an indirectly-fired biomass fueled furnace was evaluated to determine the feasibility of drying grain using crop residues as a fuel source. the furnace efficiency and total heat delivery were determined. funds for this project were provided by the department of energy through an appropriate technology grant. stalks and residue were harvested in large round bales using conventional hay-handling equipment available on most farms. calorimeter tests were made to determine the heat content available in various residues prior to combustion in the stormor bio mass heat system. this allowed total efficiency measurements by comparing total heat available and total heat delivered to the grain dryer. for example, a bale of cotton stalks returned over 60 percent of the useable heat for an efficiency of 63.7 percent. other residues such as corn stalks gave slightly lower efficiency but clearly showed that adequate heat could be obtained to dry grain using heated air and no petroleum fuels. the air from the furnace went through an air-to-air heat exchanger to prevent contamination of the grain from smoke and combustion by-products. although reducing efficiency somewhat, the heat exchanger allows grain or other materials such as peanuts to be dried for human consumption. some evidence of overheating of the firebox doors was observed which led to some warping of the doors. this warping subsequently made temperature control more difficult, since the air supply and burn rate are directly related. air temperatures of up to 160 exp 0 f were measured. the results show that biomass combustion as