Biofuel (also called agrofuel) can be broadly defined as solid, liquid, or gas fuel consisting of, or derived from biomass. The definition used here is narrower: biofuel is defined as liquid or gas transportation fuel derived from biomass. Biomass can also be used directly for heating or power: this is commonly called biomass fuel: see biomass heating systems. Biofuel is considered a means of reducing greenhouse gas emissions and increasing energy security by providing an alternative to fossil fuels.
Biofuels are used globally: biofuel industries are expanding in Europe, Asia and the Americas. The most common use for biofuels is in automotive transport (for example E10 fuel). Biofuel can be produced from any carbon source that can be replenished rapidly e.g. plants. Many different plants and plant-derived materials are used for biofuel manufacture.
- 1 Biomass
- 2 History
- 3 Carbon emissions
- 4 Bioenergy from waste
- 5 First generation biofuels
- 6 Second generation biofuels
- 7 Micro algae
- 8 Biofuels in developing countries
- 9 Efforts and promotion
- 10 Current issues in biofuel production and use
- 11 See also
- 12 References
- 13 External links
- 14 Further reading
Biomass is material derived from recently living organisms. This includes plants, animals and their by-products. For example, manure, garden waste and crop residues are all sources of biomass. It is a renewable energy source based on the carbon cycle, unlike other natural resources such as petroleum, coal, and nuclear fuels. Agricultural products specifically grown for biofuel production include corn and soybeans, primarily in the United States; rapeseed, wheat and sugar beet primarily in Europe; sugar cane in Brazil; palm oil in South-East Asia; and jatropha in India. Biodegradable outputs from industry, agriculture, forestry and households can be used for biofuel production, either using anaerobic digestion to produce biogas, or using second generation biofuel processes; examples include straw, timber, manure, rice husks, sewage, and food waste. The use of biomass fuels can therefore contribute to waste management as well as fuel security and help to prevent climate change, though alone they are not a comprehensive solution to these problems.
Humans have used biomass fuels for heating and cooking since the discovery of fire. Following the discovery of electricity, it became possible to use biofuels to generate electrical power as well. However, the discovery and use of fossil fuels: coal, gas and oil, have dramatically reduced the amount of biomass fuel used in the developed world for transport, heat and power.
Liquid biofuels have been used since the early days of the car industry. Nikolaus August Otto, the German inventor of the internal combustion engine, conceived his invention to run on ethanol. Rudolf Diesel, the German inventor of the Diesel engine, designed it to run on peanut oil. Henry Ford originally designed the Ford Model T, a car produced from 1903 to 1926, to run completely on ethanol. However, when crude oil became cheaply available (thanks to oil reserves discovered in Pennsylvania and Texas), cars began using fuels derived from mineral oil: petroleum or diesel.
Nevertheless, before World War II, biofuels were seen as providing an alternative to imported oil. Germany powered its vehicles using a blend of gasoline with alcohol fermented from potatoes, called Reichskraftsprit. In Britain, grain alcohol was blended with petrol by the Distillers Company Limited under the name Discol and marketed through Esso's affiliate Cleveland.
After the war, cheap Middle Eastern oil lessened interest in biofuels. But the oil shocks of 1973 and 1979 increased interest from governments and academics. The counter-shock of 1986 again reduced oil prices and interest.
In the United States, all cars manufactured since 1988 are required to be compatible with fuels containing at least 20% ethanol E20 fuel, and with minor modifications these cars can use 85% ethanol blended with petroleum E85 fuel. Since around 2000 renewed interest in biofuels has been seen. The drivers for biofuel use and development include rising oil prices, concerns over the potential oil peak, greenhouse gas emissions (global warming), rural development interests, and instability in the Middle East. The US president George W. Bush said in his 2006 State of the Union speech that the US should replace 75% of imported oil with biofuel by 2025.
The U.S. Dept. of Energy has earmarked $375 million to fund bioenergy research centers. Second generation biofuel production processes are in development (see below). These allow biofuel to be derived from any source of biomass, not just from food crops such as corn and soy beans.
Biofuels and other forms of renewable energy aim to be carbon neutral. This means that the carbon released during the use of the fuel, e.g. through burning to power transport or generate electricity, is reabsorbed and balanced by the carbon absorbed by new plant growth. These plants are then harvested to make the next batch of fuel. Carbon neutral fuels lead to no net increases in atmospheric carbon dioxide levels, which means that global warming need not get any worse.
