Alternative Fuels

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Posted by pompos 02/26/2009 @ 18:02

Tags : alternative fuels, energy, sciences

News headlines
IN FOCUS: Alternative fuels - The State
As a counterpoint to the Tuesday op-eds by Shannon Baxter-Clemmons (“Fuel-cell research essential to energy , economic future”) and Larry Wilson (“Fuel cells helping SC meet world energy challenge”) in support of hydrogen research, readers should note...
US to Issue Tougher Fuel Standards for Automobiles - New York Times
In 2006, during his second year as a United States senator, he co-sponsored a bill to raise fuel economy standards and another to encourage the use of alternative fuels. During the presidential campaign, he gave a speech in Detroit chastising the...
Four ways to solve the energy crisis - Seattle Post Intelligencer
Because the ethanol lobby has managed to place huge tariffs on ethanol produced abroad while freezing out the development of other alternative fuels at home. It portrays itself as this sort of savior, the domestic solution to our reliance on foreign...
Scientists Work To Plug Microorganisms Into The Energy Grid - Science Daily (press release)
When it comes to alternative fuels, currently ethanol is king. Almost all ethanol produced in the United States is fermented from readily available sugars in corn starch or corn kernels. Producing ethanol from corn has also come under much criticism...
PAFC, LGU, farmers sign jatropha deal - Business Mirror
Alternative Fuels Corp. (PAFC) said on Monday it signed a tripartite agreement for the development of a 2000-hectare jatropha plantation in Montalban, Rizal. “With the signing of the tripartite pact, the efforts of PAFC, the local government of...
Biofuel Production Will Continue to Grow - Seeking Alpha
Henry Ford was an early 20th-century visionary of alternative fuels, and planned on having his early cars powered by ethanol. In fact, his first Model T could run on gasoline combined with a biofuel alcohol mix. The car's 10 gallon (38 litre) fuel tank...
Solutions to the Draft Waxman Bill Expose Design Flaw in US ETS - Huffington Post
Domestic Green building offsets would allow regulated industries an alternative way to comply with regulatory obligations by letting them choose between reducing their own emissions or purchasing Green Building offsets from others who were able to...
ORNL Rises To The Energy Efficiency Challenge - Knoxville City View
ORNL also plays a major role in the nation's agenda for alternative fuels for transportation. In 2005 Laboratory researchers authored the seminal Billion Ton Study, which determined that the nation has sufficient biomass that can be converted to...
More officers in blue are driving green - Boston Globe
Based on a Globe sample of a few local municipalities, Framing ham, Lexington, Natick, Newton, and Waltham have joined Concord in adding hybrids or alternative-fuel vehicles to their fleets, while Ashland, Marlborough, and Pepperell have not....

Alternative fuel

Typical Brazilian filling station with four alternative fuels for sale: biodiesel (B3), gasohol (E25), neat ethanol (E100), and compressed natural gas (CNG). Piracicaba, São Paulo, Brazil.

Alternative fuels, also known non-conventional fuels, are any materials or substances that can be used as a fuel, other than conventional fuels. Conventional fuels include: fossil fuels (petroleum (oil), coal, propane, and natural gas), and nuclear materials such as uranium.

Some well known alternative fuels include biodiesel, bioalcohol (methanol, ethanol, butanol), chemically stored electricity (batteries and fuel cells), hydrogen, non-fossil methane, non-fossil natural gas, vegetable oil and other biomass sources.

The main purpose of fuel is to store energy in a form that is stable and can be easily transported from the place of production to the end user. Almost all fuels are chemical fuels, which store chemical potential energy. The end user may consume the fuel at will and release energy, usually in the form of heat, for a variety of applications, such as powering an engine or heating a building.

In 2007, there were 1.8 million alternative fuel vehicles sold in the United States, indicating an increasing popularity of alternative fuels. There is growing perceived economic and political need for the development of alternative fuel sources. This is due to general environmental, economic, and geopolitical concerns of sustainability.

The major environmental concern, according to an IPCC report, is that "Most of the observed increase in globally averaged temperatures since the mid-20th century is due to the observed increase in anthropogenic greenhouse gas concentrations" . Since burning fossil fuels are known to increase greenhouse gas concentrations in the atmosphere, they are a likely contributor to global warming.

Other concerns which have fueled demand revolve around the concept of Peak oil, which predicts rising fuel costs as production rates of petroleum enters a terminal decline. According to the Hubbert peak theory, when the production levels peak, demand for oil will exceed supply and without proper mitigation this gap will continue to grow as production drops, which could cause a major energy crisis.

In an attempt to increase demand for alternative fuels in the US, the IRS began allowing taxpayers to claim a special tax credit for using alternative fuels, known as the Alternative Fuel Vehicle Refueling Property Credit. The definition used for alternative fuel under this credit is: Any fuel containing at least 85 percent of one or more of ethanol, natural gas, compressed natural gas, liquefied natural gas, liquefied petroleum gas, or hydrogen; or any mixture which consists of two or more of biodiesel, diesel fuel, or kerosene, and at least 20% of which consists of biodiesel.

The production of alternative fuels can have widespread effects. For example, the production of corn-based ethanol has created an increased demand for the feed stock, causing rising prices in almost everything made from corn. However, in a competitive free market, an increased supply of ethanol reduces the demand for conventional fuels, and thus lowers fuel prices. The ethanol industry enables agricultural surpluses to be used to mitigate fuel shortages.

Renewable energy is energy from renewable resources such as wind power, solar power, tidal power, geothermal power, hydropower, or thermal depolymerization. Biofuels are also considered renewable if their source is sustainable. Although renewable energy is used mostly to generate electricity, it is often assumed that some form of renewable energy or at least sustainable energy is used to create alternative fuels. Several alternative fuels however, such as nuclear fuel and alternative fossil fuels, are made from non-sustainable sources, and fuels for Hydrogen fuel cells and air engines can be created by non-sustainable means as well. Such non-sustainable fuels are offered as alternatives usually because they cause less pollution at the point of use.

Biomass in the energy production industry refers to living and recently dead biological material which can be used as fuel or for industrial production. Biomass is grown from several plants, including miscanthus, switchgrass, hemp, corn, poplar, willow, sugarcane, oil palm (palm oil), and algae oil.

Most commonly, biomass refers to plant matter grown for use as biofuel, but it also includes plant or animal matter used for production of fibres, 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.

Methanol and ethanol are typically not primary sources of energy; however, they are convenient fuels for storing and transporting energy. These alcohols can be used in internal combustion engines such as flexible fuel vehicles with minor modifications.

Methanol can be produced from a wide variety of sources including fossil fuels, but also agricultural products and municipal waste, wood and varied biomass. More importantly, it can also be made from chemical recycling of carbon dioxide (such as from the CO2 rich flue gases of fossil fuel burning power plants or exhaust of cement and other factories, of even atmospheric CO2). Ethanol can be mass-produced by fermentation of the starch or sugar in a wide variety of crops (bio-ethanol), or by hydration of ethylene from petroleum and other sources.

There has been considerable debate about how useful bio-ethanol will be in replacing fossil fuels in vehicles. Concerns relate to the large amount of arable land required for crops, as well as the energy and pollution balance from the ethanol production cycle . Recent developments with cellulosic ethanol production and commercialization may allay some of these concerns.

Methanol as a fuel also has several disadvantages.

Hydrogen as a fuel has been suggested to have the capability to create a hydrogen economy. However, there is no accessible natural reserve of uncombined hydrogen, since what little there is resides in Earth's outer atmosphere. Therefore, hydrogen for use as fuel must first be produced using another energy source, making it a means to transport energy, rather than an energy source, similar to a rechargeable battery. One existing method of hydrogen production is steam methane reformation; however, this method requires methane (most commonly available as natural gas), which raises sustainability concerns. Another method of hydrogen production is through electrolysis of water, in which electricity generated from any source can be used. Photoelectrolysis, biohydrogen, and biomass or coal gasification have also been proposed as means to produce hydrogen.

According to the majority of energy experts and researchers, hydrogen is currently impractical as an alternative to fossil-based liquid fuels. While hydrogen has a very high energy content by weight, it has a very low energy content by volume, making it very challenging to store in average sized vehicles. Hydrogen can be stored as compressed hydrogen, as cryogenic liquid hydrogen, or in compounds containing hydrogen which must undergo a chemical change to release the gas such as metal hydrides. However, because of the lower volumetric energy, hydrogen gas tanks would need to be 2-3 times as large for compressed hydrogen storage as conventional gasoline tanks.

The production of the fuel cells for hydrogen cars are often expensive as most designs require large amounts of platinum as a catalyst. Other concerns involve the fragility of the fuel cell and their tendency to freeze, the flammability of hydrogen, and vehicle and infrastructure production costs. Currently, due to efficiencies of scale, it is more efficient to burn fossil fuels to produce hydrogen than to burn oil directly in car engines.

The air engine is an emission-free piston engine using compressed air as fuel. Unlike hydrogen, compressed air is about one-tenth as expensive as fossil oil, making it an economically attractive alternative (hydrogen is about 10 times more expensive than oil or 100 times more expensive than compressed air). The air engine has also broken most barriers (storage of the energy, range, ....). Models exist which can achieve speeds over 35 mph with air alone, but at least one company claims it will produce an "Air Car" hybrid by 2010 which will be able to achieve over 100 mpg with a top speed of 96 mph.

Compressed natural gas (CNG) is a cleaner burning alternative to conventional petroleum automobile fuels. The energy efficiency is generally equal to that of gasoline engines, but lower compared with modern diesel engines. CNG vehicles require a greater amount of space for fuel storage than conventional gasoline power vehicles because CNG takes up more space for each GGE (Gallon of Gas Equivalent). Almost any existing gasoline car can be turned into a bi-fuel (gasoline/CNG) car. However, natural gas is a finite resource like all fossil fuels, and production is expected to peak soon after oil does.

There are large but finite coal reserves which may increasingly be used as a fuel source during oil depletion. The Fischer-Tropsch process converts carbon dioxide, carbon monoxide into heavier hydrocarbons, including synthetic oil. It is used today in South Africa to produce most of that country's diesel from coal. The Karrick process is an improved methodology for coal liquefaction, with higher efficiency. Since there are large but finite coal reserves in the world, this technology could be used as an interim transportation fuel if conventional oil were to become scarce. There are several companies developing the process to enable practical exploitation of so-called stranded gas reserves, those reserves which are impractical to exploit with conventional gas pipelines and LNG technology.

Methane hydrate is a form of natural gas. This substance consists of methane molecules trapped within the crystalline structure of water ice and is found in deposits under ocean sediments or within continental sedimentary rock formations. It is estimated that the global inventory of methane hydrate may equal as much as 10x the amount of natural gas. With current technology, most gas hydrate deposits are unlikely to be commercially exploited as an energy source. In addition, the combustion of methane releases the greenhouse gas carbon dioxide into the atmosphere. Methane is also a greenhouse gas. In other respects methane hydrate has the same problems of fossil fuel.

Nuclear power is any nuclear technology designed to extract usable energy from atomic nuclei via controlled nuclear reactions. The most common method today is through nuclear fission, though other methods include nuclear fusion and radioactive decay. All current methods involve heating a working fluid such as water, which is then converted into mechanical work for the purpose of generating electricity or propulsion. Today, more than 15% of the world's electricity comes from nuclear power, over 150 nuclear-powered naval vessels have been built, and a few radioisotope rockets have been produced.

Fission reactors use the U-235 isotope of uranium for fuel. While uranium is a fairly common element, the U-235 isotope is relatively rare. Using current reactor technology and current usage levels, and assuming an economical price of extraction, there is approximately 50 years of viable uranium available. Alternative reactor technologies exist which can use the much more common U-238 isotope, but these breeder reactors have technical issues (resulting from the higher levels of heat and radiation produced) to overcome before they can be employed economically.

Since automobiles and trucks consume a great deal of the total energy budget of developed countries, widespread electric vehicles technology would be required to convert the energy generated from nuclear power to transportation.

The long-term radioactive waste storage problems of nuclear power have not been solved, although on-site spent fuel storage in casks has allowed power plants to make room in their spent fuel pools. Today, the only industrial solution lies with storage in underground repositories. There are widespread public concerns about the health-risks, security risks and radioactive waste disposal problems of nuclear materials.

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Environment of Tennessee

The geological environment of Tennessee is as diverse as its landscapes. Politically, Tennessee is broken up into three Grand Divisions: East, Middle, and West Tennessee. Physically, Tennessee is also separated into three main types of landforms: river valley plain, highlands and basins, and mountains.

The environment of Tennessee includes the nature centers of Discovery Center at Murfree Spring, Lichterman Nature Center and Owl's Hill Nature Center.

Executive Order 54 establishes the Energy Policy Task Force with the goal of creating a new state energy plan by December 1 of 2008. .

Another order establishes the Interagency Alternative Fuels Working Group with the goal of making Tennessee a leader in the biofuels industry. . The Working Group came up with an Alternative Fuels Strategic Plan which lays out goals for increasing biofuel and feedstock production and displacing petroleum use.

Public Chapter 489 (2007) requires all agencies and state educational institutions to create plans by January 1, 2008 to reduce or displace petroleum use in government fleet vehicles by 20%. .

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Flexible-fuel vehicle

The 2003 VW Gol 1.6 Total Flex was the first full flexible-fuel vehicle produced and sold in Brazil, capable of running on any blend of gasoline (E20 to E25) and ethanol up to E100.

A flexible-fuel vehicle (FFV) or dual-fuel vehicle (colloquially called a flex-fuel vehicle) is an alternative fuel vehicle with a internal combustion engine designed to run on more than one fuel, usually gasoline blended with either ethanol or methanol fuel, and both fuels are stored in the same common tank. Flex-fuel engines are capable of burning any proportion of the resulting blend in the combustion chamber as fuel injection and spark timing are adjusted automatically according to the actual blend detected by electronic sensors. Flex-fuel vehicles are distinguished from bi-fuel vehicles, where two fuels are stored in separate tanks and the engine runs on one fuel at a time.

The most common commercially available FFV in the market is the ethanol flexible-fuel vehicle, with more than 14 million automobiles and light duty trucks on the roads around the world by mid-2008, and concentrated in four markets, the United States (7.3 million), Brazil (6.2 million), Canada (600,000), and Europe, led by Sweden (126,500). In addition to flex-fuel vehicles running with ethanol, in Europe and the US, mainly in California, there have been successful test programs with methanol flex-fuel vehicles, known as M85 flex-fuel vehicles. There have been also successful tests using P-series fuels with E85 flex fuel vehicles, but as of June 2008, this fuel is not yet available to the general public. These successful tests with P-series fuels were conducted on Ford Taurus and Dodge Caravan flexible-fuel vehicles.

