Japan Engine Corporation (J-Eng) has reported the completion of the first fully-functional full-scale commercial engine to run on ammonia fuel – a dual-fuel 7UEC50LSJA-HPSCR (50 cm bore, seven cylinders, with high pressure SCR).
The engine has been developed as a part of the ‘Next-Generation Ship Development’ project, within the Green Innovation Fund Project administered by Japan’s New Energy and Industrial Technology Development Organization (NEDO).
The official test runs were conducted at the end of August 2025 at the J-Eng factory, under the supervision of Nippon Yusen Kaisya (NYK Line), Nihon Shipyard (NSY), Japan Marine United Corporation (JMU) and ClassNK. A series of performance verification tests in both ammonia fuel and HFO operation modes, as well as post-operation inspections of major components, were successfully completed, and the engine’s environmental performance and safety were certified by ClassNK.
This engine will be shipped in October 2025 and installed on an ammonia-fuelled medium gas carrier being constructed by JMU Ariake Shipyard. The vessel is scheduled to enter service in 2026.
J-Eng had previously conducted about 1,000h of test runs on a single-cylinder ammonia-fuelled test engine at the Mitsubishi Heavy Industries R&D Centre at Nagasaki. Using the results and insights gained from the test, J-Eng constructed the full-scale 7UEC50LSJA-HPSCR engine and began test runs on ammonia fuel in April 2025.
Over the following 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. The engine was completed, and equipped with the necessary functionality to ensure the safe operation of actual vessels and the safety of crew members.
J-ENG says it is extremely pleased and proud to be able to deliver, ahead of the rest of the world, a safe and reliable engine, the result of a meticulously planned, long-term development programme that accumulated extensive operational data over an extended period.
Trial run data for the engine shows that at 100% load and a 95% ammonia co-firing rate, nitrous oxide emissions are approximately 3ppm, with a reduction of over 90% GHG emissions. NOx emissions were confirmed to be about half those of HFO engines, with unburned ammonia emissions virtually zero (post-NOx SCR). It has been confirmed that the thermal efficiency in ammonia fuel operation mode is equivalent to or higher than that in heavy oil operation mode.
Following this first engine, J-Eng is developing a 60cm-bore ammonia-fuelled engine designed to address the anticipated market demand for larger ammonia-fuelled ships, and is actively working on several follow-on projects.
Image: Completion of testing of J-Eng’s first full-scale ammonia-fuelled engine (source: J-Eng)