In practice, biofuels are not carbon neutral. This is because energy is required to grow crops and process them into fuel. Examples of energy use during the production of biofuels include: fertilizer manufacture, fuel used to power machinery, and fuel used to transport crops and fuels to and from biofuel processing plants. The amount of fuel used during biofuel production has a large impact on the overall greenhouse gas emissions savings achieved by biofuels.
The carbon emissions produced by biofuels are calculated using a technique called Life Cycle Analysis (LCA). This uses a "cradle to grave" or "well to wheels" approach to calculate the total amount of carbon dioxide and other greenhouse gases emitted during biofuel production, from putting seed in the ground to using the fuel in cars and trucks. Many different LCAs have been done for different biofuels, with widely differing results. The majority of LCA studies show that biofuels provide significant greenhouse gas emissions savings when compared to fossil fuels such as petroleum and diesel. Therefore, using biofuels to replace a proportion of the fossil fuels that are burned for transportation can reduce overall greenhouse gas emissions.
This does assume however that the land used for growing the crops would alternatively be desert or paved area. If the land was previously a (tropical rain-) forest, the carbon absorption of this forest should be deducted from the greenhouse gas savings. This implies that the net effect of burning bio-fuels is an increase in greenhouse gasses. This effect should be incorporated in the LCA, to get a proper overview of the total net effect. Using waste material from plantation forests on previous agricultural land could be carbon positive, due to the carbon stored below ground in the root systems.
The well-to-wheel analysis for biofuels has shown that first generation biofuels can save up to 60% carbon emission and second generation biofuels can save up to 80% as opposed to using fossil fuels.
However, a 2007 study by scientists from Britain, U.S., Germany, Switzerland and including Professor Paul Crutzen, who won a Nobel Prize for his work on ozone, have reported that measurements of emissions from the burning of biofuels derived from rapeseed and corn have been found to produce more greenhouse gas emissions than they save.
The claim that biofuels result in emissions savings has also been critiqued on the grounds that it overlooks the 'displacement' effects of large-scale biofuel production, in terms of its direct and indirect role in promoting land use changes and soil carbon losses.
In 2006, a UK Government study showed that carbon emissions were reduced between 50% and 60%. This was when biofuels were used in conjunction with other fuels such as petrol and diesel.
Bioenergy from waste
Using waste biomass to produce energy can reduce the use of fossil fuels, reduce greenhouse gas emissions and reduce pollution and waste management problems. A recent publication by the European Union highlighted the potential for waste-derived bioenergy to contribute to the reduction of global warming. The report concluded that 19 million tons of oil equivalent is available from biomass by 2020, 46% from bio-wastes: municipal solid waste (MSW), agricultural residues, farm waste and other biodegradable waste streams.
Landfill sites generate gases as the waste buried in them undergoes anaerobic digestion. These gases are known collectively as landfill gas: this can be burned and is a source of renewable energy. Landfill gas (LFG) can be burned either directly for heat or to generate electricity for public consumption. Landfill gas contains approximately 50 percent methane, the same gas that is found in natural gas.
If landfill gas is not harvested, it escapes into the atmosphere: this is not desirable because methane is a greenhouse gas, with more global warming potential than carbon dioxide.  Over a time span of 100 years, methane has a global warming potential of 23 relative to CO2.  Therefore, during this time, one ton of methane produces the same greenhouse gas (GHG) effect as 23 tons of CO2. When methane burns the formula is CH4 + 2O2 = CO2 + 2H2O. So by harvesting and burning landfill gas, its global warming potential is reduced a factor of 23, in addition to providing energy for heat and power.
PhD Frank Keppler and PhD Thomas Rockmann discovered that living plants also produce methane CH4. The amount of methane produced by living plants is 10 to 100 times greater than that produced by dead plants but does not increase global warming because of the carbon cycle.
Anaerobic digestion can be used as a distinct waste management strategy to reduce the amount of waste sent to landfill and generate methane, or biogas. Any form of biomass can be used in anaerobic digestion and will break down to produce methane, which can be harvested and burned to generate heat, power or to power certain automotive vehicles.
