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Sugar cane can be used as a biofuel or food.
Saab 99 running on wood gas. Gas generator on trailer.

Biofuel can be broadly defined as solid, liquid, or gas fuel derived from recently dead biological material.This distinguishes it from fossil fuels, which are derived from long dead biological material. Biofuel can be theoretically produced from any (biological) carbon source, though the most common by far is photosynthetic plants. Many different plants and plant-derived materials are used for biofuel manufacture. Biofuels are used globally, most commonly to power vehicles and cooking stoves. Biofuel industries are expanding in Europe, Asia and the Americas.

Biofuels offer the possibility of producing energy without a net increase of carbon into the atmosphere because the plants used in to produce the fuel have removed CO2 from the atmosphere, unlike fossil fuels which return carbon which was stored beneath the surface for millions of years into the air. Biofuel is therefore more nearly carbon neutral and less likely increase atmospheric concentrations of greenhouse gases (though doubts have been raised as to whether this benefit can be achieved in practice, see below). The use of biofuels also reduces dependence on petroleum and enhances energy security.

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

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

History and policy

Humans have used biomass fuels in the form of solid biofuels 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. biofuels-p2.html National Geographic, Green Dreams, Oct 2007] However, when large supplies of crude oil were discovered in Pennsylvania and Texas, petroleum based fuels became inexpensive, and soon were widely used. Cars and trucks began using fuels derived from mineral oil/petroleum: gasoline/ petrol or diesel.

Nevertheless, before World War II, and during the high demand wartime period, biofuels were valued as a strategic alternative to imported oil. Wartime Germany experienced extreme oil shortages, and many energy innovations resulted. This includes the powering of some of its vehicles using a blend of gasoline with alcohol fermented from potatoes, called Monopolin. In Britain, grain alcohol was blended with petrol by the Distillers Company Limited under the name Discol, and marketed through Esso's affiliate Cleveland.

During the peacetime post-war period, inexpensive oil from the Middle East contributed in part to the lessened economic and geopolitical interest in biofuels. Then in 1973 and 1979, geopolitical conflict in the Middle East caused OPEC to cut exports, and non-OPEC nations experienced a very large decrease in their oil supply. This " energy crisis" resulted in severe shortages, and a sharp increase in the prices of high demand oil-based products, notably petrol/ gasoline. There was also increased interest from governments and academics in energy issues and biofuels. Throughout history, the fluctuations of supply and demand, energy policy, military conflict, and the environmental impacts, have all contributed to a highly complex and volatile market for energy and fuel.

In the year 2000 and beyond, renewed interest in biofuels has been seen. The drivers for biofuel research and development include rising oil prices, concerns over the potential oil peak, greenhouse gas emissions (causing global warming and climate change), rural development interests, and instability in the Middle East.


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.

Animal waste is a persistent and unavoidable pollutant produced primarily by the animals housed in industrial sized farms. Researchers from Washington University have figured out a way to turn manure into biomass. In April 2008 with the help of imaging technology they noticed that vigorous mixing helps microorganisms turn farm waste into alternative energy, providing farmers with a simple way to treat their waste and convert it into energy.

There are also agricultural products specifically grown for biofuel production include corn, switchgrass, and soybeans, primarily in the United States; rapeseed, wheat and sugar beet primarily in Europe; sugar cane in Brazil; palm oil and miscanthus in South-East Asia; sorghum and cassava in China; and jatropha in India. Hemp has also been proven to work as a biofuel. 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 biofuels; 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.

Bio energy from waste

Waste vegetable oil which has been filtered.

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 (LFG). This can be burned and is considered a source of renewable energy, even though landfill disposal are often non-sustainable. Landfill gas can be burned either directly for heat or to generate electricity for public consumption. Landfill gas contains approximately 50% methane, the same gas that is found in natural gas.

Biomass can come from waste plant material. 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.

Frank Keppler and 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 (in an aerobic environment) 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 (48,500 m3) of oil per year.

Liquid fuels for transportation

In some countries biodiesel is less expensive than conventional diesel.

Most transportation fuels are liquids, because vehicles usually require high energy density, as occurs in liquids and solids. Vehicles usually need high power density as can be provided most inexpensively by an internal combustion engine. These engines require clean burning fuels, in order to keep the engine clean and minimize air pollution. The fuels that are easier to burn cleanly are typically liquids and gases. Thus liquids (and gases that can be stored in liquid form) meet the requirements of being both portable and clean burning. Also, liquids and gases can be pumped, which means handling is easily mechanized, and thus less laborious.

Types of biofuels

First generation biofuels

'First-generation biofuels' refer to biofuels made from sugar, starch, vegetable oil, or animal fats using conventional technology. The basic feedstocks for the production of first generation biofuels are often seeds or grains such as wheat, which yields starch that is fermented into bioethanol, or sunflower seeds, which are pressed to yield vegetable oil that can be used in biodiesel. These feedstocks could also enter the animal or human food chain, and as the global population has risen their use in producing biofuels has been criticised for diverting food away from the human food chain, leading to food shortages and price rises.

The most common first generation biofuels are listed below.

Vegetable oil

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. MAN B&W Diesel, Wartsila and Deutz AG offer engines that are compatible with straight vegetable oil. Used vegetable oil is increasingly being processed into biodiesel, and at a smaller scale, cleaned of water and particulates and used as a fuel.


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. One part glycerol is produced for every 10 parts biodiesel. Feedstocks for biodiesel include animal fats, vegetable oils, soy, rapeseed, jatropha, mahua, mustard, flax, sunflower, palm oil, hemp, field pennycress, and algae.

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 of 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, although it can become thick/viscous at lower temperatures, depending on the feedstock used, and vehicles may require fuel line heaters. However, the majority of vehicle manufacturers limit their recommendations to 15% biodiesel blended with mineral diesel. Many newer diesel engines are made so that they can run with 100% biodiesel fuel without altering the engine itself, although this can be dependent on the fuel rail design. Since biodiesels burn cleaner than regular mineral diesel, filters may need to be replaced more often, especially as the biofuel dissolves old deposits in the fuel tank and pipes. 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.


Information on a pump in California.

Biologically produced alcohols, most commonly ethanol, and less commonly propanol and butanol, are produced by the action of microorganisms and enzymes through the fermentation of sugars or starches (easiest), or cellulose (which is more difficult). Biobutanol (also called biogasoline) is often claimed to provide a direct replacement for gasoline, because it can be used directly in a gasoline engine (in a similar way to biodiesel in diesel engines).

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. DuPont and BP are working together to help develop Butanol.

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

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

Ethanol fuel has less BTU energy content, which means it takes more fuel (volume and mass) to go the same distance. More-expensive premium fuels contain less, or no, ethanol. In high-compression engines, less ethanol, slower-burning premium fuel is required to avoid harmful pre-ignition (knocking). Very-expensive aviation gasoline (Avgas) is 100 octane made from 100% petroleum. The high price of zero-ethanol Avgas does not include federal-and-state road-use taxes.

Ethanol is very corrosive to fuel systems, rubber hoses-and-gaskets, aluminium, and combustion chambers. It is therefore illegal to use fuels containing alcohol in aircraft (although at least one model of ethanol-powered aircraft has been developed, the Embraer EMB 202 Ipanema). Ethanol is incompatible with marine fibreglass fuel tanks (it makes them leak). For higher ethanol percentage blends, and 100% ethanol vehicles, engine modifications are required.

Corrosive ethanol cannot be transported in petroleum pipelines, so more-expensive over-the-road stainless-steel tank trucks increase the cost and energy consumption required to deliver ethanol to the customer at the pump.

In the current alcohol-from-corn production model in the United States, considering the total energy consumed by farm equipment, cultivation, planting, fertilizers, pesticides, herbicides, and fungicides made from petroleum, irrigation systems, harvesting, transport of feedstock to processing plants, fermentation, distillation, drying, transport to fuel terminals and retail pumps, and lower ethanol fuel energy content, the net energy content value added and delivered to consumers is very small. And, the net benefit (all things considered) does little to reduce un- sustainable imported oil and fossil fuels required to produce the ethanol.

Many car manufacturers are now producing flexible-fuel vehicles (FFV's), which can safely run on any combination of bioethanol and petrol, up to 100% bioethanol. They dynamically sense exhaust oxygen content, and adjust the engine's computer systems, spark, and fuel injection accordingly. This adds initial cost and ongoing increased vehicle maintenance. Efficiency falls and pollution emissions increase when FFV system maintenance is needed (regardless of the 0%-to-100% ethanol mix being used), but not performed (as with all vehicles). FFV internal combustion engines are becoming increasingly complex, as are multiple- propulsion-system FFV hybrid vehicles, which impacts cost, maintenance, reliability, and useful lifetime longevity.

Alcohol mixes with both petroleum and with water, so ethanol fuels are often diluted after the drying process by absorbing environmental moisture from the atmosphere. Water in alcohol-mix fuels reduces efficiency, makes engines harder to start, causes intermittent operation (sputtering), and oxidizes aluminium ( carburetors) and steel components ( rust).

Even dry ethanol has roughly one-third lower energy content per unit of volume compared to gasoline, so larger / heavier fuel tanks are required to travel the same distance, or more fuel stops are required. With large current un- sustainable, non- scalable subsidies, ethanol fuel still costs much more per unit of distance traveled than current high gasoline prices in the United States.

Methanol is currently produced from natural gas, a non- renewable fossil fuel. It can also be produced from biomass as biomethanol. The methanol economy is an interesting alternative to the hydrogen economy, compared to today's hydrogen produced from natural gas, but not hydrogen production directly from water and state-of-the-art clean solar thermal energy processes.


Pipes carrying biogas

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

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

Oils and gases can be produced from various biological wastes:

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

Solid biofuels

Examples include wood, grass cuttings, domestic refuse, charcoal, and dried manure.


Syngas is produced by the combined processes of pyrolysis, combustion, and gasification. Biofuel is converted into carbon monoxide and energy by pyrolysis. A limited supply of oxygen is introduced to support combustion. Gasification converts further organic material to hydrogen and additional carbon monoxide.

The resulting gas mixture, syngas, is itself a fuel. Using the syngas is more efficient than direct combustion of the original biofuel; more of the energy contained in the fuel is extracted.

Syngas may be burned directly in internal combustion engines. The wood gas generator is a wood-fueled gasification reactor mounted on an internal combustion engine. Syngas can be used to produce methanol and hydrogen, or converted via the Fischer-Tropsch process to produce a synthetic petroleum substitute. Gasification normally relies on temperatures >700°C. Lower temperature gasification is desirable when co-producing biochar.

Second generation biofuels

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

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

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

Scientists also work on experimental recombinant DNA genetic engineering organisms that could increase biofuel potential.

Third generation biofuels

Algae fuel, also called oilgae or third generation biofuel, is a biofuel from algae. Algae are low-input/high-yield (30 times more energy per acre than land) feedstocks to produce biofuels and algae fuel are biodegradable:

  • With the higher prices of fossil fuels (petroleum), there is much interest in algaculture (farming algae).
  • One advantage of many biofuels over most other fuel types is that they are biodegradable, and so relatively harmless to the environment if spilled.
  • The United States Department of Energy estimates that if algae fuel replaced all the petroleum fuel in the United States, it would require 15,000 square miles (38,849 square kilometers), which is roughly the size of Maryland.

Second and third generation biofuels are also called advanced biofuels.

On the other hand, an appearing fourth generation is based in the conversion of vegoil and biodiesel into gasoline.

Fourth generation biofuels

Craig Venter's company Synthetic Genomics is genetically engineering microorganisms to produce fuel directly from carbon dioxide on an industrial scale.

Biofuels by country

Recognizing the importance of implementing bioenergy, there are international organizations such as IEA Bioenergy, established in 1978 by the OECD 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. The U.N. International Biofuels Forum is formed by Brazil, China, India, South Africa, the United States and the European Commission. The world leaders in biofuel development and use are Brazil, United States, France, Sweden and Germany.


IC Green Energy, a subsidiary of Israel Corp., aims by 2012 to process 4-5% of the global biofuel market (~4 million tons). It is focused solely on non-edible feedstock such as Jatropha, Castor, cellulosic biomass and algae. In June 2008, Tel Aviv-based Seambiotic and Seattle-based Inventure Chemical announced a joint venture to use CO2 emissions-fed algae to make ethanol and biodiesel at a biofuel plant in Israel.


In China, the government is making E10 blends mandatory in five provinces that account for 16% of the nation's passenger cars. 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 Canada, the government aims for 45% of the country’s gasoline consumption to contain 10% ethanol by 2010.


In India, a bioethanol program calls for E5 blends throughout most of the country targeting to raise this requirement to E10 and then E20.


The European Union in its biofuels directive (updated 2006) has set the goal that for 2010 that each member state should achieve at least 5.75% biofuel usage of all used traffic fuel. By 2020 the figure should be 10%. As of January 2008 these aims are being reconsidered in light of certain environmental and social concerns associated with biofuels such as rising food prices and deforestation.


France is the second largest biofuel consumer among the EU States in 2006. According to the Ministry of Industry, France's consumption increased by 62.7% to reach 682,000 toe (i.e. 1.6% of French fuel consumption). Biodiesel represents the largest share of this (78%, far ahead of bioethanol with 22%). The unquestionable biodiesel leader in Europe is the French company Diester Industrie. In bioethanol, the French agro-industrial group Téréos is increasing its production capacities. Germany itself remained the largest European biofuel consumer, with a consumption estimate of 2.8 million tons of biodiesel (equivalent to 2,408,000 toe), 0.71 million ton of vegetable oil (628.492 toe) and 0.48 million ton of bioethanol (307,200 toe).


The biggest biodiesel German company is ADM Ölmühle Hamburg AG, which is a subsidiary of the American group Archer Daniels Midland Company. Among the other large German producers, MUW (Mitteldeutsche Umesterungswerke GmbH & Co KG) and EOP Biodiesel AG. A major contender in terms of bioethanol production is the German sugar corporation, Südzucker.


The Spanish group Abengoa, via its American subsidiary Abengoa Bioenergy, is the European leader in production of bioethanol.


The government in Sweden has together with BIL Sweden, the national association for the automobile industry, that are the automakers in Sweden started the work to end oil dependency. One-fifth of cars in Stockholm can run on alternative fuels, mostly ethanol fuel. Also Stockholm will introduce a fleet of Swedish-made hybrid ethanol-electric buses. In 2005, oil phase-out in Sweden by 2020 was announced.

United Kingdom

In the United Kingdom the Renewable Transport Fuel Obligation (RTFO) (announced 2005) is the requirement that by 2010 5% of all road vehicle fuel is renewable. In 2008 a critical report by the Royal Society stated that biofuels risk failing to deliver significant reductions in greenhouse gas emissions from transport and could even be environmentally damaging unless the Government puts the right policies in place.


Typical Brazilian "flex" models from several car makers, that run on any blend of ethanol and gasoline.

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.


Colombia 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.


In 2006, the United States president George W. Bush said in a State of the Union speech that the US is "addicted to oil" and should replace 75% of imported oil by 2025 by alternative sources of energy including biofuels.

Essentially all of the ethanol fuel in the US is produced from corn. Corn is a very energy intensive crop, which requires one unit of fossil-fuel energy to create just 0.9 to 1.3 energy units of ethanol. A senior member of the House Energy and Commerce Committee Congressman Fred Upton has introduced legislation to use at least E10 fuel by 2012 in all cars in the USA.

The 2007-12-19 U.S. Energy Independence and Security Act of 2007 requires American “fuel producers to use at least 36 billion gallons of biofuel in 2022. This is nearly a fivefold increase over current levels.” This is causing a significant agricultural resource shift away from food production to biofuels. American food exports have decreased (increasing grain prices worldwide), and US food imports have increased significantly.

Most biofuels are not currently cost-effective without significant subsidies. "America's ethanol program is a product of government subsidies. There are more than 200 different kinds, as well as a 54 cents-a-gallon tariff on imported ethanol. This prices Brazilian ethanol out of an otherwise competitive market. Brazil makes ethanol from sugarcane rather than corn (maize), which has a better EROEI. Federal subsidies alone cost $7 billion a year (equal to around $1.90 a gallon)."

General Motors is starting a project to produce E85 fuel from cellulose ethanol for a projected cost of $1 a gallon. This is optimistic however, because $1/gal equates to $10/MBTU which is comparable to woodchips at $7/MBTU or cord wood at $6-$12/MBTU, and this does not account for conversion losses and plant operating and capital costs which are significant. The raw materials can be as simple as corn stalks and scrap petroleum-based vehicle tires, but used tires are an expensive feedstock with other more-valuable uses. GM has over 4 million E85 cars on the road now, and by 2012 half of the production cars for the U.S. will be capable of running on E85 fuel, however by 2012 the supply of ethanol will not even be close to supplying this much E85. Coskata Inc. is building two new plants for the ethanol fuel. Theoretically, the process is claimed to be five times more energy efficient than corn based ethanol, however it is still in development and has not been proven to be cost effective in a free market.

The greenhouse gas emissions are reduced by 86% for cellulose compared to corn’s 29% reduction.

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. China is a major bioethanol producer and aims to incorporate 15% bioethanol into transport fuels by 2010. Costs of biofuel promotion programs can be very high, though.

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.

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, fuels are easily damaged, and alternative fuels tend to be expensive. Very low cost, fuel efficient, low pollution biomass stove designs have existed since 1980 or earlier. Issues are a lack of education, distribution, excess corruption, and very low levels of foreign aid. People in developing countries are often unable to afford these solutions without assistance or financing such as microloans. 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.

Current issues in biofuel production and use

Biofuels are proposed as having such benefits as: 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, biofuel production is questioned from a number of angles. The chairman of the International Panel on Climate Change, Rajendra Pachauri, notably observed in March 2008 that questions arise on the emissions implications of that route, and that biofuel production has clearly raised prices of corn, with an overall implication for food security.

Biofuels are also seen as having 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.

Recently, an inflexion point about advantages/disadvantages of biofuels seems to be gaining momentum. The March 27, 2008 TIME magazine cover features the subject under the title "The Clean Energy Myth":

Politicians and Big Business are pushing biofuels like corn-based ethanol as alternatives to oil. All they’re really doing is driving up world food prices, helping to destroy the Amazon jungle, and making global warming worse.

In the June, 2008 issue of the journal Conservation Biology, scientists argue that because such large amounts of energy are required to grow corn and convert it to ethanol, the net energy gain of the resulting fuel is modest. Using a crop such as switchgrass, common forage for cattle, would require much less energy to produce the fuel, and using algae would require even less. Changing direction to biofuels based on switchgrass or algae would require significant policy changes, since the technologies to produce such fuels are not fully developed.

Oil price moderation

The International Energy Agency's World Energy Outlook 2006 concludes that rising oil demand, if left unchecked, would accentuate the consuming countries' vulnerability to a severe supply disruption and resulting price shock. The report suggested that biofuels may one day offer a viable alternative, but also that "the implications of the use of biofuels for global security as well as for economic, environmental, and public health need to be further evaluated".

Economists disagree on the extent that biofuel production affects crude oil prices. According to the Francisco Blanch, a commodity strategist for Merrill Lynch, crude oil would be trading 15 per cent higher and gasoline would be as much as 25 per cent more expensive, if it were not for biofuels. Gordon Quaiattini, president of the Canadian Renewable Fuels Association, argued that a healthy supply of alternative energy sources will help to combat gasoline price spikes. However, the Federal Reserve Bank of Dallas concluded that "Biofuels are too limited in scale and currently too costly to make much difference to crude oil pricing."

Rising food prices — the "food vs. fuel" debate

This topic is internationally controversial. There are those, such as the National Corn Growers Association, who say biofuel is not the main cause. Some say the problem is a result of government actions to support biofuels. Others say it is just due to oil price increases. The impact of food price increases is greatest on poorer countries. Some have called for a freeze on biofuels. Some have called for more funding of second generation biofuels which should not compete with food production so much. In May 2008 Olivier de Schutter, the United Nations food adviser, called for a halt on biofuel investment. In an interview in Le Monde he stated: "The ambitious goals for biofuel production set by the United States and the European Union are irresponsible. I am calling for a freeze on all investment in this sector." 100 million people are currently at risk due to the food price increases.

Carbon emissions

Graph of UK figures for the carbon intensity of bioethanol and fossil fuels. This graph assumes that all bioethanols are burnt in their country of origin and that prevously existing cropland is used to grow the feedstock.

Biofuels and other forms of renewable energy aim to be carbon neutral or even carbon negative. Carbon neutral 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 human contributions to atmospheric carbon dioxide levels, reducing the human contributions to global warming. A carbon negative aim is achieved when a portion of the biomass is used for carbon sequestration. Calculating exactly how much greenhouse gas (GHG) is produced in burning biofuels is a complex and inexact process, which depends very much on the method by which the fuel is produced and other assumptions made in the calculation.

Carbon emissions have been increasing ever since the industrial revolution. Prior to the industrial revolution, our atmosphere contained about 280 parts per million of carbon dioxide. After burning coal, gas, and oil to power our lives, the concentration had risen to 315 parts per million. Today, it is at the 380 level and still increasing by approximately two parts per million annually. During this time frame, the global average temperature has risen by more than 1°F since carbon dioxide traps heat near the Earth’s surface. Scientists believe that if the level goes beyond 450 parts per million, the temperature jump will be so great that we will be faced with an enormous rise in sea level due to the melting of Greenland and West Antarctic ice sheets.

The carbon emissions ( Carbon footprint) 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. 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 these studies do not take into account emissions from nitrogen fixation, deforestation, land use, or any indirect emissions.

In October 2007, a study was published by scientists from Britain, U.S., Germany and Austria, including Professor Paul Crutzen, who won a Nobel Prize for his work on ozone. They reported that the burning of biofuels derived from rapeseed and corn (maize) can contribute as much or more to global warming by nitrous oxide emissions than cooling by fossil fuel savings. Nitrous oxide is both a potent greenhouse gas and a destroyer of atmospheric ozone. But they also reported that crops with lower requirements for nitrogen fertilizers, such as grasses and woody coppicing will result in a net absorption of greenhouse gases.

In February 2008, two articles were published in Science which investigated the GHG emissions effects of the large amount of natural land that is being converted to cropland globally to support biofuels development. The first of these studies, conducted at the University of Minnesota, found that:

...converting rainforests, peatlands, savannas, or grasslands to produce food-based biofuels in Brazil, Southeast Asia, and the United States creates a ‘biofuel carbon debt’ by releasing 17 to 420 times more CO2 than the annual greenhouse gas (GHG) reductions these biofuels provide by displacing fossil fuels.

This study not only takes into account removal of the original vegetation (as timber or by burning) but also the biomass present in the soil, for example roots, which is released on continued plowing. It also pointed out that:

...biofuels made from waste biomass or from biomass grown on degraded and abandoned agricultural lands planted with perennials incur little or no carbon debt and can offer immediate and sustained GHG advantages.

The second study, conducted at Princeton University, used a worldwide agricultural model to show that:

...corn-based ethanol, instead of producing a 20% savings, nearly doubles greenhouse emissions over 30 years and increases greenhouse gases for 167 years.

Both of the Science studies highlight the need for sustainable biofuels, using feedstocks that minimize competition for prime croplands. These include farm, forest and municipal waste streams; energy crops grown on marginal lands, and algaes. These second generation biofuels feedstocks "are expected to dramatically reduce GHGs compared to first generation biofuels such as corn ethanol". In short, biofuels done unsustainably could make the climate problem worse, while biofuels done sustainably could play a leading role in solving the carbon challenge.

Sustainable biofuel production

Responsible policies and economic instruments would help to ensure that biofuel commercialization, including the development of new cellulosic technologies, is sustainable. Sustainable biofuel production practices would not hamper food and fibre production, nor cause water or environmental problems, and would actually enhance soil fertitlity. Responsible commercialization of biofuels represents an opportunity to enhance sustainable economic prospects in Africa, Latin America and impoverished Asia.

Soil erosion, deforestation, and biodiversity

It is important to note that carbon compounds in waste biomass that is left on the ground are consumed by other microorganisms. They break down biomass in the soil to produce valuable nutrients that are necessary for future crops. On a larger scale, plant biomass waste provides small wildlife habitat, which in turn ripples up through the food chain. The widespread human use of biomass (which would normally compost the field) would threaten these organisms and natural habitats. When cellulosic ethanol is produced from feedstock like switchgrass and saw grass, the nutrients that were required to grow the lignocellulose are removed and cannot be processed by microorganisms to replenish the soil nutrients. The soil is then of poorer quality. Loss of ground cover root structures accelerates unsustainable soil erosion.

Significant areas of native Amazon rainforest have been cleared by slash and burn techniques to make room for sugar cane production, which is used in large part for ethanol fuel in Brazil, and growing ethanol exports. Large-scale deforestation of mature trees (which help remove CO2 through photosynthesis — much better than does sugar cane or most other biofuel feedstock crops do) contributes to un- sustainable global warming atmospheric greenhouse gas levels, loss of habitat, and a reduction of valuable biodiversity. Demand for biofuel has led to clearing land for Palm Oil plantations.

A portion of the biomass should be retained onsite to support the soil resource. Normally this will be in the form of raw biomass, but processed biomass is also an option. If the exported biomass is used to produce syngas, the process can be used to co-produce biochar, a low-temperature charcoal used as a soil amendment to increase soil organic matter to a degree not practical with less recalcitrant forms of organic carbon. For co-production of biochar to be widely adopted, the soil amendment and carbon sequestration value of co-produced charcoal must exceed its net value as a source of energy.


Formaldehyde, Acetaldehyde and other Aldehydes are produced when alcohols are oxidized. When only a 10% mixture of ethanol is added to gasoline (as is common in American E10 gasohol and elsewhere), aldehyde emissions increase 40%. Some study results are conflicting on this fact however, and lowering the sulfur content of biofuel mixes lowers the acetaldehyde levels. Burning biodiesel also emits aldehydes and other potentially hazardous aromatic compounds which are not regulated in emissions laws.

Many aldehydes are toxic to living cells. Formaldehyde irreversibly cross-links protein amino acids, which produces the hard flesh of embalmed bodies. At high concentrations in an enclosed space, formaldehyde can be a significant respiratory irritant causing nose bleeds, respiratory distress, lung disease, and persistent headaches. Acetaldehyde, which is produced in the body by alcohol drinkers and found in the mouths of smokers and those with poor oral hygene, is carcinogenic and mutagenic.

The European Union has banned products that contain Formaldehyde, due to its documented carcinogenic characteristics. The U.S. Environmental Protection Agency has labeled Formaldehyde as a probable cause of cancer in humans.

Brazil burns significant amounts of ethanol biofuel. Gas chromatograph studies were performed of ambient air in São Paulo Brazil, and compared to Osaka Japan, which does not burn ethanol fuel. Atmospheric Formaldehyde was 160% higher in Brazil, and Acetaldehyde was 260% higher.

Social and Water impact in Indonesia

In some locations such as Indonesia deforestation for Palm Oil plantations is leading to displacement of Indigenous peoples. Also, extensive use of pesticide for biofuel crops is reducing clean water supplies.

Environmental organizations stance

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, governmental and 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. Also, besides supporting these more sustainable biofuels, environmental organisations are redirecting to new technologies that do not use internal combustion engines such as hydrogen and compressed air.

The "Roundtable on Sustainable Biofuels" is an international initiative which brings together farmers, companies, governments, non-governmental organizations, and scientists who are interested in the sustainability of biofuels production and distribution. During 2008, the Roundtable is developing a series of principles and criteria for sustainable biofuels production through meetings, teleconferences, and online discussions.

The increased manufacture of biofuels will require increasing land areas to be used for agriculture. Second and third 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; 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.

Potential for poverty reduction

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 limited agricultural resources: capital investment, land, water, and the net cost of food for the poor.

With regards to the potential for poverty reduction or exacerbation, biofuels rely on many of the same policy, regulatory or investment shortcomings that impede agriculture as a route to poverty reduction. Since 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'.

Biofuel prices

Retail, at the pump prices, including U.S. subsidies, Federal and state motor taxes, B2/B5 prices for low-level Biodiesel (B2-B5) are lower than petroleum diesel by about 12 cents, and B20 blends are the same per unit of volume as petrodiesel.

Due to the 1/3 lower energy content of ethanol fuel, even the heavily-subsidized net cost to drive a specific distance in flexible-fuel vehicles is higher than current gasoline prices.

Energy efficiency and energy balance of biofuels

Production of biofuels from raw materials requires energy (for farming, transport and conversion to final product, and the production / application of fertilizers, pesticides, herbicides, and fungicides), and has environmental consequences.

The energy balance of a biofuel is determined by the amount of energy put into the manufacture of fuel compared to the amount of energy released when it is burned in a vehicle. This varies by feedstock and according to the assumptions used. Biodiesel made from sunflowers may produce only 0.46 times the input rate of fuel energy. Biodiesel made from soybeans may produce 3.2 times the input rate of fossil fuels. This compares to 0.805 for gasoline and 0.843 for diesel made from petroleum. Biofuels may require higher energy input per unit of BTU energy content produced than fossil fuels: petroleum 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.

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.

To explain one specific example, a June 17, 2006 editorial in the Wall. St. Journal stated, "The most widely cited research on this subject comes from Cornell's David Pimental and Berkeley's Ted Patzek. They've found that it takes more than a gallon of fossil fuel to make one gallon of ethanol — 29% more. That's because it takes enormous amounts of fossil-fuel energy to grow corn (using fertilizer and irrigation), to transport the crops and then to turn that corn into ethanol."

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. Further GHG savings can be achieved by using by-products to provide heat, such as using bagasse to power ethanol production from sugarcane.

Collocation of synergistic processing plants can enhance efficiency. One example is to use the exhaust heat from an industrial process for ethanol production, which can then recycle cooler processing water, instead of evaporating hot water that warms the atmosphere.

Biofuels and solar energy efficiency

Biofuels from plant materials convert energy that was originally captured from solar energy via photosynthesis. A comparison of conversion efficiency from solar to usable energy (taking into account the whole energy budgets) shows that photovoltaics are 100 times more efficient than corn ethanol and 10 times more efficient than the best biofuel.

Centralised vs. decentralised production

There is debate around the best model for production.

One side sees centralised vegetable oil fuel production offering

  • efficiency
  • greater potential for fuel standardisation
  • ease of administrating taxes
  • possibility for rapid expansion

The other side of the argument points to

  • increased fuel security
  • rural job creation
  • less of a 'monopolistic' or ' oligopolistic' market due to the increased number of producers
  • benefits to local economy as a greater part of any profits stay in the local economy
  • decreased transportation and greenhouse gases of feedstock and end product
  • consumers close to and able to observe the effects of production

The majority of established biofuel markets have followed the centralised model with a few small or micro producers holding a minor segment of the market. A noticeable exception to this has been the pure plant oil (PPO) market in Germany which grew exponentially until the beginning of 2008 when increasing feedstock prices and the introduction of fuel duty combined to stifle the market. Fuel was produced in hundreds of small oil mills distributed throughout Germany often run as part of farm businesses.

Initially fuel quality could be variable but as the market matured new technologies were developed that made significantly improvements. As the technologies surrounding this fuel improved usage and production rapidly increased with rapeseed oil PPO forming a significant segment of transportation biofuels consumed in 2007.

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