Though technology exists to allow ethanol FFVs to run on any mixture of gasoline and ethanol, from pure gasoline up to 100% ethanol (E100), North American and European flex-fuel vehicles are optimized to run on a maximum blend of 15% gasoline with 85% anhydrous ethanol (called E85 fuel). This limit in the ethanol content is set to reduce ethanol emissions at low temperatures and to avoid cold starting problems during cold weather, at temperatures lower than 11 °C (52 °F). The alcohol content is reduced during the winter in regions where temperatures fall below 0 °C (32 °F) to a winter blend of E70 in the U.S. or to E75 in Sweden from November until March. Brazilian flex fuel vehicles are optimized to run on any mix of E20-E25 gasoline and up to 100% hydrous ethanol fuel (E100). The Brazilian flex vehicles are built-in with a small gasoline reservoir for cold starting the engine when temperatures drop below 15 °C (59 °F). An improved flex motor generation that will be launched in 2009 is designed to eliminate the need for the secondary gas tank.

As ethanol FFVs became commercially available during the late 1990s, the common use of the term "flexible-fuel vehicle" became synonymous with ethanol FFVs. In the United States flex-fuel vehicles are also known as "E85 vehicles". In Brazil, the FFVs are popularly known as "total flex" or simply "flex" cars. In Europe, FFVs are also known as "flexifuel" vehicles. Automakers, particularly in Brazil and the European market, use badging in their FFV models with the some variant of the word "flex", such as Volvo Flexifuel, or Volkswagen Total Flex, or Chevrolet FlexPower or Renault Hi-Flex, and Ford sells its Focus model in Europe as Flexifuel and as Flex in Brazil. In the US, only newer FFV models feature a yellow gas cap with the label "E85/Gasoline" written on the top of the cap to differentiate E85s from gasoline only models, and just recently, GM introduced badging with the text "Flexfuel/E85 Ethanol".

Flexible-fuel vehicles (FFVs) are based on dual-fuel systems that supply both fuels into the combustion chamber at the same time in various calibrated proportions. The most common fuels used by FFVs today are unleaded gasoline and ethanol fuel. Ethanol FFVs can run on pure gasoline, pure ethanol (E100) or any combination of both. Methanol has also been blended with gasoline in flex-fuel vehicles known as M85 FFVs, but their use has been limited mainly to demonstration projects and small government fleets, particularly in California.

The first commercial flexible fuel vehicle was the Ford Model T, produced from 1908 through 1927. It was fitted with a carburetor with adjustable jetting, allowing use of gasoline or ethanol, or a combination of both. Other car manufactures also provided engines for ethanol fuel use. Henry Ford continued to advocate for ethanol as fuel even during the prohibition. However, cheaper oil caused gasoline to prevail, until the 1973 oil crisis resulted in gasoline shortages and awareness on the dangers of oil dependence. This crisis opened a new opportunity for ethanol and other alternative fuels, such as methanol, gaseous fuels such as CNG and LPG, and also hydrogen. Ethanol, methanol and natural gas CNG were the three alternative fuels that received more attention for research and development, and government support.

Since 1975, and as a response to the shock caused by the first oil crisis, the Brazilian government implemented the National Alcohol Program -Pró-Álcool- (Portuguese: Programa Nacional do Álcool), a nationwide program financed by the government to phase out automotive fuels derived from fossil fuels in favor of ethanol made from sugar cane. It began with a low blend of anhydrous alcohol with regular gasoline in 1976, and since July 2007 the mandatory blend is 25% of alcohol or gasohol E25. In 1979, and as a response to the second oil crisis, the first vehicle capable of running with pure hydrous ethanol (E100) was launched to the market, the Fiat 147, after testing with several prototypes developed by Fiat, Volkswagen, GM and Ford. The Brazilian government provided three important initial drivers for the ethanol industry: guaranteed purchases by the state-owned oil company Petrobras, low-interest loans for agro-industrial ethanol firms, and fixed gasoline and ethanol prices. After reaching more than 4 million cars and light trucks running on pure ethanol by the late 1980s, the use of E100-only vehicles sharply declined after increases in sugar prices produced shortages of ethanol fuel.

After extensive research that began in the 90s, a second push took place in March 2003, when the Brazilian subsidiary of Volkswagen launched to the market the first full flexible-fuel car, the Gol 1.6 Total Flex. Several months later was followed by other Brazilian automakers, and by 2008 General Motors, Fiat, Ford, Peugeot, Renault, Volkswagen, Honda, Mitsubishi, Toyota and Citröen were producing popular models of flex cars and light trucks. The adoption of ethanol flex fuel vehicles was so successful, that production of flex cars went from almost 40 thousand in 2003 to 1.7 million in 2007. This rapid adoption of the flex technology was facilitated by the fuel distribution infrastructure already in place, as around 27,000 filling stations countrywide were available by 1997 with at least one ethanol pump, a heritage of the Pró-Álcool program.

In the United States, initial support to develop alternative fuels by the government was also a response to the first oil crisis, and some time later, as a goal to improve air quality. Also, liquid fuels were preferred over gaseous fuels not only because they have a better volumetric energy density but also because they were the most compatible fuels with existing distribution systems and engines, thus avoiding a big departure from the existing technologies and taking advantage of the vehicle and the refueling infrastructure. California led the search of sustainable alternatives with interest focused in methanol. Ford Motor Company and other automakers responded to California's request for vehicles that run on methanol. In 1981, Ford delivered 40 dedicated methanol fuel (M100) Escorts to Los Angeles County, but only four refueling stations were installed. The biggest challenge in the development of alcohol vehicle technology was getting all of the fuel system materials compatible with the higher chemical reactivity of the fuel. Methanol was even more of a challenge than ethanol but, fortunately, much of the early experience gained with ethanol vehicle production in Brazil was transferable to methanol. The success of this small experimental fleet of M100s led California to request more of these vehicles, mainly for government fleets. In 1983, Ford built 582 M100 vehicles; 501 went to California, and the remaining to New Zealand, Sweden, Norway, United Kingdom, and Canada.

As an answer to the lack of refueling infrastructure, Ford began development of a flexible-fuel vehicle in 1982, and between 1985 and 1992, 705 experimental FFVs were built and delivered to California and Canada, including the 1.6L Ford Escort, the 3.0L Taurus, and the 5.0L LTD Crown Victoria. These vehicles could operate on either gasoline or methanol with only one fuel system. Legislation was passed to encourage the US auto industry to begin production, which started in 1993 for the M85 FFVs at Ford. In 1996, a new FFV Ford Taurus was developed, with models fully capable of running on either methanol or ethanol blended with gasoline. This ethanol version of the Taurus became the first commercial production of an E85 FFV. The momentum of the FFV production programs at the American car companies continued, although by the end of the 1990s, the emphasis shifted to the FFV E85 version, as it is today. Ethanol was preferred over methanol because there is a large support from the farming community, and thanks to the government's incentive programs and corn-based ethanol subsidies. Sweden also tested both the M85 and the E85 flexifuel vehicles, but due to agriculture policy, in the end emphasis was given to the ethanol flexifuel vehicles. Support for ethanol also comes from the fact that it is a biomass fuel, which addresses climate change concerns and greenhouse gas emissions, though these benefits are now highly debated depending on the feedstock used for ethanol production.

The demand for ethanol fuel produced from field corn in the United States was stimulated by the discovery in the late 90s that methyl tertiary butyl ether (MTBE), an oxygenate additive in gasoline, was contaminating groundwater. Due to the risks of widespread and costly litigation, and because MTBE use in gasoline was banned in almost 20 states by 2006, the substitution of MTBE opened a new market for ethanol fuel. This demand shift for ethanol as an oxygenate additive took place at a time when oil prices were already significantly rising. By 2006, about 50 percent of the gasoline used in the U.S. contains ethanol at different proportions, and ethanol production grew so fast that the US became the world's first ethanol producer, overtaking Brazil in 2005. This shift also contributed to a sharp increase in the production and sale of E85 flex vehicles since 2002.

After the 1973 oil crisis, the Brazilian government made mandatory the use of ethanol blends with gasoline, and 100% ethanol powered cars (E100 only) were launched to the market in 1979, after testing with several prototypes developed by four carmakers. Brazilian carmakers modified gasoline engines to support ethanol characteristics and changes included compression ratio, amount of fuel injected, replacement of materials that would get corroded by the contact with ethanol, use of colder spark plugs suitable for dissipating heat due to higher flame temperatures, and an auxiliary cold-start system that injects gasoline from a small tank in the engine compartment to help starting when cold. Flexible-fuel technology started being developed only by the end of the 1990s by Brazilian engineers. The Brazilian flexible fuel car is built with an ethanol-ready engine and one fuel tank for both fuels. The small gasoline reservoir for starting the engine with pure ethanol in cold weather, used in earlier ethanol-only vehicles, was kept in the first generation of Brazilian flexible-fuel cars, mainly for users of the central and southern regions, where winter temperatures normally drop below 15 °C (59 °F). An improved flex motor generation that will be launched in 2009 will eliminate the need for this secondary gas reservoir tank.

A key innovation in the Brazilian flex technology was avoiding the need for an additional dedicated sensor to monitor the ethanol-gasoline mix, which made the first American M85 flex fuel vehicles too expensive. This was accomplished through the lambda probe, used to measure the quality of combustion in conventional engines, is also required to tell the engine control unit (ECU) which blend of gasoline and alcohol is being burned. This task is accomplished automatically through software developed by Brazilian engineers, called "Software Fuel Sensor" (SFS), fed with data from the standard sensors already built-in the vehicle. The technology was developed by the Brazilian subsidiary of Bosch in 1994, but was further improved and commercially implemented in 2003 by the Italian subsidiary of Magneti Marelli, located in Hortolândia, São Paulo. A similar fuel injection technology was developed by the Brazilian subsidiary of Delphi Automotive Systems, and it is called "Multifuel", based on research conducted at its facility in Piracicaba, São Paulo. This technology allows the controller to regulate the amount of fuel injected and spark time, as fuel flow needs to be decreased and also self-combustion needs to be avoided when gasoline is used because ethanol engines have compression ratio around 12:1, too high for gasoline.

Brazilian flex cars are capable of running on just hydrated ethanol (E100), or just on a blend of gasoline with 20 to 25% anhydrous ethanol, or on any arbitrary combination of both fuels. Pure gasoline is no longer sold in the country because these high ethanol blends are mandatory since 1993. Therefore, all Brazilian automakers have optimized flex vehicles to run with gasoline blends from E20 to E25, and with a few exceptions, these FFVs are unable to run smoothly with pure gasoline which causes engine knocking, as vehicles traveling to neighboring South American countries have demonstrated. Only two models are specifically built with a flex-fuel engine optimized to operate also with pure gasoline (E0), the Renault Clio Hi-Flex and the Fiat Siena Tetrafuel.

The flexibility of Brazilian FFVs empowers the consumers to choose the fuel depending on current market prices. As ethanol fuel economy is lower than gasoline because of ethanol's energy content is close to 34% less per unit volume than gasoline, flex cars running on ethanol get a lower mileage than when running on pure gasoline. However, this effect is partially offset by the usually lower price per liter of ethanol fuel. As a rule of thumb, Brazilian consumers are frequently advised by the media to use more alcohol than gasoline in their mix only when ethanol prices are 30% lower or more than gasoline, as ethanol price fluctuates heavily depending on the result of seasonal sugar cane harvests.

In March 2003 Volkswagen do Brasil launched in the market the Gol 1.6 Total Flex, the first commercial flexible fuel vehicle capable of running on any blend of gasoline and ethanol. GM do Brasil followed two months later with the Chevrolet Corsa 1.8 Flexpower, using an engine developed by a joint-venture with Fiat called PowerTrain. By 2008, popular manufacturers that build flexible fuel vehicles are GM (Chevrolet), Fiat, Ford, Peugeot, Renault , Volkswagen, Honda, Mitsubishi, Toyota and Citröen. Flexible fuel cars were 22% of the new car sales in 2004, 73% in 2005, and reached 87.6% in July 2008. As of December 2008, the fleet of "flex" automobiles and light commercial vehicles had reached 6.8 million vehicles, representing 14% of Brazil's motor vehicle fleet and around 20 % of all registered light vehicles.

The rapid success of flex vehicles was made possible by the existence of 33,000 filling stations with at least one ethanol pump available by 2006, a heritage of the early Pró-Álcool ethanol program. These facts, together with the mandatory use of E25 blend of gasoline throughout the country, allowed Brazil in 2008 to achieve more than 50% of fuel consumption in the gasoline market from sugar cane-based ethanol.

The latest innovation within the Brazilian flexible-fuel technology, is the development of flex-fuel motorcycles. In 2007 Magneti Marelli presented the first motorcycle with flex technology, adapted on a Kasinski Seta 125, and based on the Software Fuel Sensor (SFS) the firm developed for flex-fuel cars in Brazil. Delphi Automotive Systems also presented in 2007 its Multifuel injection technology for motorcycles. Besides the flexibility in the choice of fuels, a main objective of the fuel-flex motorcycles is to reduce CO2 emissions by 20 percent, and savings in fuel consumption in the order of 5% to 10% are expected. These flex motorcycles will be available in the market by 2009, but AME Amazonas Motocicletas announced that sales of its motorcycle AME GA (G stands for gasoline and A for alcohol) will begin in December 2008. This model is based on the fuel injection technology developed by Delphi.

The Brazilian subsidiaries of Magneti Marelli, Delphi and Bosch have announced the introduction in 2009 of a new flex engine generation that will eliminate the need for the secondary gasoline tank by warming the ethanol fuel during starting, and allowing flex vehicles to do a normal cold start at temperatures as low as minus 5 °C (23 °F), the lowest temperature expected anywhere in the Brazilian territory. Another improvement is the reduction of fuel consumption and tailpipe emissions, between 10% to 15% as compared to flex motors sold in 2008.

Brazilian flex engines are being designed with higher compression ratios, taking advantage of the higher ethanol blends and maximizing the benefits of the higher oxygen content of ethanol, resulting in lower emissions and improving fuel efficiency. The following table shows the evolution and improvement of the different generations of flex engines developed in Brazil.

Flexible-fuel vehicles were introduced in Sweden as a demonstration test in 1994, when three Ford Taurus were imported to show the technology existed. Because of the existing interest, a project was started in 1995 with 50 Ford Taurus E85 flexifuel in different parts of Sweden: Umea, Örnsköldsvik, Härnösand, Stockholm, Karlstad, Linköping, and Växjö. From 1997 to 1998 an additional 300 Taurus were imported, and the number of E85 fueling grew to 40. Then in 1998 the city of Stockholm placed an order for 2,000 of FFVs for any car manufacturer willing to produce them. The objective was to jump-start the FFV industry in Sweden. The two domestic car makers Volvo Group and Saab AB refused to participate arguing there were not in place any ethanol filling stations. However, Ford Motor Company took the offer and began importing the flexifuel version of its Focus model, delivering the first cars in 2001, and selling more than 15,000 FFV Focus by 2005, then representing an 80% market share of the flexifuel market.

