To obtain a refrigerant lower than 0°C in temperature by reducing both running cost and initial cost.

A single-effect absorption refrigerator is operated, by utilizing the exhaust heat from the low-temperature exhaust heat source of a gas engine 1 as a heat source, while the vapor of an ammonia-water solution is generated by utilizing the exhaust gas from a high-temperature exhaust heat source and a compressor 27 connected integrally with a steam turbine 21 in an interlocking way is driven by driving the turbine 21 with the vapor. The compressor 27 makes the pressure in an evaporator 14 lower than that in an absorber 12, by sucking the vapor in the evaporator 14, and as evaporation takes place in the evaporator 14, takes out the refrigerant, which will not freeze even at -20°C, through a refrigerant taking-out pipe 34.