Different Approaches for Hybridization Between Solid Oxide Fuel Cells and Internal Combustion Engines

Abstract The paper explores the hybridization of Solid Oxide Fuel Cell (SOFC) and Internal combustion Engine (ICE), It addresses design point analysis for SOFC-ICE hybrid system applications, considering the early adoption of technology. The study investigates different design cases for a 1 MW turbocharged SOFC-ICE system for marine applications in which the SOFC’s power contribution is fixed at 20% to reduce the risk and expenses associated with early technology adoption. The results show that the maximum efficiency of the SOFC-ICE system is 49.4% at 70% fuel utilization and 1.1% methane concentration at the anode inlet of SOFC. This integration provides an efficiency improvement of 5% over the standalone ICE. Moreover, the results demonstrated that the SOFC-ICE system might provide a maximum reduction in CO2 emissions of 17.6% over existing marine natural gas engines. However, the results prove the insensitivity of system efficiency to both SOFC fuel utilization and methane composition in the anode inlet. Because the system efficiency variation is no more than 1.41% or 1.1% when varying fuel utilization from 70% to 90% or varying methane concentration from 1.1% to 30.7%, respectively. Based on these findings, a SOFC-ICE hybrid system with complete external reforming and very low fuel consumption can be designed for optimal performance. Both would lengthen the SOFC stacks’ lifetime and lower SOFC design complexity and cost. These results are compared to an optimized hybrid design for stationary applications where the SOFC represented between 78% and 93% of the total system power. Intuitively, optimizing the power split in the system design at the highest fuel utilization (90%) provides higher efficiencies by 13% than fixing the SOFC power share at 20%.