio, will work well using this arrangement. In the demonstrations we use a simple flashing LED circuit to dramatically show the battery working. This circuit requires about 3V, but only about 1 or 2 mA to work.

Ionized solution or electrolyte flow; A magnetic field will exert a force on moving charged particle. The direction of this push depends on the direction and charge of the moving particle. This is the how electric motors work. As charged particles, electrons, move along a coil of wire they are pushed by the magnetic field from magnets in the motor housing. This push is perpendicular to the coil of wire, and causes it to spin.

An ionized solution or electrolyte, such as sea water, is caused to flow through a conduit while passing through a magnetic field produced between magnets of opposite polarity disposed in spaced relationship adjacent opposite wall portions of the conduit. Extending between these magnets are two spaced opposite conduit wall portions of electrically non-conducting porous material, such as porous ceramic material, through the pores of which the positive and negative ions in a solution such as sea water can pass. When subjected to the magnetic field extending between the magnets, the positive and negative ions are deflected laterally away from each other in opposite directions toward the porous walls, and are expelled from the conduit through the pores. The opposite but approximately parallel flow of positive and negative ions through this transverse magnetic field generates an electric current density, a very large percentage of which passes through the faces of the conduit's porous walls. The magnitude of the current density flowing out from the pores of the conduit and into the external medium is a measure of the relative concentration of salt water ions (in this case from a salt water solution) through the conduit. The magnets are preferably permanent magnets but may alternatively be electromagnets.

Sea water, flowing past the pores outside the conduit faster than the partially deionized solution inside the conduit will produce a Venturi suction which draws off some of the processed solution of lowered salinity through the pores into the outside flow stream. This forms a thin boundary layer of lowered salinity along the external porous surface of the conduit which assists in preventing the external ion intrusion mentioned above. An internal over-pressure sustained by a dynamic flow pressure along the external porous surface balances any hydrostatic pressure tending to force ions back into the conduit. The barrier is composed of electrically conducting walls separated from one another by an electrically insulating layer, and conductors electrically connected to these walls carry off current generated in operation and which may be used to actuate electrical devices in external circuits.

The general operating principle for the magnetic technology is a result of the physics of interaction between a magnetic field and a moving electric charge, in this case in the form of an ion. When ions pass through the magnetic field, a force is exerted on each ion. The forces on ions of opposite charges are in opposite directions.

This is similar to electric generation in living cells. Salt solutions in a test tube contain the same number of positive and negative charges, so they are electrically neutral. Not so in cells. In cells voltage gradients affect the movement of ions. The membrane potential, or better membrane voltage, is the difference of electric potentials between two aqueous solutions separated by a (lipid) membrane. In biology, the membrane voltage usually describes the voltage across the plasma membrane between inside and outside of a cell. Electron transport drives proton pumping from the matrix into the intermembrane space. There is no compensating movement of other charged ions, so pumping creates both a concentration gradient and a voltage gradient. Membrane potential (or transmembrane potential), is the voltage difference (or electrical potential difference) between the interior and exterior of a cell. Because the fluid inside and outside a cell is highly conductive, whereas a cell's plasma membrane is highly resistive, the voltage change in moving from a point outside to a point inside occurs largely within the narrow width of the membrane itself. Therefore, it is common to speak of the membrane potential as the voltage across the membrane.

Diffusion potentials arise when a dissociated salt diffuses from a region of higher concentration to lower concentration across a membrane when the permeabilities of the membrane to the charged species are unequal.
For example, the case of a salt that dissociates into an anion and a cation, the orientation of the membrane potential is such that the more dilute solution assumes the sign of the more mobile ion (in this case, the cation).
Molecules and ions move spontaneously down their concentration gradient (i.e., from a region of higher to a region of lower concentration) by diffusion. Molecules and ions can be moved against their concentration gradient, but this process, called active transport, requires the expenditure of energy. In the case of flowing sea water, fluid mechanics into electrical power.

Blue energy is the energy retrieved from the difference in the salt concentration between seawater and river water with the use of reverse electrodialysis (RED) (or osmosis) with ion specific membranes. The waste product in this process is brackish water. For example, an electrochemical cell may be constructed with salt water (a solution of sodium chloride) on one side of a membrane and pure water on the other. The membrane lets the positive sodium ions pass, but not the negative chlorine ions, so a net current results.

Electrodialysis is used to transport salt from one solution, the diluate, to another solution (concentrate) by applying an electric current. This is done in an electrodialysis cell providing all necessary elements for this process. The conentrate and diluate are separated by the membranes into the two different process streams (concentrate and diluate), Inside an electrodialysis unit, the solutions are separated by alternately arranged anion exchange membranes, permeable only for anions and cation exchange membranes, permeable only for cations. By this, the two kinds of compartments are formed, distinguishing in the membrane type facing the cathode's direction. Applying a current, cations within the diluate (blue compartment set) move toward the cathode passing the cation exchange membrane facing this side and anions move towards the anode passing the anion exchange membrane. A further transport of these ions, now being in a chamber of the concentrate (red compartments), is stopped by the respective next membrane:

The technology of reversed electrodialysis has been confirmed in laboratory conditions. As in common technologies, the cost of the membrane was an obstacle. A new, cheap membrane, based on an electrically modified polyethylene plastic, made it fit for potential commercial use.

The water potential between fresh water and sea water corresponds to a pressure of 26 bars. This pressure is equivalent to a column of water 270 metres high. However, the optimal working pressure is only half of this, 11 to 15 bar.

In the Netherlands, for example, more than 3,300 m3 fresh water runs into the sea per second on average. The energy potential is therefore 3,300 MW, based on an output of 1 MW/m3 fresh water.

The water potential between fresh water and sea water corresponds to a hydraulic head of 270 metres
Size
As in a fuel cell, the cells are stacked. A module with a capacity of 250 kW has the size of a shipping container.

Testing
2005 A 50 kW plant is located at a coastal test site in Harlingen, the Netherlands. The focus is on prevention of biofouling on the anode, cathode and membranes and increasing the membrane performance.

Statkraft in Norway has decided to build a osmotic power plant prototype in Hurum in Buskerud. The prototype is planned to produce 2-4 kW at the start in 2008.

The water potential between fresh water and sea water corresponds to a hydraulic head of 270 metres

Magnetohydrodynamics (MHD) (magnetofluiddynamics or hydromagnetics) Magnetohydrodynamics, or MHD, is a branch of the science of the dynamics of matter moving in an electromagnetic field, especially where currents established in the matter by induction modify the field, so that the field and dynamics equations are coupled. It treats, in particular, conducting fluids, whether liquid or gaseous, in which certain simplifying postulates are accepted.

Studies carried out in the United States, Russia, and Japan indicate that a combined cycle MHD-steam plant should be able to achieve an overall power station efficiency of at least 60 percent which is about 20 percent more than offered by a conventional steam plant. This should be possible at capital costs comparable with existing steam plants.

the dynamics of electrically conducting fluids. Examples of such fluids include plasmas, liquid metals, and salt water.

A magnetohydrodynamic drive or MHD propulsor, is a method for propelling seagoing vessels using only electric and magnetic fields with no moving parts, using magnetohydrodynamics.

An electric current is passed through seawater in the presence of an intense magnetic field, which is able to control water's lopsided molecular structure. Functionally, the seawater is then the moving, conductive part of an electric motor. Pushing the water out the back accelerates the vehicle in the forward direction.

MHD is attractive because it has no moving parts, which means that a good design might be silent, reliable, efficient, and inexpensive. MHD is accomplished by forcing an electrically conducting fluid or a plasma through a channel with a magnetic field applied across it and electrodes placed at right angles to flow and field Inasmuch as the current must pass through a magnetic field in an ionic media, a simple form of a pumping device is annular where the annulus is immersible in the ionic media.

To achieve extra high efficiencies, MHD is combined in a thermodynamic cycle with a (OTEC) plant and to the total power output to boost the overall efficiency into the very high percent range. An MHD pumping system can be coupled with Ocean thermal energy conversion (OTEC) and in which there are no moving parts.

A studv done for the Air Force (1973) concluded that magnetized water will not form scale on surfaces. Properly designed and installed magnetic units will prevent the formation of costly scale build-up. The kinetic energy to make it all happen comes from the motion of the water flowing through the magnetic field. As the water flows past the magnets, the molecules are aligned into a uniform directional field. Water regains it's solvency and will not allow the minerals to form hard crystals of scale. Further, the water will actually re-dissolve existing scale back into solution.

the dramatic temperature difference between ocean water below 3,000 feet - perpetually just above freezing - and the much warmer water and air above it. That temperature gap can be harnessed to create a nearly unlimited supply of energy. Although the scientific concepts behind cold-water energy have been around for decades, Craven made them real when he founded the state-funded Natural Energy Laboratory of Hawaii in 1974 on Keahole Point, near Kona. Under Craven, the lab developed the process of using cold deep-ocean water and hot surface water to produce electricity. By the 1980s the Natural Energy Lab's demonstration plant was generating net power, the world's first through so-called ocean thermal energy conversion.

