A Comparative Study on the Performance of Direct Carbon Solid Oxide Fuel Cells Powered with Different Rank Coals

Assessing the effect of coal characteristics on the performance of direct carbon solid oxide fuel cells (DC-SOFCs) is a prerequisite for developing DC-SOFCs powered with coal. In this study, three types of coal with different ranks were used to power DC-SOFCs and the effects of the characteristics of different coals and their subsequent pyrolysis products on the output performance of DC-SOFCs were investigated. Results indicate that the peak power density of the anthracite-powered fuel cell is the highestup to 45 mW/cm2owing to its low ash content and high H2 concentration in the pyrolysis gas. However, the low reactivity of the semicoke derived from anthracite pyrolysis resulted in the poor stability of the anthracite-powered fuel cell. The low-rank lignite exhibits a high ash content and low H2 and CO concentrations in the pyrolysis gas, resulting in a lower peak power density of the DC-SOFC powered with lignite fuel than that powered with anthracite and bituminous fuel. However, the reactivity of the semicoke from lignite pyrolysis is higher than that of the other semicokes when deashed lignite is used as fuel, and the peak power density of the DC-SOFC is the largest at 21.8 mW/cm2 and the discharge life is the longest. Based on the pyrolysis behavior of coals and the electrochemical performance of DC-SOFCs powered with different types coal, an anode zone reaction process is proposed. Considering the output power density and stability of the cell, a low-rank coal with low ash and high reactivity is a promising fuel for DC-SOFCs.