Utilization Modes for Solid Carbon Conversion in Fuel Cells

The search for technological breakthroughs in carbon conversion involved various fuel cell arrangements to attain the best possible delivery mode for the solid fuel or the oxidant to the electrochemical reaction site. This paper summarizes different approaches from the mechanistic point of view of engaging the solid fuel and oxygen in order to achieve efficient oxidation of carbon. Also, the operating principle and experimental results are presented for a fluidized bed direct carbon fuel cell (FB-DCFC) integrated with a Boudouard type dry gasifier. Power densities up to 175 mW/cm(2) were demonstrated at 850 degrees C for conversion of activated carbon in this fuel cell arrangement, which corresponds to more than 4 W of sustained power generated by the FB-DCFC. A CO "shuttle" mechanism is proposed to explain the operation and behavior of FB-DCFC in CO2 as well as in inert gas environments.