Conventional wisdom has held that natural gas is cleaner than coal — and supporters have even promoted it as a “bridge fuel” for cutting climate pollution as countries move to renewable energy. But that assertion is running up against new research amid a political fight over President Joe Biden’s temporary decision to limit the growth of liquefied natural gas exports, Benjamin Storrow writes. Gas contributes more to global warming than once thought, according to a number of researchers who study the carbon content of fuels — even as its growing role as a power source in the U.S. has helped bring down emissions compared with the era when coal was king. Concern among scientists and environmental opposition to natural gas has accelerated in recent months. In December, 170 climate scientists signed onto a letter asking Biden to reject plans to build more LNG export terminals. They said the process of shipping gas overseas is “at least 24 percent worse for the climate than coal” — a contention that industry groups call at odds with settled science. “The notion that … LNG and natural gas reduce emissions by displacing coal is completely well established,” Dan Byers, vice president of policy at the U.S. Chamber of Commerce, told Ben. But now gas’s climate impact is in for much more scrutiny. The White House last month paused LNG export permits so the Department of Energy can study their effect on climate change and domestic fuel prices, a move that provoked a storm of criticism from Republicans. Carbon emissions in the U.S. electricity sector fell by a third between 2005 and 2022, the same period when gas-fired generation has toppled coal as the nation’s leading power source. But the scientists are debating so-called life-cycle emissions — soup-to-nuts pollution from the wellhead to the gas burner. Methane, the major component of gas with potent planet-warming effects, enters the atmosphere when oil and gas producers flare or vent it. Studies on how much methane leaks from the gas supply chain, including pipelines, vary widely. Methane can also escape as a result of LNG exports, which rely on the energy-intensive process of supercooling gas to turn it into a liquid. Coal’s carbon dioxide emissions are trapped in the air for a century. But the heat-trapping effect of methane emissions is more intense in the shorter term. That has complicated efforts to nail down exactly how much effect a large-scale LNG export business could have on the climate. A 2019 study by the Department of Energy on the life-cycle climate emissions of LNG exports to Asia found it ranged from 54 percent to 2 percent less than local coal over two decades. The numbers were similar for LNG delivered to Europe. But the genesis of the uptick in discussion about LNG emissions is based on a forthcoming Cornell University study, which has yet to be peer-reviewed. Study author Robert Howarth, a Cornell professor and longtime sparring partner with the gas industry, said previous research hasn’t accounted for emissions associated with liquefying the fuel. “We’re the world’s largest producer of natural gas. We were not 10-15 years ago. We are the largest exporter of natural gas. We didn’t export any 10 years ago,” Howarth said in an interview with Ben. “It’s totally the wrong trajectory.” Howarth’s critics say his numbers are inflated and that his research is motivated by politics. “It feels like we’ve got like a flat earth situation going on with these claims,” the Chamber's Byers said.
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