2025-03-24-未来能源研究所-解读能源部关于美国液化天然气出口的报告（英）_9页_669kb

Summary of the Department of Energy's Report on US Liquefied Natural Gas Exports

1. Introduction

The United States has become the world's largest LNG exporter, with exports rising from less than 0.1 Bcf/d in 2015 to nearly 12 Bcf/d in 2023. In December 2024, the Department of Energy (DOE) published a report assessing the consequences of continued LNG export growth through 2050. The Trump administration lifted a prior pause in approvals and extended public comment periods. This report, along with S&P Global's analysis, examines the economic and environmental impacts of increased US LNG exports, focusing on methane emissions, domestic gas prices, global demand projections, and substitution effects.

2. Methane Emissions from the US Supply Chain

Methane emissions are a key concern in the debate over LNG exports. The DOE assumes a low methane leak rate of 0.56 percent, based on engineering models and data from the Environmental Protection Agency. However, empirical studies using remote sensing techniques have found much higher leak rates, such as 2.95 percent in the Permian basin and 9.63 percent in some regions.

The report highlights that the DOE's assumption does not reflect the economic reality of gas markets. The marginal gas supply that responds to increased LNG export demand is more likely to come from low-leak regions like the Appalachian basin, with an estimated effective methane leak rate of around 1.7 percent. This value is significantly higher than the DOE's but lower than the 2.8 percent used in the Howarth (2024) study. The implications of this discrepancy are substantial for both studies' climate impact assessments.

3. Effects on US Natural Gas Prices

The DOE report estimates that a 32.6 Bcf/d increase in LNG exports would raise US wholesale gas prices at Henry Hub by about 31 percent, from $3.53 to $4.62/MMBtu. However, the RFF working paper by Brian Prest suggests a much higher price increase of about 2.5 percent per Bcf/d of exports, which is more than double the DOE estimate. This discrepancy arises because the DOE model assumes a high supply elasticity, which is inconsistent with real-world data.

Prest estimates a long-run gas supply elasticity of less than 0.3, suggesting that the actual price increase would be more significant than the DOE's projection. The higher price increase would lead to reduced domestic gas consumption, thereby lowering CO₂ emissions from combustion.

4. Future Global Natural Gas Demand and US LNG Exports

The DOE report models 20 scenarios to estimate future global LNG demand, assuming that the Paris Agreement commitments are met. It forecasts that US LNG export capacity of 43.6 Bcf/d is sufficient to meet demand in all but the "business-as-usual" scenario. By 2030, US LNG supply is expected to rise to 19 Bcf/d, and by 2040, to 39 Bcf/d.

S&P Global projects a much higher growth in US LNG exports, estimating a 270 percent increase from 6 Bcf/d in 2020 to 24 Bcf/d in 2030. Its projection is closer to the current approved export capacity, suggesting that further permitting delays could reduce potential economic gains. By 2040, S&P Global anticipates that the US role in the global LNG market will remain largely unchanged, whereas the DOE predicts a significant increase in supply.

5. What Do US LNG Exports Replace?

The environmental impact of US LNG exports depends on what they substitute for globally. The DOE analysis shows that 37 percent of US LNG exports displace natural gas from other countries, 13 percent increase global gas consumption, 13 percent displace coal, 6 percent displace oil, and 25 percent displace zero-emission sources like renewables and nuclear.

S&P Global estimates a similar pattern but with a greater displacement of coal and oil and a smaller substitution of non-fossil sources. It also does not account for the rebound effect of increased gas supply leading to higher energy consumption, which could increase GHG emissions. The DOE report, however, estimates that the cumulative increase in CO₂-equivalent emissions from US LNG exports between 2020 and 2050 would be about 710 MMT, representing only 0.05 percent of global emissions.

6. Key Conclusions

• DOE underestimates methane emissions and overestimates the price elasticity of gas supply, leading to less accurate climate impact assessments.
• Substantial uncertainty remains regarding long-term global LNG demand, influenced by economic factors and environmental policies.
• LNG may substitute for both high- and low-carbon energy sources, with unclear net effects on global emissions.
• The business-as-usual scenario is likely to result in higher global emissions, though the impact is relatively small in the context of global totals.
• The DOE's pause on permits may have overhyped the potential impacts of LNG exports, as demand is expected to exceed approved capacity only by 2040 or later, depending on global policy shifts.
• Major Asian countries are key long-term demand sources, and their shift toward cleaner energy could weaken the business case for new LNG exports.

7. References

• Alvarez et al. (2018) on methane emissions in the US oil and gas supply chain.
• Chen et al. (2022) on methane emissions in the Permian basin.
• Howarth (2024) on the carbon intensity of US LNG.
• Lu et al. (2023) on methane emissions from US oil and gas fields.
• Omara et al. (2018, 2022) on methane leak rates from US well sites.
• Prest (forthcoming) on the marginal methane molecule and its implications for gas supply and emissions.
• Sherwin et al. (2024) on methane leak rates from aerial measurements.
• Yergin et al. (2024) on the impact of US LNG exports.
• Zhang et al. (2020) on methane emissions from the Permian basin using satellite data.