A 3 MW landfill power plant would power 1,900 homes. It would eliminate 6,000 tons per year of methane from getting into the environment. It would eliminate 18,000 tons per year of CO2 from fossil fuel replacement. This is the same as removing 25,000 cars from the road, or planting 36,000 acres (146 km²) of forest, or not using 305,000 barrels of oil per year.
First generation biofuels
The most common first generation biofuels are listed below.
Vegetable oil can be used for either food or fuel; the quality of the oil may be lower for fuel use. Vegetable oil can be used in many older diesel engines (equipped with indirect injection systems), but only in warm climates. In most cases, vegetable oil is used to manufacture biodiesel, which is compatible with most diesel engines when blended with conventional diesel fuel. No engine manufacturer explicitly states that straight vegetable oil can be used in their engines. Used vegetable oil (e.g. from deep fat fryers) can be filtered and processed into biodiesel.
Biodiesel is the most common biofuel in Europe. It is produced from oils or fats using transesterification and is a liquid similar in composition to mineral diesel. Its chemical name is fatty acid methyl (or ethyl) ester (FAME). Oils are mixed with sodium hydroxide and methanol (or ethanol) and the chemical reaction produces biodiesel (FAME) and glycerol. 1 part glycerol is produced for every 10 parts biodiesel.
Biodiesel can be used in any diesel engine when mixed with mineral diesel. In some countries manufacturers cover their diesel engines under warranty for 100% biodiesel use, although Volkswagen Germany, for example, asks drivers to make a telephone check with the VW environmental services department before switching to 100% biodiesel (see biodiesel use). Many people have run their vehicles on biodiesel without problems. However, the majority of vehicle manufacturers limit their recommendations to 15% biodiesel blended with mineral diesel. In many European countries, a 5% biodiesel blend is widely used and is available at thousands of gas stations .
In the USA, more than 80% of commercial trucks and city buses run on diesel. Therefore "the nascent U.S. market for biodiesel is growing at a staggering rate—from 25 million gallons per year in 2004 to 78 million gallons by the beginning of 2005. By the end of 2006 biodiesel production was estimated to increase fourfold to more than 1 billion gallons," energy expert Will Thurmond writes in an article for the July-August 2007 issue of THE FUTURIST magazine.
Butanol is often claimed to provide a direct replacement for gasoline, because can be used directly in a gasoline engine (in a similar way to biodiesel in diesel engines). It is not in widespread production, and engine manufacturers have not made statements about its use[verification needed]. While on paper (and a few lab tests) it appears that butanol has sufficiently similar characteristics with gasoline such that it should work without problem in any gasoline engine, no widespread experience exists. Butanol is formed by ABE fermentation (acetone, butanol, ethanol) and experimental modifications of the process show potentially high net energy gains with butanol as the only liquid product. Butanol will produce more energy and allegedly can be burned "straight" in existing gasoline engines (without modification to the engine or car) , and is less corrosive and less water soluble than ethanol, and could be distributed via existing infrastructures.
Ethanol is the most common biofuel worldwide. It is an alcohol fuel. It is produced by fermentation of sugars derived from wheat, corn, sugar beet and sugar cane. The production methods used are enzymatic digestion (to release sugars from stored starches e.g. from wheat and corn), fermentation of the sugars, distillation and drying. Ethanol can be used in petrol engines as a replacement for gasoline; it can be mixed with gasoline to any percentage, see common ethanol fuel mixtures for information on ethanol. All petrol engines can run on blends of up to 15% bioethanol with petroleum/gasoline. For higher percentage blends, engine modifications are needed. Many car manufacturers are now producing flex-fuel vehicles, which can run on any combination of bioethanol and petrol, up to 100% bioethanol.
Biogas is produced by the process of anaerobic digestion of organic material by anaerobes. It can be produced either from biodegradable waste materials or by the use of energy crops fed into anaerobic digesters to supplement gas yields. The solid byproduct, digestate, can be used as a biofuel or a fertiliser.
Biogas contains methane and can be recovered from industrial anaerobic digesters and mechanical biological treatment systems. Landfill gas is a less clean form of biogas which is produced in landfills through naturally occurring anaerobic digestion. If it escapes into the atmosphere it is a potent greenhouse gas.