In 2005 both Volvo and Saab introduced to the Sweden market their flexifuel models. Saab began selling its 9-5 2.0 Biopower, joined in 2006 by its 9-5 2.3 Biopower. Volvo introduced its S40 and V50 with flexible-fuel engines, joined in late 2006 by the new C30. All Volvo models were initially restricted to the Sweden market, until 2007, when these three models were launched in eight new European markets. In 2007, Saab also started selling a BioPower version of its popular Saab 9-3 line. In 2008 the Saab-derived Cadillac BLS was introduced with E85 compatible engines, and Volvo launched the V70 with a 2.5-litre turbocharged Flexifuel engine.

All flexible-fuel vehicles in Sweden use an E75 winter blend instead of E85 to avoid engine starting problems during cold weather. This blend was introduced since the winter 2006-07 and E75 is used from November until March. For temperature below minus 15 °C (5 °F) E85 flex vehicles require an engine block heater. The use of this device is also recommended for gasoline vehicles when temperatures drop below minus 23 °C (minus 10 °F). Another option when extreme cold weather is expected is to add more pure gasoline in the tank, thus reducing the ethanol content below the E70 winter blend, or simply not to use E85 during extreme low temperature spells.

Sweden has achieved the largest E85 flexible-fuel vehicle fleet in Europe, with a sharp growth from 717 vehicles in 2001 to 126,505 by September 2008. The recent and accelerated growth of the Swedish fleet of E85 flexifuel vehicles, as they are popularly known, is the result of the National Climate Policy in Global Cooperation Bill passed in 2005, which not only ratified the Kyoto Protocol but also sought to meet the 2003 EU Biofuels Directive regarding targets for use of biofuels, and also let to the 2006 government's commitment to eliminate oil imports by 2020.

In order to achieve these goals several government incentives were implemented. Ethanol, as the other biofuels, was exempted of both, the CO2 and energy taxes until 2009, resulting in a 30% price reduction at the pump of E85 fuel over gasoline. Furthermore, other demand side incentives for flexifuel vehicle owners include a USD 1,800 bonus to buyers of FFVs, exemption from the Stockholm congestion tax, up to 20% discount on auto insurance, free parking spaces in most of the largest cities, owner annual registration taxes, and a 20% tax reduction for flexifuel company cars. Also, a part of the program, the Swedish Government ruled that 25% of their vehicle purchases (excluding police, fire and ambulance vehicles) must be alternative fuel vehicles. By the first months of 2008, this package of incentives resulted in sales of flexible-fuel cars representing 25% of new car sales.

On the supply side, since 2005 the gasoline fuelling stations selling more than 3 million liters of fuel a year are required to sell at least one type of biofuel, resulting in more than 1,200 gas stations selling E85 by August 2008. Despite all the sharp growth of E85 flexifuel cars, by 2007 they represented just 2% of the 4 million Swedish vehicle fleet. In addition, this law also mandated all new filling stations to offer alternative fuels, and stations with an annual volume of more than 1 million liters are required to have an alternative fuel pump by December 2009. Therefore, the number of E85 pumps is expected to reach by 2009 nearly 60% of Sweden’s 4,000 filling stations.

The Swedish-made Koenigsegg CCXR, a limited edition and version of the CCX, is currently the fastest and most powerful flexible fuel vehicle with its twin-supercharged V8 producing 1018 hp when running on biofuel, as compared to 806 hp on 91 octane US unleaded gasoline.

Flexifuel vehicles are sold in 18 European countries, including Austria, Belgium, Czech Republic, Denmark, Estonia, France, Germany, Hungary, Ireland, Italy, the Netherlands, Norway, Poland, Spain, Sweden, Switzerland, and the United Kingdom. Ford, Volvo and Saab are the main automakers offering flexifuel autos in the region.

Biofuel cars in general get strong tax incentives in France, including a 0 or 50% reduction on the tax on new vehicles, and a 40% reduction on CO2 tax for new cars. For company cars there is a corporate car tax free for 2 years and a recovery of 80% of the value added tax (VAT) on E85 vehicles. Also, E85 fuel price is set significantly lower than diesel or gasoline, resulting in E85 at € 0.80, diesel at € 1.15, and gasoline at € 1.30 per liter, as of April 2007. By May 2008, France had 211 pumps selling E85, even though the government made plans for the installation of up to 500 E85 pumps by year end 2007. French automakers Renault and PSA (Citroen & Peugeot) announced they will start selling FFV cars beginning in the summer 2007.

Biofuel emphasis in Germany is on biodiesel, and no specific incentives have been granted for E85 flex-fuel cars, however there is complete exemption of taxes on all biofuels while there is a normal tax of € 0.65 per liter of petroleum fuels. The distribution of E85 began in 2005, and with 219 stations as of September 2008, Germany ranks second after Sweden with the most E85 fueling stations in the EU. As of January 2008 retail prices of E85 was € 0.95 per liter, and gasoline was priced at € 1.37 per liter (for gasoline RON 95), then providing enough margin to compensate for ethanol's lower fuel economy. Ford has offered the Ford Focus since August 2005 in Germany. Ford is about to offer also the Mondeo and other models as FFV versions between 2008 and 2010. The Saab 9-5 and Saab 9-3 Biopower, the Peugeot 308 Bioflex, the Citroen C4 Bioflex, the Audi A5, two models of the Cadillac BLS, and five Volvo models are also available in the German market by 2008.

Ireland is the third best seller European market of E85 flex-fuel vehicles, after Sweden and France. Bioethanol (E85) in Ireland is made from whey, a waste product of cheese manufacturing. The Irish government established several incentives, including a 50% discount in vehicle registration taxes (VRT), which can account for more than one third of the retail price of a new car in Ireland (around € 6,500). The bioethanol element of the E85 fuel is excise-free for fuel companies, allowing retail prices to be low enough to offset the 25 per cent cut in fuel economy that E-85 cars offer, due to ethanol's lower energy content than gasoline. Also, the value added tax (VAT) on the fuel can also be claimed back. E-85 fuel is available across the country in more than 20 of Maxol service stations. In October 2005, the 1.8 Ford Focus FFV became the first flexible-fuel vehicle to be commercially sold in Ireland. Later Ford launched the C-max and the Mondeo flexifuel models. Saab and Volvo also have E85 models available.

The UK government established several incentives for E85 flex-fuel vehicles. These include a fuel duty rebate on E85 fuel of 20 p per liter, until 2010; a £ 10 to 15 reduction in the vehicle excise duty (VED); and a 2% annual company car tax discount for flex-fuel cars. Despite the small number of E85 pump stations available, limited to the Morrisons supermarket chain stations, most automakers offer the same models in the UK that are available in the European market. In 2005 the Ford Focus Flexi-Fuel became the first flexible-fuel car sold in the UK, though E85 pumps opened until 2006. Volvo now offers its flexifuel models S80, S40, C30, V50 and V70. Other models available in the UK are the Ford C-Max Flexi-Fuel, and the Saab models 9-5 and 9-3 Flex-Fuel Biopower, and the new Saab Aero X BioPower E100 bioethanol.

In 2007 there were over 6 million E85 flex fuel vehicles running on the US roads, up from almost 5 million in 2005. The E85 blend is used in gasoline engines modified to accept such higher concentrations of ethanol, and the fuel injection is regulated through a dedicated sensor, which automatically detects the amount of ethanol in the fuel, allowing to adjust both fuel injection and spark timing accordingly to the actual blend available in the vehicle's tank. The American E85 flex fuel vehicle was developed to run on any mixture of unleaded gasoline and ethanol, anywhere from 0% to 85% ethanol by volume. Both fuels are mixed in the same tank, and E85 is sold already blended. In order to reduce ethanol evaporative emissions and to avoid problems starting the engine during cold weather, the maximum blend of ethanol was set to 85%. There is also a seasonal reduction of the ethanol content to E70 (called winter E85 blend) in very cold regions, where temperatures fall below 0 °C (32 °F) during the winter. In Wyoming for example, E70 is sold as E85 from October to May.

E85 flex-fuel vehicles are becoming increasingly common in the Midwest, where corn is a major crop and is the primary feedstock for ethanol fuel production. Also the US government has been using flex-fuel vehicles for many years. By 2008 almost any type of automobile and light duty vehicles is available in the market with the flex-fuel option, including sedans, vans, SUVs and pick-up trucks.

A 2005 survey found that 68% of American flex-fuel car owners were not aware they owned an E85 flex. This is due to the fact that the exterior of flex and non-flex vehicles look exactly the same; there is no sale price difference between them; the lack of consumer's awareness about E85s; and also the decision of American automakers of not putting any kind of exterior labeling, so buyers can be aware they are getting an E85 vehicle. In contrast, all Brazilian automakers clearly mark FFVs with badging or a high quality sticker in the exterior body, with a logo with some variant of the word Flex. Since 2006 many new FFV models in the US feature a bright yellow gas cap to remind drivers of the E85 capabilities, and GM is also using badging with the text "Flexfuel/E85 Ethanol" to clearly mark the car as an E85 FFV.

Some critics have argued, including U.S. Representative Jay Inslee, that American automakers have been producing E85 flex models motivated by a loophole in the CAFE (Corporate Average Fuel Economy) requirements, that allows for a fuel economy credit for every flex-fuel vehicle sold, whether or not in practice these vehicles are fueled with E85. This loophole might allow the car industry to meet the CAFE targets in fuel economy just by spending between USD 100 to USD 200 that it cost to turn a conventional vehicle into a flex-fuel, without investing in new technology to improve fuel economy, and saving them the potential fines for not achieving that standard in a given model year. In an example presented by the National Highway Traffic Safety Administration (NHTSA), the agency responsible for establishing the CAFE standards, the special treatment provided for alternative fuel vehicles, "turns a dual fuel vehicle that averages 25 mpg on gasoline or diesel... to attain the 40 mpg value for CAFE purposes." The current CAFE standards are 27.5 mpg for automobiles and 22.2 mpg for light-duty trucks." In late 2007, CAFE standards received their first overhaul in more than 30 years through the Energy Independence and Security Act of 2007, and now are set to rise to 35 mpg by the year 2020.

A major restriction hampering sales of E85 flex vehicles or fuelling with E85, is the limited infrastructure available to sell E85 to the public, as by October 2008 there were only 1,802 gasoline filling stations selling E85 to the public in the entire US, with a great concentration of E85 stations in the Corn Belt states, lead by Minnesota with 357 stations, the most that any other state, followed by Illinois with 189, Wisconsin with 118, and Missouri with 112. Only seven states do not have E85 available to the public, Alaska, Hawaii, Maine, New Hampshire, New Jersey, Rhode Island, and Vermont. The main constraint for a more rapid expansion of E85 availability is that it requires dedicated storage tanks at filling stations, at an estimated cost of USD 60,000 for each dedicated ethanol tank. The Energy Policy Act of 2005, signed into law by President Bush on 8 August 2005, in its Section 701 requires the federal government's fleet of vehicles capable of operating on alternative fuels to be operated on these fuels exclusively, unless a waiver is granted if the alternative fuel is not reasonably available; or if the cost of the fuel required is unreasonably more expensive compared to gasoline. The Federal vehicle fleet consists of 650,000 vehicles, of which 121,778 are alternative fuel vehicles, mostly E85s.

The BioFuels Security Act is a proposed legislative Act of Congress (bill) intended to phase out current single-fueled vehicles (fossil fuel vehicles) in favor of flexible-fuel vehicles. Under this proposal, contemporary single-fuel vehicles would cease production in 2016 . Also the E85 and Biodiesel Access Act introduced by Congresswoman Stephanie Herseth Sandlin (D-SD) and Congressman John Shimkus (R-IL), be included in any energy legislation that may be approved during this session of Congress. Currently the IRS limits the tax credit only to the amount a duel fuel dispenser exceeds the cost of a conventional dispenser. The E85 and Biodiesel Access Act would increase the credit from 30 percent of the cost of clean fueling property to 50 percent and increase the maximum credit to $100,000. This law would also extend the existing credit which is scheduled to expire at the end of 2009. Also several members of the United States Congress have recently called for mandatory production of flexible fuel vehicles. Regarding energy policy, President-elect Barack Obama pledged during his electoral campaign to significantly reduce oil consumption, with measures that among others include mandating all new vehicles to have FFV capability by the end of 2013.

Chrysler, General Motors, and Ford have each pledged to manufacture 50 percent of their entire vehicle line as flexible fuel in model year 2012, if enough fueling infrastructure develops. The new plug-in series-hybrid vehicle Chevrolet Volt by General Motors, expected to be launched in the North American market in 2010, will take advantage of the E-Flex technology used today in GM's E-85 flex cars as one of the options that will be developed to recharge the batteries.

In January 2007 GM brought UK-sourced Saab 9-5 Biopower E85 flex-fuel vehicles to Australia as a trial, in order to measure interest in ethanol-powered vehicles in the country. Saab Australia placed the vehicles with the fleets of the Queensland Government, the media, and some ethanol producers. E85 is not available widely in Australia, but the Manildra Group provided the E85 blend fuel for this trial.

Saab Australia became the first car maker to produce an E85 flex-fuel car for the Australian market with the Saab 9-5 BioPower. One month later launched the new 9-3 BioPower, the first vehicle in Australia to give drivers a choice of three fuels, E85, diesel or gasoline, and both automobiles are sold for a small premium. Australia's largest independent fuel retailer, United Petroleum, announced plans to install Australia's first commercial E85 fuel pumps, one in Sydney and one in Melbourne.

As part of the North American auto market, by 2007 Canada had available 51 models of E85 flex-vehicles, most from Chrysler, Ford and General Motors, including automobiles, pickup trucks, and SUVs. The country has around 600,000 capable flex fuel E85s on the roads by early 2008, however, most users are not aware they own an E85, as vehicles are not clearly labeled as such, and only the newer models have a yellow cap in the fuel tank informing that the vehicle can handle E85. Another major restriction for greater E85 fuel use is the fact that by June 2008 Canada had only three public E85 pumps, all located in Ontario, in the cities of Guelph, Chatham, and Woodstock. E85 fueling is available primarily for fleet vehicles, including 20 government refueling stations not available for the public. The main feedstocks for E85 production in Canada are corn and wheat, and there are several proposals being discussed to increase the actual use of E85 fuel in FFVs, such as creating an ethanol-friendly highway or ethanol corridor.

In 2006 New Zealand began a pilot project with two E85 Ford Focus Flexi-Fuel evaluation cars. The main feedstock used in New Zealand for ethanol production is whey, a by-product of milk production.

Government officials and businessmen from Paraguay began negotiations in 2007 with Brazilian automakers in order to import flex cars that run on any blend of gasoline and ethanol. If successful, Paraguay would become the first destination for Brazilian flex-fuel car exports. In May 2008, the Paraguayan government announced a plan to eliminate import taxes of flex-fuel vehicles and an incentive program for ethanol production. The plan also includes the purchase of 20,000 flex cars in 2009 for the government fleet.

