Everllence and its Japanese licensee Mitsui E&S are testing a commercial-scale ammonia-fuelled two-stroke marine engine at the Tamano Factory in Japan, as the shipping industry seeks pathways to decarbonise.

The dual-fuel engine, designated the Everllence B&W 7S60ME-LGIA (Liquid Gas Injection Ammonia) Mk 10.5, is being tested following research and development work that began at Everllence’s Research Centre Copenhagen in 2019. Engineers ran a two-stroke ammonia research engine on one cylinder in July 2023 and on all four cylinders in November 2024.

The commercial engine is now undergoing testing at Mitsui E&S’s facility on the Seto Inland Sea, with collaboration from Everllence experts. Mitsui E&S developed the world’s first LNG-fuelled engine in 1994.

“Here at Mitsui E&S, we’re not only developing the engine, but also an ammonia supply system,” said Takahiro Murakami, manager in the Ammonia Project Group at the Tamano Factory. “This engine has been run on methanol and LPG. Now, with ammonia, it will have basically no CO₂ emissions. While ammonia and hydrogen can both help reduce emissions, ammonia is easier to handle.”

The shipping industry, which moves approximately 90% of global trade, emits about 3% of global greenhouse gases. The International Maritime Organization has set a target to reach net-zero emissions by 2050.

Ammonia, traditionally used as a fertiliser feedstock, is being considered as a marine fuel. When produced from renewable energy using green hydrogen synthesised via electrolysis and nitrogen extracted from the air, ammonia contains no carbon and emits no CO₂ when burned.

However, ammonia is toxic and requires safety protocols to prevent leaks. Its combustion can produce nitrogen oxides (NOx), which must be mitigated through catalytic converters.

The 60-bore engine at the Tamano Factory stands approximately three floors tall and is attached to a selective catalytic reduction (SCR) reactor to reduce NOx emissions. The reactor converts NOx into nitrogen and water by adding urea or ammonia to the exhaust gas.

The fuel is transferred from storage tanks into a supply system that runs at a pressure of around 80 bar through the engine. The injectors pressurise the fuel to around 650 bar. Ammonia has a vapour pressure of about 9 bar, meaning it remains liquid during the pressure steps. The pipes containing ammonia are double-walled to prevent leaks.

More than 200 sensors monitor the engine, creating a heat map of the combustion chamber. Data is monitored at an Everllence test centre in a shipping container at the site.

“We are essentially building a full-scale engine lab remotely,” said Tobias Stübbe, a research engineer in Everllence’s dual-fuel department in Copenhagen. “It’s not just about performance and emissions. We also get data on mechanical stress, control systems and hydraulic behaviour.”

After more than a year of tests and adjustments, the Everllence team reported positive results.

“We are happy to say that we have a stable and reliable engine,” said Michael Foteinos, engine performance engineer in Everllence’s dual-fuel department in Copenhagen. “Our tests show ammonia combustion results in very low NOx emissions, while keeping ammonia emissions well within acceptable limits. Engine operation remains stable even at very low loads, and the transition between diesel and ammonia is seamless.”

The emissions of nitrous oxide (N₂O), a greenhouse gas, have also been monitored. Tests and observations indicated that with appropriate tuning, the engine runs in a way that prevents conditions where N₂O could form.

Most ammonia today is produced from natural gas. Scaling up production of green ammonia will require renewable power capacity and new global supply chains.

“Ammonia as a marine fuel is a viable solution and very much part of the predicted future fuels mix by 2050,” said Daniel Struckmeier, managing director of Everllence Japan Ltd.