A fuel cell system and method for using a peak shaving gas, the system including: a fuel inlet configured to receive fuel from a fuel source; a catalytic partial oxidation (CPOx) reactor configured to at least partially oxidize the fuel during startup of the system; a blower configured to provide air to the CPOx reactor; a gas analyzer configured to determine a composition of fuel provided to the CPOx reactor from the fuel inlet; an oxidation catalyst configured to reduce an O2 content of fuel received from the CPOx reactor; a reforming catalyst configured to partially reform fuel received from the oxidation catalyst; and a stack of fuel cells configured to generate electricity using fuel received from the reforming catalyst.