Patent ID: 8808934

Claim:
A method for a proton exchange membrane fuel cell power plant ( 5 ) configured to provide power output ( 57 ) (a) to a stationary load or (b) as motive power to a vehicle ( 59 ), said method characterized by: in response to an idle signal provided by the load indicating a change from substantial power being demanded ( 68 ) by the load to nearly zero power being demanded by the load— (a) disconnecting the power output ( 57 ) of the power plant from the stationary load or the vehicle ( 59 ) and connecting a predetermined fixed resistive load ( 60 ) to the power output in place of the stationary load or the vehicle, said resistive load configured to dissipate a predetermined small fraction of fuel cell stack maximum power when the stack applies a predetermined critical voltage to the resistive load, below which fuel cell corrosion is not excessive; (b) monitoring the voltage of at least one fuel cell of the power plant; (c) reducing ( 40 ) the amount of air supplied to said air inlets; and (d) recycling cathode exhaust gas ( 42 ) of fuel cells of said power plant to air inlets ( 34 ) of said fuel cells in an amount to limit the voltage of the at least one cell to less than said critical voltage.