Natural gas flaring destroys less methane than thought

Flaring – the practice of burning natural gas that escapes from oil and gas wells to reduce methane emissions – is much less effective than previously thought, according to a new study by Genevieve Plant and colleagues. After airborne sampling over three regions that account for more than 80% of flaring in the United States, the researchers conclude that methane emissions are five times higher than previously thought, due to both unlit flares and inefficient combustion. Methane is one of the most important greenhouse gases in terms of its contribution to global warming and is also a major driver of tropospheric ozone formation. Under industry and government assumptions, flaring consumes methane emissions at oil and gas operations with 98% efficiency, but these assumptions have rarely been tested with real-world data. To remedy this, Plant et al. looked at 300 unique flares in the Permian, Eagle Ford, and Bakken basins in the U.S. They estimate that only 91% of methane is consumed in these regions, due to poorly combusting and unlit flares. If these flares remained lit and operated at 98% efficiency, the reduction in emissions would be equivalent to removing 2.9 million cars from the road each year, the researchers note. In a related Perspective, Riley Duren and Deborah Gordon note that half a million people live within five kilometers of flares in these three basins, and that "unlit and partially combusted flares have the potential to expose front-line communities to a cocktail of co-pollutants that present risks of acute and/or chronic health impacts."