FUEL CELL SYSTEM AND METHOD FOR OPERATING SAME

A fuel cell system according to the present invention includes: a fuel cell apparatus; a heating medium circulation passage (9) through which a heating medium circulates, the heating medium exchanging heat with off gas; a first heat exchanger provided on the heating medium circulation passage (9) and configured to produce condensation water; a cooling mechanism provided on the heating medium circulation passage (9) and configured to cool down the heating medium before the heating medium is supplied to the first heat exchanger; a first temperature detector (28) configured to detect a temperature of the heating medium after the heating medium is cooled down by the cooling mechanism and before the heating medium is supplied to the first heat exchanger; and a controller (101) configured to control the cooling mechanism such that the temperature detected by the first temperature detector (28) becomes a first temperature which is set to such a temperature as to allow necessary condensation water for a reforming reaction to be produced by the first heat exchanger.