Tighter emissions rules could soon require ships using LNG as fuel to switch to lower-carbon forms of methane, such as biomethane and e-methane, according to a new study from DNV.
In its report, “Methane in Shipping – LNG-fuelled ships and the switch to low-GHG methane,” the classification society notes that there are already around 800 LNG-capable ships in service, in addition to 700 LNG carriers using boil-off gas as fuel. There are also approximately 600 more LNG-capable ships and nearly 300 additional LNG carriers currently on order.
Even so, conventional LNG may not remain compliant for much longer. Depending on engine type and the timing of future rules, continued use of fossil LNG could conflict with proposed fuel regulations within as little as three years in the most aggressive scenario, or by 2035 in the latest case.
DNV notes that LNG still has support among many owners and operators as a bridging fuel, while others argue the sector should move more decisively away from fossil fuels toward electrification, hydrogen, and hydrogen-derived fuels such as ammonia and methanol.
The report says the uptake of low-GHG methane depends on three pillars: the ship technology needed to use it, the production and availability of the fuel itself, and the bunkering infrastructure required to deliver it onboard.
DNV also assesses the compliance horizon for three different engine configurations against both FuelEU Maritime and the proposed IMO Net Zero Framework (NZF). Although the NZF is not yet finalised, DNV says it still provides an important signal about the likely direction of future IMO greenhouse gas regulation.
Under FuelEU Maritime, assuming the rules remain unchanged, LNG-fuelled ships may be able to continue operating until around 2035, depending on engine type, without needing to adopt low-GHG methane. Under the IMO NZF, however, if a framework became effective from 2029, the compliance window would be shorter.
A key uncertainty is the well-to-tank (WtT) greenhouse gas intensity factor that will ultimately be applied. With a low WtT factor, many LNG-fuelled ships might not need low-GHG methane until 2031 or 2032. With a high WtT factor, some could need it as early as 2029.
DNV also points out that WtT intensity can vary substantially between LNG suppliers. Using source-specific WtT values rather than generic defaults would improve accuracy and encourage producers to reduce upstream emissions.
The same applies to methane slip. Real shipboard or testbed measurements, rather than default factors, could benefit newer dual-fuel engines. Several manufacturers have already reported lower methane slip emissions than those assumed in current default values, particularly for low-pressure dual-fuel 2-stroke and 4-stroke engines. That could help extend the compliance horizon for some ships.
Overall, DNV concludes that LNG still appears to offer a credible bridging pathway toward low-GHG methane, with a potentially longer compliance horizon than fuel oils. Production of low-GHG methane is already more advanced than that of many other low-carbon fuel candidates. However, future uptake will depend heavily on whether the shipping industry is prepared to pay for it.
