Finnish technology group Wärtsilä has introduced new NextDF technology for its Wärtsilä 25DF liquefied natural gas (LNG) dual-fuel engine to cut methane emissions.
LNG as a fuel is considered an important transition marine fuel, bridging the gap between conventional diesel fuels and future carbon-neutral or carbon-free alternatives. However, the main component of LNG is methane, and when burned as a fuel, a very small amount may not combust properly, leading to methane escaping into the atmosphere.
Across the shipping industry, the use of LNG and cutting methane emissions is one of the most effective ways to decrease overall greenhouse gas (GHG) emissions from engines over the next 10 years, according to Wärtsilä.
From an international shipping perspective, the International Maritime Organization (IMO) is considering methane emissions in the upcoming GHG regulations. At a regional level, the EU is implementing a set of methane-related measures in FuelEU Maritime (2025 onwards) and the EU Emission Trading System (EU ETS) (2026 onwards).
The effect of methane emissions will be introduced as a percentage of the mass of the fuel used by the engine. Under EU regulations, four-stroke engines that are not certified for lower emissions must adhere to a default methane emission rate of 3.1 percent of fuel consumption.
To offer flexibility in meeting greenhouse gas intensity limits, the FuelEU Maritime regulation will not only impose penalties for non-compliance but also enable vessels to gain value from exceeding compliance requirements by allowing them to bank or pool their compliance surplus across reporting periods.
According to Wärtsilä, the NextDF feature is expected to reduce methane emissions to less than two per cent of fuel use across all load points, achieving as low as 1.1 per cent in a wide load range. What’s more, the nitrogen oxide (NOx) emissions “are lower than on the standard Wärtsilä 25DF engine”, which already has low emission levels below IMO Tier III, the company noted.
“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. 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 decarbonisation,” commented Stefan Nysjö , Vice President of Power Supply, Wärtsilä Marine.
“The Wärtsilä 25DF engine has already set an industry benchmark for low methane slip, down to as low as 1.4 percent at certain load points. By making available our NextDF technology for the Wärtsilä 25DF engine enables operators to go even further in reducing methane emissions. This increases overcompliance with EU regulations, therefore offering tangible financial benefits for shipping operators, whilst simultaneously helping them to futureproof their vessels in the longer term,” he added.
The NextDF feature for the Wärtsilä 25DF engine will be available for delivery in the second half of 2025.
This is the second Wärtsilä dual-fuel engine to be made available with NextDF technology. In 2023, Wärtsilä introduced the new technology for its Wärtsilä 31DF engine.
Thanks to the modular design of Wärtsilä’s engine platform, the NextDF feature can be retrofitted to existing Wärtsilä 31DF and Wärtsilä 25DF engines.
To remind, the Wärtsilä 31DF engine, launched in 2015, was selected for new 6,000 dwt LNG-fueled tankers ordered by British fleet operator James Fisher Everard, a part of the James Fisher group of companies.
The ships are under construction at China Merchants Jinling Shipyard (Yangzhou) Dingheng in cooperation with design consultant FKAB Marine Design.