Ammonia-based Solid Oxide Fuel Cell for zero emission maritime power: a case study

Implementing environmentally friendly fuels and high efficiency propulsion technologies to replace the Internal Combustion Engine (ICE) fueled by fossil fuels such as Heavy Fuel Oil (HFO) and Marine Gas Oil (MGO) on board ships represents an attractive solution for maritime power. In this context, fuel cells can play a crucial role, thanks to their high energy efficiency and ultra-low to zero criteria pollutant emissions and environmental impact. This paper performs the technical feasibility analysis for replacing the conventional diesel engine powertrain on board a commercial vessel with an innovative system consisting of ammonia-fuel-based Solid Oxide Fuel Cell (SOFC) technology. Taking into account the size of the diesel engines installed on board and the typical cruise performed by the commercial vessel, the ammonia consumption, as well as the optimal size of the innovative propulsion system have been assessed. In particular, the SOFC powertrain is sized at the same maximum power output as the main reference diesel engine. The mass and energy balances of the ammonia-based SOFC system have been performed in Aspen PlusTM environment. The gravimetric (kWh kg-1) and volumetric (kWh m-3) energy density features of the ammonia storage technology as well as the weight and volume of the proposed propulsion system are evaluated for verifying the compliance with the ship's weight and space requirements. Results highlight that the proposed propulsion system involves an increase in weight both in the engine room and in the fuel room compared to the diesel engine and fuel. In particular, a cargo reduction of about 2.88% is necessary to fit the ammonia-based SOFC system compared to the space available in the reference diesel-fueled ship.