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Sugar cane can be used as a biofuel or food.

Biofuel (if cultivated, then also called agrofuel or agrifuel) can be broadly defined as solid, liquid, or gas fuel consisting of, or derived from recently dead biological material, most commonly plants. This distinguishes it from fossil fuel, which is derived from long dead biological material.

Biofuel can be theoretically produced from any (biological) carbon source. The most common by far is photosynthetic plants that capture solar energy. Many different plants and plant-derived materials are used for biofuel manufacture.

Biofuels are used globally and biofuel industries are expanding in Europe, Asia and the Americas. The most common use for biofuels is as liquid fuels for automotive transport. The use of renewable biofuels provides increased independence from petroleum and enhances energy security.^[1]

There are various current issues with biofuel production and use, which are presently being discussed in the popular media and scientific journals. These include: the effect of moderating oil prices, the "food vs fuel" debate, carbon emissions levels, sustainable biofuel production, deforestation and soil erosion, impact on water resources, human rights issues, poverty reduction potential, biofuel prices, energy balance and efficiency, and centralised versus decentralised production models.

One of the greatest technical challenges is to develop ways to convert biomass energy specifically to liquid fuels for transportation. To achieve this, the two most common strategies are:

• 1. To grow sugar crops (sugar cane, and sugar beet), or starch (corn/maize), and then use yeast fermentation to produce ethanol (ethyl alcohol).There is a new sugar crop for Ethanol production - Sweet sorghum (see here)
• 2. To grow plants that (naturally) produce oils, 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 be converted into biofuels such as woodgas, methanol or ethanol fuel. Some researchers are working to improve these processes.

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.

Liquid biofuels have been used since the early days of the automobile 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, and Henry Ford originally designed the Ford Model T, a car produced from 1903 to 1926, to run completely on hemp derived biofuel.^[2][3] 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 include the powering of some of 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.

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 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

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.^[4]

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.

See also Biomass

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.^[5][6]

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 considered a source of renewable energy, even though landfill disposal are often non-sustainable. [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.^[7][8] Over a time span of 100 years, methane has a global warming potential of 23 relative to CO₂.^[7] 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.^[9] 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 of oil per year.

See also Waste-to-Energy

Liquid fuels for transportation

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 only liquids meet the requirements of being both portable and clean burning. Also, liquids can be pumped, which means handling is easily mechanized, and thus less laborious.

First generation biofuels

'First-generation biofuels' refer to biofuels made from sugar, starch, vegetable oil, or animal fats using conventional technology.^[10] 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 - there are two types: 1. waste vegetable oil (WVO) if it is from a restaurant, etc. 2. straight vegetable oil (SVO) or pure plant oil (PPO). For engines designed to burn #2 diesel fuel, the viscosity of vegetable oil must be lowered, otherwise incomplete combustion and carbon build up will ultimately damage the engine.


• Biodiesel - non-petroleum-based diesel fuel typically produced by transesterification from vegetable oils or animal fats, which can be used (alone, or blended with conventional petrodiesel) in unmodified diesel-engine vehicles.


• Bioalcohols - produced by converting biomass into alcohol. The process involves fermentation of biomass sugars using enzymes, yeasts and bacteria (methanol, ethanol, butanol).


• BioGas - produced by the biological breakdown of organic matter in the absence of oxygen, by anaerobic digestion or fermentation of biodegradable materials such as manure or sewage, municipal waste, and energy crops.


• Solid Biofuels - wood, grass cuttings, domestic refuse, charcoal, and dried manure.


• Syngas (from synthesis gas) - produced by gasification of coal or municipal waste.

Second generation biofuels

Biofuel technologies are able to manufacture biofuels from biomass. Biomass is a wide-ranging term meaning any source of organic carbon that is renewed rapidly as part of the carbon cycle. Biomass is all derived from plant materials but can include animal materials.

Second generation biofuel technologies have been developed because first generation biofuels manufacture has important limitations. First generation biofuel processes are useful, but limited: there is a threshold above which they cannot produce enough biofuel without threatening food supplies and biodiversity. They are not cost competitive with existing fossil fuels such as oil, and some of them produce only limited greenhouse gas emissions savings. When taking emissions from production and transport into account, life-cycle emissions from first-generation biofuels frequently exceed those of traditional fossil fuels.

Second generation biofuels can help solve these problems and can supply a larger proportion of our fuel supply sustainably, affordably, and with greater environmental benefits.

First generation bioethanol is produced by fermenting plant-derived sugars to ethanol, using a similar process to that used in beer and wine-making. This requires the use of 'food' crops such as sugar cane, corn, wheat, and sugar beet. These crops are required for food, so if too much biofuel is made from them, food prices could rise and shortages might be experienced in some countries. Corn, wheat and sugar beet also require high agricultural inputs in the form of fertilizers, which limit the greenhouse gas reductions that can be achieved.

The goal of second generation biofuel processes is to extend the amount of biofuel that can be produced sustainably by using biomass comprised of the residual non-food parts of current crops, such as them stems, leaves and husks that are left behind once the food crop has been extracted, as well as other crops that are not used for food purposes, such as switch grass, cereals that bear little grain and more fibre, and also industry waste such as wood chips, skins and pulp from fruit pressing etc.

The problem that second generation biofuel processes are addressing is to extract useful feedstocks from this woody or fibrous biomass, where the useful sugars are locked in by lignin and cellulose. All plants contain cellulose and lignin. These are complex carbohydrates (molecules based on sugar). Lignocellulosic ethanol is made by freeing the sugar molecules from cellulose using enzymes, steam heating, or other pre-treatments. These sugars can then be fermented to produce ethanol in the same way as first generation bioethanol production. The by-product of this process is lignin. Lignin can be burned as a carbon neutral fuel to produce heat and power for the processing plant and possibly for surrounding homes and businesses.

The greenhouse gas emissions savings for lignocellulosic ethanol are greater than those obtained by first generaiton biofuels. Lignocellulosic ethanol can reduce greenhouse gas emissions by around 90% when compared with fossil petroleum ^[1]

An operating lignocellulosic ethanol production plant is located in Canada, run by IOGEN Corporation ^[2]. The demonstration-scale plant produces around 700,000 litres of bioethanol each year. A commercial plant is under construction. Many further lignocellulosic ethanol plants have been proposed in North America and around the world.

In the future, there might be bio-synthetic liquid fuel available. It can be produced by the Fischer-Tropsch process, also called Biomass-To-Liquids (BTL).^[3]

The following second generation biofuels are under development:

• Biohydrogen. 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, or alternatively, this might be accomplished with some organisms that produce hydrogen directly under certain conditions. BioHydrogen can be used in fuel cells to produce electricity.
• Bio-DME. Bio-DME, Fischer-Tropsch, BioHydrogen diesel, Biomethanol and Mixed Alcohols all use syngas for production. This syngas is produced by gasification of biomass, however, it can be produced much easier from coal or natural gas, which is done on very large scales in power plants and in gas-to-liquid processes. HTU (High Temperature Upgrading) diesel is produced from particularly wet biomass stocks using high temperature and pressure to produce an oil.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.
• Biomethanol. Biomethanol is the same as methanol but it is produced from biomass. Biomethanol can be blended with petrol up to 10-20% without any infrastructure changes.^[4]
• DMF. Recent advances in producing DMF from fructose and glucose using catalytic biomass-to-liquid process have increased its attractiveness.
• HTU diesel. HTU diesel is produced from wet biomass. It can be mixed with fossil diesel in any percentage without need for infrastructure.^[5]
• Fischer-Tropsch diesel. (FT) diesel is produced using the Fischer-Tropsch gas-to-liquids technology. FT diesel can be mixed with fossil diesel at any percentage without need for infrastructure change.
• Mixed Alcohols (i.e., mixture of mostly ethanol, propanol and butanol, with some pentanol, hexanol, heptanol and octanol). 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).^[6][7] 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.

On the other hand, Biodiesel from non-food crops that can be grown on marginal land (as Jatropha) are considered second generation biofuels and are nowadays available in mass production.

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^[22] and algae fuel are biodegradable:

• With the higher prices of oil, 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.^[23][24][25]

• 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 a few thousand miles larger than Maryland.^[22]

On the other hand, an appearing fourth generation is based in the conversion of vegoil and biodiesel into gasoline. ^[24]

Fourth generation biofuels

Craig Venter's company Synthetic Genomics is genetically engineering microorganisms to produce fuel directly from carbon dioxide on an industrial scale. ^[25]

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. ^{[42] [43]}

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.^[44]

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.^[45]

• Food vs Fuel


• Biofuel Impact on the Environment


• Biofuel Energy Efficiency and Energy Balance of Biofuels

References

External links

Governmental & quasi-governmental

• International Panel for Sustainable Resource Management (UN).
• UN International Biofuels Forum.
• Goverments must take the lead on use of biofuels, says UN Secretary-General.
• U.S. Renewable Fuel Standard (EPA).
• Annual Biofuel progress reports of all EU member states
• Alternative Fuel Price Report.
• NNFCC: The UK's National Centre for biofuels and renewable technologies
• "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
• All Biofuels international organizations Biofuels TP.
• Inquirer.net, Carabao may be key to biofuel, says scientist

Academic & media

• Biofuel Boom: Greenwashing and Crimes Against Humanity, Deconstructing Dinner (Radio)
• Biofuels for Transportation, André L. Boehman and Robert L. McCormick
• The Potential of Bagasse-Based Cogeneration in the US, Kevin Ho, Columbia University, 2006.
• If we want to save the planet, we need a five-year freeze on biofuels, George Monbiot, The Guardian, March 29, 2007.
• Foodstuff as Imperial Weapon: Biofuels and Global Hunger, Fidel Castro, Counterpunch, March 31, 2007.
• Biofuels and bio-lubricants', Biofuels and bio-lubricants a growing business, 18 June 2007.
• Biofuels and the Prospect of Converting Plant Fibres into Gasoline Using Enzymes — A Review from the Science Creative Quarterly, January 22, 2007.
• EU Opens Tender to Distil Wine Into Biofuel
• "The Agrofuels Trap" — Foreign Policy in Focus, September 10, 2007.
• Biofuels, Bioproducts and Biorefining - a news and technology journal and portal
• 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
• IEA Bioenergy
• Biofuels in New Zealand: Radio documentary, Part 1 (broadcast 26 May 2007) and Part 2 (broadcast 2 June 2007)
• Liquid Transportation Fuels from Biomass: Technology and Policy Considerations — a 5-day course at MIT reviewing technology, environmental, economic and agricultural policy issues.
• www.gmanews.tv/largevideo, Malunggay may be used in biofuel production - 01/25/2008
• ENN: New Techniques Create Butanol, A Superior Biofuel

Watchdog groups

• 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.
• Oliomap.com The Long Tail of biofuels
• Biofuelwatch
• Biofuels for Transportation: Global Potential and Implications for Sustainable Agriculture and Energy in the 21st Century