Patent ID: 8293412

Claim:
A method of operating a fuel cell system, comprising: providing a water inlet stream into a solid oxide reversible fuel cell stack operating in an electrolysis mode; generating a first exhaust stream from the fuel cell stack, wherein the first exhaust stream comprises hydrogen and water vapor; separating at least a portion of the hydrogen from the first exhaust stream to form a separate separated hydrogen portion and a second exhaust stream comprising water vapor using a hydrogen pump comprising at least one exchange membrane operated at a temperature of about 100° C. to about 200° C.; and providing at least a portion of the second exhaust stream from the hydrogen pump into the water inlet stream; wherein the water vapor in the first exhaust stream is not condensed between the steps of generating the first exhaust stream and separating the at least a portion of the hydrogen from the first exhaust stream; and wherein the water vapor in the first and the second exhaust streams is maintained in a gaseous state during the steps of separating the at least a portion of hydrogen from the first exhaust stream and providing the at least a portion of the second exhaust stream.