FUEL CELL SYSTEM AND ITS DRIVE METHOD

PROBLEM TO BE SOLVED: To provide a fuel cell system capable of effectively using a fuel gas, and of improving fuel cost, and to provide its drive method. SOLUTION: This fuel cell system is equipped with: a fuel cell 1 for generating power by being supplied with hydrogen gas and an oxidizer gas; a hydrogen gas supply passage 10 for supplying the hydrogen gas to the fuel gas 1; a hydrogen off-gas circulation passage 20 for returning the hydrogen off-gas discharged from the fuel cell 1 to the supply passage 10; an ejector 6 installed in the supply passage 10 for sending the hydrogen off-gas in the circulation passage 20 to the supply passage 10; a hydrogen pump 7 installed in the circulation passage 20 or on the downstream side of the ejector 6 in the supply passage 10 for increasing the pressure of the hydrogen off-gas; a pump consumption current detection sensor 27 for detecting the load stat of the hydrogen pump 7; and a discharge valve 25 for discharging the hydrogen off-gas from the circulation passage 20. COPYRIGHT: (C)2004,JPO