To economically perform supply of hot water and air conditioning by utilizing engine exhaust heat and soil heat.

A water circulation circuit 8 is connected with a heat exchanger 3 for recovering exhaust heat connected with a gas engine 1, and a heat exchanger 9 for supply of hot water and a heat exchanger 11 for heating constituting a heat exchanger 10 for air conditioning are provided in the water circulation circuit 8. A soil heat circulation circuit 21 is connected with a soil heat recovery device 19 for recovering soil heat, and a soil heat supply circuit 23 for air conditioning and a soil heat supply circuit 25 for auxiliary supply of hot water are connected with the soil heat circulation circuit 21. A heat exchanger 26 for cooling constituting the heat exchanger 10 for air conditioning is provided in the soil heat supply circuit 23 for air conditioning to perform heating by utilizing exhaust heat from the gas engine 1 or cooling by utilizing soil heat. A heat exchanger 31 for auxiliary supply of hot water is provided in a hot-water supply circuit 12 to utilize soil heat in auxiliary heat source for supply of hot water.