Biocombustibles / Biofuels
Biofuel. What is?

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1207 - Wikipedia - Biofuel defined broadly is solid, liquid, or gas fuel consisting of, or derived from biomass. The more narrow definition is liquid or gas fuel derived from biomass and used as a fuel in transportation. This article uses the narrow definition. When biomass used directly as a fuel is commonly called biomass fuel


Biomass is recently living organisms or their metabolic byproducts - such as feces from cows. It is a renewable energy source, unlike other natural resources such as petroleum, coal, and nuclear fuels. Agricultural products specifically grown for use as biofuels include corn and soybeans, primarily in the United States; flaxseed and rapeseed, primarily in Europe; sugar cane in Brazil; palm oil in South-East Asia; and jatropha (though not an agricultural product) in India. 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 can be converted to biogas through anaerobic digestion. Biomass used as fuel often consists of 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.

Carbon neutral

Biofuels are currently significantly less carbon neutral than other forms of renewable energy due to the high use of fossil fuels in the production of biofuels. The combustion of biofuels produce carbon dioxide and other greenhouse gases. The carbon in biofuels is often taken to have been recently extracted from atmospheric carbon dioxide by plants as they have grown. The potential for biofuels to be considered to be "carbon neutral" depends upon the carbon that is emitted being reused by further plant growth. Clearly however, cutting down trees in forests that have grown for hundreds, or thousands of years for use as a biofuel, without the replacement of this biomass would not have a carbon neutral effect. 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.

Much research is being done about the use of microalgae as an energy source, with applications for biodiesel, ethanol, methanol, methane, and even hydrogen. The production of biofuels to replace oil and natural gas is in active development, focusing on the use of cheap organic matter (usually cellulose, agricultural and sewage waste) in the efficient production of liquid and gas biofuels which yield high net energy gain. One advantage of biofuel over most other fuel types is that it is biodegradable, and so relatively harmless to the environment if spilled.


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[citation needed] 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.

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.

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.

Bioenergy from wastes

The use of waste derived biofuels (biowastes) has many benefits. A recent publication by the European Union projected the potential of waste derived bioenergy to contribute to prevention of global warming. It concluded that 19 million tons of oil equivalent is available from biomass by 2020, 46% of which would be derived from bio-wastes: MSW, agricultural residues, farm wastes and other biodegradable waste streams.

Landfills generate a by-product known as landfill gas, which is an excellent source of renewable energy. Landfill gas (LFG) can be used either directly by industry or to generate electricity for public consumption. In fact, when handled effectively, this previously ignored resource has a lot to offer. Landfill gas contains approximately 50 percent methane, which makes it an excellent source of energy. On the down side, methane has a global warming potential of 21 relative to CO2. In other words, one ton of methane produces the same greenhouse gas (GHG) effect as 21 tons of CO2.

Biofuels in developing countries

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 flues) and alternative fuels. But most of these have difficulties. One is that flues 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.

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.

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.

First Generation Biofuels

'First-generation fuels refer to biofuels made from sugar, starch, vegetable oil, or animal fats using conventional technology'

Biofuels are commonly used throughout the world. The most common use for biofuels is automotive transport. Essentially a biofuel can be produced from any short term carbon cycle organic compound; due to this there is a high variety of resources and therefore many types of biofuels, below is a list of the more commonly used biofuels.

Vegetable oil

Vegetable oil used as a fuel is produced using the same methods as vegetable oil used for consumption. The quality of the oil may be a lot lower for fuel use. Vegetable oil can be used in many older diesel engines (equipped with indirect injection systems), 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.


Biodiesel is the most common biofuel in Europe. It is produced from any oil or fat using transesterification to get a liquid similar to mineral diesel. It can be used in any diesel engine and can be mixed with mineral diesel in any percentage. 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). Many people have run thousands of miles on biodiesel without problem, and many studies have been made on 100% biodiesel. In many European countries, 5% biodiesel blend is widely used and is available at thousands of gas stations.


Ethanol is the most common biofuel worldwide. It is an alcohol fuel. It can be produced from wheat, corn and sugar cane and many other biomass stocks. The production methods used are fermentation of the sugars, distillation and drying. Ethanol can be used in the petrol engine as a replacement to gasoline; it can be mixed with gasoline to any percentage, see common ethanol fuel mixtures for information on ethanol. However, until the recent introduction of new engines, cars would need to have their engines modified in order to run with 100% alcohol.


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[verification needed]. While on paper (and a few lab tests) it appears that butanol has sufficiently similar characteristics with gasoline such that it should work without problem in any gasoline engine, no widespread experience exists. Butanol is formed by ABE fermentation (acetone, butanol, ethanol) and experimental modifications of the process show potentially high net energy gains with butanol as the only liquid product. 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.


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.


Biologically produced alcohols, most commonly ethanol and less commonly propanol and butanol, are produced by the action of microorganisms and enzymes through fermentation.


Biogas is produced by the process of anaerobic digestion of organic material by anaerobes. It can be produced either from biodegradable waste materials or by the use of energy crops fed into anaerobic digesters to supplement gas yields. The solid byproduct, digestate, can 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 landfills through naturally occurring anaerobic digestion. If it escapes into the atmosphere it is a potent greenhouse gas.

Oils and gases can be produced from various biological wastes:

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

Solid Biofuels Examples include wood, charcoal, and dried excrement.

