ISWG-GHG 20-3-9: The IMO life cycle GHG assessment framework
Credit: IMO
ISWG-GHG 20-3-9: Further considerations of the development of the IMO life cycle GHG assessment (LCA) framework.
Literature review on well-to-tank emissions from liquefied natural gas (LNG) - a case study.
Submitted by the Clean Shipping Coalition (CSC).
Executive Summary
This document shares the findings of a literature review and summary report on the well-to-tank (WtT) GHG intensity of liquefied natural gas (LNG).
Background
Although this document is focused on information relevant to the ongoing development of the LCA Guidelines, and more specifically on LNG and methane emission factors, it is also designed to support the co-sponsor’s broader objectives in respect of shipping's decarbonization and the implementation of the 2023 IMO Strategy on Reduction of GHG Emissions from Ships (2023 IMO GHG Strategy). It is essential that all three critical elements necessary for the successful implementation of the 2023 IMO GHG Strategy – the carbon intensity indicator (CII), the global fuel standard (GFS), and a GHG pricing mechanism – are underpinned by comprehensive LCA Guidelines and aligned in a way that ensures an integrated set of policies that effectively drive the just and equitable energy transition committed to in the strategy. This requires a strong, enforceable energy efficiency measure to drive down fuel burn and costs, a GFS ideally aligned with a pathway that will give a good chance of keeping warming below 1.5°C, LCA Guidelines which reward truly zero-emission fuels, and a GHG pricing mechanism that bridges the price gap between fossil and ZNZs, driving emission reductions and generating resources to incentivize the uptake of ZNZs and ensure a just and equitable transition (JET). Without such an integrated set of measures, achieving the 2023 IMO GHG Strategy’s emission and JET goals while avoiding unintended negative impacts in respect of the decarbonization of the wider economy will be all but impossible.
Introduction
Liquefied natural gas (LNG) has been proposed as an alternative marine fuel for the energy transition but is nearly all methane (CH4), a more potent greenhouse gas (GHG) than carbon dioxide (CO2). Methane is 28 times more powerful than CO2 at trapping heat on a 100-year period (also known as global warming potential, or GWP100), and 80 times more powerful on 20-year period (GWP20).
Methane emissions occur throughout the LNG life cycle, including production and extraction (fracking), liquefaction (turning methane gas into liquid), transport, storage, and combustion (as a fuel for ships or elsewhere). A critical source of life cycle methane emissions is its leakage directly to the atmosphere, known as methane slip.
This document summarizes the findings of an extensive literature review conducted by Energy and Environmental Research Associates (EERA) and also draws on a summary report based on that review. The EERA report aggregates GHG intensity values from the Canadian LNG value chain from the WtT, utilizing primary sources such as life cycle reports and emission inventory studies that provide emission rates for various greenhouse gas species. This analysis applies the same methodologies used in the prior FuelEU WtT LNG study, set out in document ISWG-GHG 17/3 (CSC) and underpins document MEPC 83/7/28 (Pacific Environment et al.). The study also includes a discussion of Canada’s national greenhouse gas report, and observations from methane satellites. The summary report, based on the EERA analysis, contextualizes the EERA findings and makes recommendations to ensure LNG and methane based fuels are accurately characterized to support decisions on the marine sector’s energy transition.
EERA report methods and sources
The EERA literature review, set out in annex 1 to this document, targeted emissions sources throughout the WtT supply chain, including natural gas production and extraction, processing, compression, transport (by pipeline, rail, and tanker), storage, and bunkering. Collected data include emissions of CO2, CH4, and N2O, along with CO2eq values, which express the cumulative impact of these emissions in terms of the global warming potential GWP of CO2. Canadian-focused studies often reported emissions in CO2eq without specifying the individual contributions of CO2, CH4, and N2O. Data were provided primarily based on 100-year (GWP100) potentials. Throughout the review, the focus lay on GWPs consistent with the IPCC AR5 and AR6 report and standardized values into CO2eq/MJ for ease of comprehension and comparison purposes.
