Methane Emissions from Natural Gas Production Sites in the United States: Data Synthesis and National Estimate

Methane Emissions from Natural Gas Production Sites in the United States: Data Synthesis and National Estimate

Natural gas

Methane

Gas emissions

Gas industry

Environmental Protection Agency

Magnesium compounds

Natural gas well production

We used site-level methane (CH4) emissions data from over 1000 natural gas (NG) production sites in eight basins, including 92 new site-level CH4 measurements in the Uinta, northeastern Marcellus, and Denver-Julesburg basins, to investigate CH4 emissions characteristics and develop a new national CH4 emission estimate for the NG production sector. The distribution of site-level emissions is highly skewed, with the top 5% of sites accounting for 50% of cumulative emissions. High emitting sites are predominantly also high producing (>10 Mcfd). However, low NG production sites emit a larger fraction of their CH4 production. When combined with activity data, we predict that this creates substantial variability in the basin-level CH4 emissions which, as a fraction of basin-level CH4 production, range from 0.90% for the Appalachian and Greater Green River to >4.5% in the San Juan and San Joaquin. This suggests that much of the basin-level differences in production-normalized CH4 emissions reported by aircraft studies can be explained by differences in site size and distribution of site-level production rates. We estimate that NG production sites emit total CH4 emissions of 830 Mg/h (95% CI: 530-1200), 63% of which come from the sites producing 4 emissions estimate is 2.3 times higher than the U.S. Environmental Protection Agency's estimate and likely attributable to the disproportionate influence of high emitting sites. 2018 American Chemical Society.

12915-12925

21

52

Environmental Science and Technology

2018

Omara, Mark

Zimmerman, Naomi

Sullivan, Melissa R.

Li, Xiang

Ellis, Aja

Cesa, Rebecca

Subramanian, R.

Presto, Albert A.

Robinson, Allen L.

journalArticle

0013936X

10.1021/acs.est.8b03535