Ed Ireland's Remarks at the TCEQ Public Hearing on the ozone proposed state implementation plan, July 14, 2011
Ed Ireland’s Remarks to TCEQ SIP Hearing
July 14, 2011
TCEQ’s June 8, 2011 “Revisions to the State of Texas Air Quality Implementation Plan for the Control of Ozone Air Pollution” (SIP) contains an estimate of VOCs from oil and gas facilities in the Dallas/Fort Worth 9-county non-attainment area. These estimates are in Table 3-18 on page 3-28 of that document. In that table, total VOC emissions for oil and gas production for 2012 in the DFW 9-county non-attainment area are estimated to be 113.1 tons per day.
The narrative associated with the table says that the oil and gas production county-specific 2010 gas emissions were estimated based on oil and gas production information from the Texas Railroad Commission and emission factors based on equipment surveys from the Eastern Research Group in 2010 and other sources based on well data outside the Barnett Shale.
Unfortunately the estimates of VOC emissions based on these studies are not anywhere close to the actual emissions data, which are contained in the TCEQ Barnett Shale Phase 2 Special Inventory data. The result is a huge over-statement of VOC emissions for Barnett Shale gas wells. I estimate that the SIP estimates of VOC emissions are overstated by over 5 times.
These conclusions are based on data from 7 companies that are members of the Barnett Shale Energy Education Council: Chesapeake Energy, Devon Energy, EOG Resources, Encana Natural Gas, Quicksilver Resources, XTO Energy and Pioneer Resources. These companies account for approximately two-thirds of the 10,721 Barnett Shale natural gas wells in the 9-county area and 80% of total production in those counties.
Based on the Phase 2 Special Inventory data which these companies submitted to TCEQ a few months ago, the average natural gas well located within the 9-county DFW non-attainment area has VOC emissions of between .45 and 1.14 tons per year, significantly less than the 25 tons per year allowed under the permit by rule. The average is 0.7 tons of VOC per well per year.
Admittedly this is a simplistic approach, but if 0.7 tons per year is extrapolated to all 10,721 Barnett Shale natural gas wells in the 9-county area, total emissions of VOCs from these natural gas wells are 7,504 tons per year or 21 tons per day. Compared to the 113.1 tons per day estimate that is in the SIP, TCEQ is overstating oil and gas VOCs by a factor of 5.4.
To put the oil and gas VOC emissions of 21 tons per day into perspective, TCEQ estimates that 2012 VOC emissions from all mobile sources will be 129 tons per day. That is, TCEQ’s estimates say that VOC emissions from mobile sources will be 6 times higher than oil and gas emissions. Or to put it another way: All the cars and trucks in the Dallas/Fort Worth Metroplex emit 6 times more volatile organic compounds that all the Barnett Shale natural gas wells.
There are two factors that account for the huge differences between 113 tons per day used in the SIP and 21 tons per day as shown in the emissions inventory: (1) the studies that the estimated 113 tons per day are based on contained numerous bad assumptions, such as assuming that Barnett Shale gas wells produce high VOC natural gas (over 10%) when in fact Barnett Shale gas in the 9-county area is less than 2% VOC; and (2) the SIP does not recognize the voluntary best management practices that the natural gas industry is employing in the Barnett Shale, such as the extensive use of low-bleed or no-bleed pneumatic valves.
There have been calls for oil and gas VOC emissions to be reduced from the 113.1 tons per day in the SIP to 100 tons per day. As you see by this analysis, the Phase 2 Emissions Inventory emissions data show that VOC emissions are already 79 tons per day below that goal. No further reductions are necessary.
While the numbers in my analysis are estimates based on a partial data set, I submit to you that the VOC estimates in the current version of the SIP are grossly overstated and need to be revised using the actual Phase 2 Emissions Inventory data that TCEQ has in hand.
The importance of using the best available numbers in the SIP is obvious: it helps move the DFW area closer to compliance with EPA ozone standards. TCEQ must use the actual emissions inventory data and not rely on inaccurate estimates. I respectfully request that that the State Implementation Plan be revised accordingly.