Oils and gases can be produced from various biological wastes:
- Thermal depolymerization of waste can extract methane and other oils similar to petroleum.
- GreenFuel Technologies Corporation developed a patented bioreactor system that uses nontoxic photosynthetic algae to take in smokestacks flue gases and produce biofuels such as biodiesel, biogas and a dry fuel comparable to coal.
Examples include wood, charcoal, and dried excrement.
Second generation biofuels
The following second generation biofuels are under development:
- HTU diesel
- Fischer-Tropsch diesel
- Mixed Alcohols (i.e., mixture of mostly ethanol, propanol and butanol, with some pentanol, hexanol, heptanol and octanol)
Bio-DME, Fischer-Tropsch, BioHydrogen diesel, Biomethanol and Mixed Alcohols all use syngas for production. This syngas is produced by gasification of biomass. HTU (High Temperature Upgrading) diesel is produced from particularly wet biomass stocks using high temperature and pressure to produce an oil.
BioHydrogen is the same as hydrogen except it is produced from a biomass feedstock. This is done using gasification of the biomass and then reforming the methane produced. BioHydrogen can be used in fuel cells to produce electricity.
Bio-DME is the same as DME but is produced from a bio-sources. Bio-DME can be produced from Biomethanol using catalytic dehydration or it can be produced from syngas using DME synthesis. DME can be used in the compression ignition engine.
HTU diesel is produced from wet biomass. It can be mixed with fossil diesel in any percentage without need for infrastructure. 
Fischer-Tropsch diesel (FT)diesel is produced using gas-to-liquids technology. FT diesel can be mixed with fossil diesel at any percentage without need for infrastructure change.
Mixed alcohols are produced from syngas with catalysts similar to those used for methanol. Most R&D in this area is concentrated in producing mostly ethanol. However, some fuels are marketed as mixed alcohols (see Ecalene)  . Mixed alcohols are superior to pure methanol or ethanol, in that the higher alcohols have higher energy content. Also, when blending, the higher alcohols increase compatibility of gasoline and ethanol, which increases water tolerance and decreases evaporative emissions. In addition, higher alcohols have also lower heat of vaporization than ethanol, which is important for cold starts. (For another method for producing mixed alcohols from biomass see bioconversion of biomass to mixed alcohol fuels)
Wood diesel A new biofuel was developed by the University of Georgia from wood chips. The oil is extracted and then added to unmodified diesel engines. Either new plants are used or planted to replace the old plants. The charcoal byproduct is put back into the soil as a fertilizer. According to the director Tom Adams since carbon is put back into the soil, this biofuel can actually be carbon negative not just carbon neutral. Carbon negative decreases carbon dioxide in the air reversing the greenhouse effect not just reducing it.
Much research is being done about the use of microalgae as an energy source, with applications for biodiesel, ethanol, methanol, methane and hydrogen. The production of biofuels to replace oil and natural gas is in active development, focusing on the use of cheap organic matter (usually cellulose, agricultural and sewage waste) in the efficient production of liquid and gas biofuels which yield high net energy gain. One advantage of many biofuels over most other fuel types is that they are biodegradable, and so relatively harmless to the environment if spilled.
Biofuels in developing countries
Biofuel industries are becoming established in many developing countries. Many developing countries have extensive biomass resources that are becoming more valuable as demand for biomass and biofuels increases. The approaches to biofuel development in different parts of the world varies. Countries such as India and China are developing both bioethanol and biodiesel programs. India is extending plantations of jatropha, an oil-producing tree that is used in biodiesel production. The Indian sugar ethanol program sets a target of 5% bioethanol incorporation into transport fuel Ethanol India website. China is a major bioethanol producer and aims to incorporate 15% bioethanol into transport fuels by 2010.
Amongst rural populations in developing countries, biomass provides the majority of fuel for heat and cooking. Wood, animal dung and crop residues are commonly burned. Figures from the International Energy Agency show that biomass energy provides around 30% of the total primary energy supply in developing countries; over 2 billion people depend on biomass fuels as their primary energy source. world resources institute document on wood fuels
The use of biomass fuels for cooking indoors is a source of health problems and pollution. 1.3 million deaths were attributed to the use of biomass fuels with inadequate ventilation by the International Energy Agency in its World Energy Outlook 2006. Proposed solutions include improved stoves and alternative fuels. However, flues are easily damaged, and alternative fuels tend to be expensive. People in developing countries are unlikely to be able to afford to put these solutions in place. Organizations such as Intermediate Technology Development Group work to make improved facilities for biofuel use and better alternatives accessible to those who cannot get them.
