J-ENG Unveils World’s First Ammonia-Fuelled Engine

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Environment Corporate News Shipping Asia
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Japan Engine Corporation (J-ENG) has announced a major breakthrough in the maritime sector’s decarbonization efforts with the completion of the world’s first full-scale commercial engine powered by ammonia.

The seven-cylinder, 50 cm bore 7UEC50LSJA-HPSCR engine was finalized on August 30 after successful test runs at J-ENG’s Akashi factory. The trials were overseen by NYK Line, Nihon Shipyard, Japan Marine United (JMU), and classification society ClassNK.

Designed as a dual-fuel unit, the engine can run on both ammonia and heavy fuel oil. During testing, it achieved safe and stable operation, with ClassNK confirming compliance with safety and environmental standards. J-ENG reported that emissions testing showed a greenhouse gas reduction of more than 90 percent when operating at a 95 percent ammonia co-firing rate, with virtually no unburned ammonia detected after exhaust treatment. Nitrogen oxide emissions were roughly half those of conventional heavy oil engines.

The engine is slated for delivery in October 2025 and will be fitted on an ammonia-fuelled mid-size gas carrier now under construction at JMU’s Ariake Shipyard. The vessel is scheduled to enter service in 2026.

The achievement follows extensive development work. Between 2023 and 2024, J-ENG completed about 1,000 hours of testing on a single-cylinder prototype at Mitsubishi Heavy Industries’ Nagasaki R&D Center. The full-scale version has since undergone 700 hours of further trials focusing on efficiency, leak prevention, and safety for onboard crews.

J-ENG said this marks the beginning of ammonia’s broader adoption as a marine fuel. Work is already progressing on a larger 60 cm bore engine intended for wider ship applications. In addition, the company is building a new production facility, supported by Japan’s GX Economic Transition Bonds, to expand manufacturing capacity by 2028.

“We are proud to deliver the world’s first safe and reliable ammonia-fuelled engine to the market,” J-ENG said, noting that the project represents a long-term effort to build operational expertise and advance zero-emission shipping.