PURPOSE: To simplify the structure of the captioned system carried by a submarine or the like by storing the water produced by combustion in fuel tanks, and CO2 produced by combustion in oxygen tanks emptied of oxygen at a predetermined temperature and pressure.

CONSTITUTION: A diesel engine 25 received in a pressure shell 36 of a submarine, operating by recycling its exhaust gases, comprises tanks 2, 3 of oxygen used to support combustion and a service tank 1. The tanks 1-3 are connected to an inlet mixing chamber 37 of the engine 25 via a decompression/flow- adjustment valve 24. A fuel tank 4 with a flexible diaphragm 5 is received in the shell 36. Water produced by combustion can be received in a chamber above the diaphragm 5. CO2 produced by combustion can be stored in oxygen tanks 2 or 3 which have been emptied of oxygen used to support combustion. The storage temperature of the stored CO2 is slightly above the sea water temperature. The minimum storage pressure is 40 kg/cm2.