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{{dablink|For articles on specific fuels used in vehicles, see [[Biogas]], [[Bioethanol]], [[Biobutanol]],  [[Biodiesel]], and [[Straight vegetable oil]]}}
'''Biofuel''' is defined as solid, liquid or gaseous [[fuel]] obtained from relatively recently lifeless or living biological material and is different from [[fossil fuel]]s, which are [[petroleum#formation|derived from long dead biological material]]. Also, various plants and plant-derived materials are used for biofuel manufacturing.


'''Biofuel''' is [[derived]] from [[biomass]] — recently living [[organism]]s or their [[metabolic]] [[byproduct]]s, such as [[manure]] from [[cows]]. It is a [[renewable energy]] source, unlike other [[natural resource]]s such as [[petroleum]], [[coal]], and [[nuclear reactor|nuclear]] fuels.
Globally, biofuels are most commonly used to power vehicles, heat homes, and for cooking. Biofuel industries are expanding in Europe, Asia and the Americas. Recent technology developed at Los Alamos National Lab even allows for the conversion of pollution into renewable bio fuel.<ref>[http://www.lanl.gov/discover/removing_greenhouse_gases  lanl.gov, Green Freedom: Out of Thin Air]</ref>  Agrofuels are biofuels which are produced from specific crops, rather than from waste processes such as landfill off-gassing or recycled vegetable oil.<ref>[http://www.tni.org/detail_page.phtml?&act_id=17068 Call for a moratorium on EU agrofuel incentives - Transnational Institute]- 1 July 2007</ref>


One definition of ''biofuel'' is "any fuel with an 80% [[minimum]] content by [[volume]] of materials derived from living organisms harvested within the ten years preceding its manufacture".{{Fact|date=February 2007}}
There are two common strategies of producing liquid and gaseous agrofuels.  One is to grow crops high in sugar (sugar cane, sugar beet, and sweet sorghum<ref>[http://www.energycurrent.com/?id=3&storyid=10539 ICRISAT: Sweet sorghum balances food and fuel needs]</ref>) 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, jatropha, or pongamia pinnata.  When these oils are heated, their viscosity is reduced, and they can be burned directly in a [[diesel engine]], or they can be chemically processed to produce fuels such as [[biodiesel]].  Wood and its byproducts can also be converted into biofuels such as woodgas, methanol or [[ethanol fuel]]<ref name="forestry biofuels">{{cite journal|last=Pu|first=Yunqiao|coauthors=Dongcheng Zhang, Preet M. Singh and Arthur J. Ragauskas|date=December 19, 2007|title=The new forestry biofuels sector|journal=Biofuels, Bioproducts and Biorefining (BioFPR)|volume=2|issue=1|pages=58–73|url=http://www.biofpr.com|doi=10.1002/bbb.48}}</ref>.  It is also possible to make cellulosic ethanol from non-edible plant parts, but this can be difficult to accomplish economically.<ref name="Oliver R. Inderwildi, David A. King 2009 343">{{cite journal | doi = 10.1039/b822951c | author = Oliver R. Inderwildi, David A. King | title = Quo Vadis Biofuels | year = 2009 | journal = Energy & Environmental Science | volume = 2 | pages = 343}}</ref>.


Like coal and petroleum, biomass is a form of stored [[solar energy]]. The energy of the sun is "captured" through the process of [[photosynthesis]] in growing plants. (''See also: [[Systems ecology]]'')  One advantage of biofuel over most other fuel types is that it is [[biodegradable]], and so relatively harmless to the environment if spilled.
==Biomass==


[[Agriculture|Agricultural]] products specifically grown for use as biofuels include [[maize|corn]] and [[soybeans]], primarily in the [[United States]]; [[flaxseed]] and [[rapeseed]], primarily in [[Europe]]; [[sugar cane]] in [[Brazil]]; and [[palm oil]] in South-East [[Asia]]. Biodegradable outputs from industry, agriculture, [[forestry]] and households can be used; examples include [[straw]], [[timber]], [[manure]], [[rice]] husks, [[sewage]], [[biodegradable waste]], and food leftovers.  They are converted to [[biogas]] through [[anaerobic digestion]]. Biomass used as fuel often consists of [[:Category:Underutilized crops|underutilized]] types, like [[chaff]] and animal waste.  The quality of timber or grassy biomass does not have a direct impact on its value as an energy-source.
Biomass or biofuel 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.   


Much research is being done about the use of [[Algaculture#Algae as an energy source|microalgae as an energy source]], with applications for biodiesel, ethanol, methanol, methane, and even hydrogen. Use of [[hemp]] is increasing, but politics restrains it.  
It is used to produce power, heat & steam and fuel, through a number of different processes. Although renewable, biomass often involves a burning process that produces emissions such as Sulphur Dioxide (SO<sub>2</sub>), Nitrogen Oxides (NO<sub>x</sub>) and Carbon Dioxide (CO<sub>2</sub>), but fortunately in quantities far less than those emitted by coal plants. However, proponents of coal plants feel that their way of doing it is a lot cheaper and there is a lot of dispute over this.


In some industrialized countries like [[Germany]], food is cheaper than fuel compared by price per [[joule]] {{Fact|date=February 2007}}, mostly because fuel is taxed more than food. Central heating units supplied by food-grade [[wheat]] or maize are available.  
When biomass is combusted to produce heat, it releases carbon than was absorbed by the plant material during the plant's lifecycle. This is because (1) approximately one third of the carbon absorbed by the plant during its life is sequestered in its roots, which are left in the soil to rot and fertilize nearby plant life, and (2) combustion of biomass produces 1-10% solid ash (depending on type of plant used), which is extremely high in carbon (this ash is commonly used as fertilizer).


Biofuel can be used both for central and decentralized production of electricity and heat. As of 2005, bioenergy covers approximately 15% of the world's energy consumption {{Fact|date=February 2007}}. Most bioenergy is consumed in developing countries and is used for direct heating, as opposed to [[electricity]] production.
Animal waste is a persistent and unavoidable pollutant produced primarily by the animals housed in industrial-size 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.<ref> New study advances method to make energy from farm waste, [http://www.usatoday.com/money/economy/2008-04-17-3411772115_x.htm], 4/17/2008.</ref>


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]].  The [[carbon]] in biofuels was recently extracted from atmospheric [[carbon dioxide]] by growing plants, so burning it does not result in a net increase of carbon dioxide in the [[Earth's atmosphere]]. Therefore, many people believe that a way to reduce the amount of carbon dioxide released into the atmosphere is to use biofuels to replace non-renewable sources of energy.
There are also agricultural products specifically grown for biofuel production including 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 and pongamia pinnata in India; pongamia pinnata in Australia and the tropics. 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. Biomass can come from waste plant material. The use of biomass fuels can therefore contribute to waste management as well as fuel security and help to prevent global warming, though alone they are not a comprehensive solution to these problems.


Dried compressed [[peat]] is also sometimes considered a biofuel. However, it does not meet the criteria of being a renewable Biofuel form of energy, or of the carbon being recently absorbed from atmospheric carbon dioxide by growing plants. Though more recent than petroleum or coal, on the time scale of human industrialisation, peat is a fossil fuel and burning it does contribute to atmospheric CO<sub>2</sub>.
== Energy from bio waste ==


==History==
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 the equivalent of 19 million tons of oil  is available from biomass by 2020, 46% from bio-wastes: municipal solid waste (MSW), agricultural residues, farm waste and other biodegradable waste streams.<ref>European Environment Agency (2006) [http://www.eea.europa.eu/publications/eea_report_2006_7 How much bioenergy can Europe produce without harming the environment?] EEA Report no. 7</ref><ref>Marshall, A. T. (2007) [http://www.waste-management-world.com/display_article/289598/123/ARCHI/none/none/1/Growing-bigger/ Bioenergy from Waste: A Growing Source of Power], Waste Management World Magazine April, p34-37</ref>
Solid biofuels such as [[wood]] or dried waste have been used since man learned to control [[fire]].


Liquid biofuels for industrial applications was used since the early days of the car industry. [[Nikolaus August Otto]], the German inventor of the combustion engine, conceived his invention to run on ethanol. [[Rudolf Diesel]], the German inventor of the [[Diesel engine]], conceived it to run on peanut oil. [[Henry Ford]] originally had designed the [[Ford Model T]], a car produced from 1903 to 1926, to run completely on ethanol, after surreptitious efforts {{Fact|date=February 2007}} were successful at thwarting Ford's desires to mass produce electric cars. However, when crude oil was cheaply extracted from deeper in the soil (thanks to oil reserves discovered in Pennsylvania and Texas), cars began using fuels from oil.  
Landfill sites generate gases as the waste buried in them undergoes anaerobic digestion. These gases are known collectively as landfill gas (LFG). This is considered a source of renewable energy, even though landfill disposal is 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 gas found in natural gas. Land fill gas can be easily purified and then fed into the Natural Gas grid.  


