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 ResourcesDivision of Air Quality

Mike Abraczinskas, EIT, CPM

Overview• Background• Photochemical Modeling– Methodology– Results

• Projected Ozone Impacts • Comparison to Other Studies on Shale Gas-

Related Impacts on Ozone Concentrations• Conclusions

2

List of Key Abbreviations

3

NCDAQ North Carolina Division of Air Quality

CMAQ Community Multi-scale Air Quality Model

MATS Model Attainment Test Software

NEI National Emissions Inventory

NOx Nitrogen Oxides

SEMAP Southeastern Modeling, Analysis and Planning

SMOKE Emissions processor

VOC Volatile Organic Compounds

WRF Weather Research and Forecasting Model

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

Ozone Formation

5

O3Sunlight High

Temperatures

NOx from combustionVOCs

North Carolina’s VOC Emissions BySource Category

6

CY2011 Man-made Total = 309,465 tonsCY2011 Total with Biogenic Sources = 1,370,553 tons

*DAQ data is currently under review

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

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

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

SEMAP Components

10

Shale Gas Emissions

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

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

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

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

Shale Gas ModelingImpacts on Lee County Emissions

15

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

CMAQ Photochemical Modeling Results

Numbers in orange represent average monitor-specific ozone design-value increasesacross all projected year-2018 RRF days from shale gas development emissions. 17

CMAQ Photochemical Modeling Results

18

County MonitorBase07 Ozone Design Value (ppb)1

Future18 Ozone Design Value (ppb)2

Sanford18 Ozone Design Value (ppb)3

Change from Future18 to Sanford18 (ppb)

Lee Blackstone 74 59.5 61.4 1.9

Chatham Pittsboro 71.7 55.4 56.3 0.9

Wake Fuquay-Varina 77 62.3 62.6 0.3

Montgomery Candor 73 58.8 59 0.2

Wake Millbrook 79 63.6 63.7 0.1

Durham Durham 74 59 59.1 0.1

Cumberland Wade 75.3 60.5 60.6 0.1

Granville Butner 79.3 63.5 63.6 0.1

Johnston West Johnston 75 59.7 59.8 0.1

Franklin Franklinton 76.3 61.2 61.3 0.1

Cumberland Golfview 77.7 63.1 63.1 0.0

1. Base 2007 ozone design values2. Future 2018 model predicted ozone design values3. Future 2018 model predicted ozone design values with emissions from shale gas development in the Sanford

Sub-basin

CMAQ Photochemical Modeling Results

19

Little to no increase in days with ozone > 65ppb.

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

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

Sanford 120 368 3.7 0.049 3.4Marcellus1 3500 40,000 129 0.0369 5Haynesville2 565 1875 82 0.145 5

•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.

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