A comprehensive review of solid oxide fuel cells operating on various promising alternative fuels

Solid oxide fuel cells (SOFCs) are promising clean and efficient power generation devices. Unlike low temperature fuel cells, SOFCs could run on various alternative fuels such as hydrocarbons, alcohols, solid carbon and ammonia. Currently, several excellent reviews on SOFC developments are available in the literature but a review dedicated to alternative fuels-fed SOFCs is lacking. Herein, we comprehensively review the electrochemical performances and stabilities of SOFCs operating on various fuels. Although comparable maximum power densities to hydrogen were frequently obtained, some degradation problems induced by these fuels influence the long-term stable operation of SOFCs. Therefore, degradation mechanisms are firstly demonstrated, followed by potential strategies from three perspectives of thermodynamics, kinetics and structure to solve degradation issues. It is found that suitable operating conditions, advanced anode materials or optimized anode structures are likely to enhance the cell life span and performance. Besides, remaining challenges and future prospects of SOFCs fed by each fuel are separately elaborated for further improvements. Generally, the new engineering designs, material developments and latest knowledge presented in this review could provide useful guidance for the development and practical commercialization of SOFCs using promising alternative fuels.