In 2006, tax incentives were established in Thailand for the introduction of compressed natural gas (CNG) as an alternative fuel, by eliminating import duties and lowering excise taxes on CNG-compatible cars. Then in 2007, Thai authorities approved incentives for the production of "eco-cars", with the goal of the country to become a regional hub for the production of small, affordable and fuel-efficient cars. Seven automakers joint in the program, Toyota, Suzuki, Nissan, Mitsubishi, Honda, Tata and Volkswagen. Now in 2008 the government announced priority for E85, expecting these flex-fuel vehicles to become widely available in Thailand in 2009, three years ahead of schedule. The incentives include cuts in excise tax rates for E85-compatible cars and reduction of corporate taxes for ethanol producers to make sure E85 fuel supply will be met. This new plan however, brought confusion and protests by the automakers which sign-up for the "eco-cars", as competition with the E85 flex-fuel cars will negatively affect their ongoing plans and investments, and their production lines will have to be upgraded at a high cost for them to produce flex-fuel cars. They also complained that flex-fuel vehicles popular in a few countries around the world, limiting their export potential as compared with other engine technologies.

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Alternative fuel vehicle

Typical Brazilian filling station with four alternative fuels for sale: biodiesel (B3), gasohol (E25), neat ethanol (E100), and compressed natural gas (CNG). Piracicaba.

Alternative Fuel Vehicle refers to a vehicle that runs on a fuel other than "traditional" petroleum fuels (petrol or diesel); any method of powering an engine that does not involve solely petroleum (e.g. electric car, petrol-electric hybrid, solar powered). Due to a combination of heavy taxes on fuel, particularly in Europe; tightening environmental laws, particularly in California; the potential for peak oil, and the possibility of further restrictions on greenhouse gas emissions, work on alternative power systems for vehicles has become a high priority for governments and vehicle manufacturers around the world.

Greasestock is an event held yearly in Yorktown Heights, New York which is one of the largest showcases of alternative fuel vehicles in the United States.

The air engine is an emission-free piston engine that uses compressed air as a source of energy. The first compressed air car was invented by a French engineer named Guy Nègre, working The expansion of compressed air may be used 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 is cold air (−15 °C), which could also be used to air condition the car. The source for air is a pressurized carbon-fiber tank holding air at 3,000 lbf/in² (20 MPa). 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.

Battery Electric Vehicles (BEVs) are electric vehicles whose main energy storage is in the chemical energy of batteries. BEVs are the most common form of what is defined by the California Air Resources Board (CARB) as zero emission (ZEV) passenger automobiles, because they produce no emissions while being driven. The electrical energy carried onboard a BEV to power the motors is obtained from a variety of battery chemistries arranged into battery packs. For additional range genset trailers or pusher trailers are sometimes used, forming a type of hybrid vehicle. Batteries used in electric vehicles include "flooded" lead-acid, absorbed glass mat, NiCd, nickel metal hydride, Li-ion, Li-poly and zinc-air batteries.

Attempts at building viable, modern battery-powered electric vehicle began in the 1950s with the introduction of the first modern (transistor controlled) electric car - the Henney Kilowatt. Despite the poor sales of the early battery-powered vehicles, development of various battery-powered vehicles continued through the 1960(notably General Motors with the EV1), but cost, speed and inadequate driving range continued to make them impractical. Battery powered cars have primarily used lead-acid batteries and NiMH batteries. Lead-acid batteries' recharge capacity is considerably reduced if they're discharged beyond 75% on a regular basis, making them a less-than-ideal solution. NiMH batteries are a better choice, but are considerably more expensive than lead-acid. Lithium-ion battery powered vehicles such as the Venturi Fetish have recently demonstrated excellent performance and range, but they remain very expensive.

Providing the range limitation issue of battery powered cars can be overcome, their great advantage over say hydrogen, or ammonia, as a means of using renewable electricty as the ulitmate power source, is that they have around 3 times the fian efficiency, from say wind turbine to wheel.

Ammonia has been proposed as an alternative fuel, since it can run in spark ignited or diesel engines with minor modifications, and despite its toxicity is reckoned to be no more dangerous than petrol or LPG . It can be made from renewable electricity, and having half the density of petrol or diesel can be readily carried in sufficient quantities in vehicles. On combustion it has no emissions other than nitrogen and water vapour.

The first commercial vehicle that used ethanol as a fuel was the Ford Model T, produced from 1908 through 1927. It was fitted with a carburetor with adjustable jetting, allowing use of gasoline or ethanol, or a combination of both. Other car manufactures also provided engines for etanol fuel use. In the United States, alcohol fuel was produced in corn-alcohol stills until Prohibition criminalized the production of alcohol in 1919. The use of alcohol as a fuel for internal combustion engines, either alone or in combination with other fuels, lapsed until the oil price shocks of the 1970s. Furthermore, additional attention was gained because of its possible environmental and long-term economical advantages over fossil fuel.

Both ethanol and methanol have been use as an automotive fuel. While both can be obtained from petroleum or natural gas, ethanol has attracted more attention because it is considered a renewable resource, easily obtained from sugar or starch in crops and other agricultural produce such as grain, sugarcane or even lactose. Since ethanol occurs in nature whenever yeast happens to find a sugar solution such as overripe fruit, most organisms have evolved some tolerance to ethanol, whereas methanol is toxic. Other experiments involve butanol, which can also be produced by fermentation of plants. Support for ethanol comes from the fact that it is a biomass fuel, which addresses climate change and greenhouse gas emissions, though these benefits are now highly debated, including the heated 2008 food vs fuel debate.

Ethanol has the property of slowly decomposing certain rubber compounds such as are found in the fuel lines and seals used in vehicles produced before the mid 1980s. Also, because gasoline is more volatile than ethanol, it can be harder to start some engines using higher ethanol percentages than they were designed to use, especially when the engine is cold during the winter. Ethanol is also electrically conductive (gasoline is an effective insulator) which can cause problems with some early electric fuel pump designs and fuel tank sensors. Corrosion of magnesium and aluminium parts is also a concern at higher ethanol percentages. Most modern cars are designed to run on gasoline are capable of running with a blend from 10% up to 15% ethanol mixed into gasoline (E10-E15). With a small amount of redesign, gasoline-powered vehicles can run on ethanol concentrations as high as 85% (E85), the maximum set in the United States and Europe due to cold weather during the winter, or up to 100% (E100) in Brazil, with a warmer climate. Ethanol has close to 34% less energy per volume than gasoline, consequently fuel economy ratings with ethanol blends are significantly lower than with pure gasoline, but this lower energy content does not translate directly into a 34% reduction in mileage, because there are many other variables that affect the performance of a particular fuel in a particular engine, and also because ethanol has a higher octane rating which is beneficial to high compression ratio engines.

Reacting to the high price of oil and its growing dependence on imports, in 1975 Brazil launched the Pro-alcool program, a huge government-subsidized effort to manufacture ethanol fuel (from its sugar cane crop) and ethanol-powered automobiles. These ethanol-only vehicles were very popular in the 1980s, but became economically impractical when oil prices fell - and sugar prices rose - late in that decade. In May 2003 Volkswagen built for the first time a commercial ethanol flexible fuel car, the Gol 1.6 Total Flex. These vehicles were a commercial success and by 2008 other nine Brazilian manufacturers are producing flexible fuel vehicles: Chevrolet, Fiat, Ford, Peugeot, Renault, Honda, Mitsubishi, Toyota and Citroën. The adoption of the flex technology was so rapid, that flexible fuel cars reached 87.6% of new car sales in July 2008. As of August 2008, the fleet of "flex" automobiles and light commercial vehicles had reached 6 million new vehicles sold, representing almost 19% of all registered light vehicles. The rapid success of "flex" vehicles, as they are popularly known, was made possible by the existance of 33,000 filling stations with at least one ethanol pump available by 2006, a heritage of the Pro-alcool program.

In the United States, initial support to develop alternative fuels by the government was a also response to the oil crisis , and later on, as a goal to improve air quality. Also, liquid fuels were preferred over gaseous fuels not only because they have a better volumetric energy density but also because they were the most compatible fuels with existing distribution systems and engines, thus avoiding a big departure from the existing technologies and taking advantage of the vehicle and the refueling infrastructure. California led the search of sustainable alternatives with interest in methanol. In 1996, a new FFV Ford Taurus was developed, with models fully capable of running either methanol or ethanol blended with gasoline. This ethanol version of the Taurus was the first commercial production of a E85 FFV. The momentum of the FFV production programs at the American car companies continued, although by the end of the 90's, the emphasis was on the FFV E85 version, as it is today. Ethanol was preferred over methanol because there is a large support in the farming community and thanks to government's incentive programs and corn-based ethanol subsidies. Sweden also tested both the M85 and the E85 flexifuel vehicles, but due to agriculture policy, in the end emphasis was given to the ethanol flexifuel vehicles.

Today the most common commercially available FFV in the market is the ethanol flexible-fuel vehicle, with around 13 million vehicles on the road around the world by mid-2008, concentrated in the United States (6.8 million),Brazil (6 million), and Europe, led by Sweden (116 thousand).

The main benefit of Diesel combustion engines is that they have a 40% fuel burn efficiency; compared with just 25-30% in the best gasoline engines. In addition diesel fuel has slightly higher Energy Density by volume than gasoline. This makes Diesel engines capable of achieving much better fuel economy than gasoline vehicles.

Biodiesel is commercially available in most oilseed-producing states in the United States. As of 2005, it is somewhat more expensive than fossil diesel, though it is still commonly produced in relatively small quantities (in comparison to petroleum products and ethanol). Many farmers who raise oilseeds use a biodiesel blend in tractors and equipment as a matter of policy, to foster production of biodiesel and raise public awareness. It is sometimes easier to find biodiesel in rural areas than in cities.

Some Diesel-powered cars can run with little or no modification on 100% pure biodiesel, a fuel that can be made from vegetable oils. Vegetable oils tend to solidify in cold weather conditions so vehicle modifications may be required in order to heat the fuel prior to use under those circumstances. Modern low emission diesels (most often Euro -3 and -4 compliant), typical of the current production in the European industry, require extensive modification of injector system, pumps and seals etc. due to the higher operating pressures. The result is sensitive lubrication & sealing systems that bio diesel fuels do not protect and may even attack. This reduces the market for bio diesels as increasing numbers of new vehicles are not able to use it.

Biodiesel has lower Energy Density than fossil diesel fuel or gasoline, so biofueled vehicles are not quite able to keep up with the fuel economy of a fossil fueled diesel vehicle. But they're still better than 4 stroke gasoline engines, and they aren't burning fossil fuels.

Compressed Biogas may be used for Internal Combustion Engines after purification of the raw gas. The removal of H2O, H2S and particles can be seen as standard producing a gas which has the same quality as Compressed Natural Gas. The use of biogas is particularly interesting for climates where the waste heat of a biogas powered power plant cannot be used during the summer.

High pressure compressed natural gas, mainly composed of methane, that is used to fuel normal combustion engines instead of gasoline. Combustion of methane produces the least amount of CO2 of all fossil fuels. Gasoline cars can be retrofitted to CNG and become bifuel NGV Natural gas vehicles as the gasoline tank stays. You can switch between CNG and gasoline during operation.

Worldwide, as of 2006 there are roughly 5 million natural gas vehicles (NGVs), with the largest number of NGVs in Argentina, Brazil, Iran, Pakistan and Thailand. In Europe they are popular in Germany and Italy and are becoming more so as varous manufactueres produce factory made cars, buses, vans and heavy vehciles.

CNG vehicles are commonly used in South America, where these vehicles are mainly used as taxicabs in main cities of Argentina and Brazil. Normally, standard gasoline vehicles are retrofitted in specialized shops, which involve installing the gas cylinder in the trunk and the CNG injection system and electronics. By 2006 there were more than a 1.2 million retrofitted vehicles in Brazil, with a higher concentration in the cities of Rio de Janeiro and São Paulo.

In 2006 the Brazilian subsidiary of FIAT introduced the Fiat Siena Tetra fuel, a four-fuel car developed under Magneti Marelli of Fiat Brazil. This automobile can run on 100% ethanol (E100), E25 (Brazil's normal ethanol gasoline blend), pure gasoline (not available in Brazil), and natural gas, and switches from the gasoline-ethanol blend to CNG automatically, depending on the power required by road conditions. Other existing option is to retrofit an ethanol flexible-fuel vehicle to add a natural gas tank and the corresponding injection system. Some taxicabs in São Paulo and Rio de Janeiro, Brazil, run on this option, allowing the user to choose among three fuels (E25, E100 and CNG) according to current market prices at the pump. Vehicles with this adaptation are known in Brazil as tri-fuel cars.

A hydrogen car is an automobile which uses hydrogen as its primary source of power for locomotion. These cars generally use the hydrogen in one of two methods: combustion or fuel-cell conversion. In combustion, the hydrogen is "burned" in engines in fundamentally the same method as traditional gasoline cars. In fuel-cell conversion, the hydrogen is turned into electricity through fuel cells which then powers electric motors. With either method, the only byproduct from the spent hydrogen is water.

A small number of prototype hydrogen cars currently exist, and a significant amount of research is underway to make the technology more viable. The common internal combustion engine, usually fueled with gasoline (petrol) or diesel liquids, can be converted to run on gaseous hydrogen. However, the most efficient use of hydrogen involves the use of fuel cells and electric motors instead of a traditional engine. Hydrogen reacts with oxygen inside the fuel cells, which produces electricity to power the motors. One 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. Some believe that hydrogen cars will never be economically viable and that the emphasis on this technology is a diversion from the development and popularization of more efficient hybrid cars and other alternative technologies.

High speed cars, buses, motorcycles, bicycles, submarines, and space rockets already run on hydrogen, in various forms. There is even a working toy model car that runs on solar power, using a reversible fuel cell to store energy in the form of hydrogen and oxygen gas. It can then convert the fuel back into water to release the solar energy.

BMW's Clean Energy internal combustion hydrogen car has more power and is faster than hydrogen fuel cell electric cars. A limited series production of the 7 Series Saloon was announced as commencing at the end of 2006. A BMW hydrogen prototype (H2R) using the driveline of this model broke the speed record for hydrogen cars at 300 km/h (186 mi/h), making automotive history. Mazda has developed Wankel engines to burn hydrogen. The Wankel uses a rotary principle of operation, so the hydrogen burns in a different part of the engine from the intake. This reduces pre-detonation, a problem with hydrogen fueled piston engines.

Liquid nitrogen (LN2) is a method of storing energy. Energy is used to liquify air, and then LN2 is produced by evaporation, and distributed. LN2 is exposed to ambient heat in the car and the resulting nitrogen gas can be used to power a piston or turbine engine. The maximum amount of energy that can be extracted from 1 kg of LN2 is 213 W-hr or 173 W-hr per liter, in which a maximum of 70 W-hr can be utilized with an isothermal expansion process. Such a vehicle can achieve ranges similar to that of gasoline with a 350 liter (90 gallon) tank. Theoretical future engines, using cascading topping cycles, can improve this to around 110 W-hr/kg with a quasi-isothermal expansion process. The advantages are zero harmful emissions and superior energy densities than compressed air, and a car powered by LN2 can be refilled in a matter of minutes.

