A project was initiated to monitor the performance of several alternative energy systems installed in the municipal waste water treatment plant in Wilton, Maine. These systems include: active and passive solar, effluent heat recovery, digester gas generation, air-to-air heat recovery, and electricity generation using digester gas. The plant has been operational since September of 1978. To accomplish the monitoring, an instrumentation system has been installed and data collected since the end of May 1979. This instrumentation system includes: solar pyronometers, hydronic Btu computers, electrical and gas meters, a weather station, and numerous temperature transmitters. Data for the solar and digester systems are available in both digital and analog forms. This report is based on data collected from June 1, 1979 to April 1, 1980 with digester gas production monitoring available during a two-week period in April. Specific data are summarized for information on solar insolation; active and passive solar systems; the effluent heat pump; the generator heat recovery system; digester gas system; and exhaust air heat recovery. The evaluation of the performance of the various energy systems in Wilton, their construction and operating costs, and evaluation of the relative cost-effectiveness of the Wilton design applied to other waste water treatment facilities of various capabilities has led to the formulation of a hypothesis whic, although not conclusively proven through this work, has much evidence to support it. That is, that solar thermal energy collection combined with anaerobic sludge digestion for the purpose of producing a net excess of digester gas be used as a fuel is not cost-effective, regardless of size or location of the facility. (ERA citation 05:037078)