World’s First Hydrogen-Powered Coastal Tanker Completes Sea Trial in Japan

A 4800 DWT coastal tanker, the Kikou Maru, successfully passed sea trials, in a world first for this configuration involving a four-stroke engine propelled by hydrogen, electric propulsion motors, and lithium-ion batteries to reduce fuel consumption.

The engine was designed by Yanmar Power Solutions, and its first tests were conducted in 2024, during which it operated with an output of 500 kilowatts. In the engine trials, diesel oil was used to ignite a premix of hydrogen and air. Subsequent tests used hydrogenated vegetable oil for ignition.

The tanker chosen for this test had to be designed for hydrogen propulsion; hence, Fukuoka Shipbuilding, a part of the project, chose the current one after it was launched in 2025. The 105 m long tanker was finally sent to its owner, Uyeno TransTech.

The historic 20-mile-long sailing in Osaka Bay was part of a research program to support decarbonisation. The trial went on for two hours, during which the reported reduction in carbon dioxide emissions was 1.2 tons.

In this case, the engine produces electricity instead of just driving the propeller shafts, while electric motors provide propulsion through the two shafts.

Apart from testing the hydrogen engine on a tanker, the project includes research and development of a fuel supply system and a unique hull design to get AiP from ClassNK and also offer training and a usage manual for hydrogen-fuelled ships.

The trial produced extensive data regarding the adoption of hydrogen in coastal shipping and will be used as a benchmark to achieve efficiency in this direction.

Kazuma Kashiwagi, Director of the Environmental Bureau for Kobe, said that the trial is a vital step towards the application of hydrogen-fuelled vessels, generating zero emissions.

This could help decarbonise the shipping industry in Japan, which has set a goal of attaining carbon-neutrality in domestic shipping by 2050.

The project kicked off in 2022 and slowly progressed into different stages, including the development of a hydrogen fuel cell on an offshore vessel deployed to a wind farm, followed by a hydrogen engine for a tug.

All the tests, leading to this one, yielded important results and observations that helped achieve the next step in the development of a prototype engine for much larger vessels sailing the world’s oceans.

Apart from commercial cargo vessels, even cruise operators are testing fuel cells and hydrogen systems to produce electricity for operations in hotels and reduce port emissions.