Nevertheless, before [[World War II]], biofuels were seen as providing an alternative to imported oil in countries such as Germany, which sold 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.
If landfill gas is not harvested, it escapes into the atmosphere: this is undesirable because methane is a greenhouse gas with much more global warming potential than carbon dioxide.<ref name="IPCC2001"> [http://www.grida.no/climate/ipcc_tar/wg1/248.htm IPCC Third Assessment Report], accessed August 31, 2007.</ref><ref name="EPAGWP"> [http://www.epa.gov/nonco2/econ-inv/table.html Non-CO2 Gases Economic Analysis and Inventory: Global Warming Potentials and Atmospheric Lifetimes], U.S. Environmental Protection Agency, accessed August 31, 2007</ref> Over a time span of 100 years, one ton of methane produces the same greenhouse gas (GHG) effect as 21 tons of CO<sub>2</sub >.<ref>http://unfccc.int/ghg_data/items/3825.php</ref> When methane burns, it produces carbon dioxide in the ratio 1:1—CH<sub>4</sub> + 2O<sub>2</sub> = CO<sub>2</sub > + 2H<sub>2</sub >O. 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.


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. But since about [[2000]], rising oil prices, concerns over the potential [[oil peak]], greenhouse gas emissions ([[global warming]]), and instability in the Middle East are pushing renewed interest in biofuels. Government officials have made statements and given aid in favour of biofuels. For example, US president [[George W. Bush]] said in his [[2006]] [[State of the Union]] speech that he wants the US to replace 75% of the oil it imports from the Middle East by biofuels by [[2025]].
It was recently discovered that living plants also produce methane.<ref>{{cite journal
| journal = Nature
| volume = 439
| pages = 187–191
| year = 2006
| doi = 10.1038/nature04420
  | title = Methane emissions from terrestrial plants under aerobic conditions
| author = Frank Keppler, John T. G. Hamilton, Marc Bra, and Thomas Röckmann}}</ref> The amount 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.<ref>http://biofuel.org.uk/biofuel-from-waste.html</ref>
Anaerobic digestion can be used as a 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.


== Examples ==
A current project for a 1.6 MW landfill power plant is projected to provide power for 880 homes.<ref>[http://www.maysville-online.com/articles/2008/10/09/local_news/841ekpc.txt Construction of landfill power plant has begun] By MARLA TONCRAY, News Editor (Friday, October 10, 2008 12:57 AM EDT) The Ledger Independent - Maysville, Kentucky</ref> It is estimated that this will eliminate 3,187 tons of methane and directly eliminate 8.756 tons of carbon dioxide release per year.  This is the same as removing 12,576 cars from the road, or planting 15,606 trees, or not using 359 rail cars of coal per year.
=== Alcohols ===
Biologically produced [[alcohols]], most commonly [[ethanol]] and [[methanol]], and less commonly [[Propan-1-ol|propanol]] and [[butanol]], are produced by the action of [[microorganism]]s and [[enzyme]]s through fermentation — see [[alcohol fuel]].


* [[Methanol]], which is now produced from [[natural gas]], can also be produced from biomass — although this is not economically viable at present. The [[methanol economy]] is an interesting alternative to the [[hydrogen economy]].
==Liquid fuels for transportation==
* [[Biomass-to-liquid]] are fuels produced by [[catalysis]] from [[syngas]], which is produced from biomass by [[gasification]]. [http://i-r-squared.blogspot.com/2006/10/cellulosic-ethanol-vs-biomass.html]
* [[Ethanol fuel]] produced from sugar cane is used as [[automobile|automotive]] fuel in Brazil.  Ethanol produced from corn is used mostly as a [[Gasoline#Oxygenate blending|gasoline additive]] (oxygenator) in the US, but direct use as fuel is growing rapidly.  However, corn-based ethanol is very energy inefficent - around 3/4ths of a gallon of fuel is required to produce one gallon of ethanol (as a comparison, about 1/20th of a gallon of fuel (6%) is required to produce one gallon of gasoline). In addition, corn prices are rising as corn-based ethanol production grows. [[Cellulosic ethanol]] is manufactured from the cellulose of a wide variety of plants, including cornstalks, poplar trees, and switchgrass. It can also be manufactured from waste left over from the forest products industry. [[Iogen Corporation]] of Ontario, Canada is manufacturing it from wheat, oat and barley straw (an agricultural waste product) and other companies are attempting to do the same [http://enews.earthlink.net/article/bus?guid=20070310/45f23b50_3ca6_1552620070310-306172261]. [[ETBE]] containing 47% ethanol is the biggest biofuel contributor in Europe.
* [[Butanol]] is formed by [[Clostridium acetobutylicum|ABE fermentation]] (acetone, butanol, ethanol) and experimental modifications of the process show potentially high net energy gains with butanol as the only liquid product. Allegedly, butanol can be burned "straight" in existing gasoline engines (without modification to the engine or car), produces more energy and is less corrosive and less water soluble than ethanol, and can be distributed via existing infrastructures.
* Mixed alcohols are obtained by [[biomass-to-liquid]] technology or by [[bioconversion of biomass to mixed alcohol fuels]].  Commonly used are mixtures of ethanol, propanol, butanol, [[pentanol]], [[hexanol]], and [[heptanol]], such as [[ecalene]]<sup>TM</sup>.
* [[GTL]] and [[BTL]] produce fuels from biomass in the so called [[Fischer Tropsch]] process. The synthetic biofuel containing oxygen is used as additive in high-quality diesel and petrol.


=== Gases ===
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.
Biogas is produced by the process of anaerobic digestion of [[organic material]] by [[anaerobe]]s. It can be produced either from biodegradable waste materials or by the use of [[energy crop]]s fed into [[anaerobic digester]]s to supplement gas yields. The solid byproduct, [[digestate]], can also be used as a biofuel.


Biogas contains [[methane]] and can be recovered in industrial anaerobic digesters and [[mechanical biological treatment]] systems. Landfill gas is a less clean form of biogas which is produced in [[landfill]]s through naturally occurring anaerobic digestion. If it escapes into the atmosphere it is a potent [[greenhouse gas]].
The fuels that are easier to burn cleanly are typically liquids and [[gas]]es.  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 ==
=== First generation biofuels ===
'First-generation biofuels' are biofuels made from [[sugar]], [[starch]], [[vegetable oil]], or [[animal fat]]s using conventional technology.<ref name="UN report"> [http://esa.un.org/un-energy/pdf/susdev.Biofuels.FAO.pdf UN biofuels report]</ref> 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 instead 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====
{{Main|Vegetable oil used as fuel}}
 
Edible vegetable oil is generally not used as fuel, but lower quality oil can be used for this purpose. Used vegetable oil is increasingly being processed into biodiesel, or (more rarely) cleaned of water and particulates and used as a fuel. To ensure that the fuel injectors atomize the fuel in the correct pattern for efficient combustion, vegetable oil fuel must be heated to reduce its [[viscosity]] to that of diesel, either by electric coils or heat exchangers. This is easier in warm or temperate climates. Big corporations like [[MAN B&W Diesel]], [[Wartsila]] and [[Deutz AG]] as well as a number of smaller companies such as [[Elsbett]] offer engines that are compatible with straight vegetable oil, without the need for after-market modifications. Vegetable oil can also be used in many older diesel engines that do not use common rail or unit injection electronic diesel injection systems. Due to the design of the combustion chambers in [[indirect injection]] engines, these are the best engines for use with vegetable oil. This system allows the relatively larger oil molecules more time to burn. Some older engines, especially Mercedes are driven experimentally by enthusiasts without any conversion, a handful of drivers have experienced limited success with earlier pre-"pumped use" [[VW TDI]] engines and other similar engines with [[direct injection]]. Several companies like [[Elsbett]] or [http://www.wolf-pflanzenoel-technik.de/ Wolf] have developed professional conversion kits and sucessfully installed hundreds of them over the last decades.
 
Oils and fats can be hydrogenated to give a diesel substitute. The resulting product is a straight chain hydrocarbon, high in [[cetane]], low in [[aromatics]] and sulphur and does not contain oxygen. Hydrogenated oils can be blended with diesel in all proportions  Hydrogenated oils have several advantages over biodiesel, including good performance at low temperatures, no storage stability problems and no susceptibility to microbial attack.<ref name=evans>Evans, G. [http://www.nnfcc.co.uk/metadot/index.pl?id=6597;isa=DBRow;op=show;dbview_id=2457 "Liquid Transport Biofuels - Technology Status Report"], ''[[National Non-Food Crops Centre]]'', 2008-04-14. Retrieved on 2009-05-11.</ref>
 
====Biodiesel====
{{Main|Biodiesel|Biodiesel around the world}}
Biodiesel is the most common biofuel in Europe. It is produced from [[oil]]s or fats using [[transesterification]] and is a liquid similar in composition to fossil/mineral diesel. Its chemical name is fatty acid methyl (or ethyl) ester ([[Fatty acid methyl 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 plant|mustard]], [[flax]], [[sunflower]], [[palm oil]], [[hemp]], [[thlaspi arvense|field pennycress]], [[pongamia pinnata]] and [[algae fuel|algae]]. Pure biodiesel (B100) is by far the lowest emission diesel fuel. Although [[liquefied petroleum gas]] and hydrogen have cleaner combustion, they are used to fuel much less efficient petrol engines and are not as widely available.
 
