Japan Engine has completed the world’s first hydrogen-fuelled engine for large commercial vessels, the 6UEC35LSGH. During factory testing, the engine achieved a hydrogen co-firing rate of at least 95 per cent, reducing GHG emissions by more than 95 per cent compared with conventional heavy-fuel-oil engines.
Japan Engine, Kawasaki, and Yanmar Power Solutions are developing hydrogen-fuelled engines under NEDO’s Green Innovation Fund Project. In August 2025, Japan Engine completed what the company claims to be the world’s first ammonia-fuelled marine low-speed two-stroke engine. To mark the completion of the hydrogen engine, it was unveiled to project stakeholders at Japan Engine’s headquarters factory on September 7.
By adopting a high-pressure direct injection system, which injects fuel directly into the cylinder at high pressure, the hydrogen engine achieves stable hydrogen combustion. Safety measures have also been implemented, including a robust structure to prevent hydrogen leakage and double-walled piping for hydrogen supply lines. Approval testing was conducted in the presence of ClassNK and was completed successfully.
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Hydrogen engine on multi-purpose vessel
Going forward, as part of the “Blue Harmony” project, in January 2027, the engine will be installed on a 17,500 DWT multi-purpose vessel. Onomichi Dockyard is building this vessel for Mitsui O.S.K. Lines (MOL) and MOL Drybulk.
Hydrogen fuel will be supplied to the engine through the marine hydrogen fuel system (MHFS), consisting of marine hydrogen fuel tanks and a fuel supply system. Kawasaki developed and manufactured this system. This company will also develop and manufacture bunkering equipment for supplying liquefied hydrogen to vessel.
The vessel will then undergo sea trials before onboard demonstration testing begins in April 2028. The demonstration will further evaluate the engine’s durability and performance under actual operating conditions. In addition, Nippon Kaiji Kyokai (ClassNK) will conduct safety assessments throughout each stage of engine’s development and the vessel’s design, construction and operation.
Picture: CG rendering of the 17,500 DWT multi-purpose Vessel (image MOL).
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