Fuel processing device, fuel cell system having the same, and method of driving thereof

A fuel cell system, comprising:

• a stack that generates electrical energy through a reaction between hydrogen and oxygen;
• a fuel processing device that is connected to the stack to generate hydrogen from fuel and supplies the hydrogen to the stack;
• a fuel supply unit that supplies the fuel to the fuel processing device;
• and
• an air supply unit that supplies air to the stack and the fuel processing unit,
• wherein the fuel processing device comprises a first reformer that generates byproducts along with hydrogen through an electrolysis reaction of the fuel using the electrical energy and a second reformer that generates hydrogen through a reformation reaction of the fuel using thermal energy.

A method for driving a fuel cell system, that comprises a stack that generates electrical energy through a reaction between hydrogen and oxygen, the method comprising:

• supplying fuel to a first reformer a and second reformer to start up the fuel cell system;
• allowing the first reformer to generate the hydrogen and to supply the generated hydrogen to the stack;
• and
• allowing the second reformer to generate the hydrogen and to supply the generated hydrogen to the stack.