An optimum carbonaceous feedstock is determined for a syngas fueled solid oxide fuel cell (SOFC) for enhanced performance and reduced levelized cost and CO2 emissions. Four configurations are investigated: simple SOFC, and SOFC with the anode and/or cathode gas recycling. The effect of enriching the gasification medium with oxygen is also investigated. Thermodynamics, economic and environmental aspects of the systems are then comprehensively compared. Finally, multi-criteria particle swarm optimization is employed considering various anode and cathode recycling ratios, and feedstock compositions. The results indicate that optimum values of local power output, and levelized cost and emissions are observed at higher current densities and fuel utilization factors. The SOFC with anode and cathode recycling performs better in almost all conditions. The results further indicate that enriching the gasification medium with oxygen can greatly improve system performance while increasing the levelized cost of products. The optimization results show that exergy efficiency, levelized cost of products, and levelized emissions respectively are 43.7%, 47.2 $/MWh, and 0.530 t/MWh, for a syngas fueled SOFC using air, and 44.2%, 67.9 $/MWh, and 0.481 t/MWh, for a syngas fueled SOFC using O-2-enriched air. An appropriate feedstock for a syngas fueled SOFC with anode and cathode gas recycling is CH2.315O0.027 with 77.2 wt% carbon, 15.0 wt% hydrogen, and 2.8 wt% oxygen to achieve a well-balanced condition between exergetic, economic, and environmental indicators. In general, anode and cathode gas recycling and feedstock composition are observed to be influential parameters on the performance of SOFCs.
