A great oldie from the DOE on the basics of Biofuels.

Biomass is an organic renewable energy source that includes materials such as agriculture and forest residues, energy crops, and algae. Scientists and engineers at the U.S. Department of Energy and its national laboratories are finding new, more efficient ways to convert biomass into biofuels that can take the place of conventional fuels like gasoline, diesel, and jet fuel. This edition of Energy 101 shows how biomass is broken down and refined into sustainable biofuels via biochemical and thermochemical processes.