LPG or liquified petroleum gas is a low pressure liquified gas mixture composed mainly of propane and butane which burns in conventional gasoline combustion engines with less CO2 than gasoline. Gasoline cars can be retrofitted to LPG aka Autogas and become bifuel vehicles as the gasoline tank stays. You can switch between LPG and gasoline during operation. Estimated 10 million vehicles running worldwide.

Propane is also being used increasingly for vehicle fuels. In the U.S., 190,000 on-road vehicles use propane, and 450,000 forklifts use it for power. It is the third most popular vehicle fuel in America, behind gasoline and diesel. In other parts of the world, propane used in vehicles is known as autogas. About 9 million vehicles worldwide use autogas.

A solar car is an electric vehicle powered by solar energy obtained from solar panels on the car. Solar cars are not a practical form of transportation; insufficient power falls on the roof of a practically sized and shaped vehicle to provide adequate performance. They are raced in competitions such as the World Solar Challenge and the North American Solar Challenge. These events are often sponsored by Government agencies such as the United States Department of Energy keen to promote the development of alternative energy technology such as solar cells and electric vehicles. Such challenges are often entered by universities to develop their students engineering and technological skills as well as motor vehicle manufacturers such as GM and Honda.

The North American Solar Challenge is a solar car race across North America. Originally called Sunrayce, organized and sponsored by General Motors in 1990, it was renamed American Solar Challenge in 2001, sponsored by the United States Department of Energy and the National Renewable Energy Laboratory. Teams from universities in the United States and Canada compete in a long distance test of endurance as well as efficiency, driving thousands of miles on regular highways.

Nuna is the name of a series of manned solar powered vehicles that won the World solar challenge in Australia three times in a row, in 2001 (Nuna 1 or just Nuna), 2003 (Nuna 2) and 2005 (Nuna 3). The Nunas are built by students of the Delft University of Technology.

The World solar challenge is a solar powered car race over 3021 km through central Australia from Darwin to Adelaide. The race attracts teams from around the world, most of which are fielded by universities or corporations although some are fielded by high schools.

A steam car is a car that has a steam engine. Wood, coal, ethanol, or others can be used as fuel. The fuel is burned in a boiler and the heat converts water into steam. When the water turns to steam, it expands. The expansion creates pressure. The pressure pushes the pistons back and forth. This turns the driveshaft to spin the wheels forward. It works like a coal-fueled steam train, or steam boat. The steam car was the next logical step in independent transport.

Steam cars take a long time to start, but some can reach speeds over 100 mph (161 km/h) eventually. the late model doble could be brought to operational condition in less than 30 seconds, and were fast, with high acceleration, but they were ridiculously expensive.

A steam engine uses external combustion, as opposed to internal combustion. Gasoline-powered cars are more efficient at about 25-28% efficiency. In theory, a combined cycle steam engine in which the burning material is first used to drive a gas turbine can produce 50% to 60% efficiency. However, practical examples of steam engined cars work at only around 5-8% efficiency.

The best known and best selling steam-powered car was the Stanley Steamer. It used a compact fire-tube boiler under the hood to power a simple two-piston engine which was connected directly to the rear axle. Before Henry Ford introduced monthly payment financing with great success, cars were typically purchased outright. This is why the Stanley was kept simple; to keep the purchase price affordable.

Steam produced in refrigeration also can be use by a turbine in other vehicle types to produce electricity, that can be employed in electric motors or stored in a battery.

Steam power can be combined with a standard oil-based engine to create a hybrid. Water is injected into the cylinder after the fuel is burned, when the piston is still superheated, often at temperatures of 1500 degrees or more. The water will instantly be vaporized into steam, taking advantage of the heat that would otherwise be wasted.

Wood gas can be used to power cars with ordinary internal combustion engines if a wood gasifier is attached. This was quite popular during World War II in several European and Asian countries because the war prevented easy and cost-effective access to oil.

Starting in the ninteen-seventies there have been experiments utilizing vaporized gasoline, specificaly the high octane component thereof to drive the pistons of internal combustion engines. The only documented attempts were achieved by Tom Ogle of El Paso, Texas and Jack Talbert of Manhattan, Kansas. Tom Ogle was awarded a United States Patent in 1978 for his design. Talbert's design was based primarily on the work of his father George Talbert originally conducted in the late nineteen-sixties.

A flexible-fuel vehicle (FFV) or dual-fuel vehicle is an alternative fuel automobile or light duty truck with a multifuel engine that can use more than one fuel, usually mixed in the same tank, and the blend is burned in the combustion chamber together. These vehicles are colloquially called flex-fuel, or flexifuel in Europe, or just flex in Brazil. FFVs are distinguished from bi-fuel vehicles, where two fuels are stored in separate tanks. The most common commercially available FFV in the world market is the ethanol flexible-fuel vehicle, with the major markets concentrated in the United States, Brazil, Sweden, and some other European countries. In addition to flex-fuel vehicles running with ethanol, in the US and Europe there were successful test programs with methanol flex-fuel vehicles, known as M85 FFVs, and more recently there have been also successful tests using p-series fuels with E85 flex fuel vehicles, but as of June 2008, this fuel is not yet available to the general public.

Ethanol flexible-fuel vehicles have standard gasoline engines that are capable of running with ethanol and gasoline mixed in the same tank. These mixtures have "E" numbers which describe the percentage of ethanol in the mixture, for example, E85 is 85% ethanol and 15% gasoline. (See common ethanol fuel mixtures for more information.) Though technology exists to allow ethanol FFVs to run on any mixture up to E100, in the U.S. and Europe, flex-fuel vehicles are optimized to run on E85. This limit is set to avoid cold starting problems during very cold weather. The alcohol content might be reduced during the winter, to E70 in the U.S. or to E75 in Sweden. Brazil, with a warmer climate, developed vehicles that can run on any mix up to E100, though E20-E25 is the mandatory minimum blend, and no pure gasoline is sold in the country.

The US has the biggest fleet of flex-fuel vehicles in the world, with 6.8 million as of February 2008, followed by Brazil with 6.0 million as of August 2008. However, the actual number of American FFVs using E85 is much lower, as surveys conducted in the US have found that 68% of American flex-fuel car owners were not aware they owned an E85 flex. This is due to the fact that the exterior of flex and non-flex vehicles look exactly the same; there is no sale price difference between them; the lack of consumer's awareness about E85s; and also the decision of American automakers of not putting any kind of exterior labeling, so buyers can be aware they are getting an E85 vehicle. In contrast, all Brazilian automakers put a visible fixture or decal in the exterior body, with some variant of the prefix "flex" to clearly identify the flex-fuel models. As of 2007, new FFV models feature a yellow gas cap with the label "E85/gasoline" written on the cap, in order to remind drivers of the E85 capabilities.. Use of E85 is also affected by the relative low number of E85 filling stations across the country, as just over 1,750 were available by August 2008, and highly concentrated in the Corn Belt states, led by Minnesota with 353 stations, followed by Illinois with 181, and Wisconsin with 114.

Also, there have been claims that American automakers are producing E85 flex models motivated by a loophole in the CAFE (Corporate Average Fuel Economy) requirements, that allows for a fuel economy credit for every flex-fuel vehicle sold, whether or not in practice these vehicles are fueled with E85. This loophole might allow the car industry to meet the CAFE targets in fuel economy just by spending between USD 100 to USD 200 that it cost to turn a conventional vehicle into a flex-fuel, without investing in new technology to improve fuel economy, and saving them the potencial fines for not achieving that standard in a given model year.

In the United States E85 flexible-fuel vehicles use a technology that allows the fuel mixture to be automatically detected by one or more sensors, and once detected, the ECU tunes the timing of spark plugs and fuel injectors so that the fuel will burn cleanly in the vehicle's internal combustion engine. Originally, sensors in both the fuel-line and in the exhaust system were used for flexible fuel vehicles. In recent years, manufacturers have instead opted to use only sensors in the exhaust manifold, before the catalytic converter, and to eliminate the fuel inline sensor. A separate small storage tank for gasoline used for a cold starting the engine in early US models is no longer required.

Brazilian flex-fuel technology developed an engine capable of running on any blend between E20-E25 gasohol to E100 ethanol fuel, and uses the lambda probe to measure the quality of combustion in conventional engines, so informing the engine control unit (ECU) which blend of gasoline and alcohol is being actually burned. This task is accomplished automatically through software developed by Brazilian engineers, called "Software Fuel Sensor" (SFS), fed with data from the standard sensors already built-in the vehicle, avoiding the need for an additional dedicated sensor to monitor the ethanol-gasoline mix. The technology was developed by the Brazilian subsidiary of Bosch in 1994, but was further improved and commercially implemented in 2003 by the Italian subsidiary of Magneti Marelli, located in Hortolândia, São Paulo. A similar fuel injection technology was developed by the Brazilian subsidiary of Delphi Automotive Systems, and it is called "Multifuel", based on research conducted at its facility in Piracicaba, São Paulo. This technology allows the controller to regulate the amount of fuel injected and spark time, as fuel flow needs to be decreased and also self-combustion needs to be avoided when gasoline is used because ethanol engines have compression ratio around 12:1, too high for gasoline.

A hybrid vehicle uses multiple propulsion systems to provide motive power. This most commonly refers to gasoline-electric hybrid vehicles, which use gasoline (petrol) and electric batteries for the energy used to power internal-combustion engines (ICEs) and electric motors. These powerplants are usually relatively small and would be considered "underpowered" by themselves, but they can provide a normal driving experience when used in combination during acceleration and other maneuvers that require greater power.

The Honda Insight is a 2-seater hatchback hybrid automobile manufactured by Honda. It was the first mass-produced hybrid automobile sold in the United States, introduced in 1999, and produced until 2006. Honda now offers the Civic as an optional hybrid.

Toyota, GM and Ford are currently developing plug-in hybrids.

In very small vehicles, the power demand decreases, so human power can be employed to make a significant improvement in battery life. Two such commercially made vehicles are the Sinclair C5 and the TWIKE.

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Energy development

Energy consumption from 1989 to 1999

Energy development is the ongoing effort to provide sufficient primary energy sources and secondary energy forms to fulfill civilization's needs. It involves both installation of established technologies and research and development to create new energy-related technologies. Major considerations in energy planning include resource depletion, supply production peaks, security of supply, cost, impact on air pollution and water pollution, and whether or not the source is renewable.

Technologically advanced societies have become increasingly dependent on external energy sources for transportation, the production of many manufactured goods, and the delivery of energy services. This energy allows people who can afford the cost to live under otherwise unfavorable climatic conditions through the use of heating, ventilation, and/or air conditioning. Level of use of external energy sources differs across societies, as do the climate, convenience, levels of obesity, traffic congestion, pollution, production, and greenhouse gas emissions of each society.

Increased levels of human comfort generally induce increased dependence on external energy sources, although the application of energy efficiency and conservation approaches allows a certain degree of mitigation of the dependence. 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.

Primary energy sources are substances or processes with concentrations of energy at a high enough potential to be feasibly encouraged to convert to lower energy forms under human control for human benefit. Except for nuclear fuels, tidal energy and geothermal energy, all terrestrial energy sources are from current solar insolation or from fossil remains of plant and animal life that relied directly and indirectly upon sunlight, respectively. And ultimately, solar energy itself is the result of the Sun's nuclear fusion. Geothermal power from hot, hardened rock above the magma of the earth's core is the result of the decay of radioactive materials present beneath the earth's crust; which was the byproduct of a previous supernova event.

Fossil fuels, in terms of energy, involve the burning of coal or hydrocarbon fuels, which are the remains of the decomposition of plants and animals. There are three main types of fossil fuels: coal, petroleum, and natural gas. Another fossil fuel, liquefied petroleum gas (LPG), is principally derived from the production of natural gas. Heat from burning fossil fuel is used either directly for space heating and process heating, or converted to mechanical energy for vehicles, industrial processes, or electrical power generation.

Since these power plants are thermal engines, and are typically quite large, waste heat disposal becomes an issue at high ambient temperature. Thus, at a time of peak demand, a power plant may need to be shut down or operate at a reduced power level, as sometimes do nuclear power plants, for the same reasons.

Nuclear power stations use nuclear fission to generate energy by the reaction of uranium-235 inside a nuclear reactor. The reactor uses uranium rods, the atoms of which are split in the process of fission, releasing a large amount of energy. The process continues as a chain reaction with other nuclei. The heat released, heats water to create steam, which spins a turbine generator, producing electricity.

Depending on the type of fission fuel considered, estimates for existing supply at known usage rates varies from several decades for the currently popular Uranium-235 to thousands of years for uranium-238. At the present use rate, there are (as of 2007) about 70 years left of known uranium-235 reserves economically recoverable at a uranium price of US$ 130/kg. The nuclear industry argue that the cost of fuel is a minor cost factor for fission power, more expensive, more difficult to extract sources of uranium could be used in the future, such as lower-grade ores, and if prices increased enough, from sources such as granite and seawater. Increasing the price of uranium would have little effect on the overall cost of nuclear power; a doubling in the cost of natural uranium would increase the total cost of nuclear power by 5 percent. On the other hand, if the price of natural gas was doubled, the cost of gas-fired power would increase by about 60 percent.

Opponents on the other hand argue that the correlation between price and production is not linear, but as the ores' concentration becomes smaller, the difficulty (energy and resource consumption are increasing, while the yields are decreasing) of extraction rises very fast, and that the assertion that a higher price will yield more uranium is overly optimistic; for example a rough estimate predicts that the extraction of uranium from granite will consume at least 70 times more energy than what it will produce in a reactor. As many as eleven countries have depleted their uranium resources, and only Canada has mines left which produce better than 1% concentration ore. Seawater seems to be equally dubious as a source. As a consequence an eventual doubling in the price of uranium will give a marginal increase in the volumes that are being produced.

Another alternative would be to use thorium as fission fuel. Thorium is three times more abundant in Earth's crust than uranium, and much more of the thorium can be used (or, more precisely, bred into Uranium-233, reprocessed and then used as fuel). India has around 32 percent of the world’s reserves of thorium and intends on using it for itself because the country has run out of uranium.

Current light water reactors burn the nuclear fuel poorly, leading to energy waste. Nuclear reprocessing or burning the fuel better using different reactor designs would reduce the amount of waste material generated and allow better use of the available resources. As opposed to current light water reactors which use uranium-235 (0.7 percent of all natural uranium), fast breeder reactors convert the more abundant uranium-238 (99.3 percent of all natural uranium) into plutonium for fuel. It has been estimated that there is anywhere from 10,000 to five billion years worth of Uranium-238 for use in these power plants. Fast breeder technology has been used in several reactors. However, the fast breeder reactors at Dounreay in Scotland, Monju in Japan and the Superphénix at Creys-Malville in France, in particular, have all had difficulties and were not economically competitive and most have been decommissioned. The People's Republic of China intends to build breeders. India has run out of uranium and is building thermal breeders that can convert Th-232 into U-233 and burn it.

