Japan Engine Corporation (J-ENG) has completed its first fully-functional full-scale commercial ammonia engine 7UEC50LSJA-HPSCR on 30 August. This engine will be shipped in October and then installed on an ammonia-fuelled medium gas carrier being constructed by JMU Ariake Shipyard.
The vessel on which the engine will be installed is scheduled to enter service in 2026. It is an engine with 50 cm bore, seven cylinders and high pressure selective catalytic reduction (SCR). It was developed as a part of “Next-Generation Ship Development” of the Green Innovation Fund Project administered by the New Energy and Industrial Technology Development Organization (NEDO).
From August 27 to 30, the official engine test runs were conducted at J-ENG‘s factory 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. The engine’s environmental performance and safety were certified by ClassNK.
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From single-cylinder to full-scale engine
J-ENG previously conducted approximately 1000 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 optimising various performance aspects while concurrently confirming high reliability and safety features, including leak prevention and monitoring systems for toxic ammonia.
90% GHG emission reduction
Trial run data for this engine shows that at 100 per cent load and a 95 per cent ammonia co-firing rate, nitrous oxide (N₂O) emissions are approximately 3 ppm, achieving a reduction of over ninety per cent 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.
Also read: Everllence to develop pilot fuel-free ammonia genset
More engine types and new factory
Following from the first engine mentioned above (bore 50cm), J-ENG is also concurrently developing an ammonia-fuelled engine with 60 cm bore to address the wide variety of ammonia-fuelled ships expected to emerge in the future market, and is actually working on several promising follow-on projects.
Furthermore, J-ENG is proceeding with the construction of a new factory with support from a subsidised project jointly run by the Japanese Ministry of the Environment and the Ministry of Land, Infrastructure, Transport and Tourism using GX Economic Transition Bonds. This is 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 2028.
Picture by Japan Engine Corporation (J-ENG).
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