Biodiesel can be used in any [[diesel engine]] when mixed with mineral diesel.  The majority of vehicle manufacturers limit their recommendations to 15% biodiesel blended with mineral diesel. In some countries manufacturers cover their diesel engines under warranty for B100 use, although [[Volkswagen]] of [[Germany]], for example, asks drivers to check by telephone with the VW environmental services department before switching to B100<!-- (see [[Biodiesel#Use|biodiesel use]]) -->. B100 may become more viscous at lower temperatures, depending on the feedstock used, requiring vehicles to have fuel line heaters. In most cases, biodiesel is compatible with diesel engines from 1994 onwards, which use '[[Viton]]' (by [[DuPont]]) synthetic rubber in their mechanical injection systems. Electronically controlled 'common rail' and 'pump duse' type systems from the late 1990s onwards may only use biodiesel blended with conventional diesel fuel.  These engines have finely metered and atomized multi-stage injection systems are very sensitive to the viscosity of the fuel.  Many current generation diesel engines are made so that they can run on B100 without altering the engine itself, although this depends on the fuel rail design. [[NExBTL]] is suitable for all diesel engines in the world since it overperforms DIN [[EN 590]] standards.
 
Since biodiesel is an effective solvent and cleans residues deposited by mineral diesel, engine filters may need to be replaced more often, as the biofuel dissolves old deposits in the fuel tank and pipes.  It also effectively cleans the engine combustion chamber of carbon deposits, helping to maintain efficiency. In many European countries, a 5% biodiesel blend is widely used and is available at thousands of gas stations.<ref>[http://www.biodiesel.de/ ADM Biodiesel: Hamburg, Leer, Mainz<!-- Bot generated title -->]</ref><ref>[http://www.biodieselfillingstations.co.uk Welcome to Biodiesel Filling Stations<!-- Bot generated title -->]</ref>  Biodiesel is also an ''oxygenated fuel'', meaning that it contains a reduced amount of carbon and higher hydrogen and oxygen content than fossil diesel.  This improves the combustion of fossil diesel and reduces the particulate emissions from un-burnt carbon.
 
Biodiesel is safe to handle and transport because it is as biodegradable as sugar, 10 times less toxic than table salt, and has a high flashpoint of about 300 F compared to petroleum diesel fuel, which has a flash point of 125 F.<ref>http://www.hempcar.org/biofacts.shtml</ref>.
 
In the USA, more than 80% of commercial trucks and city buses run on diesel. The emerging US biodiesel market is estimated to have grown 200% from 2004 to 2005. "By the end of 2006 biodiesel production was estimated to increase fourfold [from 2004] to more than 1 billion gallons,".<ref>[http://www.wfs.org/futcontja07.htm THE FUTURIST], [http://www.prleap.com/pr/80099/ Will Thurmond]. July-August 2007</ref>
 
====Bioalcohols====
{{Main|Alcohol fuel}}
[[Image:EthanolPetrol.jpg|right|thumb|300px|Information on a pump in California.]]
Biologically produced [[alcohols]], most commonly [[ethanol]], and less commonly [[Propan-1-ol|propanol]] and [[butanol]], are produced by the action of [[microorganism]]s and [[enzyme]]s 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 [[Clostridium acetobutylicum|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),<ref>[http://www.butanol.com/ ButylFuel,LLC Main Page<!-- Bot generated title -->]</ref>  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. [[E. coli]] have also been successfully engineered to produce Butanol by hijacking their amino acid metabolism<ref name="butanol">{{cite news|url=http://www.biofpr.com/details/feature/102347/Biofuels_aim_higher.html|title=Biofuels aim higher|last=Evans|first=Jon|date=14 January 2008 |work=Biofuels, Bioproducts and Biorefining (BioFPR)|accessdate=2008-12-03}}</ref>.
 
[[Ethanol fuel]] is the most common biofuel worldwide, particularly [[Ethanol fuel in Brazil|in Brazil]]. [[Alcohol fuel]]s are produced by fermentation of sugars derived from [[wheat]], [[Maize|corn]], [[sugar beet]]s, [[sugar cane]], [[molasses]] and any sugar or starch that [[alcoholic beverage]]s 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).
 
[[Image:Koenigsegg CCXR Edition (1 von 2).jpg|thumb|left|The [[Koenigsegg CCXR]] Edition at the 2008 [[Geneva Motor Show]]. This is an "[[environmentally-friendly]]" version of the [[Koenigsegg CCX|CCX]], which can use [[E85]] and [[Common ethanol fuel mixtures#E100|E100]].]]
 
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.
Ethanol has a smaller energy density than gasoline, which means it takes more fuel (volume and mass) to produce the same amount of [[work done|work]].  An advantage of ethanol is that is has a higher [[octane rating]] than ethanol-free gasoline available at roadside gas stations which allows an increase of an engine's compression ratio for increased [[thermal efficiency]].
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 is very [[corrosive]] to fuel systems, [[rubber]] [[hose]]s and [[gasket]]s, [[aluminum]], and [[combustion chamber]]s. Therefore, it is 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 also corrodes [[fiberglass]] fuel tanks such as used in marine engines. For higher ethanol percentage blends, and 100% ethanol vehicles, engine modifications are required.
 
It is the hygroscopic (water loving) nature of relatively polar ethanol that can promote corrosion of existing pipelines and older fuel delivery systems. To characterize ethanol itself as a corrosive chemical is somewhat misleading and the context in which it can be indirectly corrosive, somewhat narrow; i.e., limited to effects upon existing pipelines designed for petroleum transport.
 
[[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.<ref>{{cite web
| url= http://www.ft.com/cms/s/0/e780d216-5fd5-11dc-b0fe-0000779fd2ac.html
| title= "OECD warns against biofuels subsidies"
|author= Andrew Bounds
|date= 2007-09-10 |publisher= ''[[Financial Times]]''
| accessdate= 2008-03-07 }} </ref>
 
Although ethanol-from-corn and other food stocks has implications both in terms of world food prices and limited, yet positive energy yield (in terms of energy delivered to customer/fossil fuels used), the technology has lead to the development of cellulosic ethanol. According to a joint research agenda conducted through the U.S. Department of Energy,<ref>see "Breaking the Biological Barriers to Cellulosic Ethanol")</ref> the fossil energy ratios (FER) for cellulosic ethanol, corn ethanol, and gasoline are 10.3, 1.36, and 0.81, respectively.<ref>Brinkman, N. et al., "Well-to-Wheels Analysis of Advanced/Vehicle Systems", 2005.</ref><ref>Farrell, A.E. et al. (2006) "Ethanol can Contribute to Energy and Environmental Goals", ''Science'', '''311''', 506-8.</ref><ref>Hammerschlag, R. 2006. "Ethanol's Energy Return on Investment: A Survey of the Literature 1999-Present", ''Environ. Sci. Technol''., '''40''', 1744-50.</ref>
 
Many car manufacturers are now producing [[flexible-fuel vehicle]]s (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.{{Citation needed|date=May 2008}} Efficiency falls and pollution emissions increase when FFV system maintenance is needed (regardless of the fuel mix being used), but not performed (as with all vehicles). FFV [[internal combustion engine]]s are becoming increasingly complex, as are multiple-[[propulsion]]-system FFV [[hybrid vehicles]], which impacts cost, maintenance, [[Reliability engineering|reliability]], and useful lifetime [[longevity]].{{Citation needed|date=May 2008}}
 
Alcohol mixes with both petroleum and with water, so [[ethanol fuel]]s 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 aluminum ([[carburetor]]s) 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 distance traveled than current high gasoline prices in the United States.<ref>{{cite web
| url= http://zfacts.com/p/436.html
| title= With only 2/3 the energy of gasoline, ethanol costs more per mile
|date= 2007-04-27 |publisher= zFacts.com
| accessdate= 2008-03-07 }} </ref>
 
[[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.<ref>[http://www.hydrogensolar.com/ Hydrogen Solar home<!-- Bot generated title -->]</ref>
 
====Bioethers====
 
Bio [[ethers]] (also referred to as [[fuel]] ethers or fuel [[oxygenates]]) are cost-effective [[compounds]] that act as [[octane]] enhancers.  They also enhance [[engine]] performance, whilst significantly reducing engine wear and [[toxic]] [[exhaust gas|exhaust emissions]]. Greatly reducing the amount of ground-level [[ozone]], they contribute to the quality of the air we breathe.<ref>http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31985L0536:EN:HTML, Council Directive 85/536/EEC of 5 December 1985 on crude-oil savings through the use of substitute fuel components in petrol</ref><ref>http://circa.europa.eu/Public/irc/env/fuel_quality/library?l=/stakeholder_october/presentations/copert_brusselsppt/_EN_1.0_&a=d COPERT Study: An assessment of the impact of ethanol-blended petrol </ref><ref>http://www.europarl.europa.eu/registre/docs_autres_institutions/commission_europeenne/sec/2007/0055/COM_SEC(2007)0055_EN.pdf Fuel Quality Directive Impact Assessment</ref>
 
====Biogas====
[[Image:Biogas pipes.JPG|right|thumb|150px|Pipes carrying biogas]]
{{Main|Biogas}}
Biogas is produced by the process of [[anaerobic digestion]] of [[organic material]] by [[anaerobe]]s.<ref>Redman, G., The Andersons Centre. [http://www.nnfcc.co.uk/metadot/index.pl?id=7198;isa=DBRow;op=show;dbview_id=2457 "Assessment of on-farm AD in the UK"], ''[[National Non-Food Crops Centre]]'', 2008-06-09. Retrieved on 2009-05-11.</ref> It can be produced either from biodegradable waste materials or by the use of [[energy crop]]s fed into [[anaerobic digester]]s 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 [[landfill]]s 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:
Oils and gases can be produced from various biological wastes:


* [[Thermal depolymerization]] of waste can extract methane and other oils similar to petroleum.
* [[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.<ref>http://www.greenfuelonline.com/</ref>
* [[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.<ref> [http://www.greenfuelonline.com/ greenfuelonline.com] </ref>


=== Solids ===
====Syngas====
Examples include wood, charcoal, and dried excrement.
{{Main|Gasification}}
[[Syngas]], a mixture of [[carbon monoxide]] and [[hydrogen]], is produced by partial combustion of biomass, that is, combustion with an amount of oxygen that is not sufficient to convert the biomass completely to carbon dioxide and water.<ref name="evans"/>  Before partial combustion the biomass is dried, and sometimes [[pyrolysis|pyrolysed]].


