Abstract Driven by energy transition in the maritime industry, alternative fuels are considered one of the main energy solutions to meeting the demand forecast and achieving Greenhouse Gas (GHG) goals set by the International Maritime Organization (IMO). Zero/low-carbon fuels include methanol, ammonia, bio-fuel, hydrogen, etc. However, in contrast to traditional fuels, alternative fuels contain highly flammable (e.g., methanol) or toxic (e.g., ammonia) chemicals, posing safety concerns that need to be addressed in a structured manner. This paper presents several case studies using a fault tree analysis tool to improve the safety of zero-carbon fueled ships. INTRODUCTION Classification societies are at the frontier of setting the stage for alternative fuel propulsion systems. There is increased progress made by IMO in developing guidelines for ships using zero-carbon fuels. Design on the first ammonia internal combustion engine has been under significant development, whereas methanol engines have evolved further in the reliability journey. Safety is the driver for pursuit of the reliability journey involving new technologies, such as alternative fuels to responsibly minimize safety exposure and reduce GHG. Methanol engines have been in service for almost 10 years, and they have cleaner burning properties enabling reduced exhaust emissions such as sulfur oxides (SOx) and particulate matter (PM) and emit less nitrogen oxides (NOx) than conventional oil fuels. However, as a safety concern, in the open air, methanol burns with a flame that is nearly invisible in daylight with no smoke. Methanol as a marine fuel has been discussed in the ABS publication, Methanol bunkering: technical and operational advisory (ABS, 2024) Although ammonia is a well-established product with extensive land-based understanding and transportation history by Liquefied Petroleum Gas (LPG) carriers/cargo, its use as a marine fuel has not been demonstrated on a commercial scale. Technology providers such as engine, fuel supply system, and fuel treatment system vendors are currently working together to develop systems and equipment that can safely handle ammonia fuel. From the relevant ammonia hazards, toxicity is the most critical when compared with other conventional and alternative fuels. Ammonia as a marine fuel has been discussed in the ABS publication, Ammonia bunkering: technical and operational advisory (ABS, 2024).
Jiang et al. (Fri,) studied this question.