Biofuel
Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels, such as oil. Biofuel can be produced from plants or from agricultural, domestic or industrial biowaste. There are many types of biofuels:
How Biofuel is Made
To make biomass into liquid or gaseous fuels, biofuels must be converted from their original form. The most basic way to do this is through fermentation of crops that are high in sugar (starch) or fat into ethanol, which can be mixed directly with gasoline to power cars. In the Northwest, oilseed crops like canola or sunflowers are used to make biofuels. For a more advanced process that requires breaking down the cell walls of plants into their most basic chemical form, energy producers use a two-step process: deconstruction followed by synthesis and upgrading. The first step, deconstruction, breaks the biomass down into its most simple components and can happen at either low or high temperatures.The second step, synthesis and upgrading, then rebuilds these components into usable fuel (either liquid or gas). There are many types of synthesis and upgrading, and they vary based on which products come out of deconstruction and what types of compounds are being made (USDA.)
Type of Biofuels
Ethanol: Ethanol (CH3CH2OH) is a renewable fuel that can be made from various plant materials, collectively known as “biomass.” Ethanol is an alcohol used as a blending agent with gasoline to increase octane and cut down carbon monoxide and other smog-causing emissions. The most common blend of ethanol is E10 (10% ethanol, 90% gasoline) and is approved for use in most conventional gasoline-powered vehicles up to E15 (15% ethanol, 85% gasoline). Some vehicles, called flexible fuel vehicles, are designed to run on E85 (a gasoline-ethanol blend containing 51%–83% ethanol, depending on geography and season), an alternative fuel with much higher ethanol content than regular gasoline. Roughly 97% of gasoline in the United States contains some ethanol. Most ethanol is made from plant starches and sugars—particularly corn starch in the United States—but scientists are continuing to develop technologies that would allow for the use of cellulose and hemicellulose, the non-edible fibrous material that constitutes the bulk of plant matter. The common method for converting biomass into ethanol is called fermentation. During fermentation, microorganisms (e.g., bacteria and yeast) metabolize plant sugars and produce ethanol (EERE.)
BIODIESEL: Biodiesel is a liquid fuel produced from renewable sources, such as new and used vegetable oils and animal fats and is a cleaner-burning replacement for petroleum-based diesel fuel. Biodiesel is nontoxic and biodegradable and is produced by combining alcohol with vegetable oil, animal fat, or recycled cooking grease. Like petroleum-derived diesel, biodiesel is used to fuel compression-ignition (diesel) engines. Biodiesel can be blended with petroleum diesel in any percentage, including B100 (pure biodiesel) and, the most common blend, B20 (a blend containing 20% biodiesel and 80% petroleum diesel) (EERE.)
RENEWABLE HYDROCARBON "DROP-IN" FUELS: Petroleum fuels, such as gasoline, diesel, and jet fuel, contain a complex mixture of hydrocarbons (molecules of hydrogen and carbon), which are burned to produce energy. Hydrocarbons can also be produced from biomass sources through a variety of biological and thermochemical processes. Biomass-based renewable hydrocarbon fuels are nearly identical to the petroleum-based fuels they are designed to replace—so they're compatible with today's engines, pumps, and other infrastructure (EERE.)