Patent ID: 7709119

Claim:
A method for operating a fuel cell including an electrolyte membrane sandwiched by a fuel electrode to which a fuel is supplied and an oxidizing agent electrode to which an oxidizing agent is supplied for generating electricity supplied to an electric power load, the method comprising: a hydrogen feedback process performed either before starting an operation of the fuel cell or after stopping the operation of the fuel cell, the hydrogen feedback process including: electrically connecting a positive electrode of an external electric power source to the oxidizing agent electrode of the fuel cell; electrically connecting a negative electrode of the external electric power source to the fuel electrode of the fuel cell; oxidizing hydrogen remaining in the oxidizing agent electrode to generate protons; reducing the protons, transferred to the fuel electrode from the oxidizing agent electrode through the electrolytic membrane, into hydrogen; and controlling, before the hydrogen feedback process, a remaining amount of hydrogen remaining in the fuel electrode side of the fuel cell, the hydrogen contained in the fuel, to be richer than an amount of oxygen remaining in the oxidizing agent electrode side of the fuel cell in terms of chemical equivalent.