Hybrid Methodology for Alternative Fuels Risk Assessment

Abstract

[Abstract] The transition towards alternative marine fuels introduces new safety challenges related to onboard storage, distribution, and fuel management, due to the markedly different physical and chemical properties of methane, methanol, ammonia, and hydrogen. While numerous studies address the risks of individual fuels, there is a lack of structured and comparable risk-assessment methodologies to support early-stage fuel selection and preliminary system design under a unified framework. This study introduces the Methodology to Alternative-fuels Hazardous Identification, a hybrid framework that integrates HAZOP-based deviation analysis with HAZID-style risk classification to enable a consistent qualitative–quantitative comparison of alternative marine fuel systems. The methodology is applied to representative storage and distribution architectures for methane, methanol, ammonia, compressed hydrogen, and liquefied hydrogen, allowing the identification of dominant risk drivers and system-level vulnerabilities across fuel options. The results reveal distinct fuel-specific risk profiles. Methane and methanol are mainly associated with moderate risks linked to operational temperature deviations and system controllability. Ammonia exhibits the most severe risk profile due to the high consequences of toxic releases, particularly under pressure-related failures. Compressed hydrogen is dominated by high-risk scenarios driven by extreme storage pressures, while liquefied hydrogen presents a mixed profile governed by the interaction between cryogenic temperature control and pressure regulation. By providing a comparative and scalable risk-assessment framework, the Methodology to Alternative-fuels Hazardous Identification (MAHI) supports informed decision-making in early design phases and complements existing regulatory safety analyses, contributing to a safer energy transition in maritime transport.