国际能源署-评估液化天然气供应和减排方案的排放量（英）-2025_40页_2mb

Summary of "Assessing Emissions from LNG Supply and Abatement Options"

Core Content

This report by the International Energy Agency (IEA) provides an analysis of greenhouse gas (GHG) emissions associated with the liquefied natural gas (LNG) supply chain, excluding end-use combustion and other fuel-switching considerations. It estimates the emissions from production, processing, transmission, liquefaction, shipping, and regasification, and explores abatement options to reduce these emissions.

Key Findings

• Global LNG Exports: In 2024, approximately 550 billion cubic metres (bcm) of LNG were exported, representing nearly 15% of global natural gas consumption.
• LNG Supply Chain Emissions: The total GHG emissions from the LNG supply chain (excluding combustion at the point of use) are estimated at around 350 million tonnes of CO₂-equivalent (Mt CO₂-eq).
• Emissions Composition:
  • CO₂ emissions: Account for 70% of total supply chain emissions, primarily from energy use in liquefaction and processing.
  • Methane emissions: Account for 30% of total emissions, mainly from upstream leakage and incomplete combustion during flaring and gas treatment.
• Emissions Intensity: The global average emissions intensity of delivered LNG is ~20 g CO₂-eq/MJ, compared to ~12 g CO₂/MJ for natural gas overall. Emissions vary widely by region and supply route.
• Regional Variations:
  • Some LNG exporters in Africa and Southeast Asia have emissions intensities exceeding 26 g CO₂/MJ.
  • Norway has one of the lowest intensities at ~6 g CO₂/MJ.
• Upstream Methane Emissions: Estimated at ~2.5 Mt in 2024, with a global average upstream methane emissions intensity of ~0.6% (equivalent to ~3.4 g CO₂-eq/MJ).
• Naturally Occurring CO₂ Emissions: Approximately 25 Mt of CO₂ is extracted annually from feed gas, with ~20 Mt emitted to the atmosphere. The global average is ~1.2 g CO₂/MJ, though it varies significantly by region.
• CO₂ Capture Potential: Around 7 Mt of CO₂ can be captured annually from the LNG supply chain, with notable examples including ~0.75 Mt from Snøhvit in Norway and ~4 Mt from Gorgon in Australia.
• Flaring: In 2023, ~150 bcm of natural gas was flared globally, with ~3.5 bcm directly at LNG facilities. Flaring contributes to both CO₂ and methane emissions, adding ~0.3 g CO₂/MJ of feed gas.
• Liquefaction Emissions: The liquefaction process is the most energy-intensive part of the supply chain, emitting around 6 g CO₂-eq/MJ of LNG. CO₂ accounts for ~90% of these emissions, mainly from compressors and turbines.
• Shipping Emissions: In 2024, around 800 petajoules (PJ) of fuel was used for LNG transport, resulting in ~55 Mt CO₂ and ~10 Mt CO₂-eq of methane emissions. This represents ~10% of total international shipping emissions.
• Emissions Intensity by Route: The average emissions intensity for LNG shipping is ~3.5 g CO₂-eq/MJ, with the highest emitting 10% of journeys producing more than ten times the emissions of the lowest emitting 10%.
• LNG Carrier Types: Different types of LNG carriers have varying emissions intensities and methane slip rates. For example, ME-GI and X-DF carriers are more efficient and have lower methane slip.

Main Emissions Sources

• Upstream Production and Processing: Major source of methane emissions and CO₂ venting.
• Liquefaction: High energy use and significant CO₂ emissions from compressors and turbines.
• Shipping: Emissions from fuel combustion and methane slip, with variations based on fuel type, engine efficiency, and voyage distance.
• Regasification: Emissions from vaporisers and cold energy recovery systems.

Key Abatement Options

• Leak Detection and Repair: Reduces methane emissions from upstream operations.
• Electrification: Can lower emissions in upstream and liquefaction stages.
• Carbon Capture, Utilisation and Storage (CCUS): Offers potential for capturing CO₂ emissions in processing and liquefaction.
• Low-Emissions Fuels: Such as hydrogen or ammonia, can reduce emissions during shipping.
• Slow Steaming: Reduces fuel consumption and emissions during long-distance voyages.
• Efficiency Improvements: Including better turbine designs, advanced engine technologies, and improved containment systems.
• Trace-and-Claim Models: Provide transparency and traceability for emissions across the supply chain.

Uncertainty and Variability

• Emissions data for LNG is subject to high uncertainty due to differences in methodologies, system boundaries, and allocation approaches.
• Methane emissions can vary more than tenfold among sources, and CO₂ emissions vary by nearly threefold.
• The report highlights the need for consistent data reporting and transparent supply chain tracking to support accurate emissions assessments and abatement efforts.

Future Outlook

• The report serves as an interim analysis leading up to a 2026 publication that will provide a toolkit for LNG producers to reduce emissions.
• The IEA emphasizes the importance of methane regulations and emissions disclosure frameworks, such as the EU Methane Regulation and the CLEAN coalition, in driving reductions.
• As new LNG supply capacity is expected to increase by ~300 bcm between 2025 and 2030, the need for sustainable practices and emissions mitigation becomes even more critical.

Conclusion

This report underscores the significant environmental impact of the LNG supply chain, particularly in terms of methane and CO₂ emissions, and outlines key mitigation strategies to reduce these emissions. It highlights the importance of technological innovation, policy frameworks, and transparent data reporting in achieving a more sustainable LNG industry.