(Bloomberg) -- A leaky valve at a Phillips 66 facility in Texas poured tons of planet-warming natural gas into the atmosphere over three days in August, a mishap that was disclosed to regulators only months later when the event was spotted by satellite imagery.

The release of 9.5 million cubic feet of gas, reported to Texas regulators last month, is the latest example of outside researchers spotting pollution events that energy companies fail to disclose. Natural gas consists mostly of methane, a powerful contributor to global warming that is a major focus of the COP28 climate summit underway in Dubai.

Policymakers see curbing methane as among the cheapest, fastest ways to limit the rise in global temperatures. The Biden administration recently finalized rules that will force companies to replace leaky equipment, while the European Union struck a deal requiring energy companies to check infrastructure for leaks.

Satellites that can detect emissions are set to play a significant role in holding polluters accountable for their climate impact. “You can run but you can’t hide,” US Special Presidential Envoy for Climate Change John Kerry said at COP28 on Monday. “And we have to be prepared to name and shame.” Methane has more than 80 times the warming power of carbon dioxide during its first 20 years in the atmosphere.

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US oil and gas operators are set to face greater scrutiny over their methane emissions under the new Environmental Protection Agency rules announced at COP28 that will also force operators to regularly search for escaping gas. The government estimates the requirements would prevent some 58 million tons of methane from being released into the atmosphere from 2024 to 2038.

“Phillips 66 is committed to complying with environmental regulations, including the new methane reporting rules,” the company said in a statement. "We are continuing to investigate this incident to prevent recurrences and ensure timely reporting to regulatory agencies.”

The leak became public in late November after Carbon Mapper, a California nonprofit affiliated with NASA’s Jet Propulsion Laboratory, published data showing a cloud of methane spewing from a particular spot in rural Upton County, Texas. The finding was based on a scan of the region performed in August by an instrument attached to the International Space Station. Bloomberg Green identified a Phillips 66 compressor station at the location and asked the company about the event on Nov. 22. The company reported the emissions to state regulators six days later.

Although Texas doesn’t regulate methane, companies must promptly notify state regulators if they release large amounts of certain other pollutants found in untreated natural gas, such as butane and propane. In its report, Phillips 66 said field personnel noticed a leaky pressure relief valve on Aug. 21 and fixed it the same day. It’s unclear who else in the company was notified. 

The Texas Commission on Environmental Quality said in a statement that it assesses whether operators took measures to minimize emissions and evaluates compliance with reporting requirements: “Based on the results of an investigation of a reportable incident the TCEQ may pursue enforcement actions when appropriate against regulated entities which may include the assessment of a penalty.”

Assuming the natural gas released by Phillips 66 contained 80% methane, about 146 metric tons of methane was released, according to calculations by Bloomberg. The event had a similar short-term warming impact as the annual emissions from about 2,600 US cars.

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Phillips 66 isn’t the only energy company in the US that’s failed to initially disclose its emissions to regulators this year.

As Bloomberg Green reported, Exxon Mobil Corp. didn’t initially report a methane release in New Mexico to state regulators and the operator blamed the oversight on human error, saying someone forgot to file a form. Texas said in February it would investigate why pipeline operator Targa Resources Corp. failed to report an unexpected release of tons of gas within 24 hours as required.

--With assistance from Jennifer A Dlouhy.

©2023 Bloomberg L.P.