Efforts and promotion
Recognizing the importance of implementing bioenergy, there are international organizations such as IEA Bioenergy, established in 1978 by the International Energy Agency (IEA), with the aim of improving cooperation and information exchange between countries that have national programs in bioenergy research, development and deployment.
In Brazil, the government hopes to build on the success of the Proálcool ethanol program by expanding the production of biodiesel which must contain 2% biodiesel by 2008, increasing to 5% by 2013. Columbia mandates the use of 10% ethanol in all gasoline sold in cities with populations exceeding 500,000. In Venezuela, the state oil company is supporting the construction of 15 sugar cane distilleries over the next five years, as the government introduces a E10 (10% ethanol) blending mandate. An EU directive has set the goal of replacing 5.75% of transportation fuel by biofuels by 2010 in all member states. In Canada, the government aims for 45% of the country’s gasoline consumption to contain 10% ethanol by 2010. In Southeast Asia, Thailand has mandated an ambitious 10% ethanol mix in gasoline starting in 2007. For similar reasons, the palm oil industry plans to supply an increasing portion of national diesel fuel requirements in Malaysia and Indonesia. In India, a bio-ethanol program calls for E5 blends throughout most of the country targeting to raise this requirement to E10 and then E20. In China, the government is making E10 blends mandatory in five provinces that account for 16% of the nation's passenger cars.
The European Union has set a goal:
- For 2010 that each member state should achieve at least 5.75% biofuel usage of all used traffic fuel.
- For 2020, 10 % . 
A senior member of the House Energy and Commerce Committee Congressman Fred Upton has legislation to use at least E10 fuel by 2012 in all cars in the USA. The fuel is less expensive and is cleaner for the environment. It has higher octane so all cars made after 2012 can be made with a higher compression rating to get better fuel economy.
Oregon Governor Ted Kulongoski signed legislation in July 2007 that will require all gasoline sold in the state to be blended with 10% bioethanol (a blend known as BE10) and all diesel fuel sold in the state to be blended with 2% biodiesel (a blend known as BD2). 
Current issues in biofuel production and use
Biofuels can provide benefits including: reduction of greenhouse gas emissions, reduction of fossil fuel use, increased national energy security, increased rural development and a sustainable fuel supply for the future.
However, biofuels have limitations. The feedstocks for biofuel production must be replaced rapidly and biofuel production processes must be designed and implemented so as to supply the maximum amount of fuel at the cheapest cost, while providing maximum environmental benefits. Broadly speaking, first generation biofuel production processes cannot supply us with more than a few percent of our energy requirements sustainably. The reasons for this are described below. Second generation processes can supply us with more biofuel, with better environmental gains. The major barrier to the development of second generation biofuel processes is their capital cost: establishing second generation biodiesel plants has been estimated at €500million Nexant Chem Systems study
Rising food prices/the "food vs. fuel" debate
Due to rising demand for biofuels, farmers worldwide have an increased economic incentive to grow crops for biofuel production instead of food production. Without political intervention, this could lead to reduced food production and increased food prices and inflation. The impacts of this would be greatest on poorer countries or countries that rely on imported food for their subsistence.
In early 2007 there were a number of reports linking stories as diverse as food riots in Mexico due to rising prices of corn for tortillas and reduced profits at Heineken, the large international brewer, to the increasing use of corn (maize) grown in the US Midwest for bio-ethanol production. (In the case of beer, the barley area was cut in order to increase corn production. Barley is not currently used to produce bioethanol.)
Environmental campaigner George Monbiot has argued in the British newspaper The Guardian for a 5-year freeze on biofuels while their impact on poor communities and the environment is assessed.  One problem with this approach is that economic drivers are required in order to push through the development of more sustainable second generation biofuel processes: these will be stalled if biofuel production decreases. A more viable solution is to increase political and industrial support for, and rapidity of, second generation biofuel implementation from non food crops, including cellulosic biofuels.
The most recent UN report on biofuel raises issues regarding food security and biofuel production.