IPCC. (2021). Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. https://docs.imo.org/Shared/Download.aspx?did=154044
https://saynotolng.org/wp-content/uploads/2025/08/report-summary-Canadian-LNG.pdf
Canadian GHG reporting program and the TROPOMI methane satellite
Canada is mandated to track and report GHG emissions from large industrial facilities through its Greenhouse gas reporting program (GHGRP), which relies on industry self-reporting. However, real time satellite measurements of methane emissions for the Canadian oil and gas sector taken by the Tropospheric monitoring instrument (TROPOMI) are substantially higher than those self-reported by industry. While assessments show that governments, such as the United States, are underreporting methane emissions by about 30%, analysis of publicly available data and satellite measurements indicate that Canada may be underreporting methane emissions by 54% (figure 1).
The WtT of Canadian LNG is higher than EU imports
The EERA assessment of the full WtT LNG value chain shows that GHG emissions (including CH4, N2O, and CO2) from Canadian LNG (28.58 gCO2eq/MJ, AR5 GWP100) are higher than the EU weighted average (e.g. 20.22 gCO2eq/MJ, AR5 GWP100) for EU imports.
https://open.canada.ca/data/en/dataset/a8ba14b7-7f23-462a-bdbb-83b0ef629823
https://www.transportenvironment.org/uploads/files/WTT_CO2e_LNG_Imports_TE.pdf
Due to the fact that Canada has no LNG export facilities to-date, methane emissions for Canadian LNG are projections, rather than measured real world values. For liquefaction - an emissions-intensive stage of the LNG chain - forecasted average Canadian methane emissions (3.48 gCO2eq/MJ) are far lower than those observed in the United States (12.55 gCO2eq/MJ). Although lower-than-average methane emissions from liquefaction may be expected for Canada under low-carbon scenarios (with facilities powered by renewable electricity), some forecasts, such as for the new Ksi Lisims facility (0.43 gCO2eq/MJ) are an order of magnitude lower, which raises questions about their real-world validity. These projections of low-carbon scenarios fail to account for limited transmission capacity and long upgrade timelines. Proposed LNG projects are at risk of relying on natural gas-powered electricity instead of discussed hydropower or renewable sources, as the combined electricity demand of all proposed LNG facilities far exceed the current supply.
Transporting Canadian LNG for export could further increase the fuel’s overall emissions profile, especially due to significant methane leaks. Analysis of the global LNG tanker fleet shows that around 90% of the LNG carrying capacity uses engine types that are known to leak unburned methane during operation. Emissions from those engines can be more than 45 times higher than other engine types. This means that much of the LNG being transported could release high levels of methane pollution in addition to emissions of CO2 from combustion. To accurately assess the full lifecycle emissions of LNG, it's essential to account for the type of engine used during transport and the leaks associated with it.
Conclusion and recommendations
Despite projecting low-carbon scenarios for its LNG facilities, Canadian LNG is no cleaner than LNG from other nations. Furthermore, recent political developments in British Columbia, Canada, have reversed requirements for low-carbon LNG facilities, meaning Canadian LNG could be even worse once export operations commence due to non-renewable sources of electricity being used during production. LNG is not a solution despite government and industry claims about its climate benefits, and Canadian-produced LNG will not solve this issue – it may even make it worse. Recommendations to the Working Group based on this assessment include:
Support realistic emissions accounting by backing default emissions factors based on actual measurement data, such as from the TROPOMI.
Acknowledge the full scope of methane’s impact, including short-term warming on a 20-year timescale and its health risks.
Oppose any policy that rewards LNG, especially if those rewards can be sold or traded. LNG should not be given preference in any framework or carbon pricing scheme.
Continue to champion a just and equitable transition – one that respects Indigenous Rights, and prioritizes clean energy, community well-being, and sustainable development.
Lock out LNG and other methane based marine fuels from the development and implementation of the IMO Net-Zero Framework and national clean transportation strategies and taxonomy.
The facilities' combined annual electricity demand (~43 TWh) is nearly 70% of British Columbia’s total electricity load: https://cleanenergycanada.org/expanding-b-c-lng-involves-risky-trade-offs-for-provinceselectricity-system-economy-and-climate-goals-report/
Action requested of the Working Group
The Working Group is invited to consider the information provided in this document, in particular the recommendations in paragraph 10, when revising the 2024 IMO LCA Guidelines, and take action as appropriate.
