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PRIME2: Model Evaluations

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A renewed interest and scrutiny of downwash shortcomings has fueled a parallel, yet complementary effort, led by industry and EPA. Industrial groups funded the update to the Plume Rise Model Enhancements (PRIME) formulation in AERMOD based on new equations derived from wind tunnel measurements. Concurrently, EPA’s Office of Research and Development (ORD) conducted research that led to new enhancements to the downwash formulation.2 The new PRIME equations (PRIME2), along with EPA-ORD’s building downwash improvements, have been included as alpha options in an upcoming new EPA version of AERMOD.
As part of the renewed interest in building downwash, the PRIME2 subcommittee under the A&WMA APM committee was formed to: (1) establish a mechanism to review, approve and implement new science into the model for this and future improvements; and (2) provide a technical review forum to improve the PRIME building downwash algorithms. Collaboration and cooperation from EPA’s ORD and OAQPS have been on-going during this research project. These efforts included a downwash summit at EPA’s RTP facilities on February 16, 2018 where representatives of the PRIME2 committee and research funders met with EPA’s ORD and OAQPS staff to discuss the newly developed building downwash improvements. During that meeting it was decided that these enhancements would be included as new alpha options in AERMOD. The intent is that these experimental options will be tested by the user community to create enough justification to transition them to a beta status (approved on a case-by-case basis) and eventually to default options in AERMOD. An evaluation of some of these new downwash options is presented.

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PRIME2: Model Evaluations

  1. 1. Sergio Guerra, PhD | GHD Ron Petersen, PhD, CCM | Petersen Research and Consulting EUEC 2019, San Diego CA February 26, 2019 PRIME2 Model Evaluation -AERMOD 18081 -AERMOD D18227_ORD -AERMOD D18227_PRM2
  2. 2. Objectives PRIME2 Subcommittee was formed to: • Establish a mechanism to review, approve and implement new science into the model for this and future improvements • Provide a technical review forum to improve the PRIME building downwash algorithms PRIME2 Model Evaluation
  3. 3. Next Steps: Implementation Model Improvements Submitted to EPA AERMOD with PRIME2 and ORD Switches EPA releases New PRIME2 as Alpha option App W Sec 3.2.2 reqs. EPA releases PRIME2 as Beta option Notice of proposed rulemaking (NPRM) New PRIME is released as default regulatory option Alpha option needs to meet the alternative refined model requirements in App W, Section 3.2.2 before it can become a Beta option. These requirements include: 1-Model has received a scientific peer review; 2-Model can be demonstrated to be applicable to the problem on a theoretical basis; 3-The data bases to perform analysis are available and adequate; 4-Appropriate performance evaluations show model is not biased toward underestimation; & 5-A protocol on methods and procedures to be followed has been established PRIME2 Model Evaluation
  4. 4. Why a New Downwash Model? • AERMOD’s PRIME algorithm based on research carried out before 2000 • Original theory based on a limited number of building dimensions and building types • Theory is not suitable for porous, streamlined, wide or elongated structures • Theory based on theoretical assumptions that can be improved PRIME2 Model Evaluation
  5. 5. Background • Industry funding obtained in 2016 and early 2017 to carry out PRIME2 research • Initial results presented at EPA’s 2016 Regional, State, and Local Modelers’ Workshop http://www.cleanairinfo.com/regionalstatelocalmodelingworkshop/archive/2016/Pre sentations/1-14_CPP_AERMOD-PRIME-Next-Generation_Downwash_Model.pdf • Journal article documenting flaws in downwash theory was published in JAWMA, August 2017 https://www.tandfonline.com/doi/full/10.1080/10962247.2017.1279088 • 2017 EPA Releases White Papers • EPA ORD has been doing building downwash research and has made some improvements to PRIME PRIME2 Model Evaluation
  6. 6. New equation documented https://doi.org/10.1016/j.jweia.2017.11.027 PRIME2 Model Evaluation
  7. 7. Update AERMOD AERMOD Fortran Files Modified PRIME.f Where all building downwash calculations are carried out Calc1.f Where approach wind conditions come from Modifications • New Zeff • New Ueff, SWeff, SVeff • New U30, SW30 and SV30 for input to new equation Modifications • New turbulence equation • New wind speed equation Recompile and Create AERMOD/PRIME2 7 PRIME2 Model Evaluation
