Biomass (e.g., plant biomass, animal biomass, and municipal waste biomass) is processed to produce useful products, such as fuels. For example, systems can use feedstock materials, such as cellulosic and/or lignocellulosic materials, to produce ethanol and/or butanol, e.g., by fermentation....http://www.google.ca/patents/US20090286295?utm_source=gb-gplus-sharePatent US20090286295 - PROCESSING BIOMASS
