Biofuels are transportation fuels such as ethanol and biomass-based diesel fuel that are made from biomass materials. These fuels are usually blended with petroleum fuels (gasoline and distillate/diesel fuel and heating oil), but they can also be used on their own. Using ethanol or biodiesel reduces the consumption of gasoline and diesel fuel made from crude oil, which can reduce the amount of crude oil imported from other countries. Ethanol and biodiesel are also cleaner-burning fuels than pure gasoline and diesel fuel.
Ethanol is an alcohol fuel made from the sugars found in grains such as corn, sorghum, and barley.
Most of the fuel ethanol used in the United States is distilled from corn. Scientists are working on ways to make ethanol from all parts of plants and trees rather than just grain and are experimenting with fast-growing woody crops such as poplar and willow trees and switchgrass to see if they can be used to produce ethanol.
United States Department of Agriculture (USDA) research geneticists study switchgrass as a source of ethanol.
Nearly all of the gasoline now sold in the United States is about 10% ethanol by volume. Any gasoline-powered engine in the United States can use E10 (gasoline with 10% ethanol), but only specific types of vehicles can use mixtures with fuel containing more than 10% ethanol. A flexible-fuel vehicle can use gasoline with ethanol content greater than 10%. The U.S. Environmental Protection Agency ruled in October 2010 that cars and light trucks of model year 2007 and newer can use E15 (gasoline with 15% ethanol). E85, a fuel that contains 51%–83% ethanol, depending on location and season, is mainly sold in the Midwest and can only be used in a flexible-fuel vehicle.
Biomass-based diesel fuels include biodiesel and renewable diesel. They are both called biomass-based diesel fuels because they are mostly produced for use in diesel engines, but they can also be used as heating fuels. Both fuels are made from biomass or materials derived from biomass, but they differ in how they are produced and in their physical properties. Biomass-based diesel fuels can be used in diesel engines without modifying the engines.
A biodiesel and standard gasoline pump
Source: Stock photography (copyrighted)