  8. 8. Key Features of PRIME2 • Lateral turbulence enhancement in the wake is less than vertical turbulence enhancement (currently PRIME has them identical) • Wake effects decrease as approach roughness increases • Wake effects for streamlined structures are reduced • Building wake effects decay rapidly back to ambient levels above the top of the building versus the current theory that has these effects extending up to 3 building heights • The approach turbulence and wind speed is calculated at a more appropriate height versus the current theory where half the wake height at 15 building heights downwind of the building is used PRIME2 Model Evaluation
  9. 9. EPA ORD AERMOD/PRIME Modifications Current PRIMEThree ORD model enhancements 1. Fix mismatch in plume vertical spread at transition between cavity and far wake. 2. Use effective wind speed, Ueff, for primary plume versus stack height for concentration calculations 3. Adjust cap on ambient turbulence from 0.06 to 0.07. No effect on PRIME2. Fix 1 Current PRIME Ueff at Stack Top Fix 2 @ (Hp+RecH)/2 RecH) = 0 Hp PRIME2 Model Evaluation
  10. 10. PRIME2 Switches PRIME2Ueff defines the height used to compute effective parameters Ueff, Sweff, Sveff and Tgeff at plume height and at 30 m. PRIME2UTurb enables enhanced calculations of turbulence and wind speed Streamline defines the set of constants for modeling all structures as streamlined. If omitted, rectangular building constants are used. PRIME2 Model Evaluation
  11. 11. ORD Switches PRIMEUeff controls the heights for which the wind speed is calculated for the main plume concentrations. • Average between plume height and receptor height recommended in ORD version • Default is current method in AERMOD, stack height wind speed. PRIMETurb adjusts the vertical turbulence intensity, wiz0 from 0.6 to 0.7. PRIMECav modifies the cavity calculations If no switch applied, current AERMOD methodology used. PRIME2 Model Evaluation
  12. 12. Case Study Evaluation Conducted for the following four cases: • Arconic (formerly Alcoa )- Davenport, IA • Mirant Potomac River Generating Station- Alexandria, VA • Basic American Foods- Blackfoot, ID • Oakley Generating Station- Oakley, CA The evaluation compares the following averages for each case: • 1-hour (H1H) • 24-hr (H1H) • Annual PRIME2 Model Evaluation
  13. 13. Arconic- Davenport, IA (formerly Alcoa) PRIME2 Model Evaluation Met data: Davenport, IA met data, 2010-2014 from IDNR (http://www.iowadnr.gov/Environmental-Protection/Air- Quality/Modeling/Dispersion-Modeling/Meteorological-Data). Q Stack Height Stack Temp. Stack Vel. Stack Diam. Height of BPIP Cont. Bdg. g/s m K m/s m m S_349 1.94 21.34 310.93 17.82 2.46 16.7-17.5 Stack
  14. 14. Arconic – Summary Results in µg/m3 PRIME2 Model Evaluation Arconic 349 w BPIP H1H Average 18081 D18227-ORD D18227-PRM2 H1H 1-hr 172.7 166.0 95.9 24-hr 30.0 26.8 19.7 Annual 3.0 4.5 1.0
  15. 15. Arconic H1H Comparisons for 1-hr, 24-hr and Annual Averages 172.7 30.0 3.0 166.0 26.8 4.5 95.9 19.7 1.0 0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 160.0 180.0 200.0 1-hr 24-hr Annual Q(µg/m3) Arconic 349 w BPIP H1H 18081 D18227-ORD D18227-PRM2 PRIME2 Model Evaluation
  16. 16. Arconic Q-Q Plots PRIME2 Model Evaluation
  17. 17. Arconic: BPIP inputs ran with AERMOD v18081 PRIME2 Model Evaluation
  18. 18. Arconic: BPIP inputs ran w AERMOD vD18227_ORD PRIME2 Model Evaluation
  19. 19. Arconic: BPIP inputs ran w AERMOD vD18227_PRM2 PRIME2 Model Evaluation
  20. 20. Mirant Potomac River Generating Station, Alexandria, VA PRIME2 Model Evaluation Met data: Reagan Airport, VA original 1992 met data reprocessed with AERMETv18081. Q Stack Height Stack Temp. Stack Vel. Stack Diam. Height of BPIP Cont. Bdg. g/s m K m/s m m BS4 1 48.2 303.71 18.42 2.44 35.3 Stack
  21. 21. Mirant – Summary Results in µg/m3 PRIME2 Model Evaluation Mirant BS4 w BPIP H1H Average 18081 D18227-ORD D18227-PRM2 H1H 1-hr 21.1 32.3 26.7 24-hr 6.9 11.5 7.6 Annual 0.6 1.1 0.3
  22. 22. Mirant H1H Comparisons for 1-hr, 24-hr and Annual Averages 21.1 6.9 0.6 32.3 11.5 1.1 26.7 7.6 0.3 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 1-hr 24-hr Annual Q(µg/m3) Mirant BS4 w BPIP H1H 18081 D18227-ORD D18227-PRM2 PRIME2 Model Evaluation
  23. 23. Mirant Q-Q Plots PRIME2 Model Evaluation
  24. 24. Mirant: BPIP inputs ran with AERMOD v18081 PRIME2 Model Evaluation
  25. 25. Mirant: BPIP inputs ran with AERMOD vD18227_ORD PRIME2 Model Evaluation
  26. 26. Mirant: BPIP inputs ran with AERMOD vD18227_PRM2 PRIME2 Model Evaluation
  27. 27. Basic American Foods, Blackfoot, ID PRIME2 Model Evaluation Met data: On-site met data from the Blackfoot Met Tower operated by the Idaho National Laboratory and supplemented with data from the Pocatello Regional Airport, 2002-2006.
