ABSTRACT
As one of the promising sustainable energy generation technologies, fuel cells have gained significant research interest and recent technological developments. There are various types of fuel cells, of which, the direct carbon fuel cells offer the opportunity for direct conversion of carbonaceous fuels to electricity. In this paper, the major aspects of biomass-fueled direct carbon fuel cells (DCFCs) are comprehensively reviewed. Current DCFC technologies are categorized based on the nature of electrolyte into one of four main types, i.e., molten carbonate, molten hydroxide, solid oxide, and hybrid type with various cell arrangements. The characterization technologies for biomass/biomass char fuels are summarized, including X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and others. The information gained on fuel properties may be used to predict the electrochemical performance of DCFCs with the corresponding fuels. The performance of DCFCs fueled by various biomass chars is also summarized. Among all four types of DCFCs, SOFCs are the most widely employed. Finally, a brief summary of parameters that affect the cell performance is presented, such as the fuel property, temperature, external mechanical pressure, and stirring. The maximum power density, open circuit voltage (OCV), and current density vary within a large range depending on these parameters and the DCFC type. Although the biomass-fueled direct carbon fuel cell technology has some promise, it is still in the stages of research and development. The review concludes by identifying the main barriers to be addressed before widespread adoption of biomass-fueled DCFCs.
