Wärtsilä: Ammonia for vessels, Gas for Data Centers

Wärtsilä announces that its 4‑stroke engine solution for ammonia fuel now offers a higher power rating. As part of the company’s ongoing development of ammonia‑fuelled engine solutions, the upgrade to the Wärtsilä 25 Ammonia engine raises output to 315 kW per cylinder at 900 rpm and 345 kW per cylinder at 1000 rpm, matching the power level of the LNG‑fuelled Wärtsilä 25DF engine. A key benefit of the upgrade is that fewer cylinders are required for a given power demand, which will reduce installation complexity and simplify maintenance.

25 Ammonia Engine

The power increase also supports the conversion of the engine between LNG and ammonia fuel operation. With this new power range of 1.9-3.1 MW, the Wärtsilä 25 Ammonia engine is an ideal choice for a wide range of applications, both as a main engine or as an auxiliary engine. What’s more, by aligning with the power level of the LNG-fuelled Wärtsilä 25DF, retrofitability is improved resulting in greater flexibility in fuel choice for shipowners. The increased power rating was demonstrated during type approval tests carried out in autumn 2025 under the supervision of classification society representatives.

“With decarbonisation front and centre of our strategy, we continue to enhance the capabilities of our ammonia engine solution. This power increase builds on our extensive testing and development work and helps make ammonia‑fuelled ship operations more practical and affordable, while maintaining high standards of safety and reliability,” says Stefan Nysjö, Vice President of Power Supply, Wärtsilä Marine.

The Wärtsilä 25 engine platform is a next-generation, medium-speed marine engine designed for safe and reliable power generation, low emissions, efficient operation and easy integration. The Wärtsilä 25 Ammonia features a modular design and delivers proven reliability for a wide range of vessels and propulsion arrangements.

The increased power version of the Wärtsilä 25 Ammonia engine is now released to the commercial market for deliveries in 2028.

Wärtsilä 34SG Engines for Data Centers in Ohio

Wärtsilä has received an order to supply 412 MW of engine power to support a major new hyperscale data center project in Ohio, United States. The project includes 40 Wärtsilä 34SG (spark gas) engines. This order brings Wärtsilä’s total engine capacity sold into the US data center market to over 1.6 GW. The order was booked as intake by Wärtsilä in Q2 2026.

The 34SG model’s modular engine technology offers high efficiency, proven reliability, low water consumption, and strong performance in high-temperature environments, making it well suited for AI-driven and high-performance data center applications. Its modular design accommodates data center developers looking for power solutions that can be deployed in modular blocks, scaling up to 500MW+.

 “This project underscores the confidence data center developers place in Wärtsilä’s engine technology to deliver fast, flexible power at scale. As AI and cloud demand accelerate, operators need energy solutions that are efficient, resilient, and available on their timeline – not the grid’s. Wärtsilä provides that foundation, delivering dependable, high performance power that scales as quickly as their infrastructure. The customer chose Wärtsilä for its proven reliability, rapid deployment, and strong operational efficiency across diverse operating conditions,” says Risto Paldanius, Vice President, Americas at Wärtsilä Energy. 
 
The power plant will provide highly flexible, primary power, enabling the data center to operate off-grid and avoid long interconnection delays common to the US market. Equipment deliveries are scheduled to align with an anticipated commercial operation date of early 2028. 

This is Wärtsilä’s fourth data center related order in the USA.