Finland-headed international energy and marine technology group Wärtsilä Oyj has introduced its innovative NextDF feature for the Wärtsilä 25DF dual-fuel engine. While operating on liquefied natural gas (LNG), the NextDF feature reduces methane emissions to less than two percent of fuel use across all load points, achieving as low as 1.1 percent in a wide load range.

Liquefied natural gas (LNG) is considered an important transition marine fuel, bridging the gap between conventional fossil diesel fuels and future carbon-neutral or carbon-free alternatives such as liquefied biomethane (bioLNG), aka renewable natural gas (RNG).

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.

Tightening emissions

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 ten years, complementing other efforts to reduce carbon dioxide (CO₂) emissions.

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 methane-related measures in FuelEU Maritime from 2025 onwards and the EU Emission Trading System (EU ETS) from 2026 onwards.

The effect of methane emissions will be introduced as a percentage of the mass of the fuel used by the engine. For EU regulation, four-stroke engines not certified with lower emission values will have to adhere to a default methane emission of 3.1 percent of fuel use.

To provide flexibility in meeting the GHG intensity limits, the FuelEU Maritime regulation will not only impose costs if a vessel does not comply, but it will also allow vessels to capture value from overcompliance through banking or pooling compliance surplus between reporting periods.