Natural gas has long been viewed in some quarters as a bridge fuel on the way to eliminating most burning of fossil fuels. When it’s burned, it emits about half as much carbon dioxide as coal. But scientists project that if 3.2% of all the natural gas being extracted leaks into the atmosphere instead of being burned to make electricity, the greenhouse effect is worse than from burning coal. That’s because methane is so much more powerful at trapping Earth’s heat than is CO2 in the short run—84-86 times more potent over 20 years. But methane leaves the atmosphere after a dozen years, while CO2 hangs around a lot longer. Thus, over a century, methane is only 34 times more potent as a greenhouse gas.
For as long as the oil and gas industry have been around, flaring methane has been practiced. Burning it means the heat-trapping molecules don’t reach the atmosphere, although some CO2 is produced in the process. But flares are often unlit, with the valves open, meaning the methane leaks into the air, unburned. According to one study, there have been a lot more unlit flares in the Permian lately.
Last year, overall U.S. greenhouse emissions fell slightly. But there was a simultaneous rise in methane emissions. According to Rob Jackson, professor of Earth system science at Stanford University and chair of the Global Carbon Project, “Last year’s jump in methane is one of the biggest we’ve seen over the past 20 years” […] “It’s too early to say why, but increases from both agriculture and natural gas use are likely. Natural gas consumption surged more than 2% last year.”
Scientists haven’t yet figured out the two previous accelerations in methane emissions—in 2007 and 2014—so uncertainty prevails. The obvious suspects, fossil fuel burning, agriculture, and the effects of climate shifts on wetlands are all likely to be part of the equation.
Replacing coal with natural gas to generate electricity, thereby reducing the release of greenhouse gases and the other polluting emissions for which coal is notorious, has been underway across the nation for nearly a decade and a half. Getting at much of that gas has been made possible by hydraulic fracturing, injecting a pressurized slurry of chemicals and water into tight shale formations to pry the fuel from the rock, a process with serious environmental deficits. Oil is extracted by fracking, too. So much so that U.S. oil production is at an all-time peak after having fallen steadily from 1970.
Over the past dozen years, industry and its professional and amateur cheerleaders have downplayed methane leaks at drill sites and other installations while glorying at the growth in U.S. oil production and the switch to natural gas. Beneficial in every way, they assert.
However, a study published two months ago found that North American fracking is a growing contributor to global methane emissions. A study released a year ago shows that these rose 40% from 2006 to 2015. Industry lobbyists and the Environmental Protection Agency, which depends for its analysis on the reliability of industry data, claim that methane emissions are down and the leakage rate has fallen. However, the new Permian Basin study shows twice as big a percentage of emissions as the EPA calculation. Perhaps that has to do with bad methodology.
Industry also claims that it’s on a path to reduce methane emissions significantly nationwide. The giant Exxon has promised it will cut methane emissions from a 2017 baseline of 0.32% to 0.25% by 2025. As McKenna notes, Permian Basin study’s estimate of a 3.7% emissions rate would seem to indicate that Exxon and the other producers in the region have a long, long way to go. They should start by not skewing the data.