Application of parametric trend life cycle assessment for investigating the carbon footprint of ammonia as marine fuel

Abstract Purpose This study aimed to determine whether ammonia can genuinely help to reduce the carbon footprint of maritime activities. Given this, it was decided to investigate the life cycle of ammonia and its impact on the environment regarding the global warming potential. Methods To achieve this goal, the parametric trend life cycle assessment was applied to yield a general and reliable observation. The research was combined with a comprehensive dataset of over 2061 bulk carriers and eight different ammonia production methods: steam methane reforming, photovoltaics, electrolysis via wind, biomass downdraft gasifier, biomass circulating fluidized bed gasifier (CFBG) system, underground coal gasification (UCG) with carbon capture and storage (CCS), UCG without CCS, and 3-step Cu-Cl cycle. In addition, an existing ME-LGI (ME-liquid gas injection) engine was selected as the propulsion system. Results The results from PT-LCA revealed that for estimating the carbon impact of ammonia as marine fuel from a well-to-wake (WTW) perspective, it is mandatory to focus on the well-to-tank (WTT) phase. The lowest carbon production pathway for the global warming potential (GWP) is the 3-step Cu-Cl cycle and eventually is the most potential route for using ammonia as fuel in the maritime industry. Finally, this study concludes with some formulas, based on regression analysis, which serves as rapid indications for comparing the overall carbon impact of thousands of bulk carriers equipped with the ME-LGI engine, carrying ammonia as fuel from different production methods. Conclusions Given these fuel production routes, the research has also demonstrated that ME-LGI engines can be a groundbreaking way to reduce the carbon footprint of ships. Additionally, the research findings showed that the environmental indicators proposed in this article have the potential to make a significant contribution to the industry. They are anticipated to assist stakeholders in overcoming the discrepancy problem generated by past studies that were so dissimilar from case to case that the scope, boundary of analysis, data, and assumptions they employed were far from current standards and rules. In addition, the GWP according to the ship power was compared and reviewed in terms of the well-to-wake (WTW). Thus, the proposed methodology for developing ammonia ship environmental indicators is to provide valuable insight into environmental policy and decision-making processes.