Food surpluses exist in many developed countries. For example, the UK wheat surplus was around 2 million tonnes in 2005 (Defra figures after exports, ). This surplus alone could produce sufficient bioethanol to replace around 2.5% of the UK's petroleum consumption, without requiring any increase in wheat cultivation or reduction in food supply or exports. However, above a few percent (i.e. if the UK wanted to replace more than around 5% of its fuel with biofuel), there would be direct competition between first generation biofuel production and food production. This is one reason why second generation biofuel production processes are becoming increasingly important.
Second generation biofuel production processes use non food crops. These include the stalks of wheat and corn, wood, special energy or biomass crops (e.g. Miscanthus) and waste biomass. These processes could utilise the waste products of current food-based agriculture to manufacture fuel sustainably. Second generation biofuel processes are in development: pilot plants are established for the production of ethanol from wheat straw and of syn-diesel from wood chippings. It is important to note that carbon in waste biomass is used by other organisms, e.g. it is broken down in the soil to produce nutrients, and provides a habitat for wildlife. The large scale use of such "waste" biomass by humans might threaten these habitats and organisms.
Researchers at the Overseas Development Institute have argued that biofuels could help to reduce poverty in the developing world, through increased employment, wider economic growth multipliers and energy price effects. However, this potential is described as 'fragile', and is reduced where feedstock production tends to be large scale, or causes pressure on land access. With regards to potential for poverty reduction, biofuels rely on many of the same policy, regulatory or investment shortcomings that impede agriculture as a route to poverty reduction. As many of these shortcomings require policy improvements at a country level, rather than a global one, they argue for a country-by-country analysis of the potential poverty impacts of biofuels. This would consider, among other things, land administration systems, market coordination and prioritising investment in biodiesel as this 'generates more labour, has lower transportation costs and uses simpler technology'.
Energy efficiency and energy balance of biofuels
Production of biofuels from raw materials requires energy (for farming, transport and conversion to final product as well as the production of fertilizers, pesticides and herbicides). The level of energy expenditure varies by location: more intensive agricultural regimes such as those found in Western countries are more energy intensive. The more machinery is used for farming, the greater the energy expended in the process; developing countries tend to have less intensive agricultural methods. It is possible to produce biomass without incurring large agricultural energy costs: for example, wild-harvesting excess wood from established forests can be done without much energy input. However the yield of biomass from such resources is not consistent or large enough to support biofuel manufacture on a large scale.
The energy balance of a biofuel is determined by the amount of energy put in to the manufacture of fuel compared to the amount of energy released when it is burned in a vehicle and some biofuels can produce up to 2-36 times the input rate of fossil fuels. Biofuels tend to require higher energy inputs per unit energy than fossil fuels: oil can be pumped out of the ground and processed more efficiently than biofuels can be grown and processed. However, this is not necessarily a reason to use oil instead of biofuels, nor does it have an impact on the environmental benefits provided by a given biofuel.
Other factors connected to energy balance are a) cost and b) environmental impact. High energy impacts do not necessarily mean that the resulting fuel will be bad for the environment: energy can be derived from renewable resources to power biofuel manufacture.
Energy balance is not necessarily a measure of a good biofuel. Biofuels should be affordable, sustainable, abundant and provide good GHG emissions savings when compared with fossil fuels.
Energy balance/ efficiency of conversion is relevant when considering how best to use a given amount of biomass resources. For example, given limited resources should biomass be converted into heat and power or liquid transport fuels? Looking at energy balance and the efficiency of energy conversion can help to use biomass resources efficiently and with maximum environmental gain.
Studies have been done that calculate energy balances for biofuel production. Some of these show large differences depending on the biomass feedstock used and location. 
The energy balance is more favourable for biofuels made from crops grown in subtropical or tropical areas than those made from crops grown in temperate areas. This is largely due to the increased yield of biomass from crops in areas that receive more sunlight.
Life cycle assessments of biofuel production show that under certain circumstances, biofuels produce only limited savings in energy and greenhouse gas emissions. Fertiliser inputs and transportation of biomass across large distances can reduce the GHG savings achieved. The location of biofuel processing plants can be planned to minimize the need for transport, and agricultural regimes can be developed to limit the amount of fertiliser used for biomass production. A European study on the greenhouse gas emissions found that well-to-wheel (WTW) CO2 emissions of biodiesel from seed crops such as rapeseed could be almost as high as fossil diesel. It showed a similar result for bio-ethanol from starch crops, which could have almost as many WTW CO2 emissions as fossil petrol. This study showed that second generation biofuels have far lower WTW CO2 emissions.
