Experimental and Modeling Study of Biomass Conversion in a Solid Carbon Fuel Cell

Pulverized samples of charred biomass from rice straw, wood, almond shell, and corn stover were converted within a solid carbon fuel cell (SCFC) using a yttria stabilized zirconia oxide ion conducting electrolyte. Open circuit cell potentials against air for all solid fuels tested at 900°C were in the range 1.00 to 1.07 V, in good agreement with expected values. Measurements of cell performance indicated peak power densities of 34 to 39 mW/cm2 for the biomass fuels, which compared favorably with a peak power density of 38 mW/cm2 for an activated carbon fuel used for benchmarking purposes. Comparison with previous measurements for activated carbon in our laboratory, where peak power densities in excess of 220 mW/cm2 were demonstrated in optimized cells, suggests great promise for biomass utilization in a SCFC. Further modeling of corn stover and activated carbon revealed that the lower specific surface area and bulk density of the biomass chars is offset by a higher fuel reactivity in the dry gasification environment inside the SCFC anode compartment. The modeling also defined the limits of the SCFC operating window for high effective char utilization and demonstrated that high current densities can be supported when biomass chars are employed.