A fuel cell power module includes a cylindrical housing encasing a fuel cell stack and an air supply. The housing has a major interior surface. The fuel cell stack can be cylindrical or hexagonal, and comprises fuel cells having an anode and an anode flow field plate, a cathode and a cathode flow field plate, and a membrane electrolyte interposed between the anode and the cathode. The air supply is directed to the plurality of fuel cell cathode flow field plates via a plenum defined by a space between the fuel cell stack and the housing major interior surface. The hexagonal fuel cell stack can be formed by a plurality of fuel cell groups shaped such that when aligned the fuel cell groups together constitute the hexagonal fuel cell stack.