1. Three-State Air Quality Study (3SAQS) Three-State Data Warehouse (3SDW) Emission Inventory Comparison 2008 vs 2011 vs 2018 vs 2020 University of North Carolina (UNC-IE) Cooperative Institute for Research in the Atmosphere (CIRA) ENVIRON International Corporation (ENVIRON) June 19, 2014

2. 2 3SAQS Inventory Comparison Overview Objective: Compare the base and future year emission inventories for CO, UT, and WY to support the QA of the data and to inform the air quality evaluation Display the differences (what), limited analysis for why Why two different future years? Inventories: SimulationNon-O&GO&GNatural 3SAQS Base 2008NEI2007v5 NEI2008v2 WRAP Phase IIIWestJumpAQMS 2008 3SAQS 2020 (2008-based) NEI2007v53SAQS Phase IWestJumpAQMS 2008 3SAQS Base 2011NEI2011v63SAQS Phase I3SAQS 2011 3SAQS 2018 (2011-based) NEI2011v63SAQS Phase I3SAQS 2011

3. 3 3SAQS Inventory Comparison Overview Compare the inventories across 15 sectors: – Aircraft/Locomotive/ Marine (ALM) – Nonroad Mobile – Onroad Mobile – EGU Point – nonEGU Point – Nonpoint – Residential Wood Combustion (RWC) – Livestock ammonia – Fertilizer Ammonia – Area Oil & Gas – Point Oil & Gas – Fire – Fugitive Dust – Windblown Dust – Biogenic

4. Annual NOx Emissions by State and Inventory

5. Annual VOC Emissions by State and Inventory

6. Annual CH4 Emissions by State and Inventory

7. Annual SO2 Emissions by State and Inventory

8. Annual NH3 Emissions by State and Inventory

9. Annual PM2.5 Emissions by State and Inventory

10. 10 State Base Year Differences (O&G methane excluded from chart)

11. 11 State Base Year Differences (O&G methane excluded from chart)

12. 12 State Base Year Differences (O&G methane excluded from chart)

13. 13 State Base->Future Differences (O&G methane excluded from chart) Very similar trends from base to future year, despite different starting and ending years

14. 14 State Base->Future Differences (O&G methane excluded from chart) Very similar trends from base to future year, despite different starting and ending years

15. 15 State Base->Future Differences (O&G methane excluded from chart) Notable differences in the trends for non-EGU point and area O&G

16. 16 3SAQS Inventory Comparison Significant Trends 2008  2011 Sector/Poll COUTWY Oil and Gas/VOC ++- Oil and Gas/CH4 ++ Onroad/All --- Windblown Dust -- Nonpoint/VOC - NEGU Point/NOx +-+ Biogenic/VOC +++ 2008  2020 Sector/Poll COUTWY Oil and Gas/VOC +++ Oil and Gas/CH4 ++ Oil and Gas/NOx - Onroad/All --- EGU Point/SO2 ---- EGU Point/PM10 - ALM/NOx - 2011  2018E Sector/Poll COUTWY Oil and Gas/VOC +++ Oil and Gas/CH4 +++ Onroad/All --- EGU Point/SO2 ---- EGU Point/PM10 - ALM/NOx -

17. 17 Colorado Oil and Gas Methane 2008 2011 Over 13 Mtons/year of CH4 in 2011 inventory from fixed roof tank condensates 483,000 tons/year of CH4 from all sources in 2008 inventory ~1.4 x more VOC in 2011, ~30x more CH4 in 2011 Driven by increase in fixed roof tank emissions in the Piceance Basin (application of the ROG2TOG multiplier for condensates = 449 using profile ID SSJCB)