"The potential of OTEC is great," says Joseph Huang, a senior scientist for the National Oceanic Atmospheric Administration and an expert on the process. "The oceans are the biggest solar collector on Earth, and there's enough energy in them to supply a thousand times the world's needs. OTEC News - a news site about OTEC

Combining heat pump technologies with Solar power, Geothermal power, and Magnetohydrodynamics (MHD) and Ocean thermal energy conversion (OTEC) and with the application of Blue Energy in and with the creation of a Hydrogen Economy is a near 'total solution' for all our main energy needs! This system would last far into the future as sustainable and non polluting! Further, We have the technology to do it now and it would become economical almost immediately.

With good conservation, this and other renewable energy resources and the use of new materials we can and will solve our energy crisis.

The Venus Project

OTEC can supply the backbone of Sea Communities

Combining Magnetohydrodynamics, Ocean thermal energy conversion and Blue Energy.

Ocean energy conversion to food and energy abundance! The Sea Farming applications of Heat Pump, Ion Pump, Hydrogen systems technology!!

Seasteads could provide a nucleus for burgeoning aquaculture--based upon the nutrient-rich deep ocean water routinely pumped into the OTEC generator.

Sustainable communities are communities planned, built, or modified to promote sustainable living. They tend to focus on environmental sustainability

Ecosystems are composed of organisms interacting with each other and with their environment such that energy is exchanged and system-level processes, such as the cycling of elements, emerge. The ecosystem is a core concept in Biology and Ecology, serving as the level of biological organization in which organisms interact simultaneously with each other and with their environment. As such, ecosystems are a level above that of the ecological community (organisms of different species interacting with each other) but are at a level below, or equal to, biomes and the biosphere. Essentially, biomes are regional ecosystems, and the biosphere is the largest of all possible ecosystems. Ecosystems embody the concept that living organisms continually interact with each other and with the environment to produce complex systems with emergent properties, such that "the whole is greater than the sum of its parts" and "everything is connected". The spatial boundaries, component organisms and the matter and energy content and flux within ecosystems may be defined and measured.

Sea Farming Ecovillages are intended to be socially, economically and ecologically sustainable intentional communities. Most aim for a population of 50-150 individuals because this size is considered to be the maximum social network according to findings from sociology and anthropology Larger ecovillages of up to 2,000 individuals may, however, exist as networks of smaller "ecomunicipalities" or subcommunities to create an ecovillage model that allows for social networks within a broader foundation of support.

Human development can be viewed as the process of achieving an optimum level of health and well-being. It includes physical, biological, mental, emotional, social, educational, economic, and cultural components. Only some of these are expressed in the Human Development Index, a composite scale that has three dimensions: life expectancy at birth, adult literacy rate and mean years of schooling, and income as measured by real gross domestic product per capita. Like all one-dimensional scales that attempt to measure multiple complex variables, it is flawed by inherent inaccuracies,

OTEC can be put to use in various ways, and has the potential to solve problems related to the environment, energy, water, food, and human population.

Hydrogen Production-Hydrogen gas envisioned for the future clean energy. Hydrogen is gaining attention as an eco-friendly fuel replacement for diesel fuel and gasoline. The gas can be separated from pure water by desalination plants using electrolysis. This system makes it possible to store the ocean energy for use in remote area.
Aquaculture - Deep seawater can be used in aquaculture to raise a variety of fish and shellfish, and to improve the fertility of the sea. Sea areas that have a natural upwelling of deep seawater are fertile fishing grounds because the uncontaminated and inorganic eutrophication of the deep seawater promote the voluminous propagation of phytoplankton.
Through OTEC, two types of fresh water are obtainable - distilled water and mineral water that uses deep seawater that has aged for long time containing many minerals including magnesium and calcium.
Lithium extraction - Deep seawater contains lithium and uranium. This vast natural resource can be collected and used in lithuim batteries. The demand for lithium batteries is rising rapidly with the wide spread use of cellular phones and other mobile devices.
Air Conditioning and more - Other possible uses of deep seawater are in cosmetics, medicine, cooling systems for homes and buildings and other products.

Sustainable Ocean Living--Piece by Piece

Energy Islands are floating modular renewable energy platforms that incorporate photovoltaics, solar thermal towers, wave energy, ocean current energy turbines, wind turbines, and OTEC (ocean thermal energy conversion). Designed by architect Alex Michaelis, the concept is aimed at capturing a share of Richard Branson's Virgin Earth Prize.

Each island would be built on a floating platform and at its centre would be a plant that converts heat from the tropical sea into electricity and drinking water. Below deck would be marine turbines to harness energy from underwater currents and around the edge floating devices to provide wave power.

Vegetable farms and homes for workers will complete the colony and the power will be piped back to be used on the nearest populated land mass.

Michaelis, who is working together with his father Dominic, an engineer, estimates that each island complex could produce 250MW.

NextEnergy

Combining enough Energy Island modules to form the outside of a protected lagoon, you would be on your way to renewable power, agriculture, and aquaculture for your floating city.
Aquarius is the sea-colony concept from Marshall Savage, writer of The Millenial Project. Self-sufficient Aquarius floating cities would be the first step to colonising the galaxy. The lessons learned from building sustainable and profitable colony-cities-on-the-ocean could be transferred to floating cities in outer space.

A different group has coalesced around the concept of "Seasteads". For the seastead movement, building a sustainable floating city is an end in itself.

In the past, pioneers and malcontents would head to the frontiers, of which few now exist. The oceans, which make up 71% of the earth's surface, have always been a place for those seeking new ways of life. They are the last great unclaimed region. Ships are not well suited for permanent living, but by creating new land on the oceans we can achieve both freedom and a reasonable degree of comfort.

Freedom of movement and self-sufficiency are both intimately connected with political freedom. Fixed locations such as seamounts, islands, and atolls are much more vulnerable to the whims of nearby governments [minerva link], but a mobile seastead can always move if the political climate becomes unsuitable. While a seastead is likely to import many goods, being able to supply its own basic necessities will also add greatly to its independence. This approach to nation founding reduces - but does not eliminate - the difficulty in finding sovereignty, by operating in international waters...If the seastead is parked in area that does not get regular rain storms an alternative method of fresh water replenishment is needed. Either sea water distillation or reverse osmosis will work. Both forms of sea water reclamation require pretty hefty amounts of power. Distillation can be done with solar evaporation trays and condensers; whereas reverse osmosis runs off of electricity....

Seastead Book
Seascape One, pictured above, is a combination tourist destination and high-end condominiums designed to float around the Mediterranean Sea. It incorporates multiple renewable energy features, including wind and solar power. The tall white structure projecting above the living section is a solid sail, for clean (but slow) propulsion. Lessons learned from operating such a design should be applicable to a more rough weather seastead.
Paolo Soleri designed floating arcologies which could also be classified as "seasteads." The "Nexus" floating city project is more than a little based on a Soleri design.

This is a floating city designed to accommodate 100,000 persons. 7 kilometers long and 4 kilometers wide with the capacity to be mobile, grow its own food, produce its own electricity and, owing to it existing beyond the 12 mile governmental jurisdiction boundaries, create its own government, income system and tax base. In essence, this mobile city becomes its own independent country....The city utilizes several different types of electrical power generation. Five Ocean Thermal Energy Conversion units are positioned at strategic zones of the city to supply electricity. Banks of freestanding windmills and photovoltaic solar cells produce additional electricity. The "head" of the floating city is a small mountain range with a specially designed frontal structure that cuts Tsunami tidal waves into smaller, manageable waves with little destructive effect. It is a tidal wave barrier that requires the city to head into the on-coming wave.

The energy cycle within biomes, habitats, and ecosystems determines which populations survive and which die. All living things need energy. Ultimately, the sun is the source of all energy in an ecosystem. Different species have different functions: producers, consumers, decomposers, and scavengers. Habitats must also supply water for all living things to survive. Their needs are met through the water cycle. Within each ecosystem, there are habitats which may also vary in size. A habitat is the place where a population lives. A population is a group of living organisms of the same kind living in the same place at the same time. All of the populations interact and form a community. The community of living things interacts with the non-living world around it to form the ecosystem. The habitat must supply the needs of organisms, such as food, water, temperature, oxygen, and minerals. If the population's needs are not met, it will move to a better habitat. Two different populations can not occupy the same niche at the same time, however. So the processes of competition, predation, cooperation, and symbiosis occur. Famous manmade biomes are Biosphere 2 and Eden project..

BIOSPHERE 2 & EDEN PROJECT

Sustainable development is a prerequisite for the long-term health of humans. It refers to a systematic approach to achieving human development in a way that sustains planetary resources, based on the recognition that human consumption is occurring at a rate that is beyond Earth's capacity to support it. Population growth and the developmental pressures spawned by an unequal distribution of wealth are two major driving forces that are altering the planet in ways that threaten the long-term health of humans and other species on the planet.

