Patent ID: 7601451

Claim:
A fuel cell assembly comprising: a plurality of fuel cells arranged in a stacked configuration; an anode reactant flow path including a plurality of anode reactant flow fields through which an anode reactant flows; a cathode reactant flow path including a plurality of cathode reactant flow fields through which a cathode reactant flows; and at least one blocking device including at least one blocking member that communicates with and is operable to selectively block flow through a portion of at least one of said flow fields in said anode reactant flow path, said cathode reactant flow path, or both, wherein blocking of said flow is operable to vary an active area of at least one of said fuel cells, said blocking member rotates to selectively block flow, and the rotating blocking member directly engages with at least one of a flow channel of a flow field and an edge of a fuel cell plate.