Patent ID: 8124291

Claim:
A fuel cell system comprising: a power generating unit which generates an electric power and includes an anode, a cathode and an electrolyte membrane provided between the anode and the cathode, wherein mixture fuel having a fuel concentration is supplied to the anode, the cathode is made into contact with air, the electric power is output from between the anode and the cathode by electrochemical reaction, and unreacted fuel is discharged from the anode; a fuel circulating path which circulates the unreacted fuel from the power generating unit to the anode; a fuel supplying unit which supplies high concentration fuel having a concentration not lower than 10M to the fuel circulating path so as to add the high concentration fuel to the unreacted fuel to produce the mixture fuel, the high concentration fuel being supplied depending on a reduction of pressure of the mixture fuel; a fuel circulating unit which circulates the mixture fuel in the anode; and a control unit which controls a temperature of the power generating unit according to the fuel concentration of the mixture fuel supplied to the anode.