FUEL CELL SYSTEM AND METHOD OF OPERATING THE SYSTEM

To avoidpressure variation in a cooling water channel, extend a life of an ion exchange resin used to maintain quality of cooling water and reduce power consumption by auxiliary machinery at low cost. [0002] There is provided a polymer electrolyte fuel cell 11, a cooling water tank 12, a cooling water channel 13, a cooling water pump 14, a heat exchanger 15, a fuel-side condenser 16 and an air-side condenser 17 that cool exhaust fuel gas and exhaust oxidizer gas discharged from the fuel cell 11 to condense content water vapor, a condensed water tank 18 that stores the water condensed in the fuel-side condenser 16 and the air-side condenser 17, a water supply channel 20 having a water supply pump 19 for feeding the condensed water to the cooling water tank 12, and a water discharge channel 21 for the cooling water tank 12.