Patent ID: 8129064

Claim:
A fuel cell comprising: a fuel cell stack having an anode, an electrolyte membrane, and a cathode; a fuel injection unit that injects methanol into the fuel cell stack in order for the methanol to be supplied to the anode; a methanol vapor concentration measuring apparatus including a laser unit that irradiates light into the space of the fuel cell stack where the methanol vapor is supplied, measuring units that respectively measure intensities I 0 and I 1 of the irradiated light before and after passing through the space, and a computing unit that calculates the methanol vapor concentration by substitutin the intensities I 0 and I 1 into an equation defined as I 1 /I 0 =exp (K·L·C), where K represents the absorption coefficient of methanol vapor and is 0.005335 torr −1 cm −1 , L represents the length of the space through which the laser passes, and C represents the methanol vapor concentration to be measured, the methanol vapor concentration measuring apparatus being configured to measure methanol vapor concentration in a space by irradiating a laser into the space where methanol vapor injected into the fuel cell stack is supplied to the anode; and a controller that controls the amount of methanol into the fuel cell stack according to the measured methanol vapor concentration.