The world's first complete commercial ammonia fueled engine has been accomplished

Japan Engine Corporation (J-ENG) accomplished the first fully-functional full-scale commercial engine 7UEC50LSJA-HPSCR (50 cm bore, 7 cylinders, with High Press. SCR) on August 30, 2025. which has been developed as a part of “Next-Generation Ship Development” of Green Innovation Fund Project administered by New Energy and Industrial Technology Development Organization (NEDO).

From August 27 to 30, 2025 at J-ENG's factory, the engine official test runs were conducted under the supervision of Nippon Yusen Kaisya (NYK Line), Nihon Shipyard Co,, Ltd. (NSY), Japan Marine United Corporation(JMU) and Nippon Kaiji Kyokai (ClassNK). A series of performance verification tests in both ammonia fuel operation mode and heavy fuel oil operation mode as a dual-fuel engine, as well as post-operation inspections of major components, were successfully completed, and the engine's outstanding environmental performance and safety were certified by ClassNK.

This engine will be shipped in October 2025 and then installed on an AFMGC (Ammonia-Fueled Medium Gas Carrier) being constructed by JMU Ariake Shipyard. The vessel is scheduled to enter service in 2026.

J-ENG previously conducted approximately 1,000 hours of test runs on a single-cylinder ammonia-fuel test engine at the Mitsubishi Heavy Industries Research & Development Center at Nagasaki between May 2023 and September 2024. Using the results and insights gained from the test, J-ENG manufactured the first full-scale commercial engine 7UEC50LSJA-HPSCR and began test runs on ammonia fuel in April 2025.

Subsequently, over five months, the engine underwent meticulous testing in total 700 hours. This period focused on optimizing various performance aspects while concurrently confirming high reliability and safety features, including leak prevention and monitoring systems for toxic ammonia. The engine was thus completed, equipped with sufficient functionality to ensure the safe operation of actual vessels and the safety of crew members.

J-ENG is extremely pleased and proud to be able to deliver to customers ahead of the rest of the world this safe and reliable engine, the result of a meticulously planned, long-term development program that accumulated extensive operational data over an extended period.

Trial run data for this engine shows that at 100% load and a 95% ammonia co-firing rate, nitrous oxide (N₂O) emissions are approximately 3ppm, achieving a reduction of over 90% in greenhouse gas (GHG) emissions. Nitrogen oxide (NOx) emissions were confirmed to be approximately half those of heavy oil engines, with unburned ammonia emissions virtually zero (post-NOx SCR). It has also been confirmed that the thermal efficiency in ammonia fuel operation mode is equivalent to or higher than that in heavy oil operation mode.

Following from the first engine mentioned above (bore 50cm), J-ENG is also concurrently developing an ammonia-fueled engine with 60cm bore to address the wide variety of ammonia-fueled ships expected to emerge in the future market, and is actually working on several promising follow-on projects.

Furthermore, after achieving the development and social implementation of these engines, JENG is proceeding with the construction of a new factory with support from a subsidized project jointly run by the Ministry of the Environment and the Ministry of Land, Infrastructure, Transport and Tourism using GX Economic Transition Bonds in order to expand the production volume of ammonia fuel engines in a product mix with heavy oil engines and further promote the spread of zero-emission ships. The new factory is scheduled to commence operations in fiscal year 2028.

As a first mover in next-generation fuel engines, J-ENG will contribute to the development of Japan's shipping and shipbuilding industries by promoting the early market introduction and widespread adoption of those engines, while also contributing to the reduction of GHG(greenhouse gas) emissions in the shipping industry and the realization of carbon neutrality by 2050.