Decarbonising maritime shipping through multi-fuel solid oxide fuel cell pathways : synergies and trade-offs between environmental and social sustainability metrics

With the maritime shipping industry being responsible for the emission of about 2.5% of global greenhouse gas (GHG) emissions, decarbonising this sector has become a key regulatory target on the European as well as global level. A solution for a more sustainable operation of maritime vessels is proposed by the Horizon Europe project FuelSOME, which pursues the central goal of reducing the GHG emissions of the shipping sector by 50% until 2050. The approach of the project is to develop a multi-fuel capable propulsion system based on Solid Oxide Fuel Cell (SOFC) technology for maritime shipping. The envisioned fuel cell-based propulsion system is to be operated on ammonia, methanol and hydrogen. Regarding these fuels, short- and long-term sustainable supply chains are explored, and their life cycle sustainability impacts are explored. In cooperation with project partners, foreground data on the life cycle of the multi-fuel energy generation system was used to perform a cradle-to-grave life cycle sustainability assessment (LCSA). With a focus on e-fuels from different electricity sources, the environmental and social impacts of a maritime vessel operated on ammonia, methanol and hydrogen were assessed, using a comprehensive set of indicators. The outcomes were compared to a reference case of a fossil-fuel powered vessel, which allows for a discussion of synergies and trade-offs. Overall, certain scenarios and processes were identified as hotspots regarding environmental as well as social impacts. The fuel production was found to be the primary contributor to a majority of environmental and social impact categories. It was further found that a vessel powered by the proposed SOFC system must be operated on hydrogen produced from hydro or wind power, to reach the overarching decarbonisation goal.