Study finds natural gas climate advantage nixed by methane loss

Methane leakage from the U.S. oil and natural gas supply chain is 60% higher than EPA estimates, according to a new study (Science 2018, DOI: 10.1126/science.aar7204). The multiinstitution effort led by Ramón A. Alvarez of the Environmental Defense Fund attempted to resolve differences in methane emissions estimates. The researchers coupled ground-based, facility-specific measurements with aircraft observations in nine basins that account for some 30% of U.S. gas production. The study found that methane loss is 2.3% of gross U.S. natural gas production. Natural gas has been touted as cleaner in terms of climate than coal when burned to generate electricity, but it is a more potent greenhouse gas than CO₂. The study concludes that over the first 20 years after emission, natural gas loses its climate advantage because the impact of methane leakage offsets the climate benefit of substituting natural gas for coal. Most of the newly identified leaks came from natural gas production operations, particularly leaks from vents and hatches in tanks holding hydrocarbon liquids.