Geothermal Binary Power Generation System Using Unutilized Energy

Abstract

Binary power generating system is based on the Rankine cycle with geothermal fluid as heating source and low boiling point medium as working fluid. Because of adopting the low boiling point medium as the working fluid, the system can generate electric power from low temperature (energy) source. Employing the binary power generating system for geothermal resources, it is possible to generate electric power from formerly unutilized geothermal energy, such as wasted energy in a hot spring resorts. In Japan, some experimental geothermal binary power generating plants were constructed, but no manufacturers are producing the binary system for geothermal resources as commercial basis. However, the binary power generating system has been already used for geothermal resources worldwide such as in the USA, New Zealand, Philippines and Iceland. Fuji Electric Systems Co., Ltd. has constructed and is operating experimental geothermal binary power generating plant in order to developing commercial-type plant. The design maximum output of the experimental unit is 220kW, and isopantane is used as the working medium. The experimental unit is comprised of turbine, generator, vaporizer, pre-heater, air cooled condenser, circulating pump as major equipment for main Rankine cycle, cyclone separator, hot water storage tank, hot water supply pump for heating cycle and electrical/control equipment. The experimental unit was commissioned in early August 2006, and the experimental operation is continued since then. Fuji Electric Systems Co., Ltd. will prove, confirm the design/plan of the experimental unit based on the operating data through the operation, and will supply commercial type geothermal binary power generating plant in 2008.