PURPOSE: To generate power by a method wherein power is fed to an electric motor/generator during power being surplus in the night time, a compressor/ turbine is driven as a compressor, compressed air is stored in a compressed air tank, and during power shortage in the daytime, compressed air is fed from the compressed air tank to the compressor/turbine, and the electric motor/ generator is driven as a generator.

CONSTITUTION: A compressor/turbine 1 and an electric motor/generator 2 are arranged on one shaft. A compressed air tank 3 is communicated with the compressed air suction/exhaust hole of the compressor/turbine 1. During power being surplus at night, power is fed to the electric motor/generator 2, the compressor/turbine 1 is driven as a compressor, and compressed air is stored in the compressed air tank 3.