== Biomass in developing countries ==
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.
Unfortunately, much cooking with biofuels is done indoors, with inefficient ventilation, and fuels such as dung cause airborne pollution. This can be a serious health hazard; 1.3 million deaths were attributed to this cause by the [[International Energy Agency]] in its World Energy Outlook 2006.  


Proposed solutions include improved stoves (including those with inbuilt [[flue]]s) and alternative fuels.  But most of these have difficulties. One is that fuels are easily damaged. Another is that alternative fuels tend to be expensive, and people who use biofuels often do so precisely because they cannot afford alternatives.
Syngas may be burned directly in internal combustion engines or turbines.  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 [[diesel]] substitute, or a mixture of alcohols that can be blended into gasoline. Gasification normally relies on temperatures >700°C. Lower temperature gasification is desirable when co-producing [[biochar]] but results in a Syngas polluted with [[tar]].


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.  This is done by improving ventilation, switching to different uses of biomass such as the creation of biogas from solid biomatter, or switching to other alternatives such as [[micro-hydro power]].
====Solid biofuels====
Examples include wood, sawdust, grass cuttings, domestic refuse, charcoal, agricultural waste, non-food [[energy crop]]s (see picture), and dried [[manure]].


Many environmentalists are concerned that first-growth forest may be felled in countries such as Indonesia to make way for palm oil plantations, driven by rising demand for diesel in SE Asia and Europe.
When raw biomass is already in a suitable form (such as [[firewood]]), it can burn directly in a stove or furnace to provide heat or raise steam. When raw biomass is in an inconvenient form (such as sawdust, wood chips, grass, agricultural wastes), another option is to pelletize the biomass with a [[pellet mill]]. The resulting fuel pellets are easier to burn in a [[pellet stove]].


== Direct biofuel ==
A problem with the combustion of raw biomass is that it emits considerable amounts of pollutants such as [[particulates]] and PAHs ([[polycyclic aromatic hydrocarbons]]). Even modern pellet boilers generates much more pollutants than oil or natural gas boilers. Pellets made from agricultural residues are usually worse than wood pellets, producing much larger emissions of [[dioxins]] and [[chlorophenols]].<ref>Cedric Briens, Jan Piskorz and Franco Berruti, "Biomass Valorization for Fuel and Chemicals Production -- A Review," 2008. International Journal of Chemical Reactor Engineering, 6, R2</ref>
Direct biofuels are biofuels that can be used in existing unmodified petroleum engines. Because engine technology changes all the time, direct biofuel can be hard to define; a fuel that works well in one unmodified engine may not work in another. In general, newer engines are more sensitive to fuel than older engines, but new engines are also likely to be designed with some amount of biofuel in mind.


Straight vegetable oil can be used in some older diesel engines, but only in the warmest climates.  Usually it is turned into biodiesel instead. No engine manufacturer explicitly allows any use of vegetable oil in their engines.
Another solid biofuel is [[biochar]], which is produced by biomass [[pyrolysis]].  Biochar pellets made from agricultural waste can substitute for wood charcoal. In countries where charcoal stoves are popular, this can reduce deforestation.


Biodiesel can be a direct biofuel. In some countries manufacturers cover many of 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|biodiesel use]]). Many people have run thousands of miles on biodiesel without problem, and many studies have been made on 100% biodiesel. In many European countries, 100% biodiesel is widely used and is available at thousands of gas stations[http://www.biodiesel.de/][http://www.tescocorporate.com/biofuels.htm].
=== Second generation biofuels ===
{{Main|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 crop]]s, including [[cellulosic biofuel]]s.<ref name=2G> http://www.renewable-energy-world.com/articles/print_screen.cfm?ARTICLE_ID=308325 {{Dead link|date=March 2008}} </ref> 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<ref name="Oliver R. Inderwildi, David A. King 2009 343"/>, including [[cellulosic biofuel]]s from [[non food crop]]s.<ref>{{cite web
| url= http://www.usda.gov/oce/forum/2007%20Speeches/PDF%20PPT/CSomerville.pdf
| title= "Development of Cellulosic Biofuels"
| author= Chris Somerville
|date= |year= |month=
| format= [[PDF]]
| publisher= [[United States Department of Agriculture|U.S. Dept. of Agriculture]]
|pages= |language= |doi= |archiveurl= |archivedate= |quote=
| accessdate= 2008-01-15 }} </ref> Many second generation biofuels are under development such as [[biohydrogen]], [[biomethanol]], [[2,5-Dimethylfuran|DMF]], Bio-DME, [[Fischer-Tropsch]] diesel, biohydrogen diesel, mixed alcohols and wood diesel.


[[Butanol fuel|Butanol]] is often claimed as a direct replacement for gasoline. It is not in wide spread production at this time, and engine manufacturers have not made statements about its use{{verify source}}. 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.
[[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.


Ethanol is the most common biofuel, and over the years many engines have been designed to run on it. Many of these could not run on regular gasoline, so it is debatable whether ethanol is a replacement in them. In the late 1990s, engines started appearing that by design can use either fuel. Ethanol is a direct replacement in these engines, but it is debatable if these engines are unmodified, or factory modified for ethanol{{verify source}}.
Producing [[ethanol]] from [[cellulose]] is a difficult technical problem to solve. In nature, [[ruminant]] livestock (like [[cattle]]) eats grass and then use slow enzymatic digestive processes to break it into [[glucose]] (sugar). In [[cellulosic ethanol]] laboratories, various [[experiment]]al processes are being developed to do the same thing, and then the sugars released can be fermented to make ethanol fuel. In 2009 scientists reported developing, using "synthetic biology", "15 new highly stable fungal enzyme catalysts that efficiently break down cellulose into sugars at high temperatures", adding to the 10 previously known.<ref>EurekAlert. (2009). [http://www.eurekalert.org/pub_releases/2009-03/ciot-csc032009.php 15 new highly stable fungal enzyme catalysts that efficiently break down cellulose into sugars at high temperatures].</ref> In addition, research conducted at [[TU Delft]] by Jack Pronk has shown that [[elephant yeast]], when slightly modified can also create ethanol from non-edible ground sources (eg straw).<ref>[http://www.tnw.tudelft.nl/live/pagina.jsp?id=811b8180-6e76-47bb-8ee6-57f89b0d8b17&lang=en Jack Pronk's elephant yeast]</ref><ref>[http://www.tnw.tudelft.nl/live/pagina.jsp?id=811b8180-6e76-47bb-8ee6-57f89b0d8b17&lang=en Straw to ethanol plant in Sas van Gent]</ref>


Small amounts of biofuel are often blended with traditional fuels. The biofuel portion of these fuels is a direct replacement for the fuel they offset, but the total offset is small. For biodiesel, 5% or 20% are commonly approved by various engine manufacturers{{Fact|date=February 2007}}. See [[Common ethanol fuel mixtures]] for information on ethanol.
The recent discovery of the fungus [[Gliocladium roseum]] points toward the production of so-called [[myco-diesel]] from cellulose. This organism was recently discovered in the rainforests of northern [[Patagonia]] and has the unique capability of converting cellulose into medium length hydrocarbons typically found in diesel fuel.<ref>{{cite web
| url= http://afp.google.com/article/ALeqM5gz4TxqoKipVTNNcSTylCrzgb0IAg
| title= "Fill her up please, and make it myco-diesel"
| author=
|date= |year= |month=
| publisher= AFP
|pages= |language= |doi= |archiveurl= |archivedate= |quote=
| accessdate= 2008-11-04 }} </ref>


== International efforts ==
Scientists also work on experimental [[recombinant DNA]] [[genetic engineering]] organisms that could increase biofuel potential.
Recognizing the importance of implementing bioenergy, there are international organizations such as [[IEA Bioenergy]],<ref>http://www.ieabioenergy.com/IEABioenergy.php</ref> 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.


