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Thursday, April 25, 2013

Air Quality Issues in Natural Gas Systems

Richard K. Lattanzio
Analyst in Environmental Policy

Natural Gas Systems and Air Pollution 

Congressional interest in U.S. energy policy has focused in part on ways through which the United States could secure more economical and reliable fossil fuel resources both domestically and internationally. Recent expansion in natural gas production, primarily as a result of new or improved technologies (e.g., hydraulic fracturing, directional drilling) used on unconventional resources (e.g., shale, tight sands, and coal-bed methane), has made natural gas an increasingly significant component in the U.S. energy supply. This expansion, however, has prompted renewed questions about the potential impacts of natural gas systems on human health and the environment, including impacts on air quality. Unlike the debate over groundwater contamination or induced seismicity—where questions exist as to whether or not production activities contribute significantly to these impacts—there is little question that natural gas systems emit air pollutants. The concerns, instead, are the following:

  • Which pollutants? 
  • How much of each pollutant? 
  • From which sources? 
  • What are the impacts of the emissions? 
  • How much is the cost of abatement? 
  • What are the respective roles of federal, state, and local governments? 

Air pollutants are released by natural gas systems through the leaking, venting, and combustion of natural gas; the combustion of other fossil fuel resources; and the discharge of particulate matter during associated operations. Emission sources include pad, road, and pipeline construction; well drilling, completion, and flowback activities; and gas processing and transmission equipment such as controllers, compressors, dehydrators, pipes, and storage vessels. Pollutants include, most prominently, methane and volatile organic compounds—of which the natural gas industry is one of the highest-emitting industrial sectors in the United States—as well as nitrogen oxides, sulfur dioxide, particulate matter, and various forms of hazardous air pollutants. 

EPA’s 2012 Air Standards 

The U.S. Environmental Protection Agency (EPA), in response to a consent decree issued by the U.S. Court of Appeals, D.C. Circuit, promulgated air standards for several source categories in the crude oil and natural gas sector on August 16, 2012. These standards—effective October 15, 2012—revised existing rules and promulgated new ones to regulate emissions of volatile organic compounds (VOCs), sulfur dioxide, and hazardous air pollutants (HAPs) from many production and processing activities that had never before been covered by federal oversight. The standards control air pollution, in part, through the capture of fugitive releases of natural gas. Thus, compliance with the standards has the potential to translate into economic benefits, as producers may be able to offset abatement costs with the value of product recovered and sold. Using this assumption, EPA estimated the annual benefits of the standards to be VOC reductions of 190,000 tons, HAP reductions of 12,000 tons, methane reductions of 1.0 million tons, and a net cost savings of $11 million to $19 million after the sale of recovered product. Industry and other stakeholders have disputed these figures as both too high and too low. Moreover, the expansion of both industry production and government regulation of natural gas has sparked discussion on a number of outstanding issues, including the following:

  • defining the roles of local, state, and federal governments, 
  • determining the proper coverage of pollutants and sources, 
  • establishing comprehensive emissions data, 
  • understanding the human health and environmental impacts of emissions, and 
  • estimating the costs of pollution abatement. 

Scope and Purpose of This Report 

The report begins by briefly outlining the production, processing, transmission, and distribution phases of the natural gas industry, then characterizes the types and sources of pollutants in the sector. It then turns to the role of the federal government in regulating these emissions, including the provisions in the Clean Air Act and the regulatory activities of the EPA. It concludes with an extended discussion of the aforementioned outstanding issues. For an abbreviated version of this report, see CRS Report R42986, Air Quality Issues in Natural Gas Systems: In Brief.

Date of Report: April 16, 2013
Number of Pages: 77
Order Number: R42833
Price: $29.95

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