J-ENG launches world’s first commercial ammonia-fueled engine, advancing zero-emission shipping, boosting Japan’s maritime industry, and targeting 2050 carbon neutrality.
Japan Engine Corporation (J-ENG) has achieved a groundbreaking milestone by completing the world’s first full-scale commercial ammonia-fueled engine on August 30, 2025. This pioneering development is part of the Next-Generation Ship Development initiative under the Green Innovation Fund Project, overseen by the New Energy and Industrial Technology Development Organization (NEDO).
The engine’s official trial runs took place at J-ENG’s manufacturing facility between August 27 and 30, under the close supervision of several leading maritime organizations, including Nippon Yusen Kaisha (NYK Line), Nihon Shipyard (NSY), Japan Marine United Corporation (JMU), and Nippon Kaiji Kyokai (ClassNK). During the tests, the engine was successfully operated in both ammonia fuel mode and heavy fuel oil mode as a dual-fuel system. Following these rigorous performance assessments and component inspections, ClassNK certified the engine’s “outstanding environmental performance and safety.”
The newly developed engine will be shipped in October 2025 and installed on an ammonia-fueled medium gas carrier currently under construction at JMU’s Ariake Shipyard. The vessel is expected to begin operations in 2026, marking a key step in the practical use of ammonia as a marine fuel.
J-ENG’s journey toward this achievement began earlier with approximately 1,000 hours of single-cylinder ammonia engine testing at Mitsubishi Heavy Industries’ R&D Center in Nagasaki between May 2023 and September 2024. Building on the data and experience from those trials, J-ENG developed the first full-scale model, the 7UEC50LSJA-HPSCR, which began ammonia-fueled tests in April 2025. Over five months, the engine underwent around 700 hours of meticulous evaluations to optimize its performance while ensuring safety standards, such as leak prevention and toxic ammonia monitoring systems.
Performance results are highly promising. At 100% load and a 95% ammonia co-firing rate, nitrous oxide (N2O) emissions were just 3 ppm, representing a more than 90% reduction in greenhouse gases. Nitrogen oxide (NOx) emissions were nearly half those of conventional heavy oil engines, and unburned ammonia emissions were virtually eliminated after applying NOx Selective Catalytic Reduction (SCR). Furthermore, thermal efficiency in ammonia mode proved equal to, or better than, that achieved with heavy oil.
Looking ahead, J-ENG is also developing a larger 60 cm bore ammonia engine to accommodate future ship designs. Alongside this, the company is investing in a new factory, supported by Japan’s Ministry of the Environment and Ministry of Land, Infrastructure, Transport and Tourism through GX Economic Transition Bonds. This facility, expected to begin operations in fiscal year 2028, will boost production capacity for ammonia-fueled engines, supporting the broader adoption of zero-emission vessels.
As a trailblazer in alternative fuel technology, J-ENG aims to contribute to the advancement of Japan’s shipping and shipbuilding sectors, while aligning with global goals to cut greenhouse gas emissions and achieve carbon neutrality by 2050.
