Biofuels are considered to be one of the most important renewable energy sources and have been widely used since 2002. Biofuels are derived from biomass materials, such as trees, grass, crops or other biomaterials, which are converted into liquid or gaseous forms to produce fuels and chemicals. The two most common biofuels are ethanol and biodiesel. They are most often used to help meet transportation needs. In fact, biofuels are the only renewable liquid transportation fuels available.
Ethanol is an alcohol created from the fermentation of a biomass high in carbohydrates, a process very similar to beer brewing. Ethanol is currently derived from starches and sugars. However, scientists hope to develop methods of making ethanol a more competitive gasoline additive by producing it from low-cost biomass materials, such as cellulose and hemicellulose, which comprise the majority of plant matter. For example, agricultural residues, such as corn stover (the stalks, leaves, and husks of the plant) and wheat straw, are planned to be used in the near-term for biofuel production. The Department of Energy aims to reduce the cost of producing ethanol by as much as 60 cents per gallon by 2015 with cellulosic conversion technology.
Ethanol is generally used as an additive for vehicle fuel to boost octane and decrease the emission of carbon monoxide and other pollutants. More than 5 percent of all motor fuel is currently blended with up to 10 percent ethanol. If the use of ethanol were extended to all motor fuel, some 630,000 barrels of oil per day could be offset. Today, “flex-fuel” vehicles can use fuel blends that contain up to 85 percent ethanol.
Biodiesel is created by combining alcohol, often methanol, with vegetable oil, animal fat or used cooking grease. Soybeans are a surplus crop commonly used in the production of biodiesel fuel. It is often used as an additive, comprising 20 percent of the fuel blend, in order to cut down vehicle emissions. In its pure form, it can be used in diesel engines as a renewable alternative fuel. Contrary to ethanol blends, biodiesel fuel does not require the purchase of a new “flex-fuel” type of vehicle.
The benefits of biofuels are boundless. According to the Department of Energy, the use of biofuels strengthens both the national economy and that of rural communities, decreases U.S. dependence on imported oil, avoids use of MTBE or other highly toxic fuel additives, reduces air and water pollution, and reduces greenhouse gas emissions.
Sources: National Renewable Energy Laboratory (NREL), U.S. Department of Energy (Energy Efficiency and Renewable Energy), “Americas Untapped Depths”, The American Legion Magazine, April 2006 and Energy Information Administration