(EP859421-A1)      A fuel cell system has anode and cathode chambers (2,3) that are separated by a proton-conducting membrane (PEM). A pipeline (6) feeds acid-containing gas to the cathode chamber and another one (5) feeds a liquid fuel/coolant mixture to the anode chamber. There is a return pipeline between the anode chamber and the anode pipe, plus a cathode exhaust gas pipeline. The coolant is water.    The liquid fuel is an electrochemically oxidisable substance with the general structure H-[CH2O]n-Y with 1n5 and Y=H or CH3. In the return pipeline is located a gas separator (18) and in the cathode exhaust pipeline is located an exhaust catalyser (34). Between these two, a pipeline is provided through which the gas separated is fed into the exhaust pipeline upstream of the catalyser.    ADVANTAGE -   Compact design with improved overall efficiency.    (DE19701560-C2)      A fuel cell system has anode and cathode chambers (2,3) that are separated by a proton-conducting membrane (PEM). A pipeline (6) feeds acid-containing gas to the cathode chamber and another one (5) feeds a liquid fuel/coolant mixture to the anode chamber. There is a return pipeline between the anode chamber and the anode pipe, plus a cathode exhaust gas pipeline. The coolant is water.    The liquid fuel is an electrochemically oxidisable substance with the general structure H-[CH2O]n-Y with 1n5 and Y=H or CH3. In the return pipeline is located a gas separator (18) and in the cathode exhaust pipeline is located an exhaust catalyser (34). Between these two, a pipeline is provided through which the gas separated is fed into the exhaust pipeline upstream of the catalyser.    ADVANTAGE -   Compact design with improved overall efficiency.    (US5981096-A)      A fuel cell system has anode and cathode chambers (2,3) that are separated by a proton-conducting membrane (PEM). A pipeline (6) feeds acid-containing gas to the cathode chamber and another one (5) feeds a liquid fuel/coolant mixture to the anode chamber. There is a return pipeline between the anode chamber and the anode pipe, plus a cathode exhaust gas pipeline. The coolant is water.    The liquid fuel is an electrochemically oxidisable substance with the general structure H-[CH2O]n-Y with 1n5 and Y=H or CH3. In the return pipeline is located a gas separator (18) and in the cathode exhaust pipeline is located an exhaust catalyser (34). Between these two, a pipeline is provided through which the gas separated is fed into the exhaust pipeline upstream of the catalyser.    ADVANTAGE -   Compact design with improved overall efficiency.