it is an ingredient in many of the foods we eat and also used as feed for livestk. douglas: we think we can go to about 15 billion gallons of ethanol a year from corn kernels. but anything beyond that the competition between fuel and food starts to take place. and so to get more than 15 billion gallons of ethanol a year, we need to go to other methods. and that's why we're interested in trying to learn how to economically make ethanol from the cellulosic materials -- that is, the stalks, stems, leaves -- the nonedible parts of the plant. narrator: cellulosic material, or biomass, is basically the fibrous, woody, and generally inedible portions of plants. and it is the most plentiful biological material on earth. the challenge for nrel scientists and engineers like andy aden is to design cost-effective conversion plants that can create fuel from many different types of biomass. aden: there are lots of different types of biomass. there are agricultural residues, like corn stover or wheat straw, things that are currently left in the field after the grain has been harve