This report from the Office of Technology Assessment (OTA) explores the energy potential and policy implications of biomass during the next 20 years and assesses the technology and the economic, environmental, and social impacts of bioenergy development. Biomass-wood and other plant materials-is a renewable source of gaseous, liquid, and solid fuels that has the potential to meet a significant portion of U.S. and world energy demands. This report considers combinations of possible biomass sources as well as bioconversion technologies and applications. Four biomass processes are described in detail: combustion and gasification of wood, anaerobic digestion of animal manure, conversion of crop residue, and production of gasohol. Those biomass combinations with the greatest potential for contributing to future energy supplies are identified, and policies to reduce or eliminate barriers to their commercialization are evaluated.