Cellulosic biofuel can be made from almost any plant matter
While corn is perhaps the most familiar source of ethanol to Americans, ethanol — and other potential transportation fuels — can also be made from cellulose, hemicellulose and lignin. These are the components of stems and other non-food parts of any plant.
Technology has been available since the 1930s for converting cellulose into ethanol, but with low efficiency and high cost. Given recent concerns about energy security and also about greenhouse gases that come from burning fossil fuels, there are currently extensive efforts under way to develop cost-competitive technology for converting all three substances into liquid fuels. The term "cellulosic biofuel" has come to be used to mean any such fuels. Ethanol is just one of them, but it is probably the most familiar.
Cellulosic biofuels are at least in part renewable, and the production of cellulosic biofuel is expected to require less input of fossil fuels than corn ethanol does. Cellulosic biofuels can be made from grasses or trees grown specifically for energy, but one advantage is that they can also be made from what is ordinarily considered waste. Potential source materials include crop residues (such as corn cobs and stalks, or wheat straw); residues from forestry operations (waste from sawmills, or brush and small trees removed to reduce the risk of forest fires); grass clippings or other yard wastes; and the organic parts of municipal solid waste. Using waste would mean no need to clear or farm new land, an activity that can lead to substantial carbon emissions.