Other independent LCA studies show that biofuels save around 50% of the CO2 emissions of the equivalent fossil fuels. This can be increased to 80-90% GHG emissions savings if second generation processes or reduced fertiliser growing regimes are used (Concawe Well to Wheels LCA for biofuels).
Some mainstream environmental groups support biofuels as a significant step toward slowing or stopping global climate change. However, biofuel production can threaten the environment if it is not done sustainably. This finding has been backed by reports of the UN, the IPCC and some other smaller environmental and social groups as the EEB and the Bank Sarasin ,which generally remain negative about biofuels.
As a result, governmentaland environmental organisations are turning against biofuels made at a non-sustainable way (hereby preferring certain oil sources as jatropha and lignocellulose over palm oil ) and are asking for global support for this 
Biofuels produce greenhouse gas emissions during their manufacture. The source of these emissions are: fertilisers and agricultural processing, transportation of the biomass, processing of the fuels, and transport and delivery of biofuels to the consumer. Some biofuel production processes produce far fewer emissions than others; for example sugar cane cultivation requires fewer fertiliser inputs than corn cultivation, therefore sugar cane bioethanol reduces greenhouse gas emissions more effectively than corn derived bioethanol. However, given the appropriate agricultural techniques and processing strategies, biofuels can provide emissions savings of at least 50% when compared to fossil fuels such as diesel and petroleum.
The increased manufacture of biofuels will require increasing land areas to be used for agriculture. Second generation biofuel processes can ease the pressure on land, because they can use waste biomass, and existing (untapped) sources of biomass such as crop residues and potentially even marine algae.
In some regions of the world, a combination of increasing demand for food, and increasing demand for biofuel, is causing deforestation and threats to biodiversity. The best reported example of this is the expansion of oil palm plantations in Malaysia and Indonesia, where rainforest is being destroyed to establish new oil palm plantations. It is an important fact that 90% of the palm oil produced in Malaysia is used by the food industry Malaysian Palm Oil Council; therefore biofuels cannot be held solely responsible for this deforestation. There is a pressing need for sustainable palm oil production for the food and fuel industries; palm oil is used in a wide variety of food products. The Roundtable on Sustainable Biofuels is working to define criteria, standards and processes to promote sustainably produced biofuels. Palm oil is also used in the manufacture of detergents, and in electricity and heat generation both in Asia and around the world (the UK burns palm oil in coal-fired power stations to generate electricity).
Significant area is likely to be dedicated to sugar cane in future years as demand for ethanol increases worldwide. The expansion of sugar cane plantations will place pressure on environmentally-sensitive native ecosystems including rainforest in South America. In forest ecosystems, these effects themselves will undermine the climate benefits of alternative fuels, in addition to representing a major threat to global biodiversity.
Although biofuels are generally considered to improve net carbon output, biodiesel and other fuels do produce local air pollution, including nitrogen oxides, the principal cause of smog.
- Category:Biofuels by country
- Alcohol fuel
- Anaerobic digestion
- Biobutanol, a direct biofuel that replaces gasoline.
- Biofuel in the United States
- Biogas and Biogas powerplant
- Bioheat, a biofuel blended with heating oil.
- Biomass to liquid bio-oil
- Ecological sanitation and biogas.
- Energy content of biofuel
- Energy crop
- Energy density
- Energy Policy Act of 2005
- Bioethanol in Brazil
- Greenhouse gas
- Hybrid vehicle
- Hydrogen vehicle
- List of vegetable oils section on oils used as biodiesel
- Low-carbon economy
- Nuclear and fossil independence
- Straight vegetable oil
- Thermal depolymerization
- Vegetable oil economy
- Waste vegetable oil
- Concawe European WTW study
- Smith, Lewis (The Times) (2007, Sept.). "Study: Biofuels May Produce More Greenhouse Gas Than Oil" (HTML). Retrieved on 2007-09-24.
