Patent ID: 6916571

Claim:
A PEM fuel cell power plant having passive water management, comprising: a PEM fuel cell stack comprising plurality of fuel cells, each of said fuel cells having a membrane electrode assembly with a cathode on one side and an anode on the other side, the cathode and anode each comprising a porous flow field plate having reactant gas flow channels on one surface and water flow channels on a surface opposite to said one surface; at least one water outlet manifold near the top of said fuel cell stack, said water flow channels extending from near the bottom of each of said fuel cells generally upwardly to said at least one water outlet manifold, thereby allowing fuel reactant gas which leaks into paid water flow channels on said anode side to bubble-pump water in said water channels on said anode side upwardly to one said at least one water outlet manifold, and allowing oxidant reactant gas which leaks into said water flow channels on said cathode side to bubble-pump water in said water channels on said cathode side upwardly to one said at least one water outlet manifold; at least one vent connected to said at least one water outlet manifold to allow venting of fuel and oxidant gas from said fuel cell stack, whereby water management in said fuel cell stack is effected without a mechanical pump; at least one water inlet manifold disposed at the base of said fuel cell stack, said water channels extending from said at least one water inlet manifold generally upwardly to said at least one water outlet manifold; and conduits connecting said at least one water inlet manifold with said at least one water outlet manifold, whereby said water flows through said stack by natural convection.