DENVER — Scientists have found that oil and gas fields along Colorado’s Front Range mountains have been emitting three times more methane and nearly eight times more cancer-causing benzene than previously thought.
A study by the National Oceanic and Atmospheric Administration and partly supported by the Environmental Defense Fund is based on data gathered in 2012 from aircraft flying over drilling zones north of Denver.
For years, health and environmental officials have estimated air pollution primarily by measuring ground-level sources. State agencies didn’t begin monitoring methane until 2012, and the new study marks one of the first efforts to investigate pollution in the atmosphere above ground level.
“We’re trying to provide independent information on air pollution to help decision-makers and industry minimize their impacts,” lead scientist Gabrielle Petron told The Denver Post. “If the energy industry keeps expanding operations on the Front Range, we need to know we will have a good handling of the emissions.”
The oil and gas industry is the main source of methane in the United States, but industrial livestock operations and landfills also emit the gas. Researchers said they accounted for those numbers and subtracted.
Using an airplane, they found that oil and gas operations in Weld County emitted 19.3 tons of methane per hour, about 75 percent of total methane emissions in the area. The figure is about three times higher than an hourly average based on the Environmental Protection Agency’s annual estimates, which are drawn from industry reported emissions.
Petron, who is part of NOAA’s Cooperative Institute for Research in Environmental Sciences, also measured benzene emissions at about 380 pounds per hour, nearly eight times higher than the 50 pounds per hour estimated by the Colorado Department of Public Health and Environment. Researchers also measured volatile organic compound emissions, which contribute to ozone pollution, at 25 tons per hour — nearly double the state estimate of 13.1 tons.
New state rules are expected to reduce oil and gas industry methane pollution by 113,000 tons a year, according to officials at the CDPHE.
“We recognize that methane emissions are an issue,” said Garry Kaufman, deputy director of the department’s air pollution control division. “These new rules are just now going into effect, so the measurements in the study were gathered before they could have had any impact.”
He said the department knows about the new study but has not had a chance to thoroughly review it.
Colorado Oil and Gas Association representatives declined to comment, also saying they had not reviewed the study.
Using an airplane, they found that oil and gas operations in Weld County emitted 19.3 tons of methane per hour, about 75 percent of total methane emissions in the area.