In this study, carbon dioxide content of pipeline gas supplied to an on-site fuel cell power plant in the Greater Taipei area is higher than that specified by the manufacturer. This lowers the heating value of the fuel input and thus affects the start-up operation, the energy-conversion efficiency of the power plant, and the transient response to a stepped increase in output power. This paper reports the operation characteristics of the fuel cell power plant under these conditions. It is found that the local gas can be used to operate the fuel cell, but at a reduced net output power.