UEC-LSJA Ammonia-Fueled and UEC-LSGH Hydrogen-Fueled Engines

Japan Engine Corporation (J-ENG) is developing marine engines fueled with ammonia and hydrogen to meet IMO greenhouse gas reduction targets for international shipping. The UEC-LSJA ammonia-fueled engine and the UEC-LSGH hydrogen-fueled engine are aimed at carbon-free operation, beyond the roughly 20% reduction expected from LNG, LPG and methanol.

UEC-LSJA ammonia-fueled engine

• First full-scale commercial engine: 7UEC50LSJA-HPSCR (50 cm bore, 7 cylinders, with high-pressure SCR), completed in 2025; applications include an ammonia-fueled ammonia gas carrier
• Optimized combustion control to overcome ammonia's high ignition temperature and poor combustibility
• Trial results at 100% load and 95% ammonia co-firing: N2O about 3 ppm, GHG emissions reduced by over 90%
• NOx about half that of heavy fuel oil engines; unburned ammonia virtually zero after SCR
• Thermal efficiency in ammonia mode equivalent to or higher than in heavy oil mode
• Development: about 1,000 hours on a single-cylinder test engine (May 2023 to September 2024), then 700 hours of testing of the full-scale engine from April 2025, including leak prevention and monitoring systems for toxic ammonia

UEC-LSGH hydrogen-fueled engine

• Based on J-ENG dual-fuel gas engine technology, using high-pressure hydrogen injection for stable combustion
• First engine, UEC35LSGH (35 cm bore), expected to be completed in 2026, followed by one-year actual machine verification scheduled to finish in March 2027
• A hydrogen single-fuel engine without pilot fuel is planned after the dual-fuel version
• Developed in the HyENG joint company with Kawasaki Heavy Industries and Yanmar Power Technology (established 2021), under the NEDO Green Innovation fund; a hydrogen-fueled vessel concept has received AiP for demonstration operation