Ammonia-fueled low-speed two-stroke engine UEC50LSJA has been awarded “Marine Engineering of the Year (Dokou Memorial Award) 2025”

On July 17, the joint awards ceremony of The Japan Institute of Marine Engineering, The Japan Institute of Navigation, and The Japan Society of Naval Architects and Ocean Engineers was held at the Kaiun Club in Chiyoda-ku, Tokyo.　Japan Engine Corporation (J-ENG) has been awarded “Marine Engineering of the Year (Dokou Memorial Award) 2025” for its ammonia-fueled low-speed two-stroke engine, UEC50LSJA. This prestigious award is presented by The Japan Institute of Marine Engineering in recognition of outstanding achievements in marine engineering technology. This marks J-ENG’s second award, following its 2019 recognition for the UEC-LSJ MGO-only engine.

UEC50LSJA has been developed as part of the Green Innovation Fund Projects "Next-Generation Ship Development" led by New Energy and Industrial Technology Development Organization (NEDO).

From May 2023 to September 2024, approximately 1,000 hours of testing were conducted using a single-cylinder ammonia-fueled test engine. A full-scale ammonia-fueled engine ,UEC50LSJA was manufactured with feedbacks of result and knowledge obtained from test engine . Extensive testing totaling approximately 700 hours was conducted over a five-month period starting in April 2025.

This engine achieves stable ammonia combustion while at a high co-firing ratio through advanced combustion control, while suppressing nitrous oxide (N2O) emissions, a potent greenhouse gas. As a result, greenhouse gas emissions are reduced by more than 90% compared with conventional engines. The successful development of the world’s first practical ammonia-fueled low-speed two-stroke engine has been highly regarded and contributed to this award.

The engine is scheduled to be installed in Ammonia-fueled Medium Gas Carrier (AFMGC) being constructed by Japan Marine United Corporation for Nippon Yusen Kabushiki Kaisha (NYK Line). The vessel is expected to enter service in November 2026. After commissioning, durability and other performance aspects under actual operating conditions will continue to be verified.

J-ENG, as the first mover in next-generation fuel engines, will contribute to the development of Japan’s shipping and shipbuilding industries through the early launch and expansion of these engines, contributing to the reduction of greenhouse gas emissions in international shipping and to the achievement of carbon neutrality by 2050.