Some nuclear engineers think that pebble bed reactors, in which each nuclear fuel pellet is coated with a ceramic coating, are inherently safe and are the best solution for nuclear power. They can also be configured to produce hydrogen for hydrogen vehicles. China has plans to build pebble bed reactors configured to produce hydrogen.

The possibility of nuclear meltdowns and other reactor accidents, such as the Three Mile Island accident and the Chernobyl disaster, have caused much public fear. Research is being done to lessen the known problems of current reactor technology by developing automated and passively-safe reactors. Historically, however, coal and hydropower power generation have both been the cause of more deaths per energy unit produced than nuclear power generation. Various kinds of energy infrastructure might be attacked by terrorists, including nuclear power plants, hydropower plants, and liquified natural gas tankers. Nuclear proliferation is the spread from nation to nation of nuclear technology, including nuclear power plants but especially nuclear weapons. New technology like SSTAR ("small, sealed, transportable, autonomous reactor") may lessen this risk.

The long-term radioactive waste storage problems of nuclear power have not been fully solved. Several countries have considered using underground repositories. Nuclear waste takes up little space compared to wastes from the chemical industry which remain toxic indefinitely. Spent fuel rods are now stored in concrete casks close to the nuclear reactors. The amounts of waste could be reduced in several ways. Both nuclear reprocessing and fast breeder reactors could reduce the amounts of waste. Subcritical reactors or fusion reactors could greatly reduce the time the waste has to be stored. Subcritical reactors may also be able to do the same to already existing waste. The only way of dealing with waste today is by geological storage.

The economics of nuclear power is not simple to evaluate, because of high capital costs for building and very low fuel costs. Comparison with other power generation methods is strongly dependent on assumptions about construction timescales and capital financing for nuclear plants. See Economics of new nuclear power plants.

Depending on the source different energy return on energy investment (EROI) are claimed. Advocates (using life cycle analysis) argue that it takes 4–5 months of energy production from the nuclear plant to fully pay back the initial energy investment. Opponents claim that it depends on the grades of the ores the fuel came from, so a full payback can vary from 10 to 18 years, and that the advocates' claim was based on the assumption of high grade ores (the yields are getting worst, as the ores are leaner, for less than 0.02% ores, the yield is less than 50%).

Advocates also claim that it is possible to relatively rapidly increase the number of plants. Typical new reactor designs have a construction time of three to four years. In 1983, 43 plants were being built, before an unexpected fall in fossil fuel prices stopped most new construction. Developing countries like India and China are rapidly increasing their nuclear energy use. However, a Council on Foreign Relations report on nuclear energy argues that a rapid expansion of nuclear power may create shortages in building materials such as reactor-quality concrete and steel, skilled workers and engineers, and safety controls by skilled inspectors. This would drive up current prices.

On the other hand, in stark contrast to the claims of the nuclear industry and its talk of a renaissance, nuclear energy is in decline, according to a report 'World Nuclear Industry Status Report 2007' presented by the Greens/EFA group in the European Parliament. The report outlines that the proportion of nuclear energy in power production has decreased in 21 out of 31 countries, with five less functioning nuclear reactors than five years ago. There are currently 32 nuclear power plants under construction or in the pipeline, 20 fewer than at the end of the 1990s .

Fusion power could solve many of the problems of fission power (the technology mentioned above) but, despite research having started in the 1950s, no commercial fusion reactor is expected before 2050. Many technical problems remain unsolved. Proposed fusion reactors commonly use deuterium, an isotope of hydrogen, as fuel and in most current designs also lithium. Assuming a fusion energy output equal to the current global output and that this does not increase in the future, then the known current lithium reserves would last 3000 years, lithium from sea water would last 60 million years, and a more complicated fusion process using only deuterium from sea water would have fuel for 150 billion years.

Renewable energy is the alternative to fossil fuels and nuclear power.

Biomass production involves using garbage or other renewable resources such as corn or other vegetation to generate electricity. When garbage decomposes, the methane produced is captured in pipes and later burned to produce electricity. Vegetation and wood can be burned directly to generate energy, like fossil fuels, or processed to form alcohols.

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.

Geothermal energy harnesses the heat energy present underneath the Earth. Two wells are drilled. One well injects water into the ground to provide water. The hot rocks heat the water to produce steam. The steam that shoots back up the other hole(s) is purified and is used to drive turbines, which power electric generators. When the water temperature is below the boiling point of water a binary system is used. A low boiling point liquid is used to drive a turbine and generator in a closed system similar to a refrigeration unit running in reverse.

In hydro energy, the gravitational descent of a river is compressed from a long run to a single location with a dam or a flume. This creates a location where concentrated pressure and flow can be used to turn turbines or water wheels, which drive a mechanical mill or an electric generator.

Solar power involves using solar cells to convert sunlight into electricity, using sunlight hitting solar thermal panels to convert sunlight to heat water or air, using sunlight hitting a parabolic mirror to heat water (producing steam), or using sunlight entering windows for passive solar heating of a building. It would be advantageous to place solar panels in the regions of highest solar radiation. In the Phoenix, Arizona area, for example, the average annual solar radiation is 5.7 kWh/m²/day, or 2080.5 kWh/m²/year. Electricity demand in the continental U.S. is 3.7*1012 kW·h per year. Thus, at 100% efficiency, an area of 1.8x10^9 sq. m (around 700 square miles) would need to be covered with solar panels to replace all current electricity production in the US with solar power, and at 20% efficiency, an area of approximately 3500 square miles (3% of Arizona's land area). The average solar radiation in the United States is 4.8 kwh/m²/day, but reaches 8–9 kWh/m²/day in parts of Southwest.

The cost, assuming $500/meter², would be about $5-10 trillion dollars.

China is increasing worldwide silicon wafer capacity for photovoltaics to 2,000 metric tons by July 2008, and over 6,000 metric tons by the end of 2010. Significant international investment capital is flowing into China to support this opportunity. China is building large subsidized off-the-grid solar-powered cities in Huangbaiyu and Dongtan Eco City. Much of the design was done by Americans such as William McDonough.

Tidal power can be extracted from Moon-gravity-powered tides by locating a water turbine in a tidal current, or by building impoundment pond dams that admit-or-release water through a turbine. The turbine can turn an electrical generator, or a gas compressor, that can then store energy until needed. Coastal tides are a source of clean, free, renewable, and sustainable energy.

This type of energy harnesses the power of the wind to propel the blades of wind turbines. These turbines cause the rotation of magnets, which creates electricity. Wind towers are usually built together on wind farms.

Efficiency is increasing by about 2% a year, and absorbs most of the requirements for energy development. New technology makes better use of already available energy through improved efficiency, such as more efficient fluorescent lamps, engines, and insulation. Using heat exchangers, it is possible to recover some of the energy in waste warm water and air, for example to preheat incoming fresh water. Hydrocarbon fuel production from pyrolysis could also be in this category, allowing recovery of some of the energy in hydrocarbon waste. Meat production is energy inefficient compared to the production of protein sources like soybean or Quorn. Already existing power plants often can and usually are made more efficient with minor modifications due to new technology. New power plants may become more efficient with technology like cogeneration. New designs for buildings may incorporate techniques like passive solar. Light-emitting diodes are gradually replacing the remaining uses of light bulbs. Note that none of these methods allows perpetual motion, as some energy is always lost to heat.

Mass transportation increases energy efficiency compared to widespread conventional automobile use while air travel is regarded as inefficient. Conventional combustion engine automobiles have continually improved their efficiency and may continue to do so in the future, for example by reducing weight with new materials. Hybrid vehicles can save energy by allowing the engine to run more efficiently, regaining energy from braking, turning off the motor when idling in traffic, etc. More efficient ceramic or diesel engines can improve mileage. Electric vehicles such as Maglev, trolleybuses, and PHEVs are more efficient during use (but maybe not if doing a life cycle analysis) than similar current combustion based vehicles, reducing their energy consumption during use by 1/2 to 1/4. Microcars or motorcycles may replace automobiles carrying only one or two people. Transportation efficiency may also be improved by in other ways, see automated highway system.

Electricity distribution may change in the future. New small scale energy sources may be placed closer to the consumers so that less energy is lost during electricity distribution. New technology like superconductivity or improved power factor correction may also decrease the energy lost. Distributed generation permits electricity "consumers," who are generating electricity for their own needs, to send their surplus electrical power back into the power grid.

While new sources of energy are only rarely discovered or made possible by new technology, distribution technology continually evolves. The use of fuel cells in cars, for example, is an anticipated delivery technology. This section presents some of the more common delivery technologies that have been important to historic energy development. They all rely in some way on the energy sources listed in the previous section.

Methods of energy storage have been developed, which transform electrical energy into forms of potential energy. A method of energy storage may be chosen based on stability, ease of transport, ease of energy release, or ease of converting free energy from the natural form to the stable form.

The Indian company, Tata, is planning to release a compressed air powered car in 2008.

Batteries are used to store energy in a chemical form. As an alternative energy, batteries can be used to store energy in battery electric vehicles. Battery electric vehicles can be charged from the grid when the vehicle is not in use. Because the energy is derived from electricity, battery electric vehicles make it possible to use other forms of alternative energy such as wind, solar, geothermal, nuclear, or hydroelectric.

Hydrogen can be manufactured at roughly 77 percent thermal efficiency by the method of steam reforming of natural gas. When manufactured by this method it is a derivative fuel like gasoline; when produced by electrolysis of water, it is a form of chemical energy storage as are storage batteries, though hydrogen is the more versatile storage mode since there are two options for its conversion to useful work: (1) a fuel cell can convert the chemicals hydrogen and oxygen into water, and in the process, produce electricity, or (2) hydrogen can be burned (less efficiently than in a fuel cell) in an internal combustion engine.

The environmental movement emphasizes sustainability of energy use and development. Renewable energy is sustainable in its production; the available supply will not be diminished for the foreseeable future - millions or billions of years. "Sustainability" also refers to the ability of the environment to cope with waste products, especially air pollution. Sources which have no direct waste products (such as wind, solar, and hydropower) are seen as ideal in this regard.

The status of nuclear power is controversial. The uranium supply might last a very long time with nuclear reprocessing, with an almost-unlimited supply from sea water available once ground based mining is exhausted.

Fossil fuels such as petroleum, coal, and natural gas are not renewable. For example, the timing of worldwide peak oil production is being actively debated but it has already happened in some countries. Fossil fuels also make up the bulk of the world's current primary energy sources. With global demand for energy growing, the need to adopt alternative energy sources is also growing. Fossil fuels are also a major source of greenhouse gas emissions, leading to concerns about global warming if consumption is not reduced.

Energy conservation is an alternative or complementary process to energy development. It reduces the demand for energy by using it more efficiently.

Andy Grove argues that energy independence is a flawed and infeasible objective, particularly in a network of integrated global exchange. He suggests instead that the objective should be energy resilience: resilience goes hand in hand with adaptability, and it also is reflected in important market ideas like substitutability. In fact, resilience is one of the best features of market processes; the information transmission function of prices means that individual buyers and sellers can adapt to changes in supply and demand conditions in a decentralized way. His suggestion for how to increase the resilience of the U.S. energy economy is to shift use from petroleum to electricity (electrification), that is sticky and can be produced using multiple sources of energy, including renewables. .

On the other hand, the Pembina Institute and WWF-Canada aver in their "Renewable is Doable" plan that resilience is a feature of renewable energy .

Extrapolations from current knowledge to the future offer a choice of energy futures. Some predictions parallel the Malthusian catastrophe hypothesis. Numerous are complex models based scenarios as pioneered by Limits to Growth. Modeling approaches offer ways to analyze diverse strategies, and hopefully find a road to rapid and sustainable development of humanity. Short term energy crises are also a concern of energy development. Some extrapolations lack plausibility, particularly when they predict a continual increase in oil consumption.

Existing technologies for new energy sources, such as renewable energy technologies, particularly wind power and solar power, are promising. Nuclear fission is also promoted, and each need sustained research and development, including consideration of possible harmful side effects. Jacques Cousteau spoke of using the salinization of water at river estuaries as an energy source, which would not have any consequences for a million years, and then stopped to point out that since we are going to be on the planet for a billion years we had to be looking that far into the future. Nuclear fusion and artificial photosynthesis are other energy technologies being researched and developed.

Energy production usually requires an energy investment. Drilling for oil or building a wind power plant requires energy. The fossil fuel resources (see above) that are left are often increasingly difficult to extract and convert. They may thus require increasingly higher energy investments. If the investment is greater than the energy produced, then the fossil resource is no longer an energy source. This means that a large part of the fossil fuel resources and especially the non-conventional ones cannot be used for energy production today. Such resources may still be exploited economically in order to produce raw materials for plastics, fertilizers or even transportation fuel but now more energy is consumed than produced. (They then become similar to ordinary mining reserves, economically recoverable but not net positive energy sources.) New technology may ameliorate this problem if it can lower the energy investment required to extract and convert the resources, although ultimately basic physics sets limits that cannot be exceeded.

It should be noted that between 1950 and 1984, as the Green Revolution transformed agriculture around the globe, world grain production increased by 250%. The energy for the Green Revolution was provided by fossil fuels in the form of fertilizers (natural gas), pesticides (oil), and hydrocarbon fueled irrigation. The peaking of world hydrocarbon production (Peak oil) may test Malthus critics.

Ever since the beginning of the Industrial Revolution, the question of the future of energy supplies has occupied economists.

The history of perpetual motion machines is a long list of failed and sometimes fraudulent inventions of machines which produce useful energy "from nowhere" — that is, without requiring additional energy input.

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Renewable energy

Primary renewable energy resources - the volume of each cube shows the relative supply of each source, compared to total energy use in 2004.

Renewable energy is energy generated from natural resources—such as sunlight, wind, rain, tides and geothermal heat—which are renewable (naturally replenished). In 2006, about 18% of global final energy consumption came from renewables, with 13% coming from traditional biomass, such as wood-burning. Hydroelectricity was the next largest renewable source, providing 3% (15% of global electricity generation), followed by solar hot water/heating, which contributed 1.3%. Modern technologies, such as geothermal energy, wind power, solar power, and ocean energy together provided some 0.8% of final energy consumption.

Climate change concerns coupled with high oil prices, peak oil and increasing government support are driving increasing renewable energy legislation, incentives and commercialization. Investment capital flowing into renewable energy climbed from $80 billion in 2005 to a record $100 billion in 2006.

