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Air Quality Impacts from a Potential Shale Gas Emissions Scenario - Photochemical Modeling of Ozone Concentrations in Central North Carolina Presented to the Mining and Energy Commission Environmental Standards Committee May 15, 2015 Department of Environment And Natural Resources Division of Air Quality Mike Abraczinskas, EIT, CPM
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Overview Background Photochemical Modeling – Methodology – Results Projected Ozone Impacts Comparison to Other Studies on Shale Gas- Related Impacts on Ozone Concentrations Conclusions 2
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List of Key Abbreviations 3 NCDAQNorth Carolina Division of Air Quality CMAQCommunity Multi-scale Air Quality Model MATSModel Attainment Test Software NEINational Emissions Inventory NOxNitrogen Oxides SEMAPSoutheastern Modeling, Analysis and Planning SMOKEEmissions processor VOCVolatile Organic Compounds WRFWeather Research and Forecasting Model
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Background NCDAQ tasked with identifying impacts of shale gas activities on future air quality. NCDAQ staff evaluated emissions profiles that shale gas activities may cause. Year 6 of shale gas development and production is projected to represent “maximum activity” emissions. 4
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Ozone Formation 5 O3O3 Sunlight High Temperatures NO x from combustion VOCs
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North Carolina’s VOC Emissions By Source Category 6 CY2011 Man-made Total = 309,465 tons CY2011 Total with Biogenic Sources = 1,370,553 tons *DAQ data is currently under review
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Photochemical Modeling Utilized the 2007/2018 SEMAP modeling platform to estimate ambient air quality impacts from shale gas development. – Air Quality Model: CMAQ v.5.0.1 – 12km resolution – 2007 meteorology Model data post-processed to generate graphical air quality output, EPA MATS software for station-specific air quality predictions. 7
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The SEMAP Modeling Platform Southeastern Modeling, Analysis and Planning Collaboration among 10 southeastern states to estimate future ozone, PM2.5, and regional haze Base emissions year is 2007, back-cast from 2008 National Emissions Inventory Future emissions year is 2018 (a bit before the projected year 6 of shale gas activities) 8
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SEMAP Modeling Info 9 36-km (left) and 12-km (right) SEMAP air quality modeling grids SMOKE v2.6 – Emissions Processor WRF v3.1.1 – Meteorology Model CMAQ v5.0 – Photochemical Model
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SEMAP Components 10 Shale Gas Emissions
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Photochemical Modeling Performed four CMAQ model runs: – Base 2007 emissions – Base 2018 emissions – Scenario 1 - Base 2018 emissions merged w/ estimated shale gas emissions. – Scenario 2 - Base 2018 emissions merged w/ only the estimated NOx emissions from shale gas development. Impacts estimated by taking the difference between the base 2018 and each of the shale gas scenarios. Focused on the highest ozone days in the Base 2018 run for analysis. – Year-2018 8-hour ozone values >60 PPB in the Triangle area. 59 total days studied. 11
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Shale Gas Emissions Modeling Methodology - Geography Total shale gas emissions evenly distributed throughout the shale gas area (light blue image to the right). Surface area of estimated shale gas drilling area broken down into respective 12-squared- kilometer model grid- boxes. 12 Shale gas development area defined by Dr. Ken Taylor, State Geologist of North Carolina
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Shale Gas Emissions Modeling Methodology - Geography Each individual grid-box’s percentage to the total shale gas area determined. This percentage determined how much shale gas emissions were produced within each grid-box. Shale gas emissions merged with 2018 SEMAP emissions. 13
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Allocating Emissions to the Model Grid Shale area mask: % of total shale basin in each grid cell. Daily Shale emissions file. Each hour has identical emissions. 14
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Shale Gas Modeling Impacts on Lee County Emissions 15
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CMAQ Photochemical Modeling Results Image shows the average daily 8-hour ozone difference between the base and shale gas run for all 59 studied days. Impacts of >1 PPB confined near the projected shale gas development area. 16
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CMAQ Photochemical Modeling Results Numbers in orange represent average monitor-specific ozone design-value increases across all projected year-2018 RRF days from shale gas development emissions. 17
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CMAQ Photochemical Modeling Results 18 CountyMonitor Base07 Ozone Design Value (ppb) 1 Future18 Ozone Design Value (ppb) 2 Sanford18 Ozone Design Value (ppb) 3 Change from Future18 to Sanford18 (ppb) LeeBlackstone7459.561.41.9 ChathamPittsboro71.755.456.30.9 WakeFuquay-Varina7762.362.60.3 MontgomeryCandor7358.8590.2 WakeMillbrook7963.663.70.1 Durham 745959.10.1 CumberlandWade75.360.560.60.1 GranvilleButner79.363.563.60.1 JohnstonWest Johnston7559.759.80.1 FranklinFranklinton76.361.261.30.1 CumberlandGolfview77.763.1 0.0 1.Base 2007 ozone design values 2.Future 2018 model predicted ozone design values 3.Future 2018 model predicted ozone design values with emissions from shale gas development in the Sanford Sub-basin
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CMAQ Photochemical Modeling Results 19 Little to no increase in days with ozone > 65ppb.
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NOx-only Shale Emissions NOx only, zero VOC emissions The results are identical to the results from the shale gas model run with VOC emissions. This means: – Ozone is NOx limited – VOC emissions are insignificant to ozone formation 20
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North Carolina & Other States’ Shale Gas Development Shale Basin New Wells Cumulative Wells NOx tons/day NOx tons per new well Maximum Average Increase in Daily Max 8- hour ozone Sanford1203683.70.0493.4 Marcellus 1 350040,0001290.03695 Haynesville 2 5651875820.1455 Baseline or Best Estimate Scenario from Roy et al. (2014,2015) Moderate scenario from Kembal-Cook et al. (2010) 21 Kemball-Cook, S, Bar-Ilan, A., Grant, J., Parker, L., Jung, J. Santamaria, W., Mathews, J., Yarwood, G., 2010. Ozone impacts of natural gas development in the Haynesville Shale. Environmental Science and Technology, 44:9357-9363. Roy, A.A., P.J. Adams and A.L. Robinson, 2014. Air pollutant emissions from the development, production, and processing of Marcellus Shale natural gas. Journal of the Air & Waste Management Association, 64(1), 19-37. Roy, A.A., P.J. Adams and A.L. Robinson, 2015. Impact of natural gas development in the Marcellus 1 Shale on regional ozone levels. In press.
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Conclusions The average daily NOx emissions attributed to shale gas activities is estimated to be ~3.7 tons per day. No ozone attainment concerns anticipated. The additional emissions from this “maximum activity” scenario are predicted to increase ozone by less than 2 PPB in Lee County, and by less than 1 PPB across the remaining central NC monitoring sites. 22
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