FUEL CELL SYSTEM AND METHOD FOR OPERATING SAME

A fuel cell system of the present invention includes: a fuel cell (101); a cooling water passage (71) configured to allow cooling water for cooling the fuel cell (101) to flow therethrough; a cooling water tank (102) provided in the cooling water passage (71); a recovered water tank (104) configured to store water produced in the fuel cell system; a water circulating passage (72) configured to allow water circulating between the recovered water tank (104) and the cooling water tank (102) to flow therethrough; a power supply detection unit configured to detect electric power supply from a power supply utility to the fuel cell system; a temperature detector (118) provided in at least one of the cooling water passage (71), the cooling water tank (102), the recovered water tank (104), and the water circulating passage (72) and configured to detect a temperature of water; and a controller (110) configured to execute a temperature increasing process for increasing the temperature detected by the temperature detector (118) to a predetermined temperature or higher if the power supply detection unit detects a change from a state in which electric power is not supplied to a state in which the electric power is supplied.