Abstract
The utilisation on a large-scale basis of more sustainable solutions for the transport sector represents an essential step to comply with international standards and regulations as well as to reduce the impacts of human activities on the environment. Considering the current global emissions, the development and implementation of innovative solutions allowing for decarbonisation is particularly relevant for maritime transport. Recent studies have indicated the use of hydrogen as a promising solution from medium- and long-term perspectives. For these reasons, this work analyses possible alternative solutions suitable for large-scale ship propulsion based on hydrogen conversion. Considering the current readiness level, available know-how, and training, the use of highly reactive species such as hydrogen poses significant concerns on the safety aspects. Therefore, particular emphasis was given to the quantification of the most relevant safety aspects related to storage, fuel conditioning items, and power production systems. Quite obviously, the possible resulting scenarios are strongly affected by the selected strategy for storing hydrogen, requiring specific studies on the subject. Hence, compressed hydrogen, liquefied hydrogen, and cryo-compressed liquid hydrogen were deeply discussed in this study. For the sake of completeness, the results obtained were compared with data deriving from an existing system based on liquefied natural gas (LNG). Results showed that storage tanks represent the most safety-critical units for all the investigated alternatives evaluated in the analysis, regardless of the inherent safety metric adopted. The inherent safety footprint quantification highlighted that the adoption of emerging technologies based on cryo-compressed liquid hydrogen could improve the onboard inherent safety performance of the ship power system compared to LNG-fuelled engines.
