Hydrogen sensor cell for detecting contaminants

A method for operating a fuel cell power plant, comprising:

• operating a fuel cell stack comprising at least one fuel cell having a fuel inlet for directing a hydrogen fuel to the fuel cell to generate electric current, and a sensor cell having an anode, a cathode and a membrane between the anode and the cathode, the anode being communicated with the fuel inlet to receive a portion of fuel from the fuel inlet, the sensor cell being connected across the stack to carry the electric current whereby hydrogen from the portion of fuel is electrochemically pumped to the cathode of the sensor cell;
• and
• monitoring a parameter corresponding to level of electrochemically pumped hydrogen from the anode to the cathode of the sensor cell to detect contaminants in the fuel cell based upon variation of the parameter.