ClassNK greenlights ammonia-powered LPG/NH₃ carrier design by Kawasaki Heavy Industries, Mitsui E&S

September 8, 2025, by Sara Kosmajac

Japanese classification society Nippon Kaiji Kyokai (ClassNK) has given the stamp of approval for an ammonia-powered LPG/NH₃ carrier to compatriot shipbuilding companies Kawasaki Heavy Industries and Mitsui E&S.

As disclosed, the approval in principle (AiP)—for which Mitsui E&S and Kawasaki Heavy Industries jointly applied—validates the vessel’s feasibility from both a regulatory and safety perspective.

Officials from the classification society have elaborated that the design concept of the vessel was based on the third edition of ClassNK’s “Guidelines for ships using alternative fuels”, specifically the guidelines that oversee the safety of liquefied gas carriers that utilize ammonia as fuel, as well as the rules regarding the additional safety measures for engine rooms. Risk assessment was also conducted through HAZID.

Per ClassNK, the rules define requirements for the installation, controls, and safety devices, among other factors, with the goal of lowering the dangers to ships, seafarers, and the environment linked with the use of ammonia-powered units.

It is worth noting that, at the beginning of July this year, the classification society explored the decarbonization potential of a recently delivered dual-fuel LPG/ammonia carrier Crystal Odyssey, which was constructed by Sakaide Works of Kawasaki Heavy Industries (KHI).

During the study, several factors were considered to determine the ship’s performance, including (but not limited to) the use of LPG fuel being projected to slash carbon dioxide (CO2) emissions by around 15% and gas carrier itself being engineered – and partially fitted – to run on ammonia in the future.

As informed, Crystal Odyssey showed “excellent” performance, pointing to the potential of ammonia acting as a viable path toward net zero.

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Kawasaki Heavy Industries has so far completed several LPG/ammonia carriers. In addition to Crystal Odyssey, in September last year, a naming ceremony was held for the Liberty Pathfinder, a unit owned by compatriot maritime transport heavyweight Nippon Yusen Kabushiki Kaisha (NYK Line) and chartered out to LPG trader and importer Astomos Energy.

Liberty Pathfinder is Astomos Energy’s fifth vessel of this type. More recently, namely in at the beginning of August, the sixth unit of the series—the Luna Pathfinder—was christened.

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On the other hand, in mid-February 2025, Mitsui E&S began test operation of a large-bore low-speed ammonia dual fuel engine, describing this development as a “major step” toward shipping’s decarbonization.