Second Generation Biofuels

'Second-generation fuels are made from lignocellulosic biomass feedstock using advanced technical processes'

Second generation biofuels use biomass to liquid technology. The following second generation biofuels are under development:

* BioHydrogen
* Bio-DME
* Biomethanol
* HTU diesel
* Fischer-Tropsch diesel
* Mixed Alcohols (i.e., mixture of mostly ethanol, propanol and butanol, with some pentanol, hexanol, heptanol and octanol)

Bio-DME, Fischer-Tropsch, BioHydrogen diesel, Biomethanol and Mixed Alcohols all use syngas for production. This syngas is produced by gasification of biomass. HTU (High Temperature Upgrading) diesel is produced from particularly wet biomass stocks using high temperature and pressure to produce an oil.

BioHydrogen is the same as hydrogen except it is produced from a biomass feedstock. This is done using gasification of the biomass and then reforming the methane produced. BioHydrogen can be used in fuel cells to produce electricity.

Bio-DME is the same as DME but is produced from a bio-sources. Bio-DME can be produced from Biomethanol using catalytic dehydration or it can be produced from syngas using DME synthesis. DME can be used in the compression ignition engine.

Biomethanol is the same as methanol but it is produced from biomass. Biomethanol can be blended with petrol up to 10-20% without any infrastructure changes.

HTU diesel is produced from wet biomass. It can be mixed with fossil diesel in any percentage without need for infrastructure.

Fischer-Tropsch diesel (FT) diesel is produced using gas-to-liquids technology. FT diesel can be mixed with fossil diesel at any percentage without need for infrastructure change.

Mixed Alcohols are produced from syngas with catalysts similar to those used for methanol. Most R&D in this area is concentrated in producing mostly ethanol. However, some fuels are marketed as mixed alcohols. Mixed alcohols are superior to pure methanol or ethanol, in that the higher alcohols have higher energy content. Also, when blending, the higher alcohols increase compatibility of gasoline and ethanol, which increases water tolerance and decreases evaporative emissions. In addition, higher alcohols have also lower heat of vaporization than ethanol, which is important for cold starts. (For another method for producing mixed alcohols from biomass see bioconversion of biomass to mixed alcohol fuels)

International efforts

Recognizing the importance of implementing bioenergy, there are international organizations such as IEA Bioenergy, established in 1978 by the International Energy Agency (IEA), with the aim of improving cooperation and information exchange between countries that have national programs in bioenergy research, development and deployment.

European Union

The European Union has set a goal:

* For 2010 that each member state should achieve at least 5.75% biofuel usage of all used traffic fuel.
* For 2020, 10 %.

UN Biofuel Report

The recent UN biofuel report raises the issues about the link between biofuels, deforestation and food production. It warns western policy makers that a too rapid change to biofuels could be harmful if communities are excluded from ownership. It emphasizes that biofuels can be part of the solution to climate change but that current methods of biofuel crop growth in third world countries can have damaging effect to both the local communities and ecology. It also brings up the food crop over fuel crop question. What is the right balance between food and fuel and how can it be insured that western countries are not funding hungry third world countries to grow inedible fuel crops. For the actual report please follow.


Rising food prices

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.

In early 2007 there were a number of reports linking stories as diverse as food riots in Mexico due to rising prices of corn for tortillas and reduced profits at Heineken, the large international brewer, to the increasing use of corn (maize) grown in the US Midwest for bio-ethanol production. (In the case of beer, 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.)

Ecologist and environmental campaigner George Monbiot has argued in the British newspaper The Guardian for a 5 year freeze on biofuels while their impact on poor communities and the environment is assessed.

It is, however, important to note that the edible portions of the food crops are not the most desirable portion of the plant for creating biofuel. The cellulose contained in the inedible stalks of these plants, while more difficult to process, contain far more complex hydrocarbons (the basis of any diesel-type fuel) Much research is currently being done into processes to turn these waste products into fuel, without having to deplete the much-needed food supply.

Energy efficiency of biodiesel

Production of biofuels from raw materials requires energy (for farming, transport and conversion to final product as well as the production of fertilizers and many types of pesticides and herbicides)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. 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.

Also studies on the energy balance of these fuels show large differences depending on the biomass feedstock used and location. Biofuels made from crops grown in temperate climates (such as corn or canola) have a relatively low energy efficiency, 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. For some biofuels (like ethanol made from corn) the energy balance may even be negative.

A European study on the greenhouse gas emissions found that well-to-wheel(WTW) CO2 emissions of biodiesel from seed crop, like rapeseed could be almost as high as fossil diesel. It showed a similar result for bio-ethanol from starch crops which could have almost as many WTW CO2 emissions as fossil petrol. It also showed that second generation biofuels have a much fewer WTW CO2 emissions.

Ecological impact

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.

Biofuels are based on natural renewable organic compounds. These compounds are made by plants or animals. The energy that is stored in these chemicals originally comes from the sun (photosynthesis). When the fuels are burned the "exhaust" created is only something that was already in the atmosphere to begin with. Carbon dioxide is converted to sugar, this sugar is then used as a fuel or used to make the fuel that is eventually burned releasing the carbon dioxide back into the atmosphere.

Since vast amounts of raw material are needed for biofuel production, monocultures 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.

All crops consume nutrients and organic matter. For a sustainable system these must be replenished. The major food producers use intensive farming methods with continuous cropping being a common practice. Intensive farming precludes the sustainable techniques of rotation and fallow and therefore requires importation to replenish the soil. Importation establishes a process of mining nutrients and matter that are in themselves finite just as is oil. Therefore the crop is renewable but the imports and consumables are not renewed. There is the hazard that mass production of crops for bio fuel will further cause the consuming of natural resources and a degradation of soil that will bring about erosion and desertification creating a decline in plant production.


Even though biofuels can have a positive effect regarding the carbon cycle they can still cause local pollution; smog is one of those. Biodiesel can have this particular problem when used in certain unmodified diesel engines; due to the higher Nox output.





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