A framework for the replacement analysis of a hydrogen-based polymer electrolyte membrane fuel cell technology on board ships: A step towards decarbonization in the maritime sector

Maritime transport is one of the largest greenhouse gas emitting sectors of the global economy, responsible for around 1 GtCO2eq every year. To comply with the reduction of carbon dioxide emissions, the research is devoted introducing low and zero-carbon fuels and innovative propulsion technologies. In this context, hydrogen fuel cell powertrains can play a crucial role due to their high energy and environmental performances. In this paper, a techno-economic feasibility analysis for replacing an 8.3 MW diesel engine with a polymer electrolyte membrane fuel cell system is performed for a chemical tanker ship. For this purpose, a detailed method, that aims to estimate the volume and mass of the fuel cell system as well as of the hydrogen storage technologies, is developed. Three on board hydrogen storage technologies are considered: i) compressed hydrogen, ii) liquid hydrogen, iii) metal hydrides. Results highlight that the fuel cell-based powertrain is characterized by 60% less volume and 56% less mass compared to the diesel engine. As far as the hydrogen storage technologies are concerned, all solutions present significantly lower volumetric and gravimetric energy densities and therefore, additional volume and mass are required in comparison with diesel fuel configuration. These results involve a reduction of the total cargo capacity to comply with tanker ship physical constraints. The cargo should be reduced by 1.3%1.1% for compressed hydrogen (at 350 bar and 700 bar, respectively), 0.1% for liquid hydrogen, and 9% for metal hydrides. Finally, the economic assessment in terms of Operational Expenditures, based upon the predicted hydrogen price reduction as well as the diesel price increase, in different cost scenarios (2020-2050), are evaluated. Results show that the competitiveness of the hydrogen solution with a retail price of 4 $/kg can be achieved by considering an incentive for the avoided CO2 equal to 112 $/tons