Methane Emissions Estimate from Airborne Measurements in Uintah Basin

Methane Emissions Estimate from Airborne Measurements in Uintah Basin

Anna Karion and Colm Sweeney

The American Geophysical Union has accepted an article for publication, Methane emissions estimate from airborne measurements over a western United States natural gas field, from lead authors Anna Karion and Colm Sweeney based on joint research by the Cooperative Institute for Research in Environmental Sciences (CIRES), the National Oceanic & Atmospheric Administration’s Earth System Research Laboratory (NOAA/ESRL), and the University of California, Davis.

The paper focuses on methane emissions in the Uintah basin, Utah and is the first study to use atmospheric measurements to estimate total methane emissions in this region.  The study concludes that CH4 emissions from oil and gas production during the study period are likely to have been significantly greater than predicted by the available inventories.

Key elements from the article include:

  • Natural gas  has the potential to be an efficient energy source because its combustion produces more energy per carbon dioxide (CO2) molecule formed than coal or oil (177% and 140% respectively) [US Department of Energy, Energy Information Administration, 1999].
  • Leakage of natural gas to the atmosphere from the point of extraction to the point of consumption reduces the climate benefits of natural gas because the major component of natural gas is CH4, a greenhouse gas that is 25 times more potent than CO2 over a 100-year time horizon [IPCC, 2007].
  • If more than 3.2% of natural gas  is emitted to the atmosphere on its way from the point of extraction to a gas-fired power plant, the electricity produced will have a larger immediate climate impact than that from a coal-fired plant. [Alvarez et al., 2012].
  • A critical gap in determining the climate impact of the recent increase in US natural gas production is the lack of accurate and reliable estimates of associated emissions. Methane (CH4) emissions from natural gas production are not well quantified, and have the potential to offset the climate benefits of natural gas over other fossil fuels.
  • This study used atmospheric measurements made from aircraft in a mass balance calculation to obtain a one-day snapshot of regional CH4 emissions from a natural gas and oil production field in Uintah County, Utah.
  • This study demonstrates the mass balance technique as a valuable tool for estimating emissions from oil and gas production regions, and illustrates the need for further atmospheric measurements to determine whether the results can be extrapolated to annual emissions and to better assess CH4 emissions inventories.

The aircraft used in the study, a Mooney M20M-TLS, was instrumented with an in situ Picarro G2301-m Flight Analyzer—a carbon dioxide (CO2), methane (CH4) and water vapor (H2O) cavity ring-down spectrometer. An August 5, 2013 news post on the CIRES website summarizes the research and its findings.