Fuel cell system

A method of operating a fuel cell having an anode, a water-repellant cathode, a proton exchange electrolyte membrane interposed between the anode and cathode, and a separator having grooves formed in one surface thereof, said grooves extending straight continuously in completely spanning the one surface between opposing first and second ends thereof, the one surface of the separator being in contact with said cathode with said grooves open to and closed by said cathode, said method comprising:

• generating water by reaction of oxygen with hydrogen at the cathode, the water moving from the cathode to the anode;
• maintaining the electrolyte membrane in a moist condition by permeation of the generated water through the electrolyte membrane, from the cathode toward the anode;
• providing the cathode comprising PTFE embedded in carbon cloth forming one surface which is in contact with the separator and which is water-repellent and a catalyst coating forming a second surface opposite the one surface and facing the electrolyte membrane;
• supplying a gas containing hydrogen to the anode via a first gas flow passage;
• supplying a gas containing oxygen to the cathode via a second gas flow passage formed separately from from said first gas flow passage;
• and
• supplying water to one end of the second gas flow passage for contact in liquid state with the water-repellent surface of the cathode and for removing heat as latent heat, thereby cooling the fuel cell, said water-repellency preventing water deposition on the cathode which would decrease the effective surface area of the cathode.