Japan Engine Corporation (J-ENG) has successfully completed the development of the world's first full-scale commercial ammonia-fueled engine, marking a significant advancement in the maritime industry's decarbonization efforts. The seven-cylinder, 50 cm bore 7UEC50LSJA-HPSCR engine underwent rigorous testing at J-ENG's Akashi factory from August 27 to August 30, 2025. Key industry stakeholders, including Nippon Yusen Kaisha (NYK Line), Nihon Shipyard (NSY), Japan Marine United Corporation (JMU), and the classification society ClassNK, observed the crucial trials. ClassNK certified the engine's environmental performance and safety standards.
The dual-fuel engine is designed to operate on both ammonia and heavy fuel oil. During its testing phase, it demonstrated an impressive 95% ammonia co-firing rate, resulting in a greenhouse gas emissions reduction exceeding 90% compared to conventional engines. The engine also achieved significantly lower nitrous oxide (N2O) and nitrogen oxide (NOx) emissions, with unburned ammonia emissions being virtually eliminated after the implementation of selective catalytic reduction (SCR) system. The thermal efficiency of the engine in ammonia mode was found to be equivalent to or exceeding that when operating on heavy fuel oil. This development aligns with the International Maritime Organization's (IMO) target of achieving net-zero greenhouse gas emissions by 2050. The full-scale engine underwent an additional 700 hours of testing aimed at optimizing performance, preventing leaks, and ensuring crew safety.
The engine is scheduled for delivery in October 2025 and will be installed on a medium-sized bulk carrier currently under construction at JMU's Ariake Shipyard. This vessel is projected to enter service in 2026. The successful development builds upon extensive research, including approximately 1,000 hours of single-cylinder testing conducted between May 2023 and September 2024 at Mitsubishi Heavy Industries' R&D Center in Nagasaki.
While ammonia presents a promising solution for decarbonization, challenges remain, including its toxicity and corrosive nature, which necessitate specialized handling systems and comprehensive crew training. According to forecasts, by 2050, ammonia could account for 25% to 44% of the final energy consumption in global shipping, with other low-carbon fuels such as biofuels and hydrogen also playing their role. Additionally, ammonia has a lower energy density than traditional fuels, requiring larger storage capacity and potentially impacting vessel range. Other challenges include the need for specialized infrastructure for storage and refueling, as well as the higher cost of "green" ammonia compared to traditional fuels. The environmental impact of potential ammonia spills on marine ecosystems is also an area of ongoing research.
Japan Engine Corporation is also developing a larger, 60 cm bore ammonia-fueled engine and is investing in a new manufacturing facility expected to start operation in 2028 to increase production capacity, signaling a strong commitment to scaling up this technology. The global maritime industry is actively exploring ammonia, with numerous projects in development worldwide, underscoring the collective drive towards a more sustainable future for shipping.