When SOFC-based cogeneration systems become convenient? A cost-optimal analysis

SOFC-based cogeneration systems potentially offer high energy efficiency and reduced environmental burden, but further research is needed for successful product commercialization. This study has been performed within the framework of the EU project Comsos (Commercial-scale SOFC systems), whose aim is to validate and demonstrate fuel cell-based cogeneration systems for building applications. A Mixed Integer Linear Programming (MILP) model was developed to address the optimal design and scheduling of the SOFC-based energy system. Main techno-economic data of the SOFC modules were provided by the manufacturers and validated through the ComSos installations. The analysis was applied to non-residential applications, focusing on the supermarket sector, which is characterized by interesting features for SOFC systems, e.g., the presence of a constant electrical baseload over the whole year. The main goal of this work is to assess the influence of different parameters, including SOFC investment cost, stack lifetime and efficiency, to identify the conditions that make the SOFC technology cost-effective. The Spark Spread (SS) impact was also investigated to point out the most suitable geographical regions for the installation of SOFC cogeneration systems. The SOFC profitability was found to be highly dependent on its investment cost and the value of the spark spread. An SOFC cost of around 1.2 ke/kW is needed to make this technology profitable for SS equal to -0.05 e/kWh; while a CAPEX of around 6 ke/kW is sufficient for the SOFC to be chosen in the cost-optimal configuration when SS is 0.1 e/kWh (with stack lifetime of 5 years). Compared to the case with no SOFC, the levelized cost of electricity is reduced by 46% if the spark spread is 0.1 e/kWh and the SOFC cost is 1.2 ke/kW, which is a reasonable CAPEX for scenarios with high SOFC production volumes.