- Wärtsilä has improved its 4-stroke ammonia engine, achieving up to a 90% reduction in greenhouse gas emissions compared to diesel engines.
- The Wärtsilä 25 ammonia engine uses a low-pressure Otto cycle design, chosen for safety, efficiency, and emission reduction.
- The ammonia solution includes advanced systems like AmmoniaPac, WARMS, and NOR, focusing on safety, efficiency, and reliable operation.
- Ammonia is recognized as a key sustainable fuel for shipping, as efficiency measures alone can only reduce emissions by about 27%.
Wärtsilä has enhanced its 4-stroke engine-based ammonia fuel solution, achieving new levels of efficiency and performance. Since its launch in November 2023, the technology has undergone rigorous testing. Recent results show that using 95% ammonia can reduce greenhouse gas emissions by up to 90% compared to diesel engines. This marks an 18% improvement over earlier performance. The findings are based on both Well-to-Wake and Tank-to-Wake assessments, aligned with FuelEU Maritime standards.
Wärtsilä’s Ammonia Engine and Low-Pressure Otto Cycle Concept
The Wärtsilä 25 ammonia engine, part of the Wärtsilä 25 engine platform, was developed leveraging the company’s extensive experience with low-pressure dual-fuel engines running on LNG. Tests confirmed that ammonia is a suitable fuel for the low-pressure Otto cycle design used in this engine. This design was selected based on factors such as safety, efficiency, and the potential for reducing greenhouse gas emissions.
Testing across various engine sizes showed that the low-pressure Otto cycle’s efficiency matches that of dual-fuel LNG engines. Ammonia’s high knock resistance and strong combustion across different engine settings were also highlighted. Wärtsilä emphasized its ongoing commitment to decarbonization and continuous improvement by enhancing the ammonia engine’s safety features and performance. The low-pressure Otto cycle concept was selected to ensure optimal safety, efficiency, and reliability for customers, according to the company’s leadership.
Comprehensive Ammonia Solution and Its Role in Shipping Decarbonisation
The performance improvements of the Wärtsilä 25 ammonia engine enhance the entire ammonia solution, which includes the AmmoniaPac fuel gas supply system, the Wärtsilä Ammonia Release Mitigation System (WARMS), and the Wärtsilä NOx Reducer (NOR) for exhaust after-treatment. The solution prioritizes safety, efficiency, and reliability, supported by an advanced automation system and a maintenance agreement to ensure smooth onboard operations. Wärtsilä plans to integrate these enhancements into both new engine orders and previously contracted engines, with first deliveries expected from 2026.
The company noted that ammonia is gaining importance as a sustainable fuel option in shipping, driven by global regulations targeting net-zero emissions by mid-century. A Wärtsilä report highlighted that while fuel efficiency measures can reduce shipping emissions by up to 27%, sustainable fuels such as ammonia will be crucial in addressing the remaining 73% and achieving the International Maritime Organization’s decarbonization goals.
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Source: Wärtsilä
