Japan tests world’s first commercial-scale ammonia marine engine

In Japan, on September 1, Japan Engine Corporation completed the world’s first full-scale commercial marine engine designed to run on ammonia, marking a breakthrough for zero-carbon shipping. Developed under Japan’s Green Innovation Fund and tested in late August with partners including NYK Line, Japan Marine United, and ClassNK, the seven-cylinder engine demonstrated 95 percent ammonia co-firing, halved NOx emissions compared to heavy fuel oil, and near-zero ammonia slip.

The engine passed land-based trials at full load and will be shipped in October to Japan Marine United’s Ariake shipyard for installation on an ammonia-fueled gas carrier scheduled to launch in November 2026. Over 700 hours of factory tests confirmed high thermal efficiency and verified onboard safety systems, enabling ClassNK approval.

J‑ENG’s development effort included earlier single-cylinder tests at Mitsubishi’s Nagasaki facility and is now being extended with a 60-centimeter bore version to meet growing demand for ammonia-capable vessels. The company is also planning a new production plant, backed by Japan’s Ministry of Environment and Ministry of Land, Infrastructure, Transport and Tourism, set to open in fiscal 2028. J‑ENG aims to become a first mover in commercial ammonia engines and contribute to Japan’s maritime decarbonization goals.

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