Techno-economic evaluation of biogas-fed SOFC systems with novel biogas purification and carbon capture technologies

Small-scale biogas-fed solid oxide fuel cell (SOFC) systems, integrated with carbon capture storage (CCS) technologies, offer a sustainable solution for European farms’ heat and power demands with minimal carbon emissions. This study investigates different system configurations ranging from 20 to 200 kW, incorporating heat integration, fuel recirculation, biogas purification and CCS. Two scenarios are evaluated: an SOFC subsystem (1) with cryogenic biogas purification and a sodium carbonate loop for CCS, and (2) with dual sodium carbonate loops for biogas purification and CCS. Key performance metrics, such as system efficiency and levelized cost of electricity (LCOE), were assessed. At 60% recirculation ratio, 650 °C reforming temperature, and 85% fuel utilization, SOFC system electrical achieved the highest efficiency of 65%, with overall system efficiency of 53.6% (first configuration) and 57.4% (second configuration). Scaling effect reduced the LCOE of the first scenario from 0.165 €/kWh (20 kW) to 0.123 (200 kW), and the second scenario from 0.150 €/kWh (20 kW) to 0.116 €/kWh (200 kW). The cost breakdown reveals a significant investment cost from stack replacements. The study suggests that the optimized small-scale biogas-fed SOFC systems with CCS are viable for decentralized heat and power generation.