The Rand Corporation has issued an important study that provides “a ﬁrst-order estimate” of air pollutant emissions (excluding CO2 and methane) from unconventional shale gas development in Pennsylvania.
Estimation of regional air-quality damages from Marcellus Shale natural gas extraction in Pennsylvania examined four sources of air pollution from natural gas production: truck traffic, emissions from well sites during drilling and hydraulic fracturing, the use of diesel engines, fugitive emissions from the wellhead, and emissions from compressor stations. It measured four pollutants related to gas drilling activity: volatile organic compounds, nitrous oxide, sulfur dioxide and fine particulate matter.
RAND’s key finding is that compressor stations are responsible for 60% to 75% of air pollution from gas activities in the Keystone State. But there is a caveat, at least as it related to the subject of fracking.
It is worth stressing that a substantial portion of emissions estimated here are not speciﬁcally attributable to the ‘unconventional’ nature of shale gas. Natural gas compressor stations are necessary to produce and distribute natural gas from any source, from conventional to biomethane.
The study offers this perspective:
While statewide emissions from the extraction industry are relatively small compared to some other major sources of air pollution in the state (e.g., SO2 from GW-scale coal-ﬁred power plants), these emissions sources are nevertheless a concern in regions of signiﬁcant extraction activities.
RAND offers advice to regulators:
Our estimates indicate that regulatory agencies and the shale gas industry, in developing regulations and best practices, should account for air emissions from ongoing, long-term activities and not just emissions associated with development, such as drilling and hydraulic fracturing, where much attention has been focused to date.
That is sage advice, for two reasons. First, as RAND points out:
…most development activities do not constitute ‘major sources’ under federal air-quality regulations. Especially for those counties that already suffer from high levels of air pollution (i.e., those in or near Clean Air Act non-attainment status), these new activities may make meeting federal air-quality standards more difﬁcult…Existing regulations may therefore not be well-suited for managing emissions from a substantial number of small-scale emitters.
Secondly, there is the much larger, looming long-term issue. Shale gas development is still in its infancy in Pennsylvania. 11,500 Marcellus wells have been permitted and 6,700 shale wells drilled so far. That number could grow to over 200,000 wells (a conservative number, in my view). The number of compressor stations will similarly grow, as will the air pollution from them – unless strong, forward-looking regulations are put into place, now.
RAND urges that regulators require the use of Best Available Control Technologies (BACT) for compressors, “these include lean-burn engines, non-selective catalytic reduction, or electriﬁcation, measures.” That advice must be heeded.