Patent ID: 7651800

Claim:
A method, comprising reforming a hydrocarbon base fuel into a reformed gas containing hydrogen, said reforming being performed by a reformer comprising a precious metal base reforming catalyst, transforming carbon monoxide, removing carbon monoxide, generating electricity from hydrogen contained in the reformed gas, said generating being performed by a fuel cell, and burning a first gas containing hydrogen gas and discharged from the fuel cell and supplying said reformer with heat necessary for reforming reaction, said burning being performed by a burner for the reformer, wherein: adjusting or setting a reforming temperature of the reformer within the range of 550-640° C., a steam to carbon ratio (S/C) so as to satisfy 2.5≦S/C≦3.0 such that said first gas containing hydrogen gas and discharged from the fuel cell contains a methane concentration of 7 to 33% in volume, and stopping supplying the burner with the hydrocarbon base fuel while said first gas containing the methane concentration of 7 to 33% in volume is burning by the burner.