Biofuels are presently the only renewable source of liquid transportation fuels and offer many potential environment and economic benefits. The production of the raw biomass material and its subsequent conversion to fuels creates local jobs, provides regional economic development, and can increase farm and forestry incomes. Biofuels also offer many environment benefits including reduction of carbon dioxide emissions associated with global climate change and improved waste utilization. The chemical composition of many biofuels also leads to improved engine performance and reduces unwanted pollutants such as carbon monoxide and unburned hydrocarbons. Billions of liters of ethanol are used annually for transportation fuels, and biodiesel is gaining popularity in some regions.

Biomass (Chap. 8) is a catch-all term that also includes wood and is generally made up of woody plant residue and complex starches. The largest percentage of biomass used to create energy is wood, but other bioproducts, such as fast-growing switchgrass (Chap. 9), are being investigated as sources of energy. The three largest sources of biomass used for fuel are cellulose, hemicellulose, and lignin. Biomass processing results in the end-products, biochemical products, biofuels, and biopower, all of which can be used as fuel sources. The production of biochemical products involves converting biomass into chemicals to produce electricity; biofuels are biomass converted into liquids for transportation; and biopower is made by either burning biomass directly (as with a wood-burning stove) or converting it into a gaseous fuel to generate electric power. Currently, production of electricity from biomass constitutes 3.3 percent of the...