=== European Union ===
=== Third generation  biofuels===
{{Main|biofuels directive}}
{{Main|Algae fuel}}


The [[European Union]] has set a goal:
Algae fuel, also called oilgae or third generation biofuel, is a biofuel from [[algae]]. Algae are low-input, high-yield [[wikt:feedstock|feedstock]]s to produce biofuels.  It produces 30 times more energy per acre than land crops such as soybeans.<ref name="wapo-algae">{{cite web
| url= http://www.washingtonpost.com/wp-dyn/content/article/2008/01/03/AR2008010303907.html
| title= "A Promising Oil Alternative: Algae Energy"
|author= Eviana Hartman |date= 2008-01-06 |work= |publisher= ''[[Washington Post]]''
|pages= |language= |doi= |archiveurl= |archivedate= |quote=
| accessdate= 2008-01-15 }} </ref> With the higher prices of [[fossil fuel]]s ([[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.<ref> [http://www.globeco.co.uk/Bio-diesel_news_0007.html Globeco biodegradable bio-diesel] </ref><ref> [http://www.friendsofethanol.com/facts.html Friends of Ethanol.com biodegradable ethanol] </ref><ref> [http://www.energy-arizona.org/archive/200708280001_low_cost_algae_production_system_introduced.php Low Cost Algae Production System Introduced] </ref>


*For [[2010]] that each member state should achieve at least 5.75% biofuel usage of all used traffic fuel. By [[2006]] it seems unlikely that most of the members states will meet this goal.
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 kilometer]]s), which is roughly the size of [[Maryland]].<ref name="wapo-algae"/>
*For [[2020]], 10 % . <ref>http://ec.europa.eu/energy/energy_policy/doc/07_biofuels_progress_report_en.pdf </ref>


== Criticism ==
Second and third generation biofuels are also called advanced biofuels.
{{sectstub}}


=== Rising food prices ===
Algae, such as ''[[Botryococcus braunii]]'' and ''Chlorella vulgaris,'' are relatively easy to grow, <ref>[http://algaloildiesel.wetpaint.com/page/PROPAGATION+OF+ALGAE+BY+USE+OF+COVERED+PONDS],</ref> but the algal oil is hard to extract.  There are several approaches, some of which work better than others.<ref>[http://algaloildiesel.wetpaint.com/page/PROSPECTS+FOR+THE+BIODIESEL+INDUSTRY]</ref> Macroalgae (seaweed) also have a great potential for bioethanol and biogas production <ref>[http://www.amazon.com/Seaweed-Biofuels-Production-Bioethanol-Macroalgae/dp/3639153073/ref=sr_1_1?ie=UTF8&s=books&qid=1244139717&sr=1-1 Seaweed Biofuels: Production of Biogas and Bioethanol from Brown Macroalgae <!-- Bot generated title -->]</ref>.


Due to rising demand for biofuels, farmers in countries with limited agricultural potential are enticed to convert from production of food to production of raw material for biofuels. However, in the developing world, where a majority of people are farmers and where a vast mass of unused agricultural land exists, the biofuels opportunity may benefit millions of farmers and fuel economic development. If managed in a careless manner, the situation may lead to a rise in food prices, which may hurt others.
=== Ethanol from living algae===


In early 2007 there were a number of reports linking stories as diverse as food riots in Mexico<ref>[Enrique C. Ochoa, The Costs of Rising Tortilla Prices in Mexico, February 3, 2007|http://www.zmag.org/content/showarticle.cfm?SectionID=59&ItemID=12030]</ref> due to rising prices of corn for tortillas and reduced profits at Heineken<ref>Financial Times, London, February 25 2007, quoting Jean-François van Boxmeer, chief executive</ref>, 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, it is more that barley acreage was cut to meet growing demand for corn, rather than the direct conversion of barley to ethanol, although the latter is technically possible.)
Most biofuel production comes from harvesting organic matter and then converting it to fuel but an alternative approach relies on the fact that some algae naturally produce ethanol and this can be collected without killing the algae. The ethanol evaporates and then can be condensed and collected. The company [[Algenol]] is trying to commercialize this process.


=== Energy efficiency of biodiesel ===
===Helioculture===
[[Helioculture]] is a newly developed process which is claimed to be able to produce 20,000 gallons of fuel per acre per year, and which removes carbon dioxide from the air as a feedstock for the fuel.<ref>[http://www.nytimes.com/gwire/2009/07/27/27greenwire-start-ups-biofuel-recipe-mixes-co2-slime-and-su-7562.html Start-Up's Biofuel Recipe Mixes CO2, Slime and Sunshine], The New York Times, July 27, 2009</ref>


Production of biofuels from raw materials requires energy (for farming, transport and conversion to final product)and this varies greatly from one location to another. For example, in the US and Australia, farmers use much more oil to power their equipment than farmers in Brazil {{Fact|date=February 2007}}. However, in some areas where forests are being thinned for forest fire fuels reduction projects, the production of the necessary biomass would occur whether or not a biomass industry existed. Therefore only the transport of the biomass from the field to a processing facility is a net energy cost.  The costs of transporting wood chip have proven to be difficult to overcome.
==Biofuels by region==
{{Main|Biofuels by region}}
Recognizing the importance of implementing bioenergy, there are international organizations such as IEA Bioenergy,<ref> [http://www.ieabioenergy.com/IEABioenergy.aspx IEA bioenergy] </ref> 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 [[United Nations|U.N.]] International Biofuels Forum  is formed by [[Brazil]], [[China]], [[India]], [[South Africa]], the [[United States]] and the [[European Commission]].<ref> {{cite web
| url= http://www.un.org/News/briefings/docs/2007/070302_Biofuels.doc.htm
| title= Press Conference Launching International Biofuels Forum
| date= 2007-03-02 | publisher= [[United Nations]] Department of Public Information
|pages= |language= |doi= |archiveurl= |archivedate= |quote=
| accessdate= 2008-01-15 }} </ref> The world leaders in biofuel development and use are Brazil, United States, France, Sweden and Germany.


Also studies on the [[energy balance]] of these fuels show large differences depending on the biomass feedstock used and location. {{Fact|date=February 2007}}. 
{{See also|Biodiesel around the world}}
Biofuels made from crops grown in temperate climates (such as corn or canola) have a relatively low energy efficiency{{Fact|date=February 2007}}, whereas biofuels made from crops grown in the subtropics and the tropics (such as sugarcane, sweet sorghum, palm oil, cassava) show a very high energy efficiency{{Fact|date=February 2007}}.
For some biofuels (like ethanol made from corn) the energy balance may even be negative {{Fact|date=February 2007}}.


=== Ecological impact ===
==Issues with biofuel production and use==
Biofuels offer one of the few options to substantially mitigate [[climate change]]. Since the effects of [[global warming]] can be devastating to world agriculture, the ecological impacts of growing biofuel crops may be small compared to the potentially much larger impacts of unmitigated climate change.
{{Main|Issues relating to biofuels}}
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.


Since vast amounts of raw material are needed for biofuel production, [[monoculture]]s and
[[intensive farming]] may become more popular, which may cause environmental damages and
undo some of the progress made towards [[sustainable agriculture]].  On the other hand, in the developing world poverty is the main cause of environmental destruction. If farmers in the developing world become energy farmers who sell biofuels on the international market, their incomes would increase substantially, and pressures on the environment would decrease. In this sense, the biofuels opportunity offers a way to lower the indirect impacts of poverty on the environment.


== Energy content of biofuel ==
== Issues related to the large scale development and implementation of biofuels ==
 
According to the Swedish researcher Dr. Magnus Blinge, Chalmers Technical University, replacing all oil used in Europe by cellulose based bio-fuels would require 1,000 production plants for bio-fuels, each would need deliveries of 450 truckloads of wood every day. This would require an entirely new production and distribution system for fuels.
For a comprehensive chart of energy contents from different biofuels please see [[Energy content of Biofuel]]
In a booklet in Swedish (“Med klimatfrågan i fokus”, Volvo AB, Gothenburg 2007) published by the truck and bus company Volvo AB, the merits of seven different bio-fuels and engine solutions are briefly described and analyzed. Volvo finds that the most promising fuel, based on the criteria of the analysis, is [[DME]] (Dimethyl ether). Overall, the CEO of Volvo, [[Leif Johansson]], concludes that high level political agreements between nations will become necessary in order to implement bio-fuels on a large scale. This is because transportation systems are cross border, and these and the climate issue do not stop at country borders. In order for Volvo, to do its part in the development of the renewable fuels of the future, politicians need to decide which fuels that are going to be used on a large scale in the future.
Some authors, such as US congressman Jay Inslee and environmentalist Bracken Hendricks go even further. In their book “Apollo’s Fire”, with a foreword by President Bill Clinton, argue that a planned development program similar to the Apollo program will become necessary in order to transform US energy systems on a large scale.


==See also==
{|
{|
|- valign=top
|- valign=top
| width="30%" align=left |
|
* [[Alcohol fuel]]
* [[Bioalcohol]]
* [[Algaculture]]
* [[Biobutanol]], a direct biofuel that replaces gasoline.
* [[Anaerobic digestion]]
* [[Biodiesel]]
* Biobutanol, a direct biofuel that replaces gasoline.
* [[BioEthanol for Sustainable Transport]]
* Biodiesel
* [[Biofuelwatch]]
* [[Biofuel in the United States]]
* [[Biogas]] and [[Biogas powerplant]]
* [[Biogas]] and [[Biogas powerplant]]
* [[Bioheat]], a biofuel blended with [[heating oil]].
* [[Bioheat]], a biofuel blended with heating oil.
* [[pyrolysis|Biomass to liquid bio-oil]]
* [[Biohydrogen]]
* [[Biosphere]]  
* [[Carbon based fuel]]
* [[By-product]]
|
 
| width="30%" align=left |
* [[Energy content of biofuel]]
* [[Energy content of biofuel]]
* [[Energy crop]]
* [[Ethanol fuel]]
* [[Ethanol fuel]]
* [[Ethanol fuel in Brazil]]
* [[Gasification]]
* [[Greenhouse gas]]
* [[Green crude]]
* [[Hybrid vehicle]]
* [[Hybrid vehicle]]
* [[Hydrogen vehicle]] 
* [[List of vegetable oils]] section on oils used as biodiesel
* [[Mechanical biological treatment]]
| width="30%" align=left |
* Thermal depolymerization
* Waste vegetable oil
|}
|}


