Engine designer claims emissions and efficiency breakthroughs on dual-fuel gas engines

Ammonia thermal efficiency met, no ammonia slip catalyst required to burn fuel

In tests of its X-DF-A ammonia-diesel dual-fuel engine design in Switzerland, WinGD said it has met the thermal efficiency targets it set for its engine design – and guaranteed to customers – in a series of full-load tests.

"The tests confirm engine performance data that WinGD has published in its general technical data software, available online, and guaranteed to customers. Operation on ammonia achieved the same thermal efficiency as for diesel fuel, with pilot oil consumption at the targeted 5.0% of overall fuel consumption at full load," the company said. 

WinGD called emissions data gathered in its tests "encouraging," with ammonia emissions below 10 parts per million (ppm) and nitrogen dioxide below 3 ppm.

"NOx emissions for ammonia operation were well below those generated during diesel use," the company reported.

With emissions measured without the use of exhaust gas after-treatment, WinGD said its X-DF-A engine can run on ammonia fuel without using an ammonia slip catalyst.

WinGD began its ammonia engine development six years ago, and in 2022, tested its spray combustion chamber. This was followed by the testing of key engine components. In very early-phase tests, WinGD tested X-DF-A ammonia fuel injectors on test rigs to validate the functional, mechanical behaviour and reliability, and on a multi-cylinder methanol engine at 100% load. The later test using methanol allowed WinGD a further opportunity to verify the ammonia injection concept under harsh engine conditions and thermal stress and make improvements before testing with ammonia.

WinGD said it has secured around 30 orders for X‑DF‑A engines in the bulk carrier, container ship, tanker and LPG/ammonia carrier segments.

The first engines will be delivered from mid-2025 for ammonia carriers owned by Exmar LPG, and bulk carriers operated by CMB.TECH, deploying 52- and 72-bore engines respectively, to be built in Korea and China. These ammonia engines will be the first low-speed ammonia engines to be delivered for commercial ships.

The first WindGD ammonia engine to be developed is the 52-bore X52DF-A, followed by the 72-bore variant. X-DF-A engines operate according to the diesel principle in both diesel and ammonia modes, have the same rating field as WNinGD’s existing diesel engines and will be available with the same cylinder configurations.

Lloyd’s Register, which issued an approval in principle for WinGD’s X-DF-A engine range in 2023, reported 22 ammonia-fuelled vessels were ordered in 2024, more than double the previous year. “In 2025, the first ammonia-fuelled marine engines will be delivered, with a further surge in orders likely as the industry gains experience with the carbon-free fuel,” said the class society.

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