Landmark study reveals lower than previously believed emissions of LNG as marine fuel

Rystad Energy has published groundbreaking research demonstrating that liquefied natural gas (LNG) used as a marine fuel produces significantly lower well-to-tank emissions than previously estimated by regulators.

The independent study, commissioned by SEA-LNG, concluded that the global well-to-tank emissions intensity for LNG bunkering fuel in 2024 is 13.9 g CO2e/MJ (LHV), substantially below the EU default value of 18.5 g CO2e/MJ used in the FuelEU maritime regulations.

The research looked at emissions from five key lifecycle stages: production, transportation and processing, liquefaction, shipping, distribution, and bunkering operations. It was carried out following IMO guidelines for well-to-tank life cycle analysis and GHG definitions from the IPCC’s Fifth Assessment Report.

“Our analysis is based on asset-level data linking specific gas fields to liquefaction facilities,” said Patrick King, Vice President of Emissions Research at Rystad Energy. “This approach, supported by satellite-detected methane column data and reported asset information, offers a more accurate view of LNG actually used for bunkering, rather than relying on outdated or overly broad averages.”

The study found that carbon dioxide predominates in global WtT emissions, accounting for 84% of the total, and methane is responsible for the remaining 16% (equivalent to 2.2g CO₂e/MJ). Notably, the liquefaction stage generated 43% of all emissions, while upstream gas production accounted for 30%.

The results showed significant variation between regions and loads due to differences in gas sources, liquefaction technologies, and transportation distances. In some cases, the intensity of emissions varied by up to 6.6 g CO₂e/MJ.

With approximately 95% of ships still using petroleum-based fuels, LNG has established itself as the main alternative, now accounting for almost 20% of the global ship order book. As the shipping industry moves toward decarbonization goals, understanding accurate data on lifecycle emissions becomes increasingly crucial for regulatory and investment decision-making.

Peter Keller, President of SEA-LNG, called the report a landmark study that “sets the high standards that IMO should demand on such a key issue as emissions and performance of alternative fuels within the Net-Zero Framework.”

The results suggest that regulators, particularly those behind the EU’s FuelEU Maritime initiative, should revise their emissions factors downwards to reflect the latest research.

“Policymakers must create regulations that reflect the true carbon intensity of marine fuels, rewarding reductions throughout the supply chain,” said Steve Esau, chief operating officer of SEA-LNG. “Marine regulators should incentivize participants in the LNG supply chain to continue reducing GHG emissions.”