To reduce the load imposed on a gas compressor or the like in the daytime by storing the compressed gas generated by the compressor or the like in the deep subterranean and jetting out the compressed gas in the daytime to drive a gas turbine and to separate impurities from pure water by producing ice from factory wastewater, contaminated water or the like containing impurities by using the heat discharged at the gas compressing step as a heat source as a part of the heat recycling.

This system is provided with a gas compressing part B operated by receiving excess electric power for generating the compressed gas, a compressed gas storing part A formed by :filling with heavy muddy water 101a for storing the compressed gas, a steam boiler C for generating steam by recovering the heat discharged at the gas compressing step, an ice-making means D for producing ice by freezing the taken-in water solution containing impurities by ammonia refrigeration to use the steam generated at the boiler C as a heat source. The compressed gas is used for driving the gas turbine T in the daytime.