shift when emissions that directly impact climate change are factored in is an issue to be examined.

Dr. Robinson discussed Figure 5-1, which lists the sources of emissions described above, categorizes them as major or minor sources of pollution, describes the pollutants they emit, and assesses the quality of data. (The values should be considered the “potential to emit” because particulate filters and other technologies, if implemented effectively, can reduce the contributions of these sources.) He noted that there is reasonable understanding of the emissions from diesel-powered engines (e.g., drill rigs, fracturing pumps, and truck traffic). There is less knowledge about emissions from other sources, for example, completion venting, blowdown venting, and fracturing ponds. There may be an increase in knowledge as the field moves to more controlled “green completions” that significantly reduce fugitive emissions of methane and other gases. During the gas production phase, sources such as compressor stations, heaters and dehydrators, condensate tanks, fugitive emissions, and pneumatics emit air pollutants. Some sources have well-defined emission points, and others do not; for most, more data are needed to accurately assess their impacts. Dr. Robinson noted that the main concern is what the net effect is when these pollutants mix in the atmosphere.

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FIGURE 5-1 Sources of emissions.
NOTE: NOx = nitrogen oxide, PM = particulate matter, VOC = volatile organic compound.
SOURCE: Robinson, 2012.



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