  28. 28. Basic American Foods, Blackfoot, ID PRIME2 Model Evaluation Met data: On-site met data from the Blackfoot Met Tower operated by the Idaho National Laboratory and supplemented with data from the Pocatello Regional Airport, 2002-2006. Q Stack Height Stack Temp. Stack Vel. Stack Diam. Height of BPIP Cont. Bdg. g/s m K m/s m m EU_24 0.13 12.65 359.26 12.44 0.76 EU_25 0.06 12.65 338.71 5.76 0.91 EU_26 0.13 12.65 359.26 12.44 0.76 EU_31 0.12 12.65 344.26 14.57 1.04 EU_32 0.05 12.60 338.71 10.52 0.79 EU_33 0.05 12.60 327.59 11.34 0.61 Stack 7.0
  29. 29. BAF – Summary Results in µg/m3 PRIME2 Model Evaluation BAF EU24-27& EU31-33 w BPIP H1H Average 18081 D18227-ORD D18227-PRM2 H1H 1-hr 451.3 611.6 350.7 24-hr 146.0 152.7 119.1 Annual 48.8 51.1 35.4
  30. 30. BAF H1H Comparisons for 1-hr, 24-hr and Annual Averages 451.3 146.0 48.8 611.6 152.7 51.1 350.7 119.1 35.4 0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 1-hr 24-hr Annual Q(µg/m3) BAF EU24-27& EU31-33 w BPIP H1H 18081 D18227-ORD D18227-PRM2 PRIME2 Model Evaluation
  31. 31. BAF Q-Q Plots PRIME2 Model Evaluation
  32. 32. BAF: BPIP inputs ran with AERMOD v18081 PRIME2 Model Evaluation
  33. 33. BAF: BPIP inputs ran with AERMOD vD18227_ORD PRIME2 Model Evaluation
  34. 34. BAF: BPIP inputs ran with AERMOD vD18227_PRM2 PRIME2 Model Evaluation
  35. 35. Oakley Generating Station, Oakley, CA PRIME2 Model Evaluation Met data: Metro Oakland International Airport, CA met data for years 2009-2013. Downloaded from CARB (https://www.arb.ca.gov/toxics/harp/metfiles2.htm). Q Stack Height Stack Temp. Stack Vel. Stack Diam. Height of BPIP Cont. Bdg. g/s m K m/s m m EU_31 1 47.41 362.00 22.26 5.59 31.7 Stack
  36. 36. Oakley GS – Summary Results in µg/m3 PRIME2 Model Evaluation Oakley GS Tur1 w BPIP H1H Average 18081 D18227-ORD D18227-PRM2 H1H 1-hr 1.4 1.6 4.3 24-hr 0.4 0.4 0.8 Annual 0.1 0.1 0.1
  37. 37. Oakley GS H1H Comparisons for 1-hr, 24-hr and Annual Averages 1.4 0.4 0.1 1.6 0.4 0.1 4.3 0.8 0.1 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 1-hr 24-hr Annual Q(µg/m3) Oakley GS Tur1 w BPIP H1H 18081 D18227-ORD D18227-PRM2 PRIME2 Model Evaluation
  38. 38. Oakley GS Q-Q Plots PRIME2 Model Evaluation
  39. 39. Oakley: BPIP inputs ran with AERMOD v18081 PRIME2 Model Evaluation
  40. 40. Oakley: BPIP inputs ran with AERMOD vD18227_ORD PRIME2 Model Evaluation
  41. 41. Oakley: BPIP inputs ran with AERMOD vD18227_PRM2 PRIME2 Model Evaluation
  42. 42. Results • Performance of version D18227-PRM2 is inconsistent • Predicted values are lower than the base case for Arconic and BAF with small differences for Mirant (except for annual which has PRIME2 significantly lower). • The base case predictions are lower than the ones from the D18227- ORD and D18227-PRM2 versions for the Oakley case. PRIME2 Model Evaluation
  43. 43. Results • In general, version D18227-ORD produces higher concentrations than AERMOD 18081. • The primary reason for this is that the ORD version uses the wind speed at the average between plume centerline height and receptor height to calculate concentrations versus stack height in AERMOD. • PRIME2’s theory does not depend on the wake height but rather the building height, width, length and position relative to the stack. PRIME2 Model Evaluation
  44. 44. Future Areas of Improvements • PRIