Derived from living or recently living organisms, or biomass, the basic composition of biofuels is more complex than the composition of fossil fuels. While fossil fuels consist only of carbon and hydrogen atoms, or hydrocarbons, biofuels contain oxygen atoms, and their chemical composition may include acids, alcohols and esters.
Biobutanol is derived from biomass or produced by fermentation using organisms found in ruminant animals and soils. The basic composition of butanol consists of C (carbon), H (hydrogen) and O (oxygen). The chemical formula for the butanol molecule is C4H10O. Biobutanol provides more energy than ethanol and can be blended with gasoline to help reduce greenhouse gases. Any car that runs on gasoline can run on a biobutanol blend.
Derived from vegetable oils and animal fats, biodiesel molecules are esters of long-chain fatty acids containing single chains of 12 to 24 carbon atoms. The esters contain an alcohol and a carboxylic acid. The carboxylic acid contains COOH (carboxyl), and the alcohol contains OH (hydroxide). Biodiesel burns cleaner than traditional diesel, producing less sulfur and fewer particulates. Biodiesel delivers slightly less energy than petroleum-based diesel, however, and is more corrosive to engine parts.
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Derived from corn, sugar beets and sugar cane, other sources for ethanol production such as corn stover and switchgrass are under development. Containing carbon, hydrogen and a hydroxide group, the chemical formula for the ethanol molecule is C2H5OH. Any vehicle sold in the United States can run on E10, a blend of 10 percent ethanol and 90 percent unleaded gasoline. Providing about 50 percent of the energy of gasoline, combustion of ethanol is cleaner and produces less carbon monoxide but produces more smog.
The simplest of alcohols, methanol can be derived from any plant material as well as landfill gas, power plant emissions and atmospheric carbon dioxide. The basic composition of methanol consists of carbon, hydrogen and hydroxide. The chemical formula for the ethanol molecule is CH3OH. Methanol combustion produces a lower volume of toxins than gasoline, fewer particulates and less smog. Methanol is less expensive than gasoline or ethanol, and the cost of modifying a vehicle to run on blends of methanol is low.