Solid oxide fuel cell-internal combustion engine hybrid system for ships fueled by ammonia

This paper presents a numerical exploration of the operation of a solid oxide fuel cell-internal combustion engine (SOFC-ICE) hybrid system for ships powered (partially) by ammonia. The efficiency of this hybrid system was found to be 15% higher than the SOFC stand-alone system. The study also examines the design of the hybrid system, considering both performance and spatial constraints. While the overall system efficiency showed minimal variation with changes in the fuel utilization factor (UF_fuel), it is crucial for UF_fuel to remain above 0.5 to mitigate NO_x emissions. In addition, to address the constraints imposed by the engine's storage space, we determined that the minimum SOFC size should be 0.93 when UF_fuel is set to 0.5. Importantly, this study contributes to overcoming performance challenges associated with limited space on ships during system design. We highlight the system's capability to effectively adapt to rapid load changes using the engine based on an analysis of turbocharging and the addition of extra ammonia.