Wind power is growing at the rate of 30 percent annually, with a worldwide installed capacity of over 100 GW, and is widely used in several European countries and the United States. The manufacturing output of the photovoltaics industry reached more than 2,000 MW in 2006, and photovoltaic (PV) power stations are particularly popular in Germany and Spain. Solar thermal power stations operate in the USA and Spain, and the largest of these is the 354 MW SEGS power plant in the Mojave Desert.. The world's largest geothermal power installation is The Geysers in California, with a rated capacity of 750 MW. Brazil has one of the largest renewable energy programs in the world, involving production of ethanol fuel from sugar cane, and ethanol now provides 18 percent of the country's automotive fuel. Ethanol fuel is also widely available in the USA.

While there are many large-scale renewable energy projects and production, renewable technologies are also suited to small off-grid applications, sometimes in rural and remote areas, where energy is often crucial in human development. Kenya has the world's highest household solar ownership rate with roughly 30,000 small (20–100 watt) solar power systems sold per year.

Some renewable energy technologies are criticised for being intermittent or unsightly, yet the market is growing for many forms of renewable energy. In response to the G8's call on the IEA for "guidance on how to achieve a clean, clever and competitive energy future", the IEA reported that the replacement of current technology with renewable energy could help reduce CO2 emissions by 50% by 2050.

The majority of renewable energy technologies are powered by the sun. The Earth-Atmosphere system is in equilibrium such that heat radiation into space is equal to incoming solar radiation, the resulting level of energy within the Earth-Atmosphere system can roughly be described as the Earth's "climate." The hydrosphere (water) absorbs a major fraction of the incoming radiation. Most radiation is absorbed at low latitudes around the equator, but this energy is dissipated around the globe in the form of winds and ocean currents. Wave motion may play a role in the process of transferring mechanical energy between the atmosphere and the ocean through wind stress. Solar energy is also responsible for the distribution of precipitation which is tapped by hydroelectric projects, and for the growth of plants used to create biofuels.

Each of these sources has unique characteristics which influence how and where they are used.

Airflows can be used to run wind turbines. Modern wind turbines range from around 600 kW to 5 MW of rated power, although turbines with rated output of 1.5–3 MW have become the most common for commercial use; the power output of a turbine is a function of the cube of the wind speed, so as wind speed increases, power output increases dramatically. Areas where winds are stronger and more constant, such as offshore and high altitude sites, are preferred locations for wind farms.

Since wind speed is not constant, a wind farm's annual energy production is never as much as the sum of the generator nameplate ratings multiplied by the total hours in a year. The ratio of actual productivity in a year to this theoretical maximum is called the capacity factor. Typical capacity factors are 20-40%, with values at the upper end of the range in particularly favourable sites. For example, a 1 megawatt turbine with a capacity factor of 35% will not produce 8,760 megawatt-hours in a year, but only 0.35x24x365 = 3,066 MWh, averaging to 0.35 MW. Online data is available for some locations and the capacity factor can be calculated from the yearly output.

Globally, the long-term technical potential of wind energy is believed to be five times total current global energy production, or 40 times current electricity demand. This could require large amounts of land to be used for wind turbines, particularly in areas of higher wind resources. Offshore resources experience mean wind speeds of ~90% greater than that of land, so offshore resources could contribute substantially more energy. This number could also increase with higher altitude ground-based or airborne wind turbines.

Wind power is renewable and produces no greenhouse gases during operation, such as carbon dioxide and methane.

Plants use photosynthesis to grow and produce biomass. Also known as biomatter, biomass can be used directly as fuel or to produce biofuels. Agriculturally produced biomass fuels, such as biodiesel, ethanol and bagasse (often a by-product of sugar cane cultivation) can be burned in internal combustion engines or boilers. Typically biofuel is burned to release its stored chemical energy. Research into more efficient methods of converting biofuels and other fuels into electricity utilizing fuel cells is an area of very active work.

Liquid biofuel is usually either a bioalcohol such as ethanol fuel or an oil such as biodiesel or straight vegetable oil. Biodiesel can be used in modern diesel vehicles with little or no modification to the engine. It can be made from waste and virgin vegetable and animal oils and fats (lipids). Virgin vegetable oils can be used in modified diesel engines. In fact the diesel engine was originally designed to run on vegetable oil rather than fossil fuel. A major benefit of biodiesel use is the reduction in net CO2 emissions, since all the carbon emitted was recently captured during the growing phase of the biomass. The use of biodiesel also reduces emission of carbon monoxide and other pollutants by 20 to 40%.

In some areas corn, cornstalks, sugarbeets, sugar cane, and switchgrasses are grown specifically to produce ethanol (also known as grain alcohol) a liquid which can be used in internal combustion engines and fuel cells. Ethanol is being phased into the current energy infrastructure. E85 is a fuel composed of 85% ethanol and 15% gasoline that is sold to consumers. Biobutanol is being developed as an alternative to bioethanol. There is growing international criticism of the production of biofuel crops in association with food crops with respect to issues such as food security, environmental impacts (deforestation) and energy balance.

Solid biomass is mostly commonly usually used directly as a combustible fuel, producing 10-20 MJ/kg of heat.

Its forms and sources include wood fuel, the biogenic portion of municipal solid waste, or the unused portion of field crops. Field crops may or may not be grown intentionally as an energy crop, and the remaining plant byproduct used as a fuel. Most types of biomass contain energy. Even cow manure still contains two-thirds of the original energy consumed by the cow. Energy harvesting via a bioreactor is a cost-effective solution to the waste disposal issues faced by the dairy farmer, and can produce enough biogas to run a farm.

With current technology, it is not ideally suited for use as a transportation fuel. Most transportation vehicles require power sources with high power density, such as that provided by internal combustion engines. These engines generally require clean burning fuels, which are generally in liquid form, and to a lesser extent, compressed gaseous phase. Liquids are more portable because they can have a high energy density, and they can be pumped, which makes handling easier.

Non-transportation applications can usually tolerate the low power-density of external combustion engines, that can run directly on less-expensive solid biomass fuel, for combined heat and power. One type of biomass is wood, which has been used for millennia. Two billion people currently cook every day, and heat their homes in the winter by burning biomass, which is a major contributor to man-made climate change global warming. The black soot that is being carried from Asia to polar ice caps is causing them to melt faster in the summer. In the 19th century, wood-fired steam engines were common, contributing significantly to industrial revolution unhealthy air pollution. Coal is a form of biomass that has been compressed over millennia to produce a non-renewable, highly-polluting fossil fuel.

Wood and its byproducts can now be converted through processes such as gasification into biofuels such as woodgas, biogas, methanol or ethanol fuel; although further development may be required to make these methods affordable and practical. Sugar cane residue, wheat chaff, corn cobs and other plant matter can be, and are, burned quite successfully. The net carbon dioxide emissions that are added to the atmosphere by this process are only from the fossil fuel that was consumed to plant, fertilize, harvest and transport the biomass.

Processes to harvest biomass from short-rotation trees like poplars and willows and perennial grasses such as switchgrass, phalaris, and miscanthus, require less frequent cultivation and less nitrogen than do typical annual crops. Pelletizing miscanthus and burning it to generate electricity is being studied and may be economically viable.

Biogas can easily be produced from current waste streams, such as paper production, sugar production, sewage, animal waste and so forth. These various waste streams have to be slurried together and allowed to naturally ferment, producing methane gas. This can be done by converting current sewage plants into biogas plants. When a biogas plant has extracted all the methane it can, the remains are sometimes more suitable as fertilizer than the original biomass.

Alternatively biogas can be produced via advanced waste processing systems such as mechanical biological treatment. These systems recover the recyclable elements of household waste and process the biodegradable fraction in anaerobic digesters.

Renewable natural gas is a biogas which has been upgraded to a quality similar to natural gas. By upgrading the quality to that of natural gas, it becomes possible to distribute the gas to the mass market via the existing gas grid.

Geothermal energy is energy obtained by tapping the heat of the earth itself, usually from kilometers deep into the Earth's crust. It is expensive to build a power station but operating costs are low resulting in low energy costs for suitable sites. Ultimately, this energy derives from heat in the Earth's core.

Three types of power plants are used to generate power from geothermal energy: dry steam, flash, and binary. Dry steam plants take steam out of fractures in the ground and use it to directly drive a turbine that spins a generator. Flash plants take hot water, usually at temperatures over 200 °C, out of the ground, and allows it to boil as it rises to the surface then separates the steam phase in steam/water separators and then runs the steam through a turbine. In binary plants, the hot water flows through heat exchangers, boiling an organic fluid that spins the turbine. The condensed steam and remaining geothermal fluid from all three types of plants are injected back into the hot rock to pick up more heat.

The geothermal energy from the core of the Earth is closer to the surface in some areas than in others. Where hot underground steam or water can be tapped and brought to the surface it may be used to generate electricity. Such geothermal power sources exist in certain geologically unstable parts of the world such as Chile, Iceland, New Zealand, United States, the Philippines and Italy. The two most prominent areas for this in the United States are in the Yellowstone basin and in northern California. Iceland produced 170 MW geothermal power and heated 86% of all houses in the year 2000 through geothermal energy. Some 8000 MW of capacity is operational in total.

There is also the potential to generate geothermal energy from hot dry rocks. Holes at least 3 km deep are drilled into the earth. Some of these holes pump water into the earth, while other holes pump hot water out. The heat resource consists of hot underground radiogenic granite rocks, which heat up when there is enough sediment between the rock and the earths surface. Several companies in Australia are exploring this technology.

Renewable energy systems encompass a broad, diverse array of technologies, and the current status of these can vary considerably. Some technologies are already mature and economically competitive (e.g. geothermal and hydropower), others need additional development to become competitive without subsidies. This can be helped by improvements to sub-components, such as electric generators.

The table shows an overview of costs of various renewable energy technologies. For comparison with the prices in the table, electricity production from a conventional coal-fired plant costs about 4¢/kWh. Though in some G8 nations the cost can be significantly higher at 7.88p (~15¢/kWh). Achieving further cost reductions as indicated in the table below requires further technology development, market deployment, an increase in production capacities to mass production levels, and of the establishment of an emissions trading scheme and/or carbon tax which would attribute a cost to each unit of carbon emitted; thus reflecting the true cost of energy production by fossil fuels which then could be used to lower the cost/kWh of these renewable energies.

At the end of 2008, worldwide wind farm capacity was 120,791 megawatts (MW), representing an increase of 28.8 percent during the year, and wind power produced some 1.3% of global electricity consumption. Wind power accounts for approximately 19% of electricity use in Denmark, 9% in Spain and Portugal, and 6% in Germany and the Republic of Ireland. The United States is an important growth area and installed U.S. wind power capacity reached 25,170 MW at the end of 2008.

Horse Hollow Wind Energy Center, in Texas, is the world's largest wind farm at 735.5 MW capacity. It consists of 291 GE Energy 1.5 MW wind turbines and 130 Siemens 2.3 MW wind turbines. A proposed 4,000 MW facility, called the Pampa Wind Project, is to be located near Pampa, Texas.

In the UK, a licence to build the world's largest offshore windfarm, in the Thames estuary, has been granted. The London Array windfarm, 20 km off Kent and Essex, should eventually consist of 341 turbines, occupying an area of 230 km². This is a £1.5 billion, 1,000 megawatt project, which will power one-third of London homes. The windfarm will produce an amount of energy that, if generated by conventional means, would result in 1.9 million tonnes of carbon dioxide emissions every year. It could also make up to 10% of the Government's 2010 renewables target.

Since 2004 there has been renewed interest in solar thermal power stations and two plants were completed during 2006/2007: the 64 MW Nevada Solar One and the 11 MW PS10 solar power tower in Spain. Three 50 MW trough plants were under construction in Spain at the end of 2007 with 10 additional 50 MW plants planned. In the United States, utilities in California and Florida have announced plans (or contracted for) at least eight new projects totaling more than 2,000 MW.

In developing countries, three World Bank projects for integrated CSP/combined-cycle gas-turbine power plants in Egypt, Mexico, and Morocco were approved during 2006/2007.

There are several solar thermal power plants in the Mojave Desert which supply power to the electricity grid. Solar Energy Generating Systems (SEGS) is the name given to nine solar power plants in the Mojave Desert which were built in the 1980s. These plants have a combined capacity of 354 megawatts (MW) making them the largest solar power installation in the world.

As of January 2009, the largest photovoltaic (PV) power plants in the world are the Parque Fotovoltaico Olmedilla de Alarcon (Spain, 60 MW), the Moura photovoltaic power station (Portugal, 46 MW), and the Waldpolenz Solar Park (Germany, 40 MW). Several other PV power plants were completed in Spain in 2008: Planta Solar Arnedo (30 MW), Parque Solar Merida/Don Alvaro (30 MW), Planta solar Fuente Álamo (26 MW), Planta fotovoltaica de Lucainena de las Torres (23.2 MW), Parque Fotovoltaico Abertura Solar (23.1 MW), Parque Solar Hoya de Los Vincentes (23 MW), Huerta Solar Almaraz (22.1 MW), Solarpark Calveron (21 MW), and the Planta Solar La Magascona (20 MW).

Topaz Solar Farm is a proposed 550 MW solar photovoltaic power plant which is to be built northwest of California Valley in the USA at a cost of over $1 billion. Built on 9.5 square miles (25 km2) of ranchland, the project would utilize thin-film PV panels designed and manufactured by OptiSolar in Hayward and Sacramento. The project would deliver approximately 1,100 gigawatt-hours (GW·h) annually of renewable energy. The project is expected to begin construction in 2010, begin power delivery in 2011, and be fully operational by 2013.

High Plains Ranch is a proposed 250 MW solar photovoltaic power plant which is to be built by SunPower in the Carrizo Plain, northwest of California Valley.

However, when it comes to renewable energy systems and PV, it is not just large systems that matter. Building-integrated photovoltaics or "onsite" PV systems have the advantage of being matched to end use energy needs in terms of scale. So the energy is supplied close to where it is needed.

Since the 1970s, Brazil has had an ethanol fuel program which has allowed the country to become the world's second largest producer of ethanol (after the United States) and the world's largest exporter. Brazil’s ethanol fuel program uses modern equipment and cheap sugar cane as feedstock, and the residual cane-waste (bagasse) is used to process heat and power. There are no longer light vehicles in Brazil running on pure gasoline. By the end of 2008 there were 35,000 filling stations throughout Brazil with at least one ethanol pump.

Most cars on the road today in the U.S. can run on blends of up to 10% ethanol, and motor vehicle manufacturers already produce vehicles designed to run on much higher ethanol blends. Ford, DaimlerChrysler, and GM are among the automobile companies that sell “flexible-fuel” cars, trucks, and minivans that can use gasoline and ethanol blends ranging from pure gasoline up to 85% ethanol (E85). By mid-2006, there were approximately six million E85-compatible vehicles on U.S. roads. The challenge is to expand the market for biofuels beyond the farm states where they have been most popular to date. Flex-fuel vehicles are assisting in this transition because they allow drivers to choose different fuels based on price and availability. The Energy Policy Act of 2005, which calls for 7.5 billion gallons of biofuels to be used annually by 2012, will also help to expand the market.