Human health is dependent on the healthy functioning of the earth's ecosystem. These systems would be overwhelmed if all of the earth's inhabitants were to match the consumption patterns of wealthier nations. Sustainable development requires alterations in the lifestyle of the wealthy to live within the carrying capacity of the environment.

Environmental design is the process of addressing environmental parameters when devising plans, programs, policies, buildings, or products. Environmental Design encompasses the built, natural, and human environments and focuses on fashioning physical and social interventions informed by human behaviour and environmental processes. Design asks us to find answers to the most fundamental of human questions: how should we live in the world and what should inform our actions? This complex endeavour requires an interdisciplinary approach."

The word permaculture, coined by Australians Bill Mollison and David Holmgren during the 1970s, is a portmanteau of permanent agriculture as well as permanent culture. Through a series of publications, Mollison, Holmgren and their associates documented an approach to designing human settlements, in particular the development of perennial agricultural systems that mimic the structure and interrelationship found in natural ecologies.

Permaculture design principles extend from the position that "The only ethical decision is to take responsibility for our own existence and that of our children" (Mollison, 1990). The intent was that, by rapidly training individuals in a core set of design principles, those individuals could become designers of their own environments and able to build increasingly self-sufficient human settlements — ones that reduce society's reliance on industrial systems of production and distribution that Mollison identified as fundamentally and systematically destroying the earth's ecosystems.
Elements of permaculture design
Permaculture principles draw heavily on the practical application of ecological theory to analyze the characteristics and potential relationships between design elements. Each element of a design is carefully analyzed in terms of its needs, outputs, and properties. For example a chicken needs water, moderated microclimate, food and other chickens, and produces meat, eggs, feathers and manure while doing a lot of scratching. Design elements are then assembled in relation to one another so that the products of one element feed the needs of adjacent elements. Synergy between design elements is achieved while minimizing waste and the demand for human labour or energy. Exemplary permaculture designs evolve over time, and can become extremely complex mosaics of conventional and inventive cultural systems that produce a high density of food and materials with minimal input. While techniques and cultural systems are freely borrowed from organic agriculture, sustainable forestry, horticulture, agroforestry, and the land management systems of indigenous peoples, permaculture's fundamental contribution to the field of ecological design is the development of a concise set of broadly applicable organizing principles that can be transferred through a brief intensive training.

Modern permaculture
Modern permaculture is a system design tool. It is a way of

1. looking at a whole system or problem
2. seeing connections between key elements (parts)
3. observing how the parts relate,
4. planning to mend sick systems by applying ideas learnt from long-term sustainable working systems.
In permaculture, we are learning from the working systems of nature to plan to fix the sick landscapes of human agricultural and city systems. We can apply systems thinking to the design of a kitchen tool as easily to the re-design of a farm. In permaculture we apply it to everything we need in order to build a sustainable future.

Ecological energetics provides information on the energetic interdependence of organisms within ecological systems and the efficiency of energy transfer within and between organisms and trophic levels. Nearly all energy enters the biota by green plants' transformation of light energy into chemical energy through photosynthesis; this is referred to as primary production. This accumulation of potential energy is used by plants, and by the animals which eat them, for growth, reproduction, and the work necessary to sustain life. The energy put into growth and reproduction is termed secondary production. As energy passes along the food chain to higher trophic levels (from plants to herbivores to carnivores), the potential energy is used to do work and in the process is degraded to heat. The laws of thermodynamics require the light energy fixed by plants to equal the energy degraded to heat, assuming the system is closed with respect to matter. An energy budget quantifies the energy pools, the directions of energy flow, and the rates of energy transformations within ecological systems

Summary of Permaculture Zones
ZONE 0 — The house, or home centre. Here permaculture principles would be applied in terms of aiming to reduce energy and water needs, harnessing natural resources such as sunlight, and generally creating a harmonious, sustainable environment in which to live, work and relax
ZONE 1 — Is the zone nearest to the house, the location for those elements in the system that require frequent attention, or that need to be visited often, e.g., salad crops, herb plants, soft fruit like strawberries or raspberries, greenhouse and cold frames, propagation area, worm compost bin for kitchen waste, etc.
ZONE 2 — This area is used for siting perennial plants that require less frequent maintenance, such as occasional weed control (preferably through natural methods such as spot-mulching) or pruning, including currant bushes and orchards. This would also be a good place for beehives, larger scale compost bins, etc.
ZONE 3 — Is the area where maincrops are grown, both for domestic use and for trade purposes. After establishment, care and maintenance required are fairly minimal provided mulches, etc. are used, e.g., watering or weed control once a week or so.
ZONE 4 — Is semi-wild. This zone is mainly used for forage and collecting wild food as well as timber production. An example might be coppice-managed woodland.
ZONE 5 — Is wild. There is no human intervention in zone 5 apart from the observation of natural eco-systems and cycles. Here is where we learn the most important lessons of the first permaculture principle of working with, rather than against, nature.

First and fundamentally, independence is a matter of degree. Complete independence is very hard or impossible to attain. For example, eliminating dependence on the electrical grid is one thing, and growing all of your own food is a more demanding and time-consuming proposition.

Energy-efficient landscaping is a type of landscaping designed for the purpose of conserving energy. There is a distinction between the embedded energy of materials and constructing the landscape, and the energy consumed by the maintenance and operations of a landscape.

Design techniques include:

Planting trees for the purpose of providing shade, which reduces cooling costs.
Planting or building windbreaks to slow winds near buildings, which prevents heat loss.
Wall sheltering, where shrubbery or vines are used to create a windbreak directly against a wall.
Earth sheltering and positioning buildings to take advantage of natural landforms as windbreaks.
Green roofs that cool buildings with extra thermal mass and evapotranspiration.
Reducing the heat island effect with pervious paving, high albedo paving, shade, and minimizing paved areas.
Site lighting with full cut off fixtures, light level sensors, and high efficiency fixtures
Energy-efficient landscaping techniques include using local materials, on-site composting and chipping to reduce greenwaste hauling, hand tools instead of gasoline-powered, and also may involve using drought-resistant plantings in arid areas, buying stock from local growers to avoid energy in transportation, and similar techniques.

Sustainable landscape architecture is a category of sustainable design concerned with the planning and design of outdoor space. This can include ecological, social and economic aspects of sustainability. For example, the design of a sustainable urban drainage system can: improve habitats for fauna and flora; improve recreational facilities, because people love to be beside water; save money, because building culverts is expensive and floods cause severe financial harm.

The design of a green roof or a roof garden can also contribute to the sustainability of a landscape architecture project. The roof will help manage surface water, provide for wildlife and provide for recreation.

Composting toilet
A composting toilet is any system that converts human waste into a organic compost and usable soil, through the natural breakdown of organic matter into its essential minerals. Aerobic microbes do this in the presence of moisture and air, by oxidizing the carbon in the organic material to carbon dioxide gas, and converting hydrogen atoms to water vapour.

Types
Remote composting system"Self-contained" composting toilets complete the composting "in-situ,", while "central unit" ones flush waste to a remote composting unit below the toilet. Vacuum flush systems can flush horizontally or up.

Composting toilets can be installed anywhere, such as a cabin, cottage, bunkie, yurt, RV, pool cabana, boat, shed, barn, or home.

Some composting toilets use electricity, and some electrical systems use fans to exhaust air and increase microbial activity. Others require the user to simply rotate a drum within the composting toilet to allow for an aerobic breakdown of waste.

Rate of decomposition in a large composting toilet facilitySome composting toilets have a large compartment below the toilet. Others are little larger than a traditional toilet.

Accumulated solids after 30yrs in Clivus MultrumAll composting toilets eventually need some end-product removal. A full size composting toilet does not need to have solids removed for several decades if the active tank volume is at least three times the yearly addition. This is because the waste dramatically decreases in volume -- after around 5 years only 1-2% of the original volume remains. It is then a mineralized soil which will not decompose any further. Other smaller systems may need to remove solids several times a year.

Sheet composting is the process of composting organic matter directly onto the soil as a mulch and letting it decay there, rather than in a heap. Most commonly, this is achieved by sowing a 'green manure' crop such as mustard, alfalfa, or buckwheat, which is then hoed in, preferably just before flowering. This practice can cause temporary nitrogen depletion, but this can be reduced by employing leguminous green manure crops such as lupin, winter tares, field beans, or clover, which are able to fix their own nitrogen supply in root nodules. The nitrogen is then released as the plants decay.

Proponents of this system argue that sheet composting causes fewer nutrients to be lost through leaching than heap methods, also that fresh organic matter provides a slower release of minerals when applied than when decayed. It is also said that, in the long term, sheet composting leads to higher nitrogen levels in the soil, as much is lost by vaporisation when a traditional heap heats up.

