NYK and ClassNK in nitrous oxide reactor for ammonia engines project

The project was chosen by the New Energy and Industrial Technology Development Organization (NEDO) as a "Next Generation Ship Development" as part of Japan’s Green Innovation Fund Project.

The demonstration project aims to address one black mark against the green credentials of ammonia as a marine fuel - the formation of nitrous oxide (N2O) in the exhaust. Owing to its high global warming potential at around 300 times that of carbon dioxide, nitrous oxide emissions threaten to offset the benefits of using ammonia to decarbonise shipping.

A catalytic removal system will remove the N2O produced burning ammonia in a system known as a N2O reactor. Hitachi Zosen has experience in catalytic technology in the maritime industry, including Selective Catalytic Reduction (SCR) systems for removing nitrogen oxides in exhausts.

Hitachi Zosen will develop and install an N2O reactor for an ammonia-fuelled marine two-stroke engine. The system will be installed on an NYK Line vessel due for delivery in November 2026, with NYK responsible for optimising the system placement, operating the demonstration system, and establishing and verifying the control system requirements.

ClassNK in its role as a partner organisation will verify safety of the N2O reactor and conduct research on the development of international guidelines around the technology.

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