Abstract

The rapid adoption of alternative marine fuels has introduced safety challenges not fully addressed by regulatory frameworks developed for conventional fuels. This study examines how International Maritime Organization (IMO) safety regulations respond to the dominant risk characteristics of alternative fuels, focusing on LNG, LPG, methanol, and ammonia. A comparative analysis is conducted based on physicochemical properties, hazard pathways, and corresponding provisions under the IGF Code and Interim Guidelines. The results show that while the IGF Code provides a goal-based, flammability-centered framework, its extension to fuels with different risk profiles—such as toxicity and liquid-phase hazards—creates structural mismatches between dominant hazards and regulatory trigger mechanisms. In particular, reliance on flammability-based indicators (e.g., LEL) for safety system activation in toxicity-dominant fuels reveals a misalignment between regulatory assumptions and actual risk pathways. In addition, intensified conservatism in ammonia regulations enhances safety but raises challenges related to operability and regulatory predictability. The study concludes that future regulatory development should adopt an integrated framework aligning hazard-specific indicators with regulatory mechanisms and incorporating empirical evidence through the Experience Building Phase (EBP).

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