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Modeling Guidance and Examples for Commonly Asked Questions (Part II)

Modeling Guidance and Examples for Commonly Asked Questions (Part II). Reece Parker and Justin Cherry, P.E. Air Permits Division Texas Commission on Environmental Quality Advanced Air Permitting Seminar 2014. What Is Ozone?. Stratospheric Ozone. Good. sunlight. O + O. O 2. O + O 2. O 3.

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Modeling Guidance and Examples for Commonly Asked Questions (Part II)

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  1. Modeling Guidance and Examples for Commonly Asked Questions(Part II) Reece Parker and Justin Cherry, P.E. Air Permits Division Texas Commission on Environmental Quality Advanced Air Permitting Seminar 2014

  2. What Is Ozone? • Stratospheric Ozone Good sunlight O + O O2 O + O2 O3 • Ground-level Ozone Bad sunlight VOC + NOx O3 (and other products)

  3. Ground-level Ozone Is: • The main component of smog. • Not emitted directly in the air but forms when emissions of precursors, including NOx and VOCs “cook” in the sun: • Emissions from industrial facilities, electric utilities, motor vehicle exhaust, gasoline vapors, and chemical solvents are the major man-made sources of NOx and VOCs. • Mainly a summertime pollutant because sunlight and hot weather accelerate its formation. Ozone levels can be high in both urban and rural areas, often due to transport of emissions of ozone precursors.

  4. 2008 Ground-level Ozone Standards • Primary and secondary 8-hr ozone standards: 75 ppb* *based on the 3-yr average of the annual fourth highest daily maximum 8-hr ozone concentration

  5. Type of Application Non-Attainment Review? PSD Increment: • SO2 • PM10 Property Line: • SO2 • H2S Health Effects: • Benzene PSD Review? • SO2 • PM10 Property Line: • SO2 • H2S Health Effects: • Benzene

  6. Non-attainment vs. Attainment

  7. Non-attainment Review • Provide full documentation and details to reducereview time and mitigate potential issues • Protocol document should resemble AQA without modeling results Final product?Not exactly... Ozone Impact Analysis not required. Emissions offsets to improve air quality

  8. PSD Review • If project is major by itself or a major modification, a protocol is required: • For all criteria pollutants with an increase • Must be sent to EPA Region 6 for review • May include protocol for state-only requirements • Items to include in protocol are listed in protocol checklist • Consider all the items in the protocol check list before you start on your protocol document • An ozone impacts analysis is required when a project emits: • 100 tpy or more of VOCs • and/or • 100 tpy or more of NOx

  9. Ozone Impacts Analysis Obtain representative monitoring data Determine whether the project area is VOC-limited or NOx-limited* Quantitative demonstration Qualitative demonstration *Based on TCEQ’s own SIP photochemical modeling, most of the urban and rural areas of Texas are NOx-limited.

  10. Quantitative Demonstration • Photochemical modeling: • Comprehensive Air Quality Model with extensions (CAMx) • Screening approach using AERMOD: • Demonstration based on comments by EPA for NOx-limited areas

  11. Quantitative Demonstration (Cont.) • Screening approach using AERMOD: • Conservative analysis based on NOx modeling: • Determine if the project is NOx-limited or VOC-limited • If VOC-limited, determine GLCmax at a distance of 10-11 km • Assume 90% conversion of NOx to NO2 • Assume 3 ozone molecules per NOx molecule • Add result to the representative monitored concentration • Compare to the standard

  12. Example of Quantitative Demonstration Determine a representative monitor concentration Project Location

  13. Example (Cont.) Determine a representative monitor concentration Monitor Location 3-yr avg of 4th highest daily maximum 8-hr conc. 69 ppb

  14. Example (Cont.) Determine GLCmax10-11 km from project sources

  15. Example (Cont.) Model Output Converting model result to ppb: 1.57 ppb 2.96 µg/m3 x (100 ppb)/(188 µg/m3) =

  16. Example (Cont.) • Assume 90% conversion of NOX to NO2: 1.57 ppb x 0.9 = 1.413 ppb • Assume 3 molecules ozone per molecule NOX: 3 x 1.413 ppb = 4.24 ppb • Add result to monitored concentration: 69 ppb + 4.24 ppb = 73.24 ppb • Compare to standard: 73.24 ppb < 75 ppb

