The booming U.S. production of natural gas can be less environmentally harmful than estimated if gas companies take certain steps to cut greenhouse gas emissions, says a major study Monday that was done with industry participation.
The study, billed as the first to measure the actual emissions of heat-trapping methane from natural gas wells, finds these emissions are slightly less than the most recent national estimate by the U.S. Environmental Protection Agency. In some cases, the emissions were only about 2% of EPA's estimate, done in 2011.
The main reason for the difference? Two-thirds of the wells studied were capturing or controlling the methane to reduce emissions.The EPA assumed a higher percentage of methane, which is far more potent in trapping heat in the atmosphere than carbon dioxide, would be emitted.
"This is good news in that it shows emissions can be controlled," says Eric Pooley, senior vice president of the Environmental Defense Fund, a research and advocacy group that teamed up scientists, two environmental testing firms and nine natural gas companies to produce the peer-reviewed study, published in the Proceedings of the National Academy of Sciences. The gas companies involved provided the majority of the funding.
"Industry can get it right," says Pooley, saying companies are being prodded to reduce emissions by an upcoming EPA rule — effective January 2015 — that all methane be captured when liquids are being removed after drilling.
Production of natural gas has soared nationwide in recent years as companies use hydraulic fracturing or fracking to extract gas from shale deposits. In this process, copious amounts of water, sand and chemicals are blasted into a well to break apart the rock and release the gas. But that production method, which emits far fewer greenhouse gases than coal mining, has sparked protests nationwide because of concerns that it contaminates groundwater and may trigger minor earthquakes.
The companies allowed researchers from seven universities to measure methane emissions at 190 production sites last year, including 27 wells being primed for production and 489 that had been fracked. The scientists, led by David Allen of the University of Texas-Austin, looked at how much methane was emitted at different stages.
They found the average emissions from the 27 wells where drilling liquids (prior to gas production) were being recovered were 1.7 megatons — a fraction of the EPA's estimated average of 81 megatons per well. They said technology to capture methane cut emissions 99%. They found emissions were higher or similar to EPA's estimate for other phases, including routine production and removing liquids that remain after production.
Overall, the study found emissions from these phases, if extrapolated nationwide, would total 757 to 1,157 gigatons of methane — slightly less than the EPA's estimate of about 1,200 gigatons.
These findings, if representative of the industry, suggests natural gas can be produced with "modestly low emissions," says Robert Howarth, a professor at Cornell University whose own research estimates methane emissions are much higher.
Howarth says he's skeptical they are representative. He says gas companies "do better when they know they are being carefully watched," adding they knew which sites were being measured in the new study. He says they very often don't make the efforts needed to reduce emissions.
"There was no cherry picking," says Pooley of the sites measured, noting scientists selected them based on certain criteria. "It's not like a restaurant inspector is coming so the restaurant just cleans up," he says, adding gas production is too time- and labor-intensive to do that.
Pooley says the findings show where the industry is going, not necessarily where it is today. "This is not the last word," he says, noting his group will be co-funding 15 more studies on fracking's environmental toll. "It's the first word."
He says many environmentalists may prefer solar and wind power, which don't emit greenhouse gases, but he says natural gas production "whether you like it or not, is happening and we need to minimize the environment harm."