Patent ID: 6977121

Claim:
A fuel cell power plant ( 10 ) for generating electrical current, the plant comprising: a. at least one fuel cell ( 12 ) having a fuel inlet ( 28 ) and a fuel exhaust ( 50 ) for directing flow of a hydrogen containing reducing fluid fuel into and out of the fuel cell ( 12 ); b. a fuel concentration sensor cell ( 54 ) for detecting concentration of the reducing fluid fuel in the fuel cell ( 12 ), the sensor cell ( 54 ) including; i. an anode flow field ( 56 ) and a cathode flow field ( 58 ) disposed on opposed sides of a membrane electrode assembly ( 60 ); ii. a power circuit ( 62 ) for selectively delivering electrical current through the membrane electrode assembly ( 60 ); iii. a detector ( 68 ) secured in electrical communication with the membrane electrode assembly ( 60 ) for detecting an electrical signal between opposed sides of the membrane electrode assembly ( 60 ); and, iv. wherein the sensor cell ( 54 ) is secured in fluid communication with the fuel exhaust ( 50 ) so that a portion of a fuel exhaust stream passes through the sensor cell ( 54 ); c. a porous sensor water transport plate ( 74 ) secured in fluid communication with the sensor cell ( 54 ) for directing a cooling fluid to pass adjacent the sensor cell ( 54 ) to remove heat and condensate water from the sensor cell ( 54 ) to maintain humidity of the membrane electrode assembly ( 60 ); and, d. a controller means ( 108 ) for controlling operation of the fuel cell ( 12 ) secured in electrical communication with the detector ( 68 ) and in communication with a fuel inlet valve means for controlling a rate of supply of the reducing fluid fuel to the fuel cell ( 12 ) in response to communication from the detector ( 68 ).