These are the waste streams from only one category of residues, as they exist on this planet today, anno 2006. In total they contain between a minimum 25 and maximum 176 exajoules of energy. Consider that the entire world currently consumes roughly 440 exajoules of energy (from all sources: coal, natural gas, oil, nuclear and renewables), and one understands that biomass holds great potential. Moreover, new bioconversion technologies, such as the enzymatic conversion of ligno-cellulose into sugars that can be fermented into ethanol, promise to become the most cost-effective technology for the production of liquid biofuels from these biomass residues.