Methane still leaking at Weld oil, gas sites

Pollution continues to pour from oil and gas facilities in Weld County two years after scientists gathered data from the region that showed dramatically higher levels of the greenhouse gas methane and toxic chemical benzene.

In 2012, researchers at the Boulder-based Cooperative Institute for Research in Environmental Sciences found that oil and gas operations leaked almost three times as much methane and seven times as much benzene as had been previously estimated.

That initial data set, collected from an airplane during a two-day period in May 2012, has since expanded and has continued to document significantly higher levels of methane and benzene releases over a longer period of time than were previously documented.

“In subsequent studies, we have done many more days,” said Colm Sweeney, the study’s principal investigator and an atmospheric scientist at the Cooperative Institute for Research in Environmental Sciences. “We find in these subsequent studies that we’re getting consistency, whether it’s two days or 10 days: We’re getting repeatable results in similar environments.”

CIRES is a joint institute of the University of Colorado-Boulder and the National Oceanic and Atmospheric Administration.

In May 2012, researchers led by atmospheric scientist Gabrielle Petron found that oil and gas facilities leaked 19 tons of methane hourly in Weld County, an amount almost three times greater than estimated by the Environmental Protection Agency’s Greenhouse Gas Reporting Program.

The emissions represented 75 percent of total methane pollution in the region during that two-day period. Researchers determined oil and gas activity’s share by subtracting estimates of pollution caused by other sources, including animal feedlots, landfills and wastewater treatment plants.

How much a set of new, ground-breaking emission rules enacted by the state of Colorado in April will reduce the release of these gases isn’t clear yet, although state regulators have estimated that they will be reduced by at least one-third.

Oil industry officials aren’t disputing the new findings, although they question how much can be directly tied to oil and gas facilities.  Encana Corp. (NYSE: ECA) (TSX: ECA) spokesman Doug Hock said the new air-quality rules supported by the company as well as Anadarko Petroleum Corp. (NYSE: APC) and Noble Energy Inc. (NYSE: NBL) passed recently by the state will help address the air pollution issues tied to oil and gas development.

The new rules require leak detection from tanks, pipelines and other drilling and production processes, using devices such as infrared cameras.

Hock noted, however, that CU’s aerial study cannot accurately measure pollution coming from sources on the ground such as oil and gas facilities.

“It doesn’t directly indicate where the emissions are coming from,” he said.

He said a yearlong study funded by the Environmental Defense Fund as well as Encana and other oil and gas companies and conducted by researchers at the University of Texas-Austin found that total emissions measured directly from oil and gas facilities were lower and in line with EPA estimates.

Sweeney acknowledged that direct measurements of individual oil and gas facilities were more difficult to obtain from the air. He also said that his study was limited because it could not pinpoint individual leaks, but noted that his study’s air measurements give a broader sense of emissions from all facilities.

CU scientists plan to do further research using balloons and aircraft as well as mobile laboratories and other ground-based equipment on motor vehicles, power plants, industrial activities, agriculture, wildfires and other sources.

Stan Dempsey, president of the Colorado Petroleum Association, said he has not reviewed the study’s findings, but oil companies that are members of the lobbying organization are eager to do so.

“Are we absolutely sure that all those methane emissions come from oil and gas?” he said. “What the state hasn’t done is fully investigate all the other sources of methane out there.”

Doug Flanders, director of policy and external affairs for the Colorado Oil & Gas Association, said he could not comment on the study’s results because the industry group has not had a chance to review it. He pointed out, however, that the study was done before Colorado’s new air rules went into effect. 

The EPA, which maintains an inventory of greenhouse-gas emission reports, could not explain the discrepancies in emission amounts.

As part of the CU study, researchers also detected 25 tons of volatile organic compounds, which can contribute to ozone pollution, compared with a state estimate of 13.1 tons. Colorado’s Front Range has exceeded federal ozone standards since 2007.

Researchers also found 380 pounds of benzene pollution per hour versus a state estimate of 50 pounds per hour. Car and truck tailpipes emit benzene, but findings suggest that oil and gas operations also may be a significant source of the toxic chemical, which can cause cancer.

The study, published in the Journal of Geophysical Research: Atmospheres, builds on previous findings by the researchers about pollution caused by oil and gas activity along Colorado’s Front Range. Petron and her team found during their research from 2008 to 2010 that methane pollution was twice as high as estimates from state and federal agencies when Weld had about 14,000 oil and gas wells. Today, Weld has more than 21,100 wells.

Will Allison, director of the state Air Pollution Control Division, said the state agency is assessing the study to determine the difference between its numbers and the state and EPA emissions inventories. He said it’s common for differences to occur in studies done from the air and ones conducted from the ground. Other reasons for the gap could include that the state and EPA are underestimating emissions in Weld or that the CU and NOAA study included emissions from outside Weld that were being attributed to sources in the county.

Still, Allison was not surprised by the higher levels of pollution detected by CU researchers. The findings were consistent with previous results indicating higher methane levels in areas with oil and gas development, he said.

The study justifies the state’s new rules passed in February reducing pollution, including benzene, ethane and toluene emissions, he said.

“We agree that methane leakage is an important issue and we believe that there are some common-sense, cost-effective things folks can do to limit methane leakage and other (volatile organic compound) emissions,” Allison said. “That’s what our rulemaking was targeting.”

Steve Lynn can be reached at and 303-630-1968 or 970-232-3147. Follow Lynn on Twitter at @SteveLynnBW.

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