==See also==
==References==
* Proposed [[oil phase-out in Sweden]]
{{reflist|2}}
* [[Low-carbon economy]]
* [[Ecological sanitation]]
* [[straight vegetable oil]]
* [[vegetable oil economy]]
 
== References ==
<references/>
# [http://www.itdg.org/docs/technical_information_service/biomass.pdf Biomass Technical Brief], Simon Ekless, [http://www.itdg.org/ Intermediate Technology Development Group], retrieved [[1 January]] [[2005]] from http://www.itdg.org/docs/technical_information_service/biomass.pdf.
# [http://i-r-squared.blogspot.com/2006/10/cellulosic-ethanol-vs-biomass.html Cellulosic Ethanol vs. Biomass Gasification], [[22 October]] [[2006]], retrieved [[19 November]] 2006 from http://i-r-squared.blogspot.com/2006/10/cellulosic-ethanol-vs-biomass.html
# [http://www.itdg.org/?id=smoke_report_1 Smoke — the killer in the kitchen],  [http://www.itdg.org/ Intermediate Technology Development Group], [[19 March]] 2004, retrieved [[1 January]] 2005 from http://www.itdg.org/?id=smoke_report_1
# [http://www.itdg.org/?id=smoke_report_3 Reducing exposure to indoor air pollution],  [http://www.itdg.org/ Intermediate Technology Development Group], [[19 March]] 2004, retrieved [[1 January]] 2005 from http://www.itdg.org/?id=smoke_report_3
# [http://www.globalpetroleumclub.com Biofuels Crop Index]
 
== External links ==
{{cleanup-spam}}
*[http://www.sugre.info/Vorlage.phtml Alternative Fuels Portal]
*[http://www.worldwatch.org/taxonomy/term/445 Biofuels for Transportation: Global Potential and Implications for Sustainable Agriculture and Energy in the 21st Century]
*[http://www.biopact.com/ Biopact: Bioenergy Pact Between Europe and Africa]
*[http://www.biofuelwatch.org.uk/ Biofuelwatch]
*[http://www.channel4.com/more4/news/news-opinion-feature.jsp?id=542 Channel4] Biofuels: Doing more harm than good? (article and video from Feb 2007)
*[http://energyjustice.net/biodiesel/factsheet.pdf Biodiesel Critique]
*[http://energyjustice.net/ethanol/ Ethanol Critique]
*[http://www.cus.net/renewableenergy/subcats/biomass/biomass.html Biomass]
*[http://feedstockreview.ornl.gov/pdf/billion_ton_vision.pdf "Biomass as Feedstock for a Bioenergy and Bioproducts Industry"], a 2005 joint study sponsored by the [[United States Department of Energy]] and [[United States Department of Agriculture|Department of Agriculture]]
*[http://www.aboutbioenergy.info Promotional Web Site for Biomass and Bioenergy]
*[http://energyjustice.net/biomass/ Biomass Critique]
*[http://www.our-energy.com/bioenergy_en.html Wood energy, biogas and biofuels]
*[http://www.wrm.org.uy/ World Rainforest Movement]
*[http://domesticfuel.com Domesticfuel.com]
*[http://www.gbev.org/ Ghent Bio Energy Valley]
*[http://www.aboutbioenergy.info/index.html IEA Bioenergy]
*[http://www.iea-bioenergy-task29.hr IEA Bioenergy - Task 29]
*[http://www.nnfcc.co.uk/products/energy/eindex.cfm National Non Food Crops Centre]
*[http://www.westernresearch.org/content/technology_areas/alternative_fuels/alcohols.shtml PEFI Alcohol Process Development & Demonstration (Ecalene<sup>TM</sup>)]
*[http://www.biofuels.ru Russian National Biofuels Association]
*[http://www.biofuel.be/whatisbiodiesel.html What is Biodiesel]
*[http://www.holzpellet.com/index_en.htm Wood Energy Organisation] Informations about energy out of wood
*[http://www.icrisat.org/Investors/wit_5/wit_5.htm Biofuel Crops: Power to the Poor ]
 


==Further reading==
==Further reading==
* [http://www.columbia.edu/~kjh2103/US-Bagasse-Cogen-Potential.pdf ''The Potential of Bagasse-Based Cogeneration in the US''], Kevin Ho, Columbia University, 2006.
* {{cite book|title=Biofuels Engineering Process Technology|author=Caye Drapcho, Nhuan Phú Nghiêm, Terry Walker |month=August | year=2008 |publisher=[McGraw-Hill] |isbn=0071487492; 9780071487498 |url=http://www.mhprofessional.com/product.php?isbn=0071487492}}
 
* {{cite book|title=A Biofuels Compendium|author=IChemE Energy Conversion Technology Subject Group|month=May | year=2009 |publisher=[IChemE] |isbn= 9780852955338 |url=http://www.icheme.org/biofuelscompendium}}
* [http://www.biofuelwatch.org.uk/docs/sgr_boswell.pdf ''Biofuels for Transport - a dangerous distraction?''], Dr Andrew Boswell, published in Scientists for Global Responsibility (www.sgr.org.uk) newsletter, January 2007.
* [http://www.europarl.europa.eu/registre/docs_autres_institutions/commission_europeenne/sec/2007/0055/COM_SEC(2007)0055_EN.pdf Fuel Quality Directive Impact Assessment]
* [http://www.future-science.com/page/journal/bfl/teaser.jsp Biofuels Journal]


==External links==
* [http://www.eere.energy.gov/afdc/fuels/stations_locator.html Alternative Fueling Station Locator] ([[EERE]]).
* [http://www.netregs.gov.uk/netregs/94953.aspx Biofuels guidance for businesses, including permits and licences required] on NetRegs.gov.uk
* [http://www.spectrum.ieee.org/apr08/6182 How Much Water Does It Take to Make Electricity?] -- Natural gas requires the least water to produce energy, some biofuels the most, according to a new study.
* [http://ec.europa.eu/energy/res/events/biofuels.htm International Conference on Biofuels Standards] - European Union Biofuels Standardization
*[http://www.iea.org/textbase/nppdf/free/2004/biofuels2004.pdf International Energy Agency: Biofuels for Transport - An International Perspective]
* [http://www.steelcitybiofuels.psu.edu Steel City Biofuels] - A program of the Pennsylvania State University dedicated to the dissemination of high-quality educational resources.
* [http://web.mit.edu/professional/short-programs/courses/biofuels_biomass.html Biofuels from Biomass: Technology and Policy Considerations] Thorough overview from MIT
* [http://www.guardian.co.uk/environment/biofuels The Guardian news on biofuels]
* [http://www.biofuelwatch.org.uk/ NGO Biofuelwatch


[[Category:Alternative propulsion]]
[[Category:Alternative propulsion]]
[[Category:Anaerobic digestion]]
[[Category:Biofuels| ]]
[[Category:Biodegradable waste management]]
[[Category:Fuels]]
[[Category:Biofuels]]
[[Category:Climate change]]
[[Category:Renewable energy]]
[[Category:Sustainable technologies]]

Revision as of 16:32, 21 August 2009

Biofuel is defined as solid, liquid or gaseous fuel obtained from relatively recently lifeless or living biological material and is different from fossil fuels, which are derived from long dead biological material. Also, various plants and plant-derived materials are used for biofuel manufacturing.

Globally, biofuels are most commonly used to power vehicles, heat homes, and for cooking. Biofuel industries are expanding in Europe, Asia and the Americas. Recent technology developed at Los Alamos National Lab even allows for the conversion of pollution into renewable bio fuel.<ref>lanl.gov, Green Freedom: Out of Thin Air</ref> Agrofuels are biofuels which are produced from specific crops, rather than from waste processes such as landfill off-gassing or recycled vegetable oil.<ref>Call for a moratorium on EU agrofuel incentives - Transnational Institute- 1 July 2007</ref>

There are two common strategies of producing liquid and gaseous agrofuels. One is to grow crops high in sugar (sugar cane, sugar beet, and sweet sorghum<ref>ICRISAT: Sweet sorghum balances food and fuel needs</ref>) 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, jatropha, or pongamia pinnata. When these oils are heated, their viscosity is reduced, and they can be burned directly in a diesel engine, or they can be chemically processed to produce fuels such as biodiesel. Wood and its byproducts can also be converted into biofuels such as woodgas, methanol or ethanol fuel<ref name="forestry biofuels">{{#if:Pu 

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Biomass

Biomass or biofuel 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.

It is used to produce power, heat & steam and fuel, through a number of different processes. Although renewable, biomass often involves a burning process that produces emissions such as Sulphur Dioxide (SO2), Nitrogen Oxides (NOx) and Carbon Dioxide (CO2), but fortunately in quantities far less than those emitted by coal plants. However, proponents of coal plants feel that their way of doing it is a lot cheaper and there is a lot of dispute over this.

When biomass is combusted to produce heat, it releases carbon than was absorbed by the plant material during the plant's lifecycle. This is because (1) approximately one third of the carbon absorbed by the plant during its life is sequestered in its roots, which are left in the soil to rot and fertilize nearby plant life, and (2) combustion of biomass produces 1-10% solid ash (depending on type of plant used), which is extremely high in carbon (this ash is commonly used as fertilizer).

Animal waste is a persistent and unavoidable pollutant produced primarily by the animals housed in industrial-size 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.<ref> New study advances method to make energy from farm waste, [1], 4/17/2008.</ref>

There are also agricultural products specifically grown for biofuel production including 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 and pongamia pinnata in India; pongamia pinnata in Australia and the tropics. 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. Biomass can come from waste plant material. The use of biomass fuels can therefore contribute to waste management as well as fuel security and help to prevent global warming, though alone they are not a comprehensive solution to these problems.

Energy from bio waste

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 the equivalent of 19 million tons of oil is available from biomass by 2020, 46% from bio-wastes: municipal solid waste (MSW), agricultural residues, farm waste and other biodegradable waste streams.<ref>European Environment Agency (2006) How much bioenergy can Europe produce without harming the environment? EEA Report no. 7</ref><ref>Marshall, A. T. (2007) Bioenergy from Waste: A Growing Source of Power, Waste Management World Magazine April, p34-37</ref>

Landfill sites generate gases as the waste buried in them undergoes anaerobic digestion. These gases are known collectively as landfill gas (LFG). This is considered a source of renewable energy, even though landfill disposal is 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 gas found in natural gas. Land fill gas can be easily purified and then fed into the Natural Gas grid.

If landfill gas is not harvested, it escapes into the atmosphere: this is undesirable because methane is a greenhouse gas with much more global warming potential than carbon dioxide.<ref name="IPCC2001"> IPCC Third Assessment Report, accessed August 31, 2007.</ref><ref name="EPAGWP"> Non-CO2 Gases Economic Analysis and Inventory: Global Warming Potentials and Atmospheric Lifetimes, U.S. Environmental Protection Agency, accessed August 31, 2007</ref> Over a time span of 100 years, one ton of methane produces the same greenhouse gas (GHG) effect as 21 tons of CO2.<ref>http://unfccc.int/ghg_data/items/3825.php</ref> When methane burns, it produces carbon dioxide in the ratio 1:1—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.

It was recently discovered that living plants also produce methane.<ref>{{#if:Frank Keppler, John T. G. Hamilton, Marc Bra, and Thomas Röckmann 

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}}.</ref> The amount 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.<ref>http://biofuel.org.uk/biofuel-from-waste.html</ref> Anaerobic digestion can be used as a 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 current project for a 1.6 MW landfill power plant is projected to provide power for 880 homes.<ref>Construction of landfill power plant has begun By MARLA TONCRAY, News Editor (Friday, October 10, 2008 12:57 AM EDT) The Ledger Independent - Maysville, Kentucky</ref> It is estimated that this will eliminate 3,187 tons of methane and directly eliminate 8.756 tons of carbon dioxide release per year. This is the same as removing 12,576 cars from the road, or planting 15,606 trees, or not using 359 rail cars of coal per year.

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 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

First generation biofuels

'First-generation biofuels' are biofuels made from sugar, starch, vegetable oil, or animal fats using conventional technology.<ref name="UN report"> UN biofuels report</ref> 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 instead 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

Main article: Vegetable oil used as fuel

Edible vegetable oil is generally not used as fuel, but lower quality oil can be used for this purpose. Used vegetable oil is increasingly being processed into biodiesel, or (more rarely) cleaned of water and particulates and used as a fuel. To ensure that the fuel injectors atomize the fuel in the correct pattern for efficient combustion, vegetable oil fuel must be heated to reduce its viscosity to that of diesel, either by electric coils or heat exchangers. This is easier in warm or temperate climates. Big corporations like MAN B&W Diesel, Wartsila and Deutz AG as well as a number of smaller companies such as Elsbett offer engines that are compatible with straight vegetable oil, without the need for after-market modifications. Vegetable oil can also be used in many older diesel engines that do not use common rail or unit injection electronic diesel injection systems. Due to the design of the combustion chambers in indirect injection engines, these are the best engines for use with vegetable oil. This system allows the relatively larger oil molecules more time to burn. Some older engines, especially Mercedes are driven experimentally by enthusiasts without any conversion, a handful of drivers have experienced limited success with earlier pre-"pumped use" VW TDI engines and other similar engines with direct injection. Several companies like Elsbett or Wolf have developed professional conversion kits and sucessfully installed hundreds of them over the last decades.

Oils and fats can be hydrogenated to give a diesel substitute. The resulting product is a straight chain hydrocarbon, high in cetane, low in aromatics and sulphur and does not contain oxygen. Hydrogenated oils can be blended with diesel in all proportions Hydrogenated oils have several advantages over biodiesel, including good performance at low temperatures, no storage stability problems and no susceptibility to microbial attack.<ref name=evans>Evans, G. "Liquid Transport Biofuels - Technology Status Report", National Non-Food Crops Centre, 2008-04-14. Retrieved on 2009-05-11.</ref>

Biodiesel

Main article: 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 fossil/mineral diesel. Its chemical name is fatty acid methyl (or ethyl) ester (FAME). Oils are mixed with sodium hydroxide and methanol (or ethanol) and the chemical reaction produces biodiesel (FAME) and glycerol. One part glycerol is produced for every 10 parts biodiesel. Feedstocks for biodiesel include animal fats, vegetable oils, soy, rapeseed, jatropha, mahua, mustard, flax, sunflower, palm oil, hemp, field pennycress, pongamia pinnata and algae. Pure biodiesel (B100) is by far the lowest emission diesel fuel. Although liquefied petroleum gas and hydrogen have cleaner combustion, they are used to fuel much less efficient petrol engines and are not as widely available.

Biodiesel can be used in any diesel engine when mixed with mineral diesel. The majority of vehicle manufacturers limit their recommendations to 15% biodiesel blended with mineral diesel. In some countries manufacturers cover their diesel engines under warranty for B100 use, although Volkswagen of Germany, for example, asks drivers to check by telephone with the VW environmental services department before switching to B100. B100 may become more viscous at lower temperatures, depending on the feedstock used, requiring vehicles to have fuel line heaters. In most cases, biodiesel is compatible with diesel engines from 1994 onwards, which use 'Viton' (by DuPont) synthetic rubber in their mechanical injection systems. Electronically controlled 'common rail' and 'pump duse' type systems from the late 1990s onwards may only use biodiesel blended with conventional diesel fuel. These engines have finely metered and atomized multi-stage injection systems are very sensitive to the viscosity of the fuel. Many current generation diesel engines are made so that they can run on B100 without altering the engine itself, although this depends on the fuel rail design. NExBTL is suitable for all diesel engines in the world since it overperforms DIN EN 590 standards.

Since biodiesel is an effective solvent and cleans residues deposited by mineral diesel, engine filters may need to be replaced more often, as the biofuel dissolves old deposits in the fuel tank and pipes. It also effectively cleans the engine combustion chamber of carbon deposits, helping to maintain efficiency. In many European countries, a 5% biodiesel blend is widely used and is available at thousands of gas stations.<ref>ADM Biodiesel: Hamburg, Leer, Mainz</ref><ref>Welcome to Biodiesel Filling Stations</ref> Biodiesel is also an oxygenated fuel, meaning that it contains a reduced amount of carbon and higher hydrogen and oxygen content than fossil diesel. This improves the combustion of fossil diesel and reduces the particulate emissions from un-burnt carbon.

Biodiesel is safe to handle and transport because it is as biodegradable as sugar, 10 times less toxic than table salt, and has a high flashpoint of about 300 F compared to petroleum diesel fuel, which has a flash point of 125 F.<ref>http://www.hempcar.org/biofacts.shtml</ref>.

In the USA, more than 80% of commercial trucks and city buses run on diesel. The emerging US biodiesel market is estimated to have grown 200% from 2004 to 2005. "By the end of 2006 biodiesel production was estimated to increase fourfold [from 2004] to more than 1 billion gallons,".<ref>THE FUTURIST, Will Thurmond. July-August 2007</ref>

Bioalcohols

Main article: Alcohol fuel
File:EthanolPetrol.jpg
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),<ref>ButylFuel,LLC Main Page</ref> 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. E. coli have also been successfully engineered to produce Butanol by hijacking their amino acid metabolism<ref name="butanol">{{#if: Biofuels aim higher 

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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).

File:Koenigsegg CCXR Edition (1 von 2).jpg
The Koenigsegg CCXR Edition at the 2008 Geneva Motor Show. This is an "environmentally-friendly" version of the CCX, which can use E85 and E100.

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. Ethanol has a smaller energy density than gasoline, which means it takes more fuel (volume and mass) to produce the same amount of work. An advantage of ethanol is that is has a higher octane rating than ethanol-free gasoline available at roadside gas stations which allows an increase of an engine's compression ratio for increased thermal efficiency. 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 is very corrosive to fuel systems, rubber hoses and gaskets, aluminum, and combustion chambers. Therefore, it is 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 also corrodes fiberglass fuel tanks such as used in marine engines. For higher ethanol percentage blends, and 100% ethanol vehicles, engine modifications are required.

It is the hygroscopic (water loving) nature of relatively polar ethanol that can promote corrosion of existing pipelines and older fuel delivery systems. To characterize ethanol itself as a corrosive chemical is somewhat misleading and the context in which it can be indirectly corrosive, somewhat narrow; i.e., limited to effects upon existing pipelines designed for petroleum transport.

