Comparative multi-criteria assessment of electro-fuel-based marine power systems for container ships

The decarbonization of deep-sea shipping requires alternative marine power systems capable of reducing greenhouse gas (GHG) emissions while maintaining economic viability and ensuring compliance with evolving IMO regulations. This study presents an integrated assessment of electro-fuel-based retrofit power systems for a deep-sea container ship, combining high-fidelity dynamic energy modelling, life-cycle environmental assessment, techno-economic analysis, IMO regulatory compliance assessment, multi-criteria decision analysis, and uncertainty quantification. Six retrofit configurations, comprising e-ammonia, e-methanol, and e-liquid hydrogen in dual-fuel engine and proton exchange membrane fuel cell (PEMFC) systems, are evaluated against a conventional diesel baseline using a real operational profile. Dynamic energy analysis reveals that ammonia cracking and methanol steam reforming reduce PEMFC efficiency by 3–9 % relative to direct hydrogen operation, substantially reducing the efficiency advantage of hydrogen-carrier fuels. The hydrogen PEMFC system achieves the lowest energy consumption, with a 16.3 % reduction and an 88.4 % lifecycle GHG reduction, while attaining the lowest greenhouse gas fuel intensity (GFI) of 9.99 gCO 2 eq/MJ. The ammonia dual-fuel engine provides the most cost-effective retrofit, with a marginal abatement cost of 254 $/tCO 2 eq and the lowest regulatory-adjusted total annual cost under uncertainty analysis. All retrofit configurations comply with adopted IMO GFI targets through 2040, whereas only hydrogen-based systems approach the projected 2050 net-zero trajectory. The results demonstrate that no single retrofit pathway is universally optimal: hydrogen PEMFC systems maximize environmental and long-term regulatory performance, ammonia dual-fuel engines currently provide the most economically attractive transition pathway, and methanol-based systems providing an intermediate compromise between these objectives.