Last week’s announcement of the publication of a University of Texas (UT) study examining methane emissions from U.S. natural gas production sites marks a major milestone in EDF's efforts to better quantify the amount of methane leakage across the natural gas supply chain. The UT study is the first installment of a major EDF initiative being conducted in partnership with leading research universities, scientists and natural gas companies.
About five years ago, EDF began looking into the emissions of air pollutants coming from natural gas operations in multiple geographic regions – including various parts of Texas. This was a time when the industry was undergoing a dramatic growth spurt thanks to technologies such as horizontal drilling and hydraulic fracturing (or ‘fracking’), which enable the commercial extraction of natural gas from deposits of shale rock located deep underground. We quickly learned that available estimates of how much methane was emitted were fairly uncertain.
Small amounts of natural gas, which mainly consists of methane, a powerful global warming pollutant, are lost into the air as the gas coming out of the ground makes its way from the wells that produce it and through the processing and pipeline systems bringing it to consumers. We have written elsewhere why these emissions matter for our climate, environment and public health.
Believe it or not, we actually don't know with certainty whether the methane leak rate across the natural gas supply chain is one percent, three percent or even more, as some have reported. Leak rates in or above the 1% – 3% range are enough to make natural gas use, as opposed to coal or oil, worse for the climate, at least for a period of time – even though natural gas emits less carbon dioxide than those other fossil fuels when burned. Raw natural gas leaked at well sites can also contain other pollutants that threaten the health of nearby residents.
The UT study provides important insights. Methane emissions from natural gas production, on average, were not as large as some of the high-end estimates. In fact, total methane emissions from the production process were found to be roughly in line with the current estimates of the Environmental Protection Agency, although the contribution from different source types differed.
Certain operational technologies and techniques that limit air pollution during the completion process of oil and gas wells, like “green completions,” were shown to dramatically reduce emissions from the process of bringing a well online after hydraulic fracturing; the study presents the first estimates of emissions from this so-called "flowback" process, which has been a major source of uncertainty. On the other hand, some types of equipment, such as valves and piping, emit more than current estimates suggest.
I am proud to be a part of the EDF team for having the wherewithal to help bring the UT study to fruition, along with the larger scientific initiative of which it is a part. I invite you to stay tuned in as other results are published over the next year. This new data, along with the growing body of work emerging from the broader research community, will help us understand – with much greater confidence – how the climate impacts of natural gas compare to other fuels and guide EDF’s efforts to minimize methane leakage and protect our environment and public health.