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Scientists spot huge methane cloud over Converse County

Via Wyoming News Exchange

DOUGLAS — A nearly five-mile-long cloud of methane gas hung over rural Converse County in early December, the result of five gas venting releases Dec. 6-7 by Tallgrass Energy at its Douglas Gas Plant six miles north of town on WYO59.

In Wyoming’s top energy production location – Converse County – methane gas venting (flaring) normally wouldn’t be a cause for concern.

However, this methane release made national news Jan. 31 when Bloomberg reported online that three satellites observed a big plume of the potent planet-warming gas over Wyoming. The cloud was attributed to the Tallgrass plant.

According to the Bloomberg article, “It all started with an apparent mistake. Alarms at Tallgrass Energy’s Douglas Gas Plant in Wyoming were triggered by high oxygen levels after a maintenance project didn’t go as planned. The operator told regulators it vented a total of about 2.1 metric tons of methane in five separate safety releases.”

But, Bloomberg reported, a satellite observed a methane cloud 4.6 miles long emanating from the plant, which scientists estimated was spewing planet-warming gas at a rate of 76 to 184 metric tons an hour.

Methane is a colorless, odorless and highly flammable gas. It is composed of carbon and hydrogen and is a potent greenhouse gas, meaning it affects climate change by contributing to increased warming, according to the U.S. Environmental Protection Agency.

That huge methane cloud drew the attention of scientists at the International Methane Emissions Observatory (IMEO).

“It’s highly unlikely the volume reported by the operator could account for the emissions rate observed by the satellite coming from the facility,” Manfredi Caltagirone, head of IMEO, said according to Bloomberg.

Because NASA’s Landsat 9 satellite orbits the Earth, the researchers who studied the data couldn’t verify how long the release lasted or calculate the total amount of methane spewed, but said it was likely to be far higher than what was reported, according to Bloomberg.

Tallgrass Energy Vice President of Government Affairs Steven Davidson told the Budget Feb. 11 that the methane gas release was “an intentional event done to ensure the safe and reliable operations of our facilities and conducted in accordance with regulatory requirements.”

A company statement said Tallgrass employs about 200 people in Wyoming, with 30 employees working daily in the Douglas area, and community and employee safety is paramount.

Davidson did not directly reply to questions addressing the discrepancies in the amounts of methane released reported by his company to Wyoming’s Department of Environmental Quality (DEQ) compared to the larger volumes of methane gas estimated by IMEO scientists.

However, he did emphasize that the methane gas release was, “ . . . an intentional, controlled event performed in response to a singular safety concern. The event did not pose any imminent respiratory or particulate related health concerns.”

Powder River Basin Resource Council (PRBRC) Oil & Gas Community Organizer Katherine Stahl confirmed in an email to the Budget that “. . . the amount of methane vented (was reported) as 2.1 metric tons, but scientists at the International Methane Emissions Observatory estimated a release rate of 76-184 metric tons per hour.”

Stahl contended there are health concerns with such a large methane release.

“The vented gas produced a nearly five-mile-long methane cloud over Douglas, which is concerning due to the fact that hazardous volatile organic constituents (VOCs) are always released alongside vented methane. While methane disperses into the atmosphere, where it contributes to planetary warming by trapping excess heat, VOCs are heavier and contribute to local health impacts,” Stahl wrote in the email.

Converse County Emergency Management (CCEM) Coordinator Russ Dalgarn said his agency had not received any alerts from Tallgrass regarding the methane release.

“The first I heard about a release was on Jan. 3 . . . from a Bloomberg reporter named Aaron Clark. He called me from his office in China and was asking if I knew the origin of the release. I did not at that time. Based on his questions I felt this release could have possibly come from a gas well, as there were no specifics to the release at that time,” Dalgarn said.

Dalgarn said that if his office had been contacted either during the release or immediately after, he would have determined wind speed, direction and if downwind monitoring was in place.

“If they did not have (monitoring) in place they would have been requested to do so. There are a lot of variables in a gas release. If the levels, when mixed with the air temperature, density and wind, met requirements to notify downwind residents of the release, the county would have put out a shelter-in-place recommendation for the people downwind in the affected area,” he said.

As of Feb. 10, Dalgarn said he had not spoken with Tallgrass.

Considering that Converse County is such an energy hot spot, several entities have voiced their concerns not only with possible health repercussions in situations like this one, but with accurate reporting of releases and other regulatory requirements.

On the chance that energy companies are not accurately reporting methane gas releases, it is Wyoming DEQ’s responsibility to watchdog them and hold them accountable, said Maria Katherman, a Douglas resident and Powder River Basin Resource Council board member.

“We have these companies that provide our tax base, employment, but that does not mean that we should not let them be honest about what is going on. If they released more than they said they did, then the responsible thing to do as a corporate citizen is to alert everyone around them. If they released more than they reported to DEQ, they need to reconcile that with DEQ . . . not underreport (the amount) just so they don’t have to pay a fine. The disparity between what was planned and what was going on appears to be vastly under-reported,” Katherman said Sunday morning.

“We have a big oil and gas boom going on and more coming up. We appreciate all of the jobs and the revenue, but the people who live here deserve their quality of life, too. We depend on these companies to be honest. It’s not rocket science that we have DEQ to watchdog these companies and to help us,” Katherman stated.

PRBRC sent a letter to Department of Environmental Quality Air Quality Division Administrator Nancy Vehr Feb. 6, “ . . . requesting DEQ require Tallgrass to reconcile its reporting of the Dec. 6 and 7 venting releases with the satellite image of the methane cloud and the estimates of IMEO scientists.”

“We also suggest that (the air quality division) should require the installation of a vent meter to measure the gas flow of any future emergency releases. These steps would allow for better monitoring of methane releases, boost public confidence in the reliability and trustworthiness of Tallgrass, and help protect public health. Better reporting now would also help inform future policy decisions, bearing in mind that the U.S. Environmental Protection Agency is considering additional restrictions on methane emissions from all sectors, including oil and gas,” PRBRC Chairman David Romtvedt wrote.

“It is critical that AQD (air quality division) provide information regarding their investigation into the December event, including what caused the need for emergency venting and what actions have been taken to ensure that this does not happen again,” he said. “In recognition of the public health and environmental impacts of venting, it is essential that AQD shares records of similar events at the Douglas Gas Plant. These are appropriate actions that serve to hold industry accountable. Tallgrass Midstream, LLC profits immensely from the extraction and production of Wyoming’s mineral resources. In exchange, they must openly note and be held accountable for their mistakes.

“Our beautiful state, its vibrant rural communities . . . depend on the proper regulation of methane pollution,” Romtvedt stated.

Tallgrass’ Davidson said reducing the company’s emissions in all aspects of their operations is a critical priority.

“It’s why we are strong supporters of independent, third party monitors – and why we invested in technology like Project Canary (a monitoring project). At the same time, safety remains paramount to us,” he said. “Therefore, we are constantly working on ways to ensure that our commitment to reducing emissions actually reinforces our commitment to safety, and vice-versa.”

This story was published on Feb. 15, 2023.