  17. Qualitative Demonstration • Assessment of current air quality: • Ozone trends • NOX trends • VOC trends • Analysis of the project’s potential ozone impact – Selection of Existing Photochemical Modeling Analyses: • Modeling simulation (Did photochemical modeling follow EPA guidance?) • Source characterization • Meteorological parameters and regional transport

  18. Example Qualitative Demonstration • BPA Area Ozone Design Values for all Monitoring Sites (1992-2013) Ozone Trends BPA Area 0.105 0.100 8-hr Ozone Design Value (ppm) 0.095 0.090 0.085 0.080 0.075 0.070 0.065 0.060 Site ID: 482450009 Site ID: 482450011 Site ID: 482450022 Site ID: 482450101 Site ID: 482450102 Site ID: 482450628 Site ID: 482451035 Site ID: 483611001 Site ID: 483611100 1997 NAAQS Threshold 1997 8-hr Ozone NAAQS 2008 8-hr Ozone NAAQS 2008 NAAQS Threshold

  19. Example (Cont.) Summary of NOx Emissions Data in BPA Area (tons per day) NOx Trends (BPA Area) 250 200 NOx Emissions (tons per day) 150 Nonroad Nonroad 100 Nonroad Onroad Onroad Onroad Area Area Area 50 Point Point Point 0 2005 NEI 2008 NEI 2011 NEI Point Onroad Nonroad Area

  20. Example (Cont.) Maximum BPA Area Annual Average NOX Concentration (1998-2013) NOx Trends (BPA Area) 16.0 14.0 Annual NOx Concentration (ppb) 12.0 10.0 8.0 6.0 4.0 2.0 0.0

  21. Example (Cont.) Summary of VOC Point and Area Emissions Data in BPA Area (tons per day) VOC Trends (BPA Area)

  22. Example (Cont.) Annual Average Level of Ethylene Measured in the BPA Area (1997-2013) VOC Trends (BPA Area) Ethylene Emissions 14.0 Range of Measured Annual Averages Median of Measured Annual Averages Annual Average Measurements (ppb) 12.0 10.0 8.0 6.0 4.0 2.0 0.0 Year

  23. Example (Cont.) Annual Average Level of Propylene Measured in the BPA Area (1996-2013) VOC Trends (BPA Area) Propylene Emissions 10.0 Range of Measured Annual Averages 9.0 Median of Measured Annual Averages Annual Average Measurements (ppb) 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 Year

  24. Example (Cont.) Source Characterization • Photochemical Modeling Project: • 24 Natural Gas-fired Refrigeration Compressor Turbines • 4 Acid Gas Vents • 1 Marine Flare • 2 Wet Gas Flares • 2 Dry Gas Flares • 2 Natural Gas-fired Generator Turbines • 2 Emergency Generators • Proposed Project: • 6 Natural Gas-fired Refrigeration Compressor Turbines • 1 LNG Storage LP Flare • 1 Wet/Dry Gas Ground Flare • 1 Auxiliary Boiler • 4 Thermal Oxidizers • 7 Diesel Generators • 1 Natural Gas-fired Essential Generator • 1 Blowdown Vent

  25. Example (Cont.) Source Characterization 2,665.29 tpy PSD Increment: • SO2 • PM10 Property Line: • SO2 • H2S Health Effects: • Benzene 681.46 tpy PSD Increment: • SO2 • PM10 Property Line: • SO2 • H2S Health Effects: • Benzene Photochemical Modeling PTE NOx Emissions Proposed Project PTE NOx Emissions Photochemical modeling approx. 4X more NOx than proposed project.

  26. Example (Cont.) Meteorological Parameters and Regional Transport BPA Area Surface Pressure (HPA) Relative Humidity (%)

  27. Example (Cont.) Meteorological Parameters and Regional Transport BPA Area Surface Roughness (m) Temperature (oC)

  28. Example (Cont.) Meteorological Parameters and Regional Transport BPA Area Wind Vectors (knts) Wind Velocity (knts)

  29. Example (Cont.) Model Results Photochemical modeling results in the BPA Area based on 4X as much NOx is between 0.1-0.5 ppb.

  30. Questions?

  31. Contact Information • Justin Cherry, P.E. • Air Dispersion Modeling Team • (512) 239-0955 • justin.cherry@tceq.texas.gov • Reece Parker • Air Dispersion Modeling Team • (512) 239-1348 • reece.parker@tceq.texas.gov Justin Cherry (512) 239-0955 justin.cherry@tceq.texas.gov Air Permits Division Reece Parker (512) 239-1348 reece.parker@tceq.texas.gov Air Permits Division

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