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Summary of LNG Emissions and Abatement Options

Core Content

This report by the International Energy Agency (IEA) provides an assessment of greenhouse gas (GHG) emissions from the liquefied natural gas (LNG) supply chain, including production, processing, transmission, liquefaction, shipping, and regasification. It excludes emissions from end-use combustion and does not cover other potential sources like biomethane or e-methane.

The report estimates that in 2024, around 550 billion cubic metres (bcm) of LNG were exported globally, representing just under 15% of global natural gas consumption. Over the next five years, new LNG supply capacity is expected to add nearly 300 bcm annually.

Main Emissions Sources

Greenhouse Gas Emissions Intensity

• Total GHG emissions from LNG supply chain: ~350 million tonnes of CO₂-equivalent (Mt CO₂-eq) in 2024.
• Composition of emissions:
  • 70% is CO₂ (from energy use in liquefaction and processing).
  • 30% is methane (from leaks, venting, and incomplete combustion).
• Global average emissions intensity: ~20 g CO₂-eq/MJ.
• Regional variations:
  • Some African and Southeast Asian exporters: >26 g CO₂-eq/MJ.
  • Norway: <6 g CO₂-eq/MJ.
• Key factors affecting variation:
  • Methane emissions during upstream production.
  • Energy use and CO₂ venting in processing and liquefaction.
  • Distance and efficiency of shipping routes.

Methane Emissions

• Total methane emissions from LNG feed gas: ~2.5 Mt in 2024.
• Global average upstream methane emissions intensity: ~0.6% (3.4 g CO₂-eq/MJ).
• Variation among sources:
  • Best performers: 100 times lower than worst performers.
• Additional methane emissions from LNG facilities:
  • ~0.1 Mt from incomplete combustion.
  • Adds ~0.2 g CO₂-eq/MJ to feed gas emissions.

CO₂ Emissions from Energy Use

• Global average CO₂ emissions intensity from energy use: ~2.1 g CO₂/MJ.
• Regional differences:
  • Browse Basin, Australia: ~6.3 g CO₂/MJ (mainly from Ichthys LNG).
  • Russia: <0.2 g CO₂/MJ.
• CO₂ emissions from LNG supply chain:
  • ~25 Mt of naturally occurring CO₂ is extracted annually.
  • ~20 Mt is emitted to the atmosphere.
• CO₂ capture capacity:
  • ~7 Mt CO₂ per year can be captured from LNG supply.
  • Key projects: Snøhvit (Norway), Ras Laffan (Qatar), Gorgon (Australia).

Flaring

• Global flaring in 2023: ~150 bcm of natural gas, mostly from oilfields.
• Flaring at LNG facilities:
  • ~2.5 bcm flared directly.
  • ~1 bcm flared from upstream assets.
• CO₂ emissions from flaring:
  • ~6 Mt from flaring.
  • ~0.3 g CO₂/MJ of feed gas.
• Methane emissions from flaring:
  • ~0.1 Mt from upstream.
  • ~0.1 Mt from LNG facilities.
  • Adds ~0.2 g CO₂-eq/MJ to feed gas emissions.

Liquefaction

• Most energy-intensive process in the LNG supply chain.
• Average CO₂-eq emissions intensity: ~6 g CO₂-eq/MJ.
• Energy use:
  • ~8-10% of the energy content of feed gas.
  • Primarily for cooling natural gas to -162°C.
• Emissions sources:
  • ~90% of CO₂ emissions from mechanical drive turbines.
  • Smaller contributions from flaring and naturally occurring CO₂.
• Methane emissions:
  • Occur from leaks, venting, and incomplete combustion.
  • Vary with technology and operational practices.
  • Older technologies are less efficient than newer ones.

Shipping

• Number of LNG carriers: ~760 in operation, with ~250 under construction.
• Annual round-trip voyages: ~7,000.
• Emissions from shipping:
  • ~55 Mt CO₂ and ~10 Mt CO₂-eq of methane.
  • ~3.5 g CO₂-eq/MJ of LNG transported.
• Key factors influencing emissions:
  • Distance: Average ~10,000 km, but can vary from 500 km to 27,000 km.
  • Fuel use: Boil-off gas, heavy fuel oil, and marine gas oil.
  • Engine type and performance: Four-stroke engines (DFDE, TFDE) have higher methane slip (4-6%) compared to two-stroke engines (ME-GI, X-DF) with lower methane slip (0.2-3%).
  • Ship speed and operational conditions also affect emissions.

Abatement Options

• Methane emission reduction:
  • Improve leak detection and repair.
  • Use advanced technologies to reduce venting and flaring.
• CO₂ emission reduction:
  • Increase energy efficiency in liquefaction and processing.
  • Electrify key processes.
  • Deploy carbon capture, utilisation, and storage (CCUS).
• Shipping improvements:
  • Transition to more efficient ship designs (e.g., ME-GI and X-DF).
  • Use of membrane-type containment systems.
  • Adoption of cleaner fuels and better operational practices.

Conclusion

This report serves as a foundation for future analysis and provides a toolkit for LNG producers to reduce emissions. It highlights the importance of regional differences, the role of methane and CO₂ in the supply chain, and the need for improved data collection and transparency. The findings will be integrated into a 2026 report offering more detailed guidance for emission reduction in the LNG sector.