Vermicompost (also called worm compost, vermicast, worm castings, worm humus or worm manure) is the end-product of the breakdown of organic matter by some species of earthworm. Vermicompost is a nutrient-rich, natural fertilizer and soil conditioner. The process of producing vermicompost is called vermicomposting .

The earthworm species (or composting worms) most often used are Red Wigglers (Eisenia foetida) or Red Earthworms (Lumbricus rubellus). These species are commonly found in organic rich soils throughout europe and north america and especially prefer the special conditions in rotting vegetation, compost and manure piles. Composting worms are available from nursery mail-order suppliers or angling shops where they are sold as bait. Small-scale vermicomposting is well suited to turn kitchen waste into high-quality soil, where space is limited.

Together with bacteria, earthworms are the major catalyst for decomposition in a healthy vermiposting system although other soil species also play a contributing role other organisms such as insects, mold

Organic horticulture is the science and art of growing fruits, vegetables, flowers, or ornamental plants by following the essential principles of organic agriculture in soil building and conservation, pest management, and heritage-species preservation. Mulches, cover crops, compost, manures, and ground-rock mineral supplements are soil-building mainstays. Through care and good soil condition, it is hoped that insect, fungal,or other problems that sometimes plague plants can be avoided. However, pheromone traps, insecticidal soap sprays, and other pest-control methods available to organic farmers are also sometimes utilized by organic horticulturists.

Horticulture involves five areas of study. These areas are floriculture (includes production and marketing of floral crops), landscape horticulture (includes production, marketing and maintenance of landscape plants), olericulture (includes production and marketing of vegetables), pomology (includes production and marketing of fruits), and postharvest physiology (involves maintaining quality and preventing spoilage of horticultural crops). All of these can be, and sometimes are, pursued according to the principles of organic cultivation.

Organic horticulture (or organic gardening) is based on knowledge and techniques gathered over thousands of years. In general terms, organic horticulture involves natural processes, often taking place over extended periods of time, and a holistic approach - while chemical-based horticulture focuses on immediate, isolated effects and reductionist strategies.

Organic gardening systems
There are a number of formal organic gardening and farming systems that prescribe specific techniques. They tend to be more specific than, and fit within, general organic standards. Biodynamic farming is an approach based on the esoteric teachings of Rudolf Steiner. The Japanese farmer and writer Masanobu Fukuoka invented a no-till system for small-scale grain production that he called Natural Farming. French intensive and biointensive methods and SPIN Farming (Small Plot INtensive) are all small scale gardening techniques.

Biodynamic® agriculture is a method of organic farming that treats farms as unified and individual organisms,[1] emphasizing balancing the holistic development and interrelationship of the soil, plants, animals as a closed, self-nourishing system.[2] Regarded by some proponents as the first modern ecological farming system,[3] biodynamic farming includes organic agriculture's emphasis on manures and composts and exclusion of the use of artificial chemicals on soil and plants. Methods unique to the biodynamic approach include the use of fermented herbal and mineral preparations as compost additives and field sprays and the use of a astronomical calendar to determine times of planting and harvesting.[4] Biodynamic agriculture has its basis in a spiritual world-view known as anthroposophy as propounded by founder Rudolf Steiner.

Biodynamic method of farming
Biodynamic agriculture conceives of the farm as an organism, a self-contained entity with its own individuality. "Emphasis is placed on the integration of crops and livestock, recycling of nutrients, maintenance of soil, and the health and well being of crops and animals; the farmer too is part of the whole."[5] Cover crops, green manures and crop rotations are used extensively.

No-till farming, also known as conservation tillage or zero tillage is a way of growing crops from year to year without disturbing the soil through tillage. Cultivation technique in which the soil is disturbed only along the slit or hole into which seeds are planted. Reserved detritus from previous crops covers and protects the seedbed. Primary benefits are a decreased rate of soil erosion; reduced need for equipment, fuel, and fertilizer; and significantly less time required for tending crops. The method also improves soil-aggregate formation, microbial activity in the soil, and water infiltration and storage.

Seed balls (土団子,土だんご,Tsuchi Dango {Earth Dumpling}) consist of mixing the seed for next season's crop with clay, compost, and sometimes manure then formed into small balls. Much less seed is used than in conventional growing, resulting in fewer plants which are smaller but stronger with a higher yield.

The term self-sufficiency is usually applied to varieties of sustainable living in which nothing is consumed outside of what is produced by the self-sufficient individuals. Examples of attempts at self-sufficiency in North America include voluntary simplicity, Luddism, homesteading, survivalism, and the back-to-the-land movement The term is also applied to more limited forms of self-sufficiency, for example growing one's own food or becoming economically independent of state subsidies.

Practices that enable or aid self-sufficiency include autonomous building, permaculture, sustainable agriculture, and renewable energy.

The existence of an effectively closed system makes self-sufficiency a necessity for any form of space colonization, and to an extent ocean colonization. An experimental attempt to achieve self-sufficiency could therefore include the Biosphere 2 project.

The following is a hieratical assessment of needs to be fulfilled progressively:

1. Housing and land for necessities production e.g. including entertainment, sporting and agricultural considerations.

2. Water and waste management e.g. rain, grey and brown water capture and processing.

3. Energy including household, transport and agricultural consumption e.g. fuel cell plant and equipment.

4. Means to produce marketable goods and services e.g. home call-centre to support highly specialized or skilled industries globally.

Simple living (or voluntary simplicity) is a lifestyle in which individuals consciously choose to minimize the 'more-is-better' pursuit of wealth and consumption. Adherents choose simple living for a variety of reasons, including spirituality, health, increase in 'quality time' for family and friends, stress reduction, conservation, social justice or anti-consumerism, while others choose to live more simply for reasons of personal taste or personal economy.

Simple living as a concept is distinguished from those living in forced poverty, as it is a voluntary lifestyle choice. Although asceticism may resemble voluntary simplicity, proponents of simple living are not all ascetics. The term "downshifting" is often used to describe the act of moving from a lifestyle of greater consumption towards a lifestyle based on voluntary simplicity.

Sustainable living might be defined as a lifestyle that could, hypothetically, be sustained without exhausting any natural resources. The term can be applied to individuals or societies. Its adherents most often hold true sustainability as a goal or guide, and make lifestyle tradeoffs favoring sustainability.

Most often these tradeoffs involve transport, housing, energy, and diet. Lester R. Brown concisely summarizes the situation as "sustaining progress depends on shifting from a fossil fuel-based, automobile-centered, economy to a renewable energy-based, diversified transport, reuse/recycle economy".

Sustainable architecture is framed by the larger discussion of sustainability and the pressing economic and political issues of our world. In the broad context, sustainable architecture, seeks to minimize the negative environmental impact of buildings by enhancing efficiency and moderation in the use of materials, energy, and development space.

Natural building involves a range of building systems and materials that place major emphasis on sustainability. Ways of achieving sustainability through natural building focus on durability and the use of minimally-processed, plentiful or renewable resources, as well as those which, while recycled or salvaged, produce healthy living environments and maintain indoor air quality. Natural building tends to rely on human labor, more than technology. As Michael G. Smith observes, it depends on "local ecology, geology and climate; on the character of the particular building site, and on the needs and personalities of the builders and users."[1]

The basis of natural building is the need to lessen the environmental impact of buildings and other supporting systems, without sacrificing comfort, health or aesthetics.[2] To be more sustainable, natural building uses primarily abundantly-available, renewable, reused or recycled materials. The use of rapidly renewable materials is increasingly a focus. An emphasis on building compactly and minimizing the ecological footprint is common, as are on-site handling of energy acquisition, on-site water capture, alternate sewage treatment and water reuse.

The materials common to many types of natural building are clay and sand. When mixed with water and, usually, straw or another fiber, the mixture may form cob or adobe (clay blocks). Other materials commonly used in natural building are: earth (as rammed earth or earth bag), wood (cordwood or timber frame/post-and-beam), straw, rice-hulls, bamboo and rock. A wide variety of reused or recycled materials are common in natural building, including urbanite (salvaged chunks of used concrete), tires, tire bales, discarded bottles and other recycled glass.

Several other materials are increasingly avoided by many practitioners of this building approach, due to their major negative environmental or health impacts. These include unsustainably-harvested wood, toxic wood-preservatives, portland cement-based mixes, paints and other coatings which off-gas volatile organic compounds (VOCs), and some plastics, particularly polyvinyl chloride (PVC or "vinyl") and those containing harmful plasticizers or hormone-mimicking formulations.

Superinsulation
The passivhaus standard combines superinsulation with other techniques and technologies to achieve ultra-low energy use.Superinsulation is an approach to building design, construction, and retrofitting. A superinsulated house is intended to be heated predominantly by intrinsic heat sources (waste heat generated by appliances and the body heat of the occupants), without using passive solar building design techniques or large amounts of thermal mass, and with very small amounts of backup heat. This has been demonstrated to work in very cold climates but requires close attention to construction details in addition to the insulation.

