Carbon-Free Hydrogen Production in a Steam-Carbon Electrochemical Cell

This study describes a novel electrochemical approach for the simultaneous and spontaneous production of carbon-free hydrogen and electricity. Hydrogen was generated from steam at the cathode of a yttria stabilized zirconia electrolyte by utilizing a solid carbonaceous fuel at the cell anode to maintain low oxygen activity levels within the anode chamber. The results verified that a steam-carbon cell is capable of producing carbon-free hydrogen in a fuel cell mode while generating electric power at the same time. The open circuit voltages of the cells agreed with expected values. The current-voltage behavior indicated that cell performance was governed mostly by resistive losses. A gas transport model of the solid carbon bed based on known Boudouard kinetics was developed and analyzed. The model demonstrates that the fuel bed is capable of supporting a cell current density in excess of 700 mA/cm(2) while maintaining a fuel utilization rate of over 85%.