Natural gas, long promoted as a “clean” alternative to other fossil fuels, may not be so clean after all. That’s because its main ingredient, the potent greenhouse gas methane, has been leaking from oil and gas facilities at far higher rates than governmental regulators claim. A new study finds that in the United States, such leaks have nearly doubled the climate impact of natural gas, causing warming on par with carbon dioxide (CO2)-emitting coal plants for 2 decades. (Methane doesn’t persist in the atmosphere as long as CO2 does, but while it does, its warming effect is much stronger.)
The study underscores how the benefits of natural gas, which emits less CO2 than coal when burned, are being undermined by the leaks, says Steve Hamburg, a main author of the study and the chief scientist for the Environmental Defense Fund (EDF), a New York City–based environmental group. “You’re taking a hit, and it’s an unnecessary hit,” he says. The analysis also suggests the U.S. Environmental Protection Agency (EPA) is presenting too rosy of a picture of natural gas emissions, understating industry methane leaks by approximately 60%.
Some estimates—including those of EPA—are based on assumed leakage rates for natural gas drilling processes, and piping and storage equipment that are drawn from the scientific literature. Although that approach might be accurate if everything worked as expected, the new study shows that it doesn’t, Hamburg says.
He and his EDF colleagues enlisted two dozen government, university, and nonprofit scientists to set out—sometimes on foot—to pin down the numbers. They measured methane levels in the air around natural gas wells, storage tanks, refineries, and underground pipes feeding gas to people’s homes in key gas-producing regions in states including Pennsylvania, Texas, Colorado, Utah, North Dakota, and Arkansas.
They found that in 2015, methane leaks represented 2.3% of total gas production nationwide, compared with EPA estimates of 1.4%, they report today in Science. The higher estimates stem from a small number of so-called superemitters, Hamburg says. Using infrared cameras, an airplane survey of 8000 industry sites found that 4% had unusually high methane emissions, most tied to hatches and vents in natural gas storage tanks at extraction wells. Thought to be caused by malfunctions, the leaks are rare enough that they are easily missed in most surveys, Hamburg says. “We have so much more data than the EPA does at this point, this is just not comparable.”Click here to read more.
You can read the industry's response to the study here.
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