Gas flares are leaking five times as much methane than previously thought

More lit flares and improved efficiency would be like taking nearly 3 million cars off the road

photo of natural gas flares in the foreground at the Bakken Formation in the Williston Basin in North Dakota in 2021

Flares, like the ones here, burn off the natural gas emitted during oil and gas production, turning methane into less potent carbon dioxide. But the efficiency of these flares is much lower than previously thought.

Alan Gorchov Negron/University of Michigan, Yulia Chen/Stanford University

In many oil and gas producing regions, flames light the sky. The flares burn off 98 percent of the escaping natural gas, oil and gas companies claim. But observations of three U.S. oil and gas fields show efficiency is only around 91 percent, scientists report in the Sept. 30 Science. Making up the difference would be the equivalent of taking nearly 3 million cars off the road. 

The natural gas escaping is primarily methane. This greenhouse gas lingers for only nine to 10 years in the atmosphere, but its warming potential is 80 times that of carbon dioxide. So oil and gas companies light flares — burning the methane to produce less-potent carbon dioxide and water. The industry and the U.S. government assumed those flares worked at 98 percent efficiency. But previous studies said that might be too optimistic, says Genevieve Plant, an atmospheric scientist at the University of Michigan in Ann Arbor (SN: 4/22/20).

Plant and her colleagues sent planes to sample air over more than 300 flares in the Bakken Basin in North Dakota and the Permian and Eagle Ford basins in Texas, which account for more than 80 percent of the flaring in the country. The samples showed five times as much methane unburned than previously estimated.

The drop from 98 to 91 percent efficiency might seem small, but the effects are large, says Dan Cusworth, an atmospheric scientist at the University of Arizona in Tucson who was not involved in the study. “Any percentage that is in the methane phase instead of CO2 phase is substantially more problematic.”

Half of the difference is due to flares that aren’t burning. “We expected that flares might show a range of efficiencies, but we did not expect to see so many unlit flares,” Plant says. Between 3 and 5 percent of flares weren’t working at all. If those fires were lit, and 98 percent efficiency achieved, the result could remove the equivalent of about 13 million metric tons of carbon from the atmosphere. Light ‘em up. 

Bethany was previously the staff writer at Science News for Students. She has a Ph.D. in physiology and pharmacology from Wake Forest University School of Medicine.

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