The Environmental Costs and Benefits of Fracking
This new study has been published in the Annual Review of Environment and Resources, Volume 39, pages 327 to 362, 2014.
Authors — Robert B. Jackson (Stanford), Avner Vengosh (Duke), J. William Carey (Los Alamos), Richard J. Davies (Newcastle UK), Thomas H. Darrah (Ohio State), Francis O’Sullivan (MIT), and Gabrielle Pe ́tron (Colorado)
Abstract — Unconventional oil and natural gas extraction enabled by horizontal drilling and hydraulic fracturing (fracking) is driving an economic boom, with con- sequences described from “revolutionary” to “disastrous.” Reality lies some- where in between. Unconventional energy generates income and, done well, can reduce air pollution and even water use compared with other fossil fuels. Alternatively, it could slow the adoption of renewables and, done poorly, re- lease toxic chemicals into water and air. Primary threats to water resources include surface spills, wastewater disposal, and drinking-water contamination through poor well integrity. An increase in volatile organic compounds and air toxics locally are potential health threats, but the switch from coal to natural gas for electricity generation will reduce sulfur, nitrogen, mercury, and particulate air pollution. Data gaps are particularly evident for human health studies, for the question of whether natural gas will displace coal compared with renewables, and for decadal-scale legacy issues of well leakage and plugging and abandonment practices. Critical topics for future research include data for (a) estimated ultimate recovery (EUR) of unconventional hydrocarbons, (b) the potential for further reductions of water requirements and chemical toxicity, (c) whether unconventional resource development alters the frequency of well integrity failures, (d) potential contamination of surface and ground waters from drilling and spills, (e) factors that could cause wastewater injection to generate large earthquakes, and (f) the consequences of greenhouse gases and air pollution on ecosystems and human health.
Conclusions — Throughout this review we have presented future research needs and opportunities. Rather than repeating them, we end with a brief discussion of principles for helping to reduce the environmental footprint of hydraulic fracturing and unconventional energy extraction in general.
One recommendation is for greater transparency from companies and regulating agencies. Although companies and most US states now provide some information about the chemicals used in hydraulic fracturing (e.g., the FracFocus disclosure registry; http://www.fracfocus.org), approximately one in five chemicals is still classified as a trade secret. Phasing out the use of toxic chemicals entirely would boost public confidence in the process further. Other examples of transparency are to disclose data for mud-log gases and production-gas and water chemistry to regulatory agencies and, ideally, to the public and to end the use of nondisclosure clauses for legal settlements with homeowners over issues such as groundwater contamination. The challenge is to balance the needs of companies with those of public safety.
A second recommendation would address one of the biggest research gaps today: the need for short- and long-term studies of the potential effects of unconventional energy extraction on human health. Virtually no comprehensive studies have been published on this topic. Nevertheless, decisions on when and where to drill are already being decided based on this issue. France and Bulgaria have bans on hydraulic fracturing that are directly associated with perceived health risks. In the United States, New York State has a moratorium on high-volume hydraulic fracturing until a review of the potential health effects is completed.
Third, the importance of baseline studies prior to drilling is increasingly recognized as a critical need. Pre-drilling data would include measurements of groundwater and surface-water attributes, air quality, and human health. In this review, we have not covered the many critical issues of social and community impacts of the unconventional energy boom. One suggestion is to create a baseline community needs and assets assessment (CNAA) to address potential social impacts. The CNAA should identify what jobs will be available to local workers, develop citizen-stakeholder forums and reporting mechanisms, update transportation planning and safety training, and implement strong consumer protections before drilling begins .
A fourth recommendation is to place particular focus on surface and near-surface activities rather than on what occurs deep underground. Surveys of groundwater contamination suggest that most incidents originate from the surface, including faulty wells, wastewater disposal, and spills and leaks from surface operations (60, 88, 165). These problems may be reduced through best management practices or regulations. There are additional risks associated with hydraulically fractured wells connecting with old, abandoned wells that are not properly sealed. Increased attention to improving well integrity in shale-gas operations and to potential interactions between hydraulic fracturing and abandoned wells would help reduce environmental risks and impacts.
Lastly, we believe that state and federal governments are under investing in legacy funds in the United States, the European Union, and elsewhere for addressing future problems accompanying the unconventional energy boom. Drilling millions of new oil and natural gas wells will inevitably lead to future issues (e.g., see Section 4, above). Pennsylvania, for instance, currently has no severance tax on oil and gas production and took in only ∼$200 million yearly in impact fees from 2011 to 2013. Most of this money was used to fund county and state operations, with $16 million from the fund allocated to current environmental initiatives in 2012 and 2013, including habitat restoration, flood protection, and P&A. To place these numbers in the broader context, Pennsylvania produced >$10 billion worth of natural gas in 2013 alone. At this rate, very little money will be available years to decades in the future when Marcellus and other wells age, leading to the kinds of shortfalls that some states face today from past industrial activities.
The biggest uncertainty of all is what the future energy mix across the world will be. Compared with coal, natural gas has many environmental benefits, and replacing old coal-fired power plants with new natural gas plants makes sense in places. However, natural gas and shale oil are still fossil fuels, releasing GHGs when burned. Will natural gas be a bridge fuel to a cleaner, renewables- based future? How long will the bridging take? Will natural gas be used to supplement renewables in the future or instead become the world’s primary energy source? Will the unconventional energy boom lower energy prices, making conservation less valuable and slowing the adoption of renewables? Societies face difficult choices that can be informed by strong, interdisciplinary research. The answers to these questions will drive earth and environmental sciences for decades.
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