RealEnergy, a California-based company that develops on-site power systems for commercial buildings, hopes to begin construction this month on a manure-to-energy project at the Rickreall Dairy. The project would convert manure to methane gas to fire electric power generators. Pacific Power would purchase the energy, enough to power 500 homes for a year. Most of $6 million financing would come from loans and energy-tax credits. Use of an on-site methane digester to dispose of the waste would control odor problems and permit the dairy to grow its herd.