Japan Engine Corporation (J-ENG) is poised to launch what it claims is the first functional full-scale commercial ammonia engine.
Engine tests were carried out for three days last week at J-ENG’s factory, under the supervision of Nippon Yusen Kaisya (NYK Line), Nihon Shipyard Co (NSY), Japan Marine United Corporation (JMU) and Nippon Kaiji Kyokai (ClassNK).
The engine will be shipped in October and installed on an ammonia-fuelled medium gas carrier being constructed by JMU Ariake Shipyard. The vessel is scheduled to enter service in 2026.
A series of performance verification tests were performed for the dual-fuel engine. Ammonia fuel operation mode and heavy fuel oil operation mode were tested, as well as post-operation inspections of major components. The engine’s environmental performance and safety were certified by ClassNK.
The engine was developed as a part of ‘Next-Generation Ship Development’ in the Green Innovation Fund Project administered by New Energy and Industrial Technology Development Organisation.
Trial-run data for the engine showed that at 100% load and a 95% ammonia co-firing rate, nitrous oxide (N₂O) emissions were approximately 3ppm, achieving a reduction of over 90% in greenhouse gas 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 was confirmed that the thermal efficiency in ammonia fuel operation mode outstripped that in heavy oil operation.
J-ENG is also developing an ammonia-fuelled engine with 60cm bore and proceeding with building a new factory with support from a project with Japanese government support. It is expected to open in 2028.
Ammonia engines offer zero-carbon propulsion with easier storage than hydrogen but have significant drawbacks, including high toxicity, potential for harmful nitrogen-based pollutant emissions (NOx, N2O), lower energy density than diesel, and substantial infrastructure, safety, and green production challenges.