Abstract
This article presents an interdisciplinary analysis of hydrogen (H₂) and ammonia (NH₃) as promising alternative energy carriers for maritime transport within the framework of the International Maritime Organization’s 2050 Climate Strategy. The study aimed to determine the comparative efficiency of these fuels, taking into account their thermodynamic properties, storage requirements, operational safety, infrastructural compatibility, and economic feasibility. A multi-criteria assessment method was applied, incorporating analysis of Levelized Cost of Energy (LCOE), Energy Return on Investment (EROI), Capital Expenditures (CAPEX) and Operational Expenditures (OPEX), technical readiness of port and vessel infrastructure, environmental impacts, and potential risks. Particular attention is given to toxicological aspects, fire hazards, leakage scenarios, and crew training requirements. Data from real-world and pilot projects in Japan, Norway, and the EU are presented, illustrating practical steps towards the adoption of H₂/NH₃. The findings indicate that ammonia, despite its toxicity and the need for additional safety measures, is technologically and economically more suitable for medium- and long-distance shipping due to lower transport costs and the possibility of utilising existing liquefied gas infrastructure. Hydrogen, by contrast, offers higher environmental value owing to zero CO₂ and NOₓ emissions (when used in fuel cells), but requires advanced storage systems and substantial investment in logistics, which limits its use primarily to short-sea shipping or within closed supply chains. The findings can serve as a basis for shaping fleet decarbonisation strategies, developing safety standards, and fostering innovation in marine energy. The conclusions are of practical interest to shipowners, engineering companies, environmental regulators, and policymakers in the field of green marine fuels