Patent ID: 8530103

Claim:
A fuel cell system, comprising: a power generation stack comprising a plurality of fuel cells; a hydrocarbon-oxidizing device disposed on an upstream side of the power generation stack in a fuel supply passage, and comprising an assembly, in which a fuel electrode is provided on one surface of an electrolyte, and an air electrode is provided on the other surface thereof, wherein the fuel electrode of the hydrocarbon-oxidizing device directly and electrochemically oxidizes hydrocarbons with a carbon number of 2 or more, which are contained in fuel gas, or decomposes the hydrocarbons and electrochemically oxidizes carbon obtained by decomposing the hydrocarbons; a gas concentration measurement instrument provided on an outlet side of the hydrocarbon-oxidizing device, the gas concentration measurement instrument configured to measure a concentration of the hydrocarbons with the carbon number of 2 or more, which are contained in the fuel gas supplied to the power generation stack; and a current controller programmed to increase a value of a current flow to the assembly in order to increase oxygen ions from the air electrode to the fuel electrode, wherein when the concentration of the hydrocarbons with the carbon number of 2 or more measured by the gas concentration measurement instrument is larger than a predetermined value, the current controller increases the value of the current flown to the assembly.