CHEYENNE, Wyo. — Three separate satellites detected a large methane plume stretching about 4.7 miles north of Douglas in December, according to analysis by the United Nations’ International Methane Emissions Observatory.
The errant methane — a valuable commodity and potent greenhouse gas — came from the Douglas Gas Plant, a natural gas processing plant owned and operated by Tallgrass Energy. The company purposely vented the gas over the course of two days — Dec. 6-7 — because it discovered traces of oxygen in a gas pipeline, creating a potential hazard, according to documents Tallgrass submitted to the Wyoming Department of Environmental Quality and obtained by WyoFile.
The company played by the book in conducting the gas releases for safety purposes, according to Wyoming DEQ officials. It notified the agency soon after it began venting operations and consulted with DEQ to ensure that wind and other atmospheric conditions would sweep the gas up and away from the town of Douglas, posing no risk to the public, DEQ Public Information Supervisor Kimberly Mazza said.
The company’s actions do not appear to violate its state permits, Mazza added.
Still, a local emergency management official said his office should have been notified instead of learning about the event long after the fact. And there’s a potential discrepancy in reports of the volume of gas that was released.
In its reporting to DEQ, Tallgrass estimated it had released a total 152.80 mcf (thousand cubic feet) of methane — or a range of 2.1 to 2.6 metric tons — into the atmosphere, according to a conversion calculation by the Environmental Defense Fund. It reported an additional 1.34 metric tons of volatile organic compounds in the releases.
However, a Jan. 31, 2023 Bloomberg News article cites analysis by the United Nations’ IMEO that estimated the release of gas “at a rate of 76 to 184 metric tons an hour” in order to create the plume observed by satellites. Tallgrass reported it had conducted five separate releases totalling about 6.5 hours of venting at various pressures. If the IMEO calculation is correct, Tallgrass could have vented approximately 845 metric tons of methane. That’s equal to the greenhouse gas emissions from 4,552 gasoline-powered vehicles driven for a year, according to a U.S. Environmental Protection Agency greenhouse gas calculator.
Due to the nature of the orbiting satellites, they could not capture the full event, the IMEO said. Still, the IMEO confirmed with WyoFile this week that it stands by its analysis.
DEQ is investigating whether there is a discrepancy, Mazza said. The agency has asked Tallgrass to double-check its calculations and will use its own air-quality-monitoring systems to determine the actual volume vented. Regarding the IMEO’s calculations, Mazza said the agency cannot verify such “third-hand information.
“We don’t have accuracy on that type of information,” she added, “so we’re looking into it.”
Converse County Emergency Manager Russ Dalgarn didn’t learn about the intentional methane venting, he said, until people began sharing the Bloomberg article with him. Neither Tallgrass or DEQ gave him a heads up, he said.
After making inquiries with Tallgrass and DEQ officials, Dalgarn was assured there was never a public safety risk, he told WyoFile. He also learned that, technically, neither Tallgrass or DEQ were obligated to notify local emergency managers.
“DEQ is not required to contact [local officials] because it wasn’t an emergency,” Mazza confirmed with WyoFile.
Still, Tallgrass, “as a good neighbor,” should have given his office notice, Dalgarn said. After speaking with Tallgrass officials this week, the company has agreed to update its notification protocol to include the local emergency management office in such a case.
“I think we have a good relationship with Tallgrass other than this event,” Dalgarn said. “Somehow we got missed in the communications.”
Though there were no apparent regulatory violations or fire or human health risks, the situation underscores the need for DEQ to update how it regulates methane emissions, Powder River Basin Resource Council Community Organizer Katherine Stahl said.
“First, we would like for Tallgrass to reconcile their report that they gave to the DEQ with the estimates of the scientists at the International Methane Emissions Observatory,” Stahl said.
DEQ should also require Tallgrass, and other gas facility operators, to install vent meters to ensure accurate reporting on emission volumes, she said. Overall, there needs to be a robust monitoring and reporting system in place — particularly for facilities that are close to communities.
“We would like to see better reporting and more consistent reporting and transparency on the part of these companies,” Stahl said.
Industrial methane emissions are also a significant contributor to human-caused climate change. Over a 20-year period, methane is 80 times more potent than carbon dioxide as a greenhouse gas, according to the United Nations Environment Programme.
That’s one reason the U.S. Environmental Protection Agency is updating its rules and regulations regarding methane emissions in the oil and gas industry.
“Oil and natural gas operations are the nation’s largest industrial source of methane, a highly potent climate pollutant that is responsible for approximately one-third of current warming resulting from human activities,” according to an EPA fact sheet. “These operations are also a leading source of other harmful air pollutants, including smog-forming volatile organic compounds (VOCs) and air toxics such as benzene.”
The EPA’s proposed updates, among other things, would establish a Super-Emitter Response Program. It would empower the public to use various detection and monitoring data to alert the EPA of potential emission hotspots. The program would also allow federal and state regulators to better utilize information such as the satellite data obtained and analyzed by the IMEO, according to Jon Goldstein, senior director of regulatory and legislative affairs at the Environmental Defense Fund.
The IMEO has used satellite imagery to detect several large industrial methane emission spots around the globe, and it’s an important tool that EPA and other regulatory bodies should use, he said.
“I think what these [satellite] detections are showing is the important role that a program like that could play in verifying reports and taking enforcement actions if necessary to get problems like this fixed,” Goldstein said.
This article was originally published by WyoFile and is republished here with permission. WyoFile is an independent nonprofit news organization focused on Wyoming people, places and policy.