Some may consider that superinsulation is an alternative to passive solar design (although many building designs include features of both with special attention to preventing summer overheating). Superinsulation is one of the ancestors of the passive house approach. A related approach to efficient building design may be zero energy building

There is no set definition of superinsulation, but superinsulated buildings typically include:

Very thick insulation (typically R40 walls and R60 roof)
Detailed insulation where walls meet roofs, foundations, and other walls
Airtight construction, especially around doors and windows
a heat recovery ventilator to provide fresh air
No large windows facing any particular direction (unlike passive solar, which uses large windows facing the sun and fewer/smaller windows facing other directions).
No large amounts of thermal mass
No active or passive solar heat (but may have solar water heating and/or hot water heat recycling)
No conventional heating system, just a small backup heater

A zero energy building (ZEB) or net zero energy building is a general term applied to a building with a net energy consumption of zero over a typical year. This can be measured in different ways (relating to cost, energy, or carbon emissions) and, irrespective of the definition used, different views are taken on the relative importance of energy generation and energy conservation to achieve energy balance.

Off-grid buildings often rely very little on civil services and are therefore safer and more comfortable during civil disaster or military attacks. (Off-grid buildings would not lose power or water if public supplies were compromised for some reason.)

Living in an autonomous shelter can require one to make sacrifices in one's lifestyle choices, personal behavior, and social expectations. Even the most comfortable and technologically advanced autonomous houses may require some differences in behavior. Some persons adjust easily. Others describe the experience as inconvenient, irritating, isolating, or even as an unwanted full-time job. A well-designed building can reduce this issue, but usually at the expense of reduced autonomy.

An autonomous house must be custom-built (or extensively retrofitted) to suit the climate and location. Passive solar techniques, alternative toilet and sewage systems, thermal massing designs, basement battery systems, efficient windowing, and the array of other design tactics require some degree of non-standard construction, added expense, ongoing experimentation and maintenance, and also have an effect on the psychology of the space.

Most of the research and published articles concerning autonomous building focus on residential homes.

British architects Brenda and Robert Vale have said that, as of 2002, "It is quite possible in all parts of Australia to construct a 'house with no bills', which would be comfortable without heating and cooling, which would make its own electricity, collect its own water and deal with its own waste...These houses can be built now, using off-the-shelf techniques. It is possible to build a "house with no bills" for the same price as a conventional house, but it would be (25%) smaller."[citation needed]

Theory
As an architect or engineer becomes more concerned with the disadvantages of transportation networks, and dependence on distant resources, their designs tend to include more autonomous elements. The historic path to autonomy was a concern for secure sources of heat, power, water and food. A nearly parallel path toward autonomy has been to start with a concern for environmental impacts, which cause disadvantages.

Autonomous buildings can increase security and reduce environmental impacts by using on-site resources (such as sunlight and rain) that would otherwise be wasted. Autonomy often dramatically reduces the costs and impacts of networks that serve the building, because autonomy short-circuits the multiplying inefficiencies of collecting and transporting resources. Other impacted resources, such as oil reserves and the retention of the local watershed, can often be cheaply conserved by thoughtful designs.

Autonomous buildings are usually energy-efficient in operation, and therefore cost-efficient, for the obvious reason that smaller energy needs are easier to satisfy off-grid. But they may substitute energy production or other techniques to avoid diminishing returns in extreme conservation.

An autonomous structure is not always environmentally friendly. The goal of independence from support systems is associated with, but not identical to, other goals of environmentally responsible green building. However, autonomous buildings also usually include some degree of sustainability through the use of renewable energy and other renewable resources, producing no more greenhouse gases than they consume, and other measures.

History
In the 1930s through the 1950s, Buckminster Fuller's three prototype Dymaxion houses adopted many techniques to reduce resource use, such as a "fogger" shower head to reduce water use, a packaging toilet, and a vacuum turbine for electric power. While not designed as autonomous per se, Fuller's concern with sustainable and efficient design is congruent with the goal of autonomy, and showed that it was theoretically possible. One of the three prototype Dymaxion houses that Fuller produced was made part of the conventional Graham family residence in Wichita, Kansas, and has now been reconstructed at the Henry Ford Museum.

In the 1970s, a group of activists and engineers calling themselves the New Alchemists believed the warnings of imminent resource depletion and starvation. The New Alchemists were famous for the depth of research effort placed in their projects. Using conventional construction techniques, they designed a series of "bioshelter" projects, the most famous of which was the Ark Bioshelter community for Prince Edward Island. They published the plans for all of these, with detailed design calculations and blueprints. The Ark used wind based water pumping and electricity, and was self-contained in food production. It had living quarters for people, fish tanks raising Tilapia for protein, a greenhouse watered with fish water and a closed loop sewage reclamation system that recycled human waste into sanitized fertilizer for the fish tanks. As of 2007, the successor organization to the New Alchemists still had a web page up as the [1]. The PEI Ark has been abandoned and partially renovated several times.

The 1990s saw the development of Earthships, similar in intent to the Ark project, but organized as a for-profit venture, with construction details published in a series of 3 books by Mike Reynolds. The building material is tires filled with earth. This makes a wall that has large amounts of thermal mass (see earth sheltering). Berms are placed on exposed surfaces to further increase the house's temperature stability. The water system starts with rain water, processed for drinking, then washing, then plant watering, then toilet flushing, and finally black water is recycled again for more plant watering. The cisterns are placed and used as thermal masses. Power, including electricity, heat and water heating, is from solar power.

1990s architects such as William McDonough and Ken Yeang applied environmentally responsible building design to large commercial buildings, such as office buildings, making them largely self-sufficient in energy production. One major bank building (ING's Amsterdam headquarters) in the Netherlands was constructed to be autonomous and artistic as well.

Practicality
First and fundamentally, independence is a matter of degree. Complete independence is very hard or impossible to attain. For example, eliminating dependence on the electrical grid is one thing, and growing all of your own food is a more demanding and time-consuming proposition.

Living in an autonomous shelter can require one to make sacrifices in one's lifestyle choices, personal behavior, and social expectations. Even the most comfortable and technologically advanced autonomous houses may require some differences in behavior. Some persons adjust easily. Others describe the experience as inconvenient, irritating, isolating, or even as an unwanted full-time job. A well-designed building can reduce this issue, but usually at the expense of reduced autonomy.

An autonomous house must be custom-built (or extensively retrofitted) to suit the climate and location. Passive solar techniques, alternative toilet and sewage systems, thermal massing designs, basement battery systems, efficient windowing, and the array of other design tactics require some degree of non-standard construction, added expense, ongoing experimentation and maintenance, and also have an effect on the psychology of the space.

Water
Water is the most important utility, and is fast becoming a scarce resource. There are many methods of collecting and conserving water. Use reduction is cost-effective.

The classic solution with minimal life-style changes is a proven well. However drilling a well is an uncertain activity, and can be expensive. Well water can be contaminated in some areas, and is depleted in others. Also, once drilled, a well-foot requires substantial power. However, advanced well-foots can reduce power usage by twofold or more from older models. The sono arsenic filter eliminates unhealthy arsenic in well water.

It is often more economical to design a building to use rain, with supplementary water deliveries in a drought. Rain water makes excellent soft washwater. A small reverse osmosis unit can provide drinking water.

Bottled water for drinking is often inexpensive, taste-tested, premineralized, with controlled mineral and bacterial counts. It harms autonomy, but can dramatically improve health and lifestyle in a home with autonomous water sources.

Greywater systems reuse drained wash water to flush toilets, and water lawns and gardens. Greywater systems can halve the water use of most residential buildings; however, they require the purchase of a sump, greywater pressurization pump and secondary plumbing. Some builders are installing waterless urinals and even composting toilets that completely eliminate water usage in sewage disposal.

Most desert and temperate climates get at least 250 mm (10 in) of rain per year. This means that a typical one story house with a greywater system can supply its year-round water needs from its roof alone. In the most extremely dry areas, it will require a cistern of 30 m³ (8400 U.S. gallons). Many areas average 13 mm (0.5 in) of rain per week, and these can use a cistern as small as 10 m³. It can be convenient to use the cistern as a heat sink or trap for a heat pump or air conditioning system; however this can make cold drinking water warm, and in drier years the efficiency of the HVAC system may decrease.

Cistern design can reduce costs and inconvenience. Gravity tanks on short towers are reliable, so pump repairs are less urgent. The least expensive bulk cistern is a fenced pond or pool at ground level.

The size and expense of a cistern can be reduced substantially when supplemented with water deliveries. Many autonomous homes can reduce water use below ten gallons per person per day. In a drought, water can be delivered to the house inexpensively via truck. Self delivery is possible by installing fabric water-tanks that can fit inside the bed of a pick-up truck.

