Patent ID: 7629066

Claim:
A fuel cell system for generating electric energy through an electrochemical reaction between hydrogen and oxygen, the system comprising: a stack for generating electric energy and for applying the electric energy to a load; a reformer for reforming a fuel to generate the hydrogen and for supplying the hydrogen to the stack; a fuel supply unit for supplying the fuel to the reformer; an oxygen supply unit for supplying the oxygen to the stack; a first buffer unit electrically coupled to the load, the first buffer for applying an auxiliary power to the load based on an excess use corresponding to an actual energy use of the load in excess of an average energy use of the load; a second buffer unit coupled to the reformer and the stack, the second buffer unit for adjusting an amount of the hydrogen supplied from the reformer to the stack based on the excess use, the second buffer unit being in series with a single supply line for supplying the hydrogen between the reformer and the stack; and a control unit coupled to the load, to the first buffer unit and to the second buffer unit for detecting the excess use and for controlling the first buffer unit and the second buffer unit, wherein the second buffer unit is configured to retain a portion of the supplied hydrogen and to supply the retained portion in addition to the hydrogen being supplied via the single supply line to the stack based on an energy use of the stack.