The “Development of Marine Hydrogen Engines and MHFS” project is co-developed by Japan Engine Corporation and Yanmar Power Solutions under the NEDO “Green Innovation Fund Project / Next-Generation Ship Development.”

Japan Engine has developed the world-first hydrogen-fueled engine for big commercial ships, the 6UEC35LSGH, which is also referred to as the engine in this article piece. On September 7, 2026, the completion of the engine was celebrated with its presentation to project stakeholders at the headquarters factory of Japan Engine.

At the time of factory testing, this world-first hydrogen-fueled engine for big commercial ships attained a hydrogen co-firing rate of a minimum of 95%, leading to GHG emissions reduced by more than 95% compared to conventional heavy-fuel-oil engines.

In the future, the engine will be mounted on a 17,500 DWT multipurpose vessel to be constructed by Onomichi Dockyard Co., Ltd. for Mitsui O.S.K. Lines, Ltd. and MOL Drybulk Ltd. under the Blue Harmony project, with onboard demonstration testing expected to begin in April 2028. In addition, Nippon Kaiji Kyokai, hereafter, ClassNK, is going to carry out safety evaluations at each step of the engine’s development and the vessel’s design, building, and operation.

1. What is it all about?

The rapid development and commercialization of engines using next-generation fuels is critical to the achievement of carbon neutrality for international shipping by 2050. Japan Engine, Kawasaki, and Yanmar Power Solutions are working on hydrogen-fueled engines under NEDO’s Green Innovation Fund Project.

In August 2025, Japan Engine delivered the world’s first ammonia-fueled marine low-speed two-stroke engine. As a pioneer of next-generation fuel engines, Japan Engine is supporting the growth of Japan’s shipping and shipbuilding industries by developing and bringing to market a wide range of engines and helping to reduce GHG emissions in the maritime industry and achieving carbon neutrality by 2050.

2. By way of these efforts

Japan Engine has developed the world’s first*2 hydrogen-fueled engine for large commercial vessels, the 6UEC35LSGH. The engine achieves stable hydrogen combustion with a high-pressure direct injection system that injects fuel into the cylinder at high pressure. In factory testing, the engine achieved a hydrogen co-firing ratio of at least 95%, and GHG emissions were reduced by more than 95% relative to conventional heavy-fuel-oil engines. Safety measures have also been introduced, such as a strong structure to prevent hydrogen leakage and double-walled piping for hydrogen supply lines. The approval test was conducted together with ClassNK and passed successfully.

3. Future strategies

Japan Engine has been working on the hydrogen-fueled engine as a member of “Blue Harmony,” a project to realize and commercialize hydrogen-fueled vessels. The engine will be installed on a 17,500 DWT multi-purpose vessel being built by Onomichi Dockyard for Mitsui O.S.K. Lines and MOL Drybulk in January 2027. Kawasaki developed and manufactured MHFS, which will supply the hydrogen fuel for the engine. The vessel will then be put through sea trials with on-board demonstration testing beginning in April 2028. Kawasaki will also design and construct bunkering equipment to supply liquid hydrogen to ships. The demonstration will also put the engine’s performance and reliability to the test in real-world operating conditions.