Wärtsilä rolls out first four-stroke ammonia-fuelled engine

Finnish technology group Wärtsilä has introduced the marine sector’s first commercially available four-stroke engine-based solution for ammonia fuel.

Viridis Bulk Carriers, the world’s first zero-emission shipping company, will be the first shipowner to benefit from the new ammonia solution. The company is a partnership between Amon Maritime, Mosvolds Rederi, and Navigare Logistics.

Norwegian government enterprise Enova granted some $14.1m to Viridis Bulk Carriers back in late September for the construction of two ammonia-powered bulk carriers. Earlier this month, Wärtsilä and Viridis signed a letter of intent for the Wärtsilä 25 ammonia engine solution, targeting to sign a commercial contract in early 2024.

In addition to the engine, the full solution includes an AmmoniaPac fuel gas supply system, the Wärtsilä Ammonia Release Mitigation System, and the Wärtsilä NOx Reducer for optimal exhaust after-treatment.

Sustainable ammonia is one of the leading candidates in shipping’s search for alternative clean fuels.

This new Wärtsilä 25 Ammonia solution can immediately reduce greenhouse gas emissions by more than 70%, compared to a similar-sized diesel solution, meeting current EU targets until 2050 and even exceeding the IMO target for 2040.

Ammonia-fuelled ships have been the order of the day recently with Yara Clean Ammonia and liner operator North Sea Container Line teaming up earlier this month to deliver the world’s first containership that will use pure ammonia as fuel.

Belgian owner Exmar is expected to become the first shipowner in the world to take delivery of ammonia-powered ships in the first half of 2026. Exmar has two 46,000 cu m LPG carriers contracted earlier this year with Hyundai Mipo Dockyard, with these ships set to be able to operate on ammonia or LPG.

Engine maker MAN Energy Solutions revealed it is on track to deliver its first ammonia engine in late 2024, with the full commercial release of the two-stroke engine set for 2025 while Seaspan and the Mærsk Mc-Kinney Møller Center for Zero Carbon Shipping showcased the design of an ammonia dual-fuel 15,000 teu container vessel earlier this year.