A few weeks ago, University of Texas Austin released a study showing that shale gas production releases fewer methane emissions than previously thought. If true, the study’s findings could swing the debate over hydraulic fracturing — a technique used to extract gas from shale formations — in favor of the natural gas industry.
In the last five years, developments in hydraulic fracturing (fracking) and horizontal drilling technology have revolutionized the U.S. gas industry. Consequently, the U.S. has enjoyed a boom in gas production from shale reserves which, even 10 years ago, would not have been commercially viable. Shale production now accounts for 30% of current U.S. gas production and is expected to rise to 50% by 2040. In the last five years, natural gas prices have fallen by 75%, spurred millions of dollars in investment, and created thousands of jobs.
While natural gas enjoys bipartisan support as a clean, cheap, and American-made energy resource, the techniques used to extract it are more controversial. Fracking has been blamed for everything from earthquakes to flammable tap water. And ever since a group of scientists published a study claiming that shale gas produces more greenhouse gas emissions than coal, fracking has also drawn fire over methane emissions.
Before delving into emissions studies, one must understand how methane is emitted in shale gas production. The majority of emissions come from a process known as “well completion.” Before a well is hooked to a pipeline, it must be “completed” by pumping out all of the pressurized liquids used to frack shale rock. When the liquid is removed, methane bubbles escape. In some cases, the methane is flared to become carbon dioxide, but otherwise, it is simply released into the atmosphere. The second biggest source of methane leaks is “unloading,” a process that clears a well of any liquid in the underground pipe. This has to be done once a well starts producing gas. There is considerable variation in how often it’s done and, consequently, how much methane is emitted.
Until the release of the UT Austin study, the debate over methane emissions from fracking was dominated by a study published by Cornell University in 2011. Cornell scientists claimed that shale production leaked methane at a rate of 3.6 to 7.9% of total production, two to three times higher than conventional wells. That study attributed 1.9% of those methane emissions to well completions alone. The conclusion of the study: fracking emits more greenhouse gases than the extraction and burning of coal. The study remained influential, despite this rather outlandish claim, because there wasn’t very much data out there to dispute it.
The UT Austin study paints a very different picture of fracking and verifies some of the estimates in the EPA’s annual Greenhouse Gas Inventory. The UT scientists found methane leaks of 0.53% of total production, just slightly lower than the EPA’s estimate of 0.59%. That is significantly lower than the Cornell study, but still the largest source of methane in the U.S. (followed closely by belches from cows). However, there were dramatic differences in the source of the leaks, especially in well completions. The UT study found well completions leaked 97% less than the EPA’s estimates. Lower emissions from well completions were offset by significantly higher rates from pumps and equipment, and from unloading events. The differences should provide fodder for policymakers and interest groups to improve regulations governing the use of specific types of equipment, which the EPA may assume to be more effective than it actually is.
Critics were quick to accuse the study’s authors of being in bed with the gas industry. Dr. Anthony Ingraffea, co-author of the Cornell study, called the study “fatally flawed” because of its small sample size drawn entirely from wells that participating gas companies approved for testing, all of which had emissions reduction. It is difficult to take those accusations seriously because the study was co-funded by the Environmental Defense Fund. Additionally, the study was the first of its kind to take actual measurements from fracked well sites. The EPA and Cornell studies are both based on abstract calculations of net emissions and, in the case of the Cornell study, from extrapolations based on well completions done in the Soviet Union.
While more studies still need to be done, the UT Austin study’s conclusions are good news for natural gas consumers in the U.S., and for policymakers seeking to improve regulations on the industry.