The Geysers, is a geothermal power field located 72 miles (116 km) north of San Francisco, California. It is the largest geothermal development in the world outputting over 750 MW.

By the end of 2005 worldwide use of geothermal energy for electricity had reached 9.3 GWs, with an additional 28 GW used directly for heating. If heat recovered by ground source heat pumps is included, the non-electric use of geothermal energy is estimated at more than 100 GWt (gigawatts of thermal power) and is used commercially in over 70 countries.( sec 1.2) During 2005 contracts were placed for an additional 0.5 GW of capacity in the United States, while there were also plants under construction in 11 other countries.

Portugal now has the world's first commercial wave farm, the Agucadoura Wave Park, officially opened in September 2008. The farm uses three Pelamis P-750 machines generating 2.25 MW. Initial costs are put at €8.5 million. A second phase of the project is now planned to increase the installed capacity to 21MW using a further 25 Pelamis machines.

Funding for a wave farm in Scotland was announced in February, 2007 by the Scottish Government, at a cost of over 4 million pounds, as part of a £13 million funding packages for ocean power in Scotland. The farm will be the world's largest with a capacity of 3MW generated by four Pelamis machines.

Renewable energy can be particularly suitable for developing countries. In rural and remote areas, transmission and distribution of energy generated from fossil fuels can be difficult and expensive. Producing renewable energy locally can offer a viable alternative.

Renewable energy projects in many developing countries have demonstrated that renewable energy can directly contribute to poverty alleviation by providing the energy needed for creating businesses and employment. Renewable energy technologies can also make indirect contributions to alleviating poverty by providing energy for cooking, space heating, and lighting. Renewable energy can also contribute to education, by providing electricity to schools.

Kenya is the world leader in the number of solar power systems installed per capita (but not the number of watts added). More than 30,000 very small solar panels, each producing 12 to 30 watts, are sold in Kenya annually. For an investment of as little as $100 for the panel and wiring, the PV system can be used to charge a car battery, which can then provide power to run a fluorescent lamp or a small television for a few hours a day. More Kenyans adopt solar power every year than make connections to the country’s electric grid.

Present renewable energy sources supply about 18% of current energy use and there is much potential that could be exploited in the future. As the table below illustrates, the technical potential of renewable energy sources is more than 18 times current global primary energy use and furthermore several times higher than projected energy use in 2100.

There are many different ways to assess potentials. The theoretical potential indicates the amount of energy theoretically available for energy purposes, such as, in the case of solar energy, the amount of incoming radiation at the earth's surface. The technical potential is a more practical estimate of how much could be put to human use by considering conversion efficiencies of the available technology and available land area. To give an idea of the constraints, the estimate for solar energy assumes that 1% of the world's unused land surface is used for solar power.

The technical potentials generally do not include economic or other environmental constraints, and the potentials that could be realized at an economically competitive level under current conditions and in a short time-frame is lower still.

Sustainable development and global warming groups propose a 100% Renewable Energy Source Supply, without fossil fuels and nuclear power. Scientists from the University of Kassel have been busy proving that Germany can power itself entirely by renewable energy.

Other than market forces, renewable industry often needs government sponsorship to help generate enough momentum in the market. Many countries and states have implemented incentives — like government tax subsidies, partial copayment schemes and various rebates over purchase of renewables — to encourage consumers to shift to renewable energy sources. Government grants fund for research in renewable technology to make the production cheaper and generation more efficient.

Development of loan programs that stimulate renewable favoring market forces with attractive return rates, buffer initial deployment costs and entice consumers to consider and purchase renewable technology. A famous example is the solar loan program sponsored by UNEP helping 100,000 people finance solar power systems in India. Success in India's solar program has led to similar projects in other parts of developing world like Tunisia, Morocco, Indonesia and Mexico.

Imposition of fossil fuel consumption and carbon taxes, and channel the revenue earned towards renewable energy development.

Also oil peak and world petroleum crisis and inflation are helping to promote renewables.

Many think-tanks are warning that the world needs an urgency driven concerted effort to create a competitive renewable energy infrastructure and market. The developed world can make more research investments to find better cost efficient technologies, and manufacturing could be transferred to developing countries in order to use low labor costs. The renewable energy market could increase fast enough to replace and initiate the decline of fossil fuel dominance and the world could then avert the looming climate and peak oil crises.

Most importantly, renewables is gaining credence among private investors as having the potential to grow into the next big industry. Many companies and venture capitalists are investing in photovoltaic development and manufacturing. This trend is particularly visible in Silicon valley, California, Europe, Japan.

Critics suggest that some renewable energy applications may create pollution, be dangerous, take up large amounts of land, or be incapable of generating a large net amount of energy. Proponents advocate the use of "appropriate renewables", also known as soft energy technologies, as these have many advantages.

There is no shortage of solar-derived energy on Earth. Indeed the storages and flows of energy on the planet are very large relative to human needs.

Variable but forecastable renewables (wind and solar cells) are very reliable when integrated with each other, existing supplies and demand. For example, three German states were more than 30 percent wind-powered in 2007—and more than 100 percent in some months. Mostly renewable power generally needs less backup than utilities already bought to combat big coal and nuclear plants' intermittence.

The challenge of variable power supply may be readily alleviated by grid energy storage. Available storage options include pumped-storage hydro systems, batteries, hydrogen fuel cells, thermal mass and compressed air. Initial investments in such energy storage systems may be high, although the costs can be recovered over the life of the system.

Lovins goes on to say that the unreliability of renewable energy is a myth, while the unreliability of nuclear energy is real. Of all U.S. nuclear plants built, 21 percent were abandoned and 27 percent have failed at least once. Successful reactors must close for refueling every 17 months for 39 days. And when shut in response to grid failure, they can't quickly restart. This is simply not the case for wind farms, for example.

Wave energy and some other renewables are continuously available. A wave energy scheme installed in Australia generates electricity with an 80% availability factor.

Both solar and wind generating stations have been criticized from an aesthetic point of view. However, methods and opportunities exist to deploy these renewable technologies efficiently and unobtrusively: fixed solar collectors can double as noise barriers along highways, and extensive roadway, parking lot, and roof-top area is currently available; amorphous photovoltaic cells can also be used to tint windows and produce energy. Advocates of renewable energy also argue that current infrastructure is less aesthetically pleasing than alternatives, but sited further from the view of most critics.

While most renewable energy sources do not produce pollution directly, the materials, industrial processes, and construction equipment used to create them may generate waste and pollution. Some renewable energy systems actually create environmental problems.

Another environmental issue, particularly with biomass and biofuels, is the large amount of land required to harvest energy, which otherwise could be used for other purposes or left as undeveloped land. However, it should be pointed out that these fuels may reduce the need for harvesting non-renewable energy sources, such as vast strip-mined areas and slag mountains for coal, safety zones around nuclear plants, and hundreds of square miles being strip-mined for oil sands. These responses, however, do not account for the extremely high biodiversity and endemism of land used for ethanol crops, particularly sugar cane.

In the U.S., crops grown for biofuels are the most land- and water-intensive of the renewable energy sources. In 2005, about 12% of the nation’s corn crop (covering 11 million acres (45,000 km²) of farmland) was used to produce four billion gallons of ethanol—which equates to about 2% of annual U.S. gasoline consumption. For biofuels to make a much larger contribution to the energy economy, the industry will have to accelerate the development of new feedstocks, agricultural practices, and technologies that are more land and water efficient. Already, the efficiency of biofuels production has increased significantly and there are new methods to boost biofuel production.

The major advantage of hydroelectric systems is the elimination of the cost of fuel. Other advantages include longer life than fuel-fired generation, low operating costs, and the provision of facilities for water sports. Operation of pumped-storage plants improves the daily load factor of the generation system. Overall, hydroelectric power can be far less expensive than electricity generated from fossil fuels or nuclear energy, and areas with abundant hydroelectric power attract industry.

Hydroelectric power is now more difficult to site in developed nations because most major sites within these nations are either already being exploited or may be unavailable for other reasons such as environmental considerations.

Studies of birds and offshore wind farms in Europe have found that there are very few bird collisions. Several offshore wind sites in Europe have been in areas heavily used by seabirds. Improvements in wind turbine design, including a much slower rate of rotation of the blades and a smooth tower base instead of perchable lattice towers, have helped reduce bird mortality at wind farms around the world. However older smaller wind turbines may be hazardous to flying birds. Birds are severely impacted by fossil fuel energy; examples include birds dying from exposure to oil spills, habitat loss from acid rain and mountaintop removal coal mining, and mercury poisoning.

Though a source of renewable energy may last for billions of years, renewable energy infrastructure, like hydroelectric dams, will not last forever, and must be removed and replaced at some point. Events like the shifting of riverbeds, or changing weather patterns could potentially alter or even halt the function of hydroelectric dams, lowering the amount of time they are available to generate electricity.

Although geothermal sites are capable of providing heat for many decades, eventually specific locations may cool down. It is likely that in these locations, the system was designed too large for the site, since there is only so much energy that can be stored and replenished in a given volume of earth. Some interpret this as meaning a specific geothermal location can undergo depletion.

The government of Iceland states: "It should be stressed that the geothermal resource is not strictly renewable in the same sense as the hydro resource." It estimates that Iceland's geothermal energy could provide 1700 MW for over 100 years, compared to the current production of 140 MW. Radioactive elements in the earth's crust continuously decay, replenishing the heat. The International Energy Agency classifies geothermal power as renewable.

All biomass needs to go through some of these steps: it needs to be grown, collected, dried, fermented and burned. All of these steps require resources and an infrastructure.

Some studies contend that ethanol is "energy negative", meaning that it takes more energy to produce than is contained in the final product. However, a large number of recent studies, including a 2006 article in the journal Science offer the opinion that fuels like ethanol are energy positive. Furthermore, fossil fuels also require significant energy inputs which have seldom been accounted for in the past.

Additionally, ethanol is not the only product created during production, and the energy content of the by-products must also be considered. Corn is typically 66% starch and the remaining 33% is not fermented. This unfermented component is called distillers grain, which is high in fats and proteins, and makes good animal feed. In Brazil, where sugar cane is used, the yield is higher, and conversion to ethanol is somewhat more energy efficient than corn. Recent developments with cellulosic ethanol production may improve yields even further.

According to the International Energy Agency, new biofuels technologies being developed today, notably cellulosic ethanol, could allow biofuels to play a much bigger role in the future than previously thought. Cellulosic ethanol can be made from plant matter composed primarily of inedible cellulose fibers that form the stems and branches of most plants. Crop residues (such as corn stalks, wheat straw and rice straw), wood waste, and municipal solid waste are potential sources of cellulosic biomass. Dedicated energy crops, such as switchgrass, are also promising cellulose sources that can be sustainably produced in many regions of the United States.

The ethanol and biodiesel production industries also create jobs in plant construction, operations, and maintenance, mostly in rural communities. According to the Renewable Fuels Association, the ethanol industry created almost 154,000 U.S. jobs in 2005 alone, boosting household income by $5.7 billion. It also contributed about $3.5 billion in tax revenues at the local, state, and federal levels.

The U.S. electric power industry now relies on large, central power stations, including coal, natural gas, nuclear, and hydropower plants that together generate more than 95% of the nation’s electricity. Over the next few decades uses of renewable energy could help to diversify the nation’s bulk power supply. Already, appropriate renewable resources (which excludes large hydropower) produce 12% of northern California’s electricity.

Although most of today’s electricity comes from large, central-station power plants, new technologies offer a range of options for generating electricity nearer to where it is needed, saving on the cost of transmitting and distributing power and improving the overall efficiency and reliability of the system.

Improving energy efficiency represents the most immediate and often the most cost-effective way to reduce oil dependence, improve energy security, and reduce the health and environmental impact of the energy system. By reducing the total energy requirements of the economy, improved energy efficiency could make increased reliance on renewable energy sources more practical and affordable.

Renewable energy sources are generally sustainable in the sense that they cannot "run out" as well as in the sense that their environmental and social impacts are generally more benign than those of fossil. However, both biomass and geothermal energy require wise management if they are to be used in a sustainable manner. For all of the other renewables, almost any realistic rate of use would be unlikely to approach their rate of replenishment by nature.

If renewable and distributed generation were to become widespread, electric power transmission and electricity distribution systems might no longer be the main distributors of electrical energy but would operate to balance the electricity needs of local communities. Those with surplus energy would sell to areas needing "top ups". That is, network operation would require a shift from 'passive management' — where generators are hooked up and the system is operated to get electricity 'downstream' to the consumer — to 'active management', wherein generators are spread across a network and inputs and outputs need to be constantly monitored to ensure proper balancing occurs within the system. Some governments and regulators are moving to address this, though much remains to be done. One potential solution is the increased use of active management of electricity transmission and distribution networks. This will require significant changes in the way that such networks are operated.

However, on a smaller scale, use of renewable energy produced on site reduces burdens on electricity distribution systems. Current systems, while rarely economically efficient, have shown that an average household with an appropriately-sized solar panel array and energy storage system needs electricity from outside sources for only a few hours per week. By matching electricity supply to end-use needs, advocates of renewable energy and the soft energy path believe electricity systems will become smaller and easier to manage, rather than the opposite (see Soft energy technology).

Renewable heat is the generation of heat from renewable sources. Much current discussion on renewable energy focuses on the generation of electrical energy, despite the fact that many colder countries consume more energy for heating than as electricity. In 2005 the United Kingdom consumed 354 TWh of electric power, but had a heat requirement of 907 TWh, the majority of which (81%) was met using gas. The residential sector alone consumed a massive 550 TWh of energy for heating, mainly in the form of gas. Almost half of the final energy consumed in the UK (49%) was in the form of heat.

Renewable electric power is becoming cheap and convenient enough to place it, in many cases, within reach of the average consumer. By contrast, the market for renewable heat is mostly inaccessible to domestic consumers due to inconvenience of supply, and high capital costs. Heating accounts for a large proportion of energy consumption, however a universally accessible market for renewable heat is yet to emerge. Solutions such as geothermal heat pumps may be more widely applicable, but may not be economical in all cases. Also see renewable energy development.

In 1983, physicist Bernard Cohen proposed that uranium is effectively inexhaustible, and could therefore be considered a renewable source of energy. He claimed that fast breeder reactors, fueled by uranium extracted from seawater, could supply energy at least as long as the sun's expected remaining lifespan of five billion years. Nuclear energy has also been referred to as "renewable" by the politicians George W. Bush, Charlie Crist, and David Sainsbury.

There are also environmental concerns over nuclear power, including the dangerous environmental hazards of nuclear waste and concerns that development of new plants cannot happen quickly enough to reduce CO2 emissions, such that nuclear energy is neither efficient nor effective in cutting CO2 emissions.

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Source : Wikipedia