PURPOSE: To accumulate the energy of intermittently discharged waste heat without reducing the temperature as much as possible in order to effectively make use of it by feeding after pressurizing the heat accumulating thermal medium, which has been heated by the latent heat released from a heat accumulating thermal medium storage tank, into a direct contact type heat exchanger.

CONSTITUTION: The heat accumulating thermal medium 9 heated by a heat exchanger 8 is directed to a direct contact type heat exchanger 12 by a heat accumulating thermal medium pressurizing pump 11. There, the heat accumulating thermal medium 9 heats the liquid flon 13 sprayed from a flon spraying nozzle like a shower to turn it into the high-pressure flon steam 13A. The high-pressure flon steam 13A is introduced into a flon turbine 18, and its energy is taken out as electricity. The heat accumulating thermal medium 9 which has released its heat to the flon 13 preheats the flon 13 in a flon preheater 14, and then, is recovered under power through the heat accumulating thermal medium turbine 15. It then becomes low in pressure and is recirculated into a heat accumulating thermal medium storage tank 10.