Rand yesterday published a must-read study of air emissions (but not carbon dioxide) from gas drilling and production in Pennsylvania that puts a bright spotlight on emissions from compressor stations. The study (p.5) finds compressor stations are responsible for 60% to 75% of air pollution from gas activities. iopscience.iop.org/1748-9326/8/1/014017/pdf/1748-9326_8_1_014017.pdf.
The Rand study puts a premium on installing the best pollution control technologies on compressor engines or not using diesel to fuel them. Doing so will cut the bulk of air pollutants coming from gas production, if the Rand study is correct.
The Rand study also draws conclusions about the total emissions coming from gas drilling during 2011, while recognizing uncertainty and managing that doubt with ranges. I have no reason to doubt the Rand's range estimates of various pollutants, but Rand understates the gas drilling industry's portion of Pennsylvania's total air pollutants.The Rand study compares emissions from gas activity in 2011 to total emissions in Pennsylvania during 2008. Total air emissions in Pennsylvania (and the nation), however, have dropped substantially since 2008.
As a result, if Rand compared emissions from gas activity in 2011 to total air emissions from all sources in 2011 or 2012 (not 2008), Rand would find that air emissions from gas drilling accounts for a higher portion of the total today.
Of course, the irony is that the use of much more gas to make electricity, as well as more scrubbers installed on coal plants and more renewable energy, have cut sharply air emissions since 2008. Simply put, more gas usage means less total air pollutants, because gas displaces large amounts of coal and oil that otherwise would be used and that otherwise would release much more air pollutants.