Fuel cell system and a method of generating electricity

An integrated fuel cell stack and catalytic combustor apparatus includes a fuel cell stack assembly having multiple fuel cell stacks between which is defined a cavity, each of said fuel cell stacks including a plurality of individual fuel cells; and a catalytic combustor disposed at least partially within the cavity, the catalytic combustor having a catalytic bed and a catalytic igniter. Also disclosed are a method of producing electricity including catalytically combusting surplus reactants of the reaction of an oxidant and a fuel across fuel cell stacks within a catalytic combustor disposed between the stacks to normalize the temperature profile along the fuel cell stacks, and a fuel cell system including means for normalizing a temperature profile along a length of a means for conducting an electrochemical reaction using an opposite heat generation temperature profile.