Tests of Wärtsilä’s 4-stroke engine-based solution for ammonia fuel show that a 95 per cent ammonia energy share now achieves up to a ninety per cent reduction in greenhouse gas (GHG) emissions compared to equivalent diesel engines. The extensive testing follows the engine’s introduction to the commercial marine sector in November 2023.
The tests were executed to optimise the engine’s performance parameters. The reductions measured were assessed against the FuelEU Maritime reference and measured on both a Well-to-Wake and Tank-to-Wake basis and represent a further eighteen per cent improvement on the solution’s emissions performance.
Also read: Wärtsilä brings carbon capture to shipping market
Otto cycle concept
The Wärtsilä 25 ammonia engine, which is available as part of the Wärtsilä 25 engine platform, was developed based on the company’s experience gained from low-pressure dual-fuel (DF) engines running on LNG. The recent tests have shown ammonia to be a suitable fuel for the low-pressure Otto cycle concept, which is the design that Wärtsilä has utilised for its ammonia engine solution.
The decision to opt for a low-pressure Otto cycle concept was based on several factors, including safety, efficiency and overall potential for greenhouse gas reduction, among several other parameters. Comprehensive tests conducted on different engine sizes have shown that the efficiency of the low-pressure Otto cycle concept is consistent with, and equal to, that of dual-fuel LNG engines.
Ammonia is also highly knock resistant, with robust combustion capabilities across a wide range of engine settings.
Also read: Wärtsilä, Höegh develop floating ammonia-to-hydrogen cracker
Enhancements benefit ammonia solution
The enhancements made to the Wärtsilä 25 ammonia engine’s performance benefit the entire ammonia solution, which comprises of an AmmoniaPac fuel gas supply system, the Wärtsilä Ammonia Release Mitigation System (WARMS), and the Wärtsilä NOx Reducer (NOR) for optimal exhaust after-treatment. Safety, efficiency and reliability are central to the solution design, maximised by a highly sophisticated automation system and maintenance agreement to ensure safe and efficient onboard operations.
Alongside future engine orders, the enhanced performance will also be integrated into engines already contracted as first deliveries are due to take place from 2026 onwards.
Also read: Wärtsilä spends EUR 50 million to expand R&D centre
Promising alternative fuel
Ammonia has emerged as a promising alternative fuel as the shipping industry looks for more sustainable fuel options. With global regulations having set a clear destination for shipping – net zero emissions by mid-century – ammonia will play a significant role in enabling the shipping industry to reduce its emissions.
A report from Wärtsilä highlights the role that sustainable fuels will play in achieving this target, which is set by the International Maritime Organization (IMO). According to the report, existing decarbonisation solutions, such as fuel efficiency measures, can cut shipping emissions by up to 27 per cent; however, sustainable fuels, such as ammonia, will be a critical step in eliminating the remaining 73 per cent.
Picture: Wärtsilä’s 4-stroke engine-based solution for ammonia fuel now delivers higher than ever levels of efficiency and performance (photo by Wärtsilä Corporation).
