Air Impacts of Increased Natural Gas Acquisition, Processing, and Use: A Critical Review

Abstract

During the past decade, technological advancements in the United States and Canada have led to rapid and intensive development of many unconventional natural gas plays (e.g., shale gas, tight sand gas, coal-bed methane), raising concerns about environmental impacts. Here, we summarize the current understanding of local and regional air quality impacts of natural gas extraction, production, and use. Air emissions from the natural gas life cycle include greenhouse gases, ozone precursors (volatile organic compounds and nitrogen oxides), air toxics, and particulates. National and state regulators primarily use generic emission inventories to assess the climate, air quality, and health impacts of natural gas systems. These inventories rely on limited, incomplete, and sometimes outdated emission factors and activity data, based on few measurements. We discuss case studies for specific air impacts grouped by natural gas life cycle segment, summarize the potential benefits of using natural gas over other fossil fuels, and examine national and state emission regulations pertaining to natural gas systems. Finally, we highlight specific gaps in scientific knowledge and suggest that substantial additional measurements of air emissions from the natural gas life cycle are essential to understanding the impacts and benefits of this resource.

Contribution of oil and natural gas production to renewed increase in atmospheric methane (2007–2014): top–down estimate from ethane and methane column observations

“…Particularly important in this context is the strong increase in US oil and natural gas production starting in the mid2000s (Moore et al, 2014;Wang et al, 2014), which is expected to continue through 2040 (US Energy Information Administration, 2014). This has been facilitated by the development of new extraction techniques (hydraulic fracturing and horizontal drilling), which involve additional fugitive methane emissions during flowback periods compared to conventional techniques (Field et al, 2014;Howarth, 2014).…”

Photochemical aging of volatile organic compounds associated with oil and natural gas extraction in the Uintah Basin, UT, during a wintertime ozone formation event

“…Emissions budgets of methane and other VOCs (volatile organic compounds) are poorly constrained and frequently do not agree with inventory estimates (Brandt et al, 2014;Miller et al, 2013). Many variables can affect the composition of emissions, including well life-cycle stage, extraction techniques, whether the well is producing oil or gas, and diverse infrastructure/equipment components (Moore et al, 2014;Litovitz et al, 2013;Allen et al, 2013). Wintertime ozone events, while sharing some similarities with ozone formation typically seen in urban areas during the summer, occur in different meteorological and chemical conditions and have attracted several recent measurement and modeling investigations (Schnell et al, 2009;Kotamarthi and Holdridge, 2007;Carter and Seinfeld, 2012;Edwards et al, 2013.…”

“…This activity is associated with a range of possible environmental issues. Emissions due to extraction can increase atmospheric concentrations of methane, a greenhouse gas Brandt et al, 2014); directly impact local air quality through release of air toxics (Moore et al, 2014;Adgate et al, 2014;Li et al, 2014); and contribute to photochemical ozone formation (Schnell et al, 2009;Carter and Seinfeld, 2012)…”

Resilient but not sustainable? Public perceptions of shale gas development via hydraulic fracturing

“…Research on this topic has proliferated exponentially over the last half decade; much research focuses on impacts associated with development (Sovacool 2014). Scientists have afforded particular attention to effects on the following: (1) water quality (Entrekin et al 2011, Jackson et al 2013, Olmstead et al 2013, Vidic et al 2013, Vengosh et al 2014, Llewellyn et al 2015, (2) air quality (Moore et al 2014), (3) global climate change (Alvarez et al 2012, Allen et al 2013, Newell and Raimi 2014, (4) biota/ecosystems (Drohan et al 2012, Kiviat 2013, Souther et al 2014, Milt et al 2015, (5) human health (New Brunswick Department of Health 2012, Kibble et al 2013, Adgate et al 2014, Kovats et al 2014 Institute for Applied Environmental Health 2014), (6) local and regional economics (Kinnaman 2011, Weber 2012, Fry et al 2015, and (7) community well-being (Jacquet 2014, Jacquet and Stedman 2014, Evensen 2015. These impacts could contribute to or challenge the prospects for sustainable and resilient futures in the communities where they are experienced.…”