World-first liquid-hydrogen main engine for ocean ships clears factory testing
Why it matters: This is a full-scale, low-speed two-stroke engine meant for actual deep-sea vessels, not a coastal demo. If it holds up at sea, it's a direct hydrogen-combustion rival to marine diesel on long-haul shipping, the hardest segment to decarbonise.
A Japanese consortium, Japan Engine Corporation, Kawasaki Heavy Industries, Yanmar Power Solutions, Mitsui O.S.K. Lines (MOL), MOL Drybulk, Onomichi Dockyard and class society ClassNK, has completed land-based testing of the 6UEC35LSGH, described as the world's first hydrogen-fuelled engine built for large commercial ships. Backed by Japan's NEDO Green Innovation Fund, the engine hit a hydrogen co-firing rate above 95 percent at full load, cutting greenhouse gas emissions more than 95 percent against a conventional heavy-fuel-oil engine of the same class. It uses high-pressure direct injection with double-walled piping to guard against leaks. Next stop: installation aboard a 17,500-DWT multi-purpose vessel from January 2027, then sea trials and a three-year demonstration voyage programme from FY2028.
Source: Japan Engine Corporation press release · 18 September 2026 (press release); unveiling 7 September 2026; widely reported 22 September 2026