To feed inexpensive peak saving power by effectively utilizing cold of LNG for town gas thoroughly.

In peak-off hours of power demand, cold of the liquid air stored in a cold and heat accumulation device of LNG for producing town gas, and liquid air produced using a low additional value power are stored, and evaporated natural gas is supplied to a town-gas conduit as town gas. In peak hours of demanding power, the stored liquid air is compressed by a pump through the heat accumulation device, so that cold heats of the liquid air is stored in the heat accumulating device, and the power generated by supplying the compression air obtained by evaporation to a combined cycle generator is supplied to a power line.