PURPOSE: To utilize the heat output and input accompanied with the absorption and release of hydrogen in air conditioner and the like and consequently economize oil fuel by a method wherein a plurality of sets of two vessels containing metal hydride, which is heated by the exhaust heat of an engine for release and cooled by the sea water for absorption of hydrogen, are provided therewithin.

CONSTITUTION: Firstly, when the water heated by cooling the engine 2 is sent through a solenoid valve 19 to a heat exchanger 12 by opening the valve 19, the metal hydride 8 in a metal vessel 4 is heated and releases high pressure hydrogen gas, which is led into a vessel 3 by opening the valve 28 and is absorbed by the metal hydride 7 in the vessel 3. The heat of absorption generated at this time is removed by heat-exchanging with the sea water 1 at a heat exchanger 11 and discharged outside together with the sea water 1. Secondly, when the metal hydride 8 is cooled at the heat exchanger 12 by flowing the sea water 1 in the heat exchanger 12 by closing the valves 19 and 28 and opening a valve 21, the pressure in the vessel 4 is lowered. Thirdly, after that, when the valve 28 is open again, the hydrogen gas within the metal hydride 11 is released owing to the difference between the pressure in the vessel 3 and that in the vessel 4 and transferred into the vessel 4 and cools the sea water 1 passing through the heat exchanger 11. Fourthly, when the valve 24 is closed and the valve 23 is open, the sea water is flowed through the heat exchanger 11 and cooled and led to a fan coil 15 so as to cool cabins by means of a fan 16. When the cycle of the set of the vessels 3 and 4 is completed, the set of the vessels 5 and 6 is put into operation, resulting in cooling continuously.