To realize immediate net climate benefits from the substitution of coal, diesel or gasoline with natural gas, the rate of methane loss from the entire natural gas supply chain must be less than a few percent. Since the natural gas supply chain consists of a vast network of infrastructure with countless emission sources, quantifying the total methane emissions from the U.S. natural gas supply chain represents a major challenge.  In this study, facility-level methane emissions measurements were conducted at 130 natural gas gathering facilities and processing plants in 13 U.S. states.  The results from the field campaign were combined with state and national facility databases in a Monte Carlo simulation to estimate methane emissions from U.S. natural gas gathering and processing operations. Total annual methane emissions of 2,421 (+245/-237) Gg were estimated for all U.S. gathering and processing operations, representing a methane loss rate of 0.47% (±0.05%) when normalized by annual methane production.  The methane emissions from gathering facilities were eight times that of previous EPA Greenhouse Gas Inventory (GHGI) estimates.  In April 2016, the EPA GHGI was updated based directly on the results of this study and gathering operations are now estimated to account for 27% of all methane emissions from natural gas supply chain.  In 2018, the results of this study were incorporated into a new national methane emissions model recently published in Science, which suggests that the total methane loss rate from all U.S. natural gas operations is 2.3% in comparison to the current EPA estimate of 1.4%.  


  1. Roscioli, J. R., et al (2015). Measurements of methane emissions from natural gas gathering facilities and processing plants: measurement methods.  Atmos. Meas. Tech., 8, 2017-2035.
  2. Mitchell, A.L., et al. (2015). Measurement of methane emissions from natural gas gathering facilities and processing plants: measurement results. Environ. Sci. Technol., 49 (5) 3219-3227.
  3. Marchese, A.J., et al. (2015). Methane emissions from United States natural gas gathering and processing. Environ. Sci. Technol., 49 (17), pp. 10718-10727. 
  4. Lyon, D., et al. (2015). Constructing a spatially resolved methane emission inventory for the Barnett Shale region.   Environ. Sci. Technol., 49 (13), pp. 8147–8157. 
  5. Zavala-Araiza, D., et al (2015).  Reconciling divergent estimates of oil and gas methane emissions.  Proceedings of the National Academy of Science, 112 (51) 15597-15602.
  6. Kleinman, M. T., et al. (2016).  Emissions from oil and gas operations in the United States and their air quality implications: critical review discussion.  Journal of the Air & Waste Management Association, 66 (12), pp. 1165-1170. 
  7. Zavala-Araiza, D, et al. (2017). Super-emitters in natural gas infrastructure are caused by abnormal process conditions.  Nature Communications, 8:14102. 
  8. Alvarez, R.A., et al. (2018). Assessment of methane emissions from the U.S. oil and gas supply chain.  Science. 361: 6398, pp. 186-188.

Sponsors and Industrial Partners

Environmental Defense Fund, Anadarko Petroleum, Access Midstream, Williams, SWN, Hess, DCP Midstream 


$1.9 Million

Study Team

Colorado State University (co-PI Dan Zimmerle)

Carnegie Mellon University (Allen Robinson)

Aerodyne Research (Scott Herndon)


GSI Environmental Inc.