On October 10, in the first event of this year’s Policy Workshop Webinar Series Emerging Issues in Shale Gas Development, Dr. Jim Saiers, Professor and Associate Dean of Academic Affairs at the Yale School of Forestry and Environmental Studies, joined the Yale Center for Environmental Law and Policy to present an overview of shale gas development and its implications for the environment. Focusing on Pennsylvania’s Marcellus region, Professor Saiers discussed the history of shale gas development in the United States, the processes that are used to extract it, and their potential environmental consequences. Throughout the talk, Professor Saiers highlighted the state of existing research and the diversity of opinions on these issues.
Growth in Shale Gas Development
As Professor Saiers noted, the past decade has witnessed a twelve-fold increase in the United States’ shale gas production, and currently, natural gas satisfies about a quarter of the U.S.’s total energy needs. This tremendous growth is due in large part to George Mitchell, the founder of an oil-service company, who pioneered a technique which combines horizontal drilling with high-volume slick water fracturing to reach and extract shale gas deposits.
Shale gas extraction has several stages. Before gas companies can commence drilling, they first must lease land, acquire the relevant permits, and prepare the drilling site (an intensive process that can involve clear-cutting forests or “re-engineering” the landscape to accommodate the drilling pad). The drilling and casing process takes several weeks. In the Marcellus shale, a well may extend 5,000 to 7,000 feet underground before turning horizontally. Cement casing must also be installed to maintain the integrity of the wellbore and to isolate it from surrounding water aquifers. Hydraulic fracturing or “fracking” involves shooting holes in the lateral portion of the casing with a perforation gun, and then pumping large volumes of a water-based fluid containing chemicals and sand through the borehole and out of the perforations in the casing at high pressures. This increases the fluid pressure within the shale formation and generates fractures.
Potential Environmental Impacts
This process has a number of potential environmental implications. One, featured prominently in the movie Gasland, is that the methane released during extraction could contaminate household drinking water. Professor Saiers observed that if gas wells are improperly cased, then methane can indeed migrate along the borehole and escape into drinking water aquifers. However, he cautioned that these leaks can be avoided by following best practices, and noted that methane sometimes occurs naturally in aquifers or could originate from abandoned oil and gas wells not associated with fracking.
Another concern is that the chemicals used in fracking will contaminate groundwater. Yet the seriousness of this risk is a subject of dispute. For example, Rebecca Wodder, President Obama’s former nominee for Assistant Secretary of Interior for Fish, Wildlife, and Parks, has charged that fracking creates a toxic chemical soup that pollutes groundwater and streams. By contrast, Lisa Jackson, the Administrator of the U.S. Environmental Protection Agency, has stated that she is not aware of any proven case in which the fracking process itself has affected water. Professor Saiers conceded that it’s difficult to reconcile these opposing views. However, he observed that the most likely way contamination would occur would be through surface spills and “flow-back” of frac-water, which could happen during transportation, through accidental releases at the drill sites, or because of leaks in the pits that store flow-back water.
An additional concern is the impact that shale gas has on the climate. While burning gas is cleaner than combusting coal, the carbon emissions footprint of burning gas is still non-negligible (roughly 50% of the carbon emissions from coal). Moreover, the process used to extract shale gas can release or “leak” this gas, a.k.a. methane, which is itself an extremely potent greenhouse gas, into the atmosphere. Unfortunately, estimates of how much methane is released during the extraction process vary dramatically. Thus, more research on this subject is urgently needed, since the total climate impact of natural gas development depends to a great extent on the magnitude of this methane leakage. (This critical issue will be the subject of the second webinar in the Emerging Issues in Shale Gas Development series from 12-1pm EST on Thursday, November 8, when Dr. Ramon Alvarez discusses “What It Takes To Get Sustained Climate Benefits from Natural Gas.”)
Shale gas development could have other negative environmental consequences as well, including landscape disturbance and decreased air quality. During the Q&A session following Professor Saiers’ presentation, one question also concerned the potential of fracking to lead to earthquakes. Professor Saiers stated that there is a general scientific consensus that fracking can induce some small amounts of seismic activity, but that current research suggests that it may do so at a level that is not threatening. Professor Saiers also discussed the large volumes of water used in fracking, and noted that the impact of this practice will vary depending on regional water availability.
Overall, Professor Saiers presented a relatively optimistic view of the potential to develop shale gas, particularly in the Marcellus region, in an environmentally responsible manner. However, he cautioned that more research is still needed on shale gas’ environmental impacts, and that proper regulatory controls and industry best practices (e.g., proper well construction standards, drilling at depths that are sufficiently below drinking water aquifers, and monitoring around gas wells) are necessary to prevent environmental harms. Based on our current understanding, Professor Saiers believes that shale gas can be produced safely if the right safeguards are in place, and he maintained that current development does appear to be safe in a large number of cases.
Future webinars in the Emerging Issues in Shale Gas Development series will continue to explore these critical issues of environmental science and policy. A recording of Professor Saiers’ webinar presentation is available for viewing here:
 “America’s Bounty: Gas Works,” The Economist, July 14, 2012, http://www.economist.com/node/21558459
 For example, in a recent interview with Yale Center for Environmental Law and Policy Fellow Bruce Ho, Dr. Sheila Olmstead from Resources for the Future mentioned that habitat fragmentation as a result of increased shale gas development is a potentially significant environmental impact that has yet to be fully considered. The Nature Conservancy is one organization that has been looking at this issue.