To utilize the geothermal energy in the area of its 30,000-head cattle feedlot, J.A. Albertson Land and Cattle Co. is considering the development of an integrated geothermal/bioconversion system that would use the cattle manure as a feedstock for an anaerobic-digestion plant to produce methane plus a digester-residue cattle-feed supplement. The feedlot lies within a high-temperature gradient and heat-flow area associated with the Western Snake River basin in Malheur Co., Oregon. The three digesters designed for the process will operate mesophilically (at 98/sup 0/F) with a 20-day retention time. To make up the digesters' heat losses, the geothermal water source will need to be about 135/sup 0/F and have a flow rate of 120-240 gpm, depending on the size ultimately selected for the facility. If the digester residue replaces alfalfa hay in the cattle's current rations, its value will amount to $1.15 million/yr. Burning the methane in engine/generator sets would produce 985-1970 kW of electric power that could be either sold or used as a day-to-day substitute for the geothermal heat. An economic analysis of the system is presented; DOE/ET/27230-T2