Evaluation of auxiliary-power subsystems for gas-engine heat pumps. Topical report, April 1987-October 1988

The project addresses the need to determine the practical, technical, and economic viability for a stand-alone Gas Engine Heat Pump (GEHP) system capable of generating its own needed electricity. Thirty-eight reasonable design configurations were conceived, based upon small-sized power-conversion equipment either commercially available or close to market. Nine of these configurations were analyzed due to their potential for low first cost, high conversion efficiency, availability, or simplicity. It was found that electric consumption can be reduced by over 60% through the implementation of high-efficiency, brushless, permanent magnet motors as fan and pump drivers. Of the nine selected configurations employing variable-speed fans, two were found to have simple incremental payback periods of 4.2 to 16 years, depending on the U.S. city chosen for analysis. Although the auxiliary power subsystem option is only marginally attractive from an economic standpoint, the increased gas load provided to the local gas utility may be sufficient to encourage further development. In addition, the ability of such a system to operate completely disconnected from the electric power source may be another feature that has high merit in certain markets.