Life cycle analysis of ammonia fuelled ship – case ship studies for marine vessels

In response to the International Maritime Organization's (IMO) strategy to achieve net zero greenhouse gas emissions from international shipping by around 2050, alternative fuels present a viable option and it is critical to assess the environmental performance of alternative marine fuels. Since ammonia stands out as a strong contender due to its zero-carbon content, this paper employs a life cycle analysis (LCA) methodology to assess the environmental impacts of ammonia as a marine fuel, assessing its contributing potential on global warming, acidification, eutrophication, and photochemical ozone creation. A case study of a multi-purpose dry-cargo heavy lift vessel is analysed, focusing on two key aspects: ammonia fuel and fuel containment tanks, covering production, transport, storage, bunkering, usage, and recycling. The findings highlight the advantages of various ammonia fuels from different production processes in minimizing environmental impacts across its life cycle compared to traditional fossil fuels. The results indicate that unlike blue and green ammonia, the brown ammonia–produced from fossil fuels without carbon emission reduction techniques–results in higher life cycle emission release than the traditional marine fuels. Additionally, the study extends the LCA to various ship types to showcase ammonia's benefits as a marine fuel and the potential that is associated with. Recommendations are provided for the marine industry on integrating LCA into alternative fuel evaluations, promoting a comprehensive understanding of their environmental impacts. • A comparative life cycle assessment (LCA) of ammonia-powered marine vessels, evaluating GWP, AP, EP, and POCP against conventional fuels (HFO/MDO). •LCA considers the well-to-wake emissions of various type of ammonia (brown, blue and green), with normalised datasets for robust cross-fuel comparisons. •Brown ammonia has increased life cycle emissions compared to HFO, underscoring risks of non-decarbonized production, while blue and green ammonia reduces GWP validating its role as a sustainable marine fuel. •Tank sizing is different among various ships and a tank-only LCA study illustrates the life cycle emission of the tank from cradle to grave. •Uncertainty treatment reveals the confidence level of data collect and the LCA study based on experts' judgement.