Gas Atmosphere Effects over the Anode Compartment of a Tubular Direct Carbon Fuel Cell Module

Abstract

The direct carbon fuel cell (DCFC) is an innovative low carbon technology option that has the potential to cause a paradigm shift in the way we generate electrical energy from coal resources. The technology is theoretically 100% efficient at extracting chemical energy of a carbon feedstock, with practically realizable cell efficiencies approaching 80% (cf. <40% in a state-of-the-art coal-fired power station). Since the reaction is the direct electrochemical generation of carbon dioxide, the flue gas has the potential to be pure, sequestration ready carbon dioxide with zero particulates with little to no flue gas treatment required. This study examines the performance of a tubular 8 mol% yttria stabilised zirconia (YSZ) cell using a thermal coal char as the fuel, lanthanum strontium manganate (LSM) as the cathode material and a ternary alkali metal carbonate eutectic as the secondary electrolyte over the temperature range 700-900°C. The performance was compared when varying the gas atmosphere over the anode compartment between CO2 and N2 in separate experiments. It was found that the power density was two-fold as high under CO2 at 860°C. The reason for this is attributed to agitation provided to the fuel from reverse Bouduard gasification. This result implies that the anode performance is limited by mass transport of the carbon fuel to the silver current collector.