To provide economical electric power, to generate clean electric power not emitting CO2, and to stably supply electric power.

Two heat sources of sunlight and geothermal heat (hot spring) are used for two heat exchangers as electric power sources. A working fluid (water or mixture of water and ammonia) is heated, a turbine is rotated by the release of the pressure of the heated working fluid, and the rotation of the turbine is converted to electricity by a generator. An exhaust working fluid after power generation is cooled by an ice heat exchanger and re-circulated to the heating. Electricity can be generated economically since electric power sources are free of charge, a plant can contribute to the prevention of global warming since the emission of CO2 is zero, and electric power can be stably supplied since geothermal heat (hot spring) is used.