Researchers from University of Colorado, NOAA Home in on Sources of Front Range Methane

March 27, 2019 GMT

The Cooperative Institute for Research in Environmental Sciences has developed a way to differentiate methane emissions from cows and those from oil and gas operations, which researchers say will help farmers, oil companies and regulators make more informed decisions about air pollution mitigation.

CIRES, which is a cooperative effort between the University of Colorado and the National Oceanic and Atmospheric Administration, this week announced it has developed a method by which “chemical tracers” unique to different methane sources can be seen clearly.

“Methane is an important greenhouse gas,” CIRES Ph.D. student Natalie Kille said in a news release. “But it has a high global concentration, so it can be challenging to see its specific sources.”

Based on measurements taken in 2015, researchers determined that most of the methane produced in the Denver-Julesburg Basin comes from the oil and gas industry, with the cattle industry making an important, but minor contribution.

Methane is a greenhouse gas that traps heat in the atmosphere, according to the Environmental Protection Agency. It also is emitted during the production of coal and by the decay of organic waste in landfills.

Tracers are chemicals unique to a specific source, researchers said. For example, ethane is a good tracer for oil and gas operations, and ammonia is more often associated with cattle farms. Oil and gas and cattle operations are often close to one another geographically, and it can be difficult to tell the methane sources apart.

Researchers set up ground-level instruments across the Front Range to measure the air above and take “snapshots” of chemical concentrations for methane and tracer chemicals in columns of air reaching to the top of the atmosphere. The team used the information to remove the methane background and bring the tracers to the forefront.

Researchers also used two additional instruments — a portable spectrometer developed by the Karlsruhe Institute of Technology in Germany and a solar occultation flux instrument developed by CIRES fellow Rainer Volkamer — in Eaton.

“These two instruments were set up side-by-side in Eaton within what we call the ‘methane dome’ of the Denver-Julesburg Basin,” Volkamer said in the news release. “In the areas where natural gas and cattle farming sites are present, methane is emitted and mixes together from both sources, forming a bubble inside the atmospheric boundary layer that expands and contracts as if its breathing.”

Researchers set up two more of the Karlsruhe Institute of Technology instruments outside the dome in Boulder and Westminster to help calculate the background concentration of methane.

They hope to study methane emissions over several seasons to see how they change over time.

The study was funded in part by the National Science Foundation, the Helmholtz Association of German Research Centres and the Colorado Department of Public Health and Environment.

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