- Paving the way for Agrofuels: EU policy, sustainability criteria, and climate calculations
- European Environment Agency (2006) How much bioenergy can Europe produce without harming the environment? EEA Report no. 7
- Marshall, A. T. (2007) Bioenergy from Waste: A Growing Source of Power, Waste Management World Magazine, April, p34-37
- IPCC Third Assessment Report, accessed August 31, 2007.
- Non-CO2 Gases Economic Analysis and Inventory: Global Warming Potentials and Atmospheric Lifetimes, U.S. Environmental Protection Agency, accessed August 31, 2007
- UN biofuels report
- Refuel.com biomethanol
- Refuel.com HTU diesel
- Globeco biodegradable bio-diesel
- Friends of Ethanol.com biodegradable ethanol
- Low Cost Algae Production System Introduced
- IEA bioenergy
- Biofuels Progress Report
- The Costs of Rising Tortilla Prices in Mexico - Enrique C. Ochoa, February 3, 2007
- Financial Times, London, February 25 2007, quoting Jean-François van Boxmeer, chief executive
- "Biofuels, Agriculture and Poverty Reduction" (PDF). Overseas Development Institute. 2007. Unknown parameter
- "Biofuel" does not necessarily mean ecologically friendly (EMPA report May 2007)
- European VIEWLS Biofuel report p.28 fig.4
- IPCC's Mitigation of Climate Change report negative on biofuels
- Biofuels no panacea
- Biofuels--Transporting Us to a Fossil-Free Future?
- Governmental (OECD)organisations against unsustainable biofuels
- Friends of the Earth, Oxfam, ... preferring jatropha over palm oil
- [http://www.downtoearth.org.in/full6.asp?foldername=20060715&filename=news&sec_id=49&sid=59 Environmental organisations against non-sustainabale biofuels 1
- Environmental organisations against non-sustainable biofuels 2
- Roundtable on Sustainable Biofuels website
- BBC News
- Agrofuels - towards a reality check in nine key areas
- Annual Biofuel progress reports of all EU member states
- U.S. Renewable Fuel Standard (EPA).
- Alternative Fuel Price Report.
- Roundtable on Sustainable Palm Oil
- NNFCC: The UK's National Centre for biofuels and renewable technologies
- Biofuel Review a news portal for the biofuels industry
- Biofuels Central - The Brazil Institute of the Woodrow Wilson International Center for Scholars
- Alternative Fuels Portal
- Biofuels for Transportation: Global Potential and Implications for Sustainable Agriculture and Energy in the 21st Century
- IEA Bioenergy
- Energy Justice Network
- "Biomass as Feedstock for a Bioenergy and Bioproducts Industry", a 2005 joint study sponsored by the United States Department of Energy and Department of Agriculture
- Promotional Web Site for Biomass and Bioenergy
- World Rainforest Movement
- Biofuels in New Zealand: Radio documentary, Part 1 (broadcast 26th May 2007) and Part 2 (broadcast 2nd June 2007)
- Ghent Bio Energy Valley
- IEA Bioenergy
- Russian National Biofuels Association
- What is Biodiesel
- Biofuel Crops: Power to the Poor
- Biofuel a.k.a Agrofuel
- BioenergyWiki - a wiki on biofuels and related subjects, including bioenergy sustainability.
- Biofuels for Transportation, André L. Boehman and Robert L. McCormick
- The Potential of Bagasse-Based Cogeneration in the US, Kevin Ho, Columbia University, 2006.
- Biofuels - the answer to the wrong question, Ben Courtice, Green Left Weekly, 20 October 2006.
- Biofuels for Transport - a dangerous distraction?, Dr Andrew Boswell, published in Scientists for Global Responsibility (www.sgr.org.uk) newsletter, January 2007.
- If we want to save the planet, we need a five-year freeze on biofuels, George Monbiot, The Guardian, March 29, 2007.
- Biofuels and bio-lubricants', Biofuels and bio-lubricants a growing business, 18 June 2007.
- Foodstuff as Imperial Weapon: Biofuels and Global Hunger, Fidel Castro, Counterpunch, March 31, 2007.
- Biofuels and the Prospect of Converting Plant Fibres into Gasoline Using Enzymes - A Review from the Science Creative Quarterly, January 22, 2007.
- "The Agrofuels Trap" - Foreign Policy in Focus, September 10, 2007.
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