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.<ref>Template:Citation/core{{#if:|}} </ref>

Although ethanol-from-corn and other food stocks has implications both in terms of world food prices and limited, yet positive energy yield (in terms of energy delivered to customer/fossil fuels used), the technology has lead to the development of cellulosic ethanol. According to a joint research agenda conducted through the U.S. Department of Energy,<ref>see "Breaking the Biological Barriers to Cellulosic Ethanol")</ref> the fossil energy ratios (FER) for cellulosic ethanol, corn ethanol, and gasoline are 10.3, 1.36, and 0.81, respectively.<ref>Brinkman, N. et al., "Well-to-Wheels Analysis of Advanced/Vehicle Systems", 2005.</ref><ref>Farrell, A.E. et al. (2006) "Ethanol can Contribute to Energy and Environmental Goals", Science, 311, 506-8.</ref><ref>Hammerschlag, R. 2006. "Ethanol's Energy Return on Investment: A Survey of the Literature 1999-Present", Environ. Sci. Technol., 40, 1744-50.</ref>

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.Template:Citation needed Efficiency falls and pollution emissions increase when FFV system maintenance is needed (regardless of the fuel 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.Template:Citation needed

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 aluminum (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 distance traveled than current high gasoline prices in the United States.<ref>Template:Citation/core{{#if:|}} </ref>

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.<ref>Hydrogen Solar home</ref>

Bioethers

Bio ethers (also referred to as fuel ethers or fuel oxygenates) are cost-effective compounds that act as octane enhancers. They also enhance engine performance, whilst significantly reducing engine wear and toxic exhaust emissions. Greatly reducing the amount of ground-level ozone, they contribute to the quality of the air we breathe.<ref>http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31985L0536:EN:HTML, Council Directive 85/536/EEC of 5 December 1985 on crude-oil savings through the use of substitute fuel components in petrol</ref><ref>http://circa.europa.eu/Public/irc/env/fuel_quality/library?l=/stakeholder_october/presentations/copert_brusselsppt/_EN_1.0_&a=d COPERT Study: An assessment of the impact of ethanol-blended petrol </ref><ref>http://www.europarl.europa.eu/registre/docs_autres_institutions/commission_europeenne/sec/2007/0055/COM_SEC(2007)0055_EN.pdf Fuel Quality Directive Impact Assessment</ref>

Biogas

File:Biogas pipes.JPG
Pipes carrying biogas
Main article: Biogas

Biogas is produced by the process of anaerobic digestion of organic material by anaerobes.<ref>Redman, G., The Andersons Centre. "Assessment of on-farm AD in the UK", National Non-Food Crops Centre, 2008-06-09. Retrieved on 2009-05-11.</ref> 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:

Syngas

Main article: Gasification

Syngas, a mixture of carbon monoxide and hydrogen, is produced by partial combustion of biomass, that is, combustion with an amount of oxygen that is not sufficient to convert the biomass completely to carbon dioxide and water.<ref name="evans"/> Before partial combustion the biomass is dried, and sometimes pyrolysed.

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 or turbines. 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 diesel substitute, or a mixture of alcohols that can be blended into gasoline. Gasification normally relies on temperatures >700°C. Lower temperature gasification is desirable when co-producing biochar but results in a Syngas polluted with tar.

Solid biofuels

Examples include wood, sawdust, grass cuttings, domestic refuse, charcoal, agricultural waste, non-food energy crops (see picture), and dried manure.

When raw biomass is already in a suitable form (such as firewood), it can burn directly in a stove or furnace to provide heat or raise steam. When raw biomass is in an inconvenient form (such as sawdust, wood chips, grass, agricultural wastes), another option is to pelletize the biomass with a pellet mill. The resulting fuel pellets are easier to burn in a pellet stove.

A problem with the combustion of raw biomass is that it emits considerable amounts of pollutants such as particulates and PAHs (polycyclic aromatic hydrocarbons). Even modern pellet boilers generates much more pollutants than oil or natural gas boilers. Pellets made from agricultural residues are usually worse than wood pellets, producing much larger emissions of dioxins and chlorophenols.<ref>Cedric Briens, Jan Piskorz and Franco Berruti, "Biomass Valorization for Fuel and Chemicals Production -- A Review," 2008. International Journal of Chemical Reactor Engineering, 6, R2</ref>

Another solid biofuel is biochar, which is produced by biomass pyrolysis. Biochar pellets made from agricultural waste can substitute for wood charcoal. In countries where charcoal stoves are popular, this can reduce deforestation.

Second generation biofuels

Main article: 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.<ref name=2G> http://www.renewable-energy-world.com/articles/print_screen.cfm?ARTICLE_ID=308325 Template:Dead link </ref> 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<ref name="Oliver R. Inderwildi, David A. King 2009 343"/>, including cellulosic biofuels from non food crops.<ref>Template:Citation/core{{#if:|}} </ref> Many second generation biofuels are under development such as biohydrogen, biomethanol, DMF, Bio-DME, Fischer-Tropsch diesel, biohydrogen diesel, mixed alcohols and wood diesel.

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

Producing ethanol from cellulose is a difficult technical problem to solve. In nature, ruminant livestock (like cattle) eats grass and then use slow enzymatic digestive processes to break it into glucose (sugar). In cellulosic ethanol laboratories, various experimental processes are being developed to do the same thing, and then the sugars released can be fermented to make ethanol fuel. In 2009 scientists reported developing, using "synthetic biology", "15 new highly stable fungal enzyme catalysts that efficiently break down cellulose into sugars at high temperatures", adding to the 10 previously known.<ref>EurekAlert. (2009). 15 new highly stable fungal enzyme catalysts that efficiently break down cellulose into sugars at high temperatures.</ref> In addition, research conducted at TU Delft by Jack Pronk has shown that elephant yeast, when slightly modified can also create ethanol from non-edible ground sources (eg straw).<ref>Jack Pronk's elephant yeast</ref><ref>Straw to ethanol plant in Sas van Gent</ref>

The recent discovery of the fungus Gliocladium roseum points toward the production of so-called myco-diesel from cellulose. This organism was recently discovered in the rainforests of northern Patagonia and has the unique capability of converting cellulose into medium length hydrocarbons typically found in diesel fuel.<ref>Template:Citation/core{{#if:|}} </ref>

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

Third generation biofuels

Main article: Algae fuel

Algae fuel, also called oilgae or third generation biofuel, is a biofuel from algae. Algae are low-input, high-yield feedstocks to produce biofuels. It produces 30 times more energy per acre than land crops such as soybeans.<ref name="wapo-algae">Template:Citation/core{{#if:|}} </ref> 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.<ref> Globeco biodegradable bio-diesel </ref><ref> Friends of Ethanol.com biodegradable ethanol </ref><ref> Low Cost Algae Production System Introduced </ref>

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.<ref name="wapo-algae"/>

Second and third generation biofuels are also called advanced biofuels.

Algae, such as Botryococcus braunii and Chlorella vulgaris, are relatively easy to grow, <ref>[2],</ref> but the algal oil is hard to extract. There are several approaches, some of which work better than others.<ref>[3]</ref> Macroalgae (seaweed) also have a great potential for bioethanol and biogas production <ref>Seaweed Biofuels: Production of Biogas and Bioethanol from Brown Macroalgae </ref>.

Ethanol from living algae

Most biofuel production comes from harvesting organic matter and then converting it to fuel but an alternative approach relies on the fact that some algae naturally produce ethanol and this can be collected without killing the algae. The ethanol evaporates and then can be condensed and collected. The company Algenol is trying to commercialize this process.

Helioculture

Helioculture is a newly developed process which is claimed to be able to produce 20,000 gallons of fuel per acre per year, and which removes carbon dioxide from the air as a feedstock for the fuel.<ref>Start-Up's Biofuel Recipe Mixes CO2, Slime and Sunshine, The New York Times, July 27, 2009</ref>

Biofuels by region

Main article: Biofuels by region

Recognizing the importance of implementing bioenergy, there are international organizations such as IEA Bioenergy,<ref> IEA bioenergy </ref> 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.<ref> Template:Citation/core{{#if:|}} </ref> The world leaders in biofuel development and use are Brazil, United States, France, Sweden and Germany.

Template:See also

Issues with biofuel production and use

Main article: Issues relating to biofuels

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.


Issues related to the large scale development and implementation of biofuels

According to the Swedish researcher Dr. Magnus Blinge, Chalmers Technical University, replacing all oil used in Europe by cellulose based bio-fuels would require 1,000 production plants for bio-fuels, each would need deliveries of 450 truckloads of wood every day. This would require an entirely new production and distribution system for fuels. In a booklet in Swedish (“Med klimatfrågan i fokus”, Volvo AB, Gothenburg 2007) published by the truck and bus company Volvo AB, the merits of seven different bio-fuels and engine solutions are briefly described and analyzed. Volvo finds that the most promising fuel, based on the criteria of the analysis, is DME (Dimethyl ether). Overall, the CEO of Volvo, Leif Johansson, concludes that high level political agreements between nations will become necessary in order to implement bio-fuels on a large scale. This is because transportation systems are cross border, and these and the climate issue do not stop at country borders. In order for Volvo, to do its part in the development of the renewable fuels of the future, politicians need to decide which fuels that are going to be used on a large scale in the future. Some authors, such as US congressman Jay Inslee and environmentalist Bracken Hendricks go even further. In their book “Apollo’s Fire”, with a foreword by President Bill Clinton, argue that a planned development program similar to the Apollo program will become necessary in order to transform US energy systems on a large scale.

See also

References

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Further reading

External links

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