Japanese classification society Nippon Kaiji Kyokai (ClassNK) has granted approval in principle (AiP) to NYK Line and IHI Power Systems (IPS) for their ammonia-driven tugboat.

Part of the Green Innovation Fund project within Japan’s New Energy and Industrial Technology Development Organization (NEDO), the vessel is claimed to be the world’s first ammonia-using tugboat to have secured AiP from ClassNK.

The project aims to develop vessels that incorporate a domestically produced ammonia-powered engine.

The use of ammonia as a fuel for ships is expected to help significantly cut down greenhouse gas (GHG) emissions during voyages.

However, burning ammonia still produces the GHG nitrous oxide. Design challenges while using ammonia as a fuel include ensuring stable combustion while increasing its usage ratio, controlling its combustion and preventing leakage.

Both firms are currently involved in the research and development of the new tugboat.

In a statement, NYK Line said: “For this AiP, NYK Line and IPS attempted a design to safely and practically install ammonia fuel-related equipment in a limited space on board by developing an ammonia fuel engine, selecting equipment and devising the equipment layout in the design.” 

This helped the firms design the A-Tug with a size similar to that of a conventional tugboat while overcoming the design issues typically associated with ammonia-fuelled vessels.

In fiscal 2024, the companies plan to work on conducting a demonstration operation at the port of Yokohama, Japan.

In March, ClassNK awarded AiP to Mitsui OSK Lines (MOL), Hitachi Zosen and Yanmar Power Technology (YPT) for their methane oxidation catalyst system concept for liquefied natural gas (LNG)-fuelled vessels.

MOL and Namura Shipbuilding will construct the demonstration vessel and design the installation of the system.