Biofuel is defined as solid, liquid or gaseous fuel derived from relatively recently dead biological material and is distinguished from fossil fuels, which are derived from long dead biological material. Theoretically, biofuels can be produced from any (biological) carbon source; although, the most common sources are photosynthetic plants. Various plants and plant-derived materials are used for biofuel manufacturing.

Globally, biomass fuels are most commonly used for cooking and space heating of homes, as well as central heating of homes and larger facilities. In many European countries, over 25% of heating is done with solid biofuels, including wood pellets, wood chips and straw. In Sweden, over 35% of all facilities (including homes, commercial buildings, and institutional facilities) are heated with biomass fuels that are combusted in central biomass boilers at over 90% efficency. They can also be used to generate steam and create electricity, or converted to a liquid or gas for use in transportation vehicles. The conversion of biomass into electricity or into a liquid or gaseous state generally requires electricity that is often produced with coal. The efficiency of using biomass to produce electricity, liquid biofuels, or gaseous biofuels utilizes only 25-35% of the energy content of the originaly biomass feedstock. In additon, conversion to a liquid or gas state usually requires significant amounts of water.

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. Agrofuels are biofuels which are produced from specific crops, rather than from waste processes such as landfill off-gassing or recycled vegetable oil.

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) 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. It is also possible to make cellulosic ethanol from non-edible plant parts, but this can be difficult to accomplish economically.

Source: Wiki-Pedia
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