Wärtsilä offers NextDF for 25DF dual-fuel engine

Wärtsilä has introduced its NextDF feature for its 25DF dual-fuel engine. When operating on liquefied natural gas (LNG), the feature is said to reduce methane emissions to less than 2% of fuel use across all load points, achieving as low as 1.1% in a wide load range. Nitrogen oxide (NOx) emissions are also lower compared to the standard 25DF engine, which already has emission levels below IMO Tier III, the company added.

NextDF technology is now available for the Wärtsilä 25DF dual-fuel engine. (Photo: Wärtsilä)

LNG is considered an important transition marine fuel, bridging the gap between conventional diesel fuels and future carbon-neutral or carbon-free alternatives, Wärtsilä pointed out. However, its main component is methane and, when burned as a fuel, a small amount may not combust properly, leading to methane escaping into the atmosphere.

“Enhancing dual-fuel technology to further reduce methane emissions will have a major impact on the long-term viability of LNG as a marine fuel,” said Stefan Nysjö, vice president of Power Supply, Wärtsilä Marine. ”Our work around reducing methane slip and GHG emissions is part of Wärtsilä’s effort to continuously improve efficiency and reduce emissions of our products. This innovation is one more very important step along the road to decarbonization.”

The 25DF engine currently has as low as 1.4% methane slip at certain load points, the company stated. “Making available our NextDF technology for the Wärtsilä 25DF engine enables operators to go even further in reducing methane emissions,” said Nysjö. “This increases overcompliance with EU regulations, therefore offering tangible financial benefits for shipping operators, whilst simultaneously helping them to future proof their vessels in the longer term.”

The NextDF can be retrofit to existing Wärtsilä 25DF and 31DF dual-fuel engines. It will be available for delivery for the 25DF engine in the second half of 2025.