In many areas, it is difficult to keep a roof clean enough to assure that the water collected is clean enough for drinking. Commercial reverse osmosis systems provide good quality drinking water, and some people attach devices to remineralize drinking water afterwards.

Solar stills can efficiently produce drinking water, especially high-efficiency multiple effect humidification designs, which separate the evaporator(s) and condenser(s).

New technologies, like reverse osmosis, and Aquosus, can create unlimited amounts of pure water from polluted water, ocean water, and even from humid air. Water makers are available for yachts that convert seawater and electricity into potable water and brine. Atmospheric water generators like the Vapaire extract moisture from dry desert air and filter it to pure water.

Sewerage

Sewerage as a resource
The approaches above treat human excrement as a waste rather than a resource. Humanure is composted human excrement, and can return nutrients to a garden. Recycling human excrement requires minimal life-style changes.

In the case of composting toilets, units of varying size can be used to naturally decompose human faeces into a highly useful odourless and safe compost. Without further research most health authorities forbid use of "humanure" for growing food directly in the compost (See Humanure by Joseph Jenkins). The risk is microbial and viral contamination.

State of the art home sewage treatment systems use biological treatment, usually beds of plants and aquaria, that eliminate nutrients and bacteria and convert greywater and sewage to clear water. This odor- and color-free reclaimed water can be used to flush toilets and water outside plants. When tested, it approaches standards for potable water. In climates that freeze, the plants and aquaria need to be kept in a small greenhouse space. Good systems need about as much care as a large aquarium.

Electric incinerating toilets turn excrement into a small amount of ash. They are cool to the touch, have no water and no pipes, and require an air vent in a wall. They are used in remote areas where access to septic tank resources are limited.

NASA's bioreactor is an extremely advanced biological sewage system. It can turn sewage into air and water through microbial action. NASA plans to use it in the manned Mars mission.

A big disadvantage of biological sewage treatment systems is that if the house is empty, the sewage system biota starve to death.

Another method is NASA's urine-to-water distillation system.

Sewerage as a waste
Sewage handling is not attractive, but it is essential for public health. Many diseases are transmitted by poorly functioning sewage systems.

The standard system is a tiled leach field combined with a septic tank. The basic idea is to provide a small system with primary sewage treatment. Sludge settles to the bottom of the septic tank, is partially reduced by anaerobic digestion, and fluid is dispersed in the leach field. The leach field is usually under a yard growing grass. Septic tanks can operate entirely by gravity, and if well managed, are reasonably safe.

Septic tanks have to be pumped periodically by a honey wagon to eliminate non reducing solids. Failure to pump a septic tank can cause overflow that damages the leach field, and contaminates ground water. Septic tanks may also require some lifestyle changes, such as not using garbage disposals, minimizing fluids flushed into the tank, and minimizing nondigestible solids flushed into the tank. For example, septic safe toilet paper is recommended.

However, septic tanks remain popular because they permit standard plumbing fixtures, and require few or no lifestyle sacrifices.

Composting or packaging toilets make it economical and sanitary to throw away sewage as part of the normal garbage collection service. They also reduce water use by half, and eliminate the difficulty and expense of septic tanks. However, they require the local landfill to use sanitary practices.

Incinerator systems are quite practical. The ashes are biologically safe, and less than 1/10 the volume of the original waste, but like all incinerator waste, are usually classified as hazardous waste.

Some of the oldest pre-system sewage types are pit toilets, latrines, and outhouses. These are still used in many developing countries.

Storm drains
Drainage systems are a crucial compromise between human habitability and a secure, sustainable watershed. Paved areas and lawns or turf do not allow much precipitation to filter through the ground to recharge aquifers. They can cause flooding and damage in neighbourhoods, as the water flows over the surface towards a low point.

Typically, elaborate, capital-intensive storm sewer networks are engineered to deal with stormwater. In some cities, such as the Victorian era London sewers or much of the old City of Toronto, the storm water system is combined with the sanitary sewer system. In the event of heavy precipitation, the load on the sewage treatment plant at the end of the pipe becomes too great to handle and raw sewage is dumped into holding tanks, and sometimes into surface water.

Autonomous buildings can address precipitation in a number of ways:

If a water absorbing swale for each yard is combined with permeable concrete streets, storm drains can be omitted from the neighbourhood. This can save more than $500 per house (1995) by eliminating storm drains. One way to use the savings is to purchase larger lots, which permits more amenities at the same cost. Permeable concrete is an established product in warm climates, and in development for freezing climates. In freezing climates, the elimination of storm drains can often still pay for enough land to construct swales (shallow water collecting ditches) or water impeding berms instead. This plan provides more land for homeowners and can offer more interesting topography for landscaping.

A green roof captures precipitation and uses the water to grow plants. It can be built into a new building or used to replace an existing roof.

Electricity
Since electricity is an expensive utility, the first step towards conservation is to design a house and lifestyle to reduce demand. Fluorescent lights, laptop computers and gas-powered refrigerators save both electricity and money.There are also superefficient electric refrigerators, such as those produced by the Sun frost company, which use 85% less energy than normal.

Using a solar roof, solar cells can provide electric power. Solar roofs are far more cost-effective than retrofitted solar power, because buildings need roofs anyway. Modern solar cells last about 40 years, which makes them a reasonable investment in some areas. Solar cells have only small life-style impacts: The cells must be cleaned a few times per year.

A number of areas that lack sun have wind. To generate power, the average autonomous house needs only one small wind generator, 5 m or less in diameter. On a 30 m high tower, this turbine can provide enough power to supplement solar power on cloudy days. Commercially available wind turbines use sealed, one-moving-part AC generators and passive, self-feathering blades for years of operation without service.

The largest advantage of wind power is that larger wind turbines have a lower per-watt cost than solar cells, provided there is wind. However, location is critical. Just as some locations lack sun for solar cells, some locations lack sufficient wind for an economical turbine installation. Paul Gipe (a recognized authority, see below) says that in the Great Plains of the United States a 10 m turbine can supply enough energy to heat and cool a well-built all-electric house. Economic use in other areas requires research, and possibly a site-survey.

During times of low demand, excess power can be stored in batteries for future use. However, batteries need to be replaced every few years. In many areas, battery expenses can be eliminated by attaching the building to the electric power grid and operating the power system with net metering. Utility permission is required, but such cooperative generation is legally mandated in some areas (e.g. California).

A grid-based building is less autonomous, but more economical and sustainable with fewer lifestyle sacrifices. In rural areas the grid's cost and impacts can be reduced by using single wire earth return systems.

In areas that lack access to the grid, battery size can be reduced by including a generator to recharge the batteries during extended fogs or other low-power conditions. Auxiliary generators are usually run from propane, natural gas, or sometimes diesel. An hour of charging usually provides a day of operation. Modern residential chargers permit the user to set the charging times, so the generator is quiet at night.

Recent advances in passively stable magnetic bearings may someday permit inexpensive storage of power in a flywheel in a vacuum. Well-funded groups like Canada's Ballard Power Systems are also working to develop a "regenerative fuel cell," a device that can generate hydrogen and oxygen when power is available, and combine these efficiently when power is needed.

Earth batteries tap electric currents in the earth called telluric current. They can be installed anywhere in the ground. They provide only low voltages and current. They were used to power telegraphs in the 19th century. As appliance efficiencies increase, they may become practical.

Heating
Passive solar heating can heat most buildings in even the coldest climates. In colder climates, extra construction costs can be as little as 15% more than new, conventional buildings. In warm climates, those having less than two weeks of frosty nights per year, there is no cost impact.

The basic requirement for passive solar heating is that the solar collectors must face the prevailing sunlight (south in the northern hemisphere, north in the southern hemisphere), and the building must incorporate thermal mass to keep it warm in the night.

The least expensive solar heating systems use the ground beneath a building for thermal mass. Precipitation can carry away the heat, so the ground is shielded with 6m skirts of plastic insulation. The thermal mass of this system is sufficiently inexpensive and large that it can store enough summer heat to warm a building for the whole winter, and enough winter cold to cool the building in summer. This "passive annual solar heating" is practical even in regions that get little or no sunlight in winter.

In passive annual systems, the solar collector is often separate from (and hotter or colder than) the living space. The building is often constructed from insulation, e.g. Straw-bale construction. Some buildings have been aerodynamically designed so that convection via ducts and interior spaces eliminates any need for electric fans.

A more modest "daily solar" design uses windows, R-30 insulation and a smaller thermal mass. Modern krypton- or argon-insulated windows permit normal-looking windows to provide passive solar heat without compromising insulation or structural strength. If a small heater is available for the coldest nights, a slab or basement cistern can inexpensively provide the required thermal mass.

In all systems, a small supplementary heater increases personal security and reduces lifestyle impacts for a small reduction of autonomy. The two most popular heaters for ultra-high-efficiency houses are a small heat pump, which also provides air-conditioning, or a central hydronic (radiator) air heater with water recirculating from the water heater.

Earth sheltering and windbreaks can also reduce the absolute amount of heat needed by a building. Several feet below the earth, temperature ranges from 4°C (40 °F) in North Dakota to 26 °C (80 °F)[2], in Southern Florida. Wind breaks reduce the amount of heat carried away from a building.

Rounded, aerodynamic buildings also lose less heat.

An increasing number of commercial buildings use a combined cycle with cogeneration to provide heating, often water heating, from the output of a natural gas reciprocating engine, gas turbine or stirling electric generator.[3][dead link]

Houses designed to cope with interruptions in civil services generally incorporate a wood stove, or heat from diesel fuel or bottled gas, regardless of their other heating mechanisms.

Electric heaters and electric stoves provide pollution-free heat, but use large amounts of electricity. If enough electricity is provided by solar panels, wind turbines, or other means, then electric heaters and stoves become a practical autonomous design.

Water heating
Solar water heaters are widely useful because they can save large amounts of fuel. Also, small changes in lifestyle, such as doing laundry, dishes and bathing on sunny days, can greatly increase their efficiency. To further increase the efficiency of water heating, either with or without solar, hot water heat recycling units recover heat from drainlines thereby increasing water heating capacity and reducing the energy used to heat water.

The basic trick in a solar water heating system is to use a well-insulated holding tank. Some systems are vacuum insulated, acting something like large Thermos bottles. The tank is filled with hot water on sunny days, and made available at all times. Unlike a conventional tank water heater, the tank is filled only when there is sunlight.

Good storage makes a smaller, higher-technology collector feasible. Such collectors can use relatively exotic technologies, such as vacuum insulation, and reflective concentration of sunlight.

Current practical, comfortable water-heating systems combine the solar heating system with a thermostatic gas-powered flow-through heater, so that the temperature of the water is consistent, and the amount is unlimited. This again reduces life-style impacts at some cost in autonomy.

However, this compromise can still save 50-75% of the gas otherwise used, and the resulting system is redundantly reliable. If either system fails, the other can continue to provide hot water until the equipment is repaired, fuel or sunlight becomes available, etc.

Some authorities advocate that natural gas be replaced by methane digesters, fueled by composting human excrement and kitchen scraps. However, the biowaste of single family is usually insufficient to produce enough methane for anything more than cooking.

If enough land is available, biodiesel "co-gen" can produce both electricity and hot water from oil crops grown on-site.

Cooling
Earth sheltering or annualized passive solar systems substantially reduce the cooling needed by a building. In temperate climates several feet below the earth the average temperature ranges from 4 °C (40 °F) in North Dakota to 26 °C (80 °F), in Southern Florida. Annualized passive solar buildings often have buried, sloped water-tight skirts of insulation that extend 6 m (20 ft) from the foundations, to prevent heat leakage between the earth used as thermal mass, and the surface.

Less dramatic improvements are possible. Windows can be shaded in summer. Eaves can be overhung to provide the necessary shade. These also shade the walls of the house, reducing cooling costs.

Another trick is to cool the building's thermal mass at night, and then cool the building from the thermal mass during the day. It helps to be able to route cold air from a sky facing radiator (perhaps an air heating solar collector with an alternate purpose) or evaporative cooler directly through the thermal mass. On clear nights, even in tropical areas, sky facing radiators can cool below freezing.

If a circular building is aerodynamically smooth, and cooler than the ground, it can be passively cooled by the "dome effect." Many installations have reported that a reflective or light colored dome induces a local vertical heat driven vortex that sucks cooler overhead air downward into a dome if the dome is vented properly (a single overhead vent, and peripheral vents). Some persons have reported a temperature differential as high as 8 °C (15 °F) between the inside of the dome and the outside. Buckminster Fuller discovered this effect with a simple house design adapted from a grain silo, and adapted his Dymaxion house and geodesic domes to use it.

Refrigerators and air conditioners operating from the waste heat of a diesel engine exhaust, heater flue or solar collector are entering use. These use the same principles as a gas refrigerator. Normally, the heat from a flue powers an "absorptive chiller." The cold water or brine from the chiller is used to cool air or a refrigerated space.

Cogeneration is popular in new commercial buildings. In current cogeneration systems small gas turbines or stirling engines powered from natural gas produce electricity and their exhaust drives an absorptive chiller, heats water.

A truck trailer refrigerator operating from the waste heat of a tractor's diesel exhaust was demonstrated by NRG Solutions, Inc. NRG developed a hydronic ammonia gas heat exchanger and vaporizer, the two essential new, not commercially available components of a waste heat driven refrigerator.

A similar scheme (multiphase cooling) can be by a multistage evaporative cooler. The air is passed through a spray of salt solution to dehumidify it, then through a spray of water solution to cool it, then another salt solution to dehumidify it again. The brine has to be regenerated, and that can be done economically with a low temperature solar still. Multiphase evaporative coolers can lower the air's temperature by 50F, and still control humidity. If the brine regenerator uses high heat, they also partially sterilise the air.

If enough electric power is available, cooling can be provided by conventional air conditioning using a heat pump.

Food
Food production has often been included in historic autonomous projects to provide security. Skilled, intensive gardening can support an adult from as little as 15 square meters of land. Some proven intensive, low-effort food-production systems include hydroponics, and forest gardening.

Communication
Telephone and network service will probably be purchased.

A increasing number of activists provide free or very inexpensive web and email services using cooperative computer networks that run wireless ad hoc networks. Network service is provided by a cooperative of neighbors, each operating a router as a household appliance. These minimize wired infrastructure, and its costs and vulnerabilities.

Rural electrical grids can be wired with "optical phase cable", in which one or more of the steel armor wires are replaced with steel tubes containing fiber optics.[4]

Satellite Internet access also can provide high speed connectivity to remote locations, but as of 2002, most of these services are limited in which types of network hardware and operating systems they support. They are also not yet on par with the costs of cable modem or DSL service providers.

Straw-bale construction is a building method that uses straw bales as structural elements, insulation, or both. It is commonly used in natural building. It has advantages over some conventional building systems because of its cost and easy availability, and its high insulation value.

Although grasses and straw have been in use in a range of ways in building since pre-history around the world, their incorporation in machine-manufactured modular bales seems to date back to the early 20th century in the midwestern United States, particularly the sand-hills of Nebraska, where grass was plentiful and other building materials (even quality sods) were not.

Methodology
Straw bale building typically consists of stacking rows of bales (often in running-bond) on a raised footing or foundation, with a moisture barrier between the bales and their supporting platform. Bale walls are often tied together with pins of bamboo, rebar, or wood (internal to the bales or on their faces), or with surface wire meshes, and then stuccoed or plastered, either with a cement-based mix, lime-based formulation, or earth/clay render. Bale buildings can have a structural frame of other materials, with bales simply serving as insulation and stucco substrate, ("infill" technique). Alternatively, the bales may actually provide the structural support for the building ("load-bearing" or "Nebraska-style" technique). A combination of framing and load-bearing techniques may also be employed, referred to as "hybrid" straw bale construction.

Typically, bales created on farms with baling machines have been used ("field-bales"), but recently higher-density "recompressed" bales (or "straw-blocks") are increasing the loads that may be supported; where field bales might support around 600 pounds per linear foot of wall, the high density bales bear up to 4,000 lb./lin.ft. and more. The basic bale-building method is now increasingly being extended to bound modules of other often-recycled materials, including tire-bales, as well as those of cardboard, paper, plastics and used carpeting, and to bag-contained "bales" of wood-chips, rice-hulls, etc.

Cob is a building material consisting of clay, sand, straw, water, and earth, similar to adobe. Cob is fireproof, resistant to seismic activity, and inexpensive. It can be used to create artistic, sculptural forms and has been revived in recent years by the natural building and sustainability movements. The walls of a cob house were generally about 24 inches thick, and windows were correspondingly deepset giving the homes a characteristic internal appearance. The thick walls provided excellent thermal mass which was easy to keep warm in winter and cool in summer. Walls with a high thermal mass value act as a temperature fly wheel inside the home. Surprisingly, the material held up really well in rainy climates, so long as a cob house was built with a tall foundation wall and a large roof overhang.

Rammed earth
Rammed earth walls form part of the entrance building for the Eden Project in Cornwall, England. Rammed earth wall surface detail. Apart from the patches of damage, the surface shows regular horizontal lines from the wooden form work used in constructing the wall and subtler horizontal strata from the successive compacted layers of earth used to build the wall.Rammed earth construction, also known as pisé de terre or simply pisé, is an age-old building method that has seen a revival in recent years as people seek low-impact building materials and natural building methods. Traditionally, rammed earth buildings are common in arid regions where wood is in scarce supply.

Rammed earth construction is a process of compressing a damp mixture of earth that has suitable proportions of sand, gravel and clay (sometimes with an added stabilizer) into an external supported frame that molds the shape of a wall section creating a solid wall of earth. Traditional stabilizers such as lime or animal blood were used to stabilise the material, but cement has been the stabilizer of choice for modern times. After compressing the earth the wall frames can be immediately removed and require an extent of warm dry days after construction to dry and harden. The structure can take up to two years to completely cure, and the more it cures the stronger the structure becomes. When the process is complete it is much like constructing a hand made wall of solid rock.

Formwork is set up creating the desired shape of the section of wall, damp material is poured in to a depth of between 100 to 250mm (4 to 10 inches). A pneumatically powered backfill tamper - something like a hand-held pogo stick with a flat plate on the bottom or even a manual tamper- is then used to compact the material to around 50% of its original height. Further layers of material are added and the process is repeated until the wall has reached the desired height. The wall is so solid that if desired the forms can be removed immediately. This is necessary if wire brushing to reveal texture is desired otherwise walls become too hard to brush after around 60 minutes. Walls take some time to dry out completely, but this does not prevent further work on the project. Any exposed walls should be sealed to prevent water damage - there are several proprietary products specifically designed to seal earth walls.

In modern variations of the method the rammed earth walls are constructed on top of conventional footings or a reinforced concrete base, sometimes with extra ground insulation from a horizontal layer of styrofoam. Some builders also add coloured oxides or other items such as bottles or pieces of timber to add variety to the structure.

Once completely cured the walls are very workable. It is easy to drive a nail or screw into them and they can be patched if necessary with the result being undetectable if the same material was used.

One of the significant benefits of rammed earth constructions is its excellent thermal mass; it heats up slowly during the day and releases its heat during the evening. This can even out daily temperature variations and reduce the need for air conditioning and heating. On the other hand, rammed earth is not a good insulator. Like brick and concrete (which also have excellent thermal mass), rammed earth is often insulated in colder climates. The thickness and density of the walls lends itself naturally to soundproofing and the materials used in the walls make them virtually fireproof.

Prior to the use of cement as a stabilizer, rammed earth buildings were most successful in dry climates with limited availability of building materials other than earth. Rammed earth has become a viable material in wetter climates, either through the use of cement stabilisation, through placing the earth walls within the weatherproof fabric of the building, or by the application of external insulation and weatherproofing.

Rammed earth in green building
Rammed earth structures are beneficial for natural building because they can utilize locally available materials with little embodied energy and harmful waste. Earth is a widely available building material with virtually no side effects associated with harvesting for use in construction. The earth used is typically subsoil, leaving topsoil readily available for agricultural uses. Often the soil can be used on the site where the construction takes place reducing cost and energy used for transportation. It is also affordable to build with, as the materials are inexpensive or free. It is a viable building material for low- income builders with help from unskilled workers, friends, or family. Today more than 30 percent of the world's population uses earth as a building material.

Compressing the earth can be done manually using a tamper made of a heavy flat bottom plate connected to a long vertical handle. Using a pneumatically powered tamper the material can be compressed with much less manual labor. Although the cost of material is low, constructing rammed earth without mechanical tools is a time consuming project. With a mechanical tamper and the forms ready it can take about two to three days to construct the walls for a 2000-2200 sq foot house.[2]

Rammed earth buildings reduce the need for lumber because the forms used are removable and can then be reused for different rammed earth wall construction.[3] The forms are usually made of reinforced plywood, but sheet metal or even glass fiber can be used. The form wall faces must be externally reinforced with laterally running beams to prevent outward bending of the wall faces during the compression process. The two opposing wall faces must be clamped together and the wall edges need to be securely compressed between the form faces to withstand the high amounts of pressure created during compression.

The USDA observed that rammed earth structures last indefinitely and could be built for no more than two-thirds the cost of standard frame houses. Rammed earth can carry a heavy load and using re-bar, wood or bamboo reinforcement can prevent failure caused by earthquakes or heavy storms. Mixing cement with the soil mixture can also increase the structure's load bearing capacity. The compression strength of rammed earth can be up to 625 pounds per square inch. This is only two-thirds the value of a similar thickness of concrete, but a rammed earth building is still a useful durable material.Termites won’t infest rammed earth walls and the material is reusable, biodegradable and highly fire resistant. The walls require no toxic treatments and have no risk of off-gassing toxic fumes, making it ideal for chemically sensitive dwellers.[4] Properly built rammed earth can withstand loads for thousands of years as the history of rammed earth structures around the world has proven. Stucco can finish the walls in almost any color or style; untouched the walls have the color and texture of natural earth. Blemishes can also be patched up using the soil mixture as a plaster and sanded smooth.

In the UK it has been suggested that a compression strength of 2N/mm² (290 pounds per square inch) should be assumed in the absence of data derived from testing of the earth that will be used.Concrete typically used in UK construction is mixed off site and has a compression strength of 12-16N/mm² (1700-2300 pounds per square inch, from a cube strength fcu = 30N/mm² to 40N/mm²), around seven times stronger than rammed earth. However, there are many factors that affect the width of a wall, so a plain concrete wall will not necessarily be much thinner than an equivalent in rammed earth.

Rammed earth is not only an economically viable construction technique, it results in pleasant, and energy-efficient buildings. The density and thickness of rammed earth makes it so that hot or cold temperature penetration has a slow rate of thermal conductivity. Warmth takes almost 12 hours to work its way through a 14 inch thick wall.[citation needed] The walls provide good thermal mass, which helps keep indoor temperatures stable, particularly in regions with dramatic daily temperature changes. The half-day rate of heat transfer and thermal mass of the material makes rammed earth a practical material for passive solar buildings. Rammed earth has been a popular choice for buildings where temperature fluctuations need to be kept to a minimum. It can be used in cooler climates but must be protected from heavy rain and insulated with vapor barriers.

Typically rammed earth walls are about 12 to 14 inches thick making them ideal for humidity control and noise barriers from traffic, furnaces, compressors, fans or ducts. Rammed earth also allows more air exchange than concrete structures allowing the building to breathe and not become clammy without significant heat loss as the material mass absorbs the temperature as the wall breathes

Earth sheltering is the architectural practice of using earth against building walls for external thermal mass, to reduce heat loss, and to easily maintain a steady indoor air temperature. Earth sheltering is popular among advocates of passive solar and sustainable architecture, but the idea has been around for nearly as long as humans have been constructing their own shelter. Types of Construction
Earth berming Earth is piled up against exterior walls and packed, sloping down away from the house. The roof may, or may not be, fully earth covered, and windows/openings may occur on one or more sides of the shelter. Due to the building being above grade, less moisture problems are associated with earth berming in comparison to underground/fully recessed construction.
In-hill construction The house is set into a slope or hillside. The most practical application is using a hill facing towards the equator (south in the Northern Hemisphere and north in the Southern Hemisphere). There is only one exposed wall in this type of earth sheltering, the wall facing out of the hill, all other walls are embedded within the earth/hill.
Underground/ fully recessed construction The ground is excavated, and the house is set in below grade. It can also be referred to as an Atrium style due to the common atrium/courtyard constructed in the middle of the shelter to provide adequate light and ventilation.

Benefits
The benefits of earth sheltering are numerous. They include: taking advantage of the earth as a thermal mass, offering extra protection from the natural elements, energy savings, providing substantial privacy, efficient use of land in urban settings, shelters have low maintenance requirements, and earth sheltering commonly takes advantage of passive solar building design.

Landscape and site planning
The site planning for an earth sheltered building is an integral part of the overall design; investigating the landscape of a potential building site is crucial. There are many factors to assess when surveying a site for underground construction. The topography, regional climate, vegetation, water table and soil type of varying landscapes all play dynamic roles in the design and application of earth shelters.

A green roof is a roof of a building that is partially or completely covered with vegetation and soil, or a growing medium, planted over a waterproofing membrane. This does not refer to roofs which are merely colored green, as with green shingles. It may also include additional layers such as a root barrier and drainage and irrigation systems. Container gardens on roofs, where plants are maintained in pots, are not generally considered to be true green roofs, although this is an area of debate. The term "green roof" may also be used to indicate roofs that utilize some form of "green" technology, such as solar panels or a photovoltaic module. Green roofs are also referred to as eco-roofs, vegetated roofs, living roofs, and greenroofs.

Benefits of green roofs
Green roofs are used to:

Provide amenity space for building users — in effect replacing a yard or patio
Grow fruits, vegetables, and flowers
Reduce heating (by adding mass and thermal resistance value) and cooling (by evaporative cooling) loads on a building — especially if it is glassed in so as to act as a terrarium and passive solar heat reservoir
Reduce the urban heat island effect
Increase roof life span
Reduce stormwater run off — see water-wise gardening
Filter pollutants and CO2 out of the air — see living wall
Filter pollutants and heavy metals out of rainwater
Increase wildlife habitat in built-up areas — see urban wilderness
A green roof is often a key component of an autonomous building.