"... Cellulosic ethanol and conventional, grain-based ethanol have identical molecules, but they differ in that conventional fuel ethanol is derived from only a small fraction of biomass feedstock, the edible parts of corn or other feed grains, while cellulose ethanol is made from the non-food portion of renewable feedstocks such as cereal straws and corn stover (leaves and stems) or dedicated energy crops. While the refining process for cellulosic ethanol is more complex than that of corn-based ethanol, cellulosic ethanol yields a greater net energy benefit and results in much lower greenhouse gas emissions...
The general consensus is that cellulosic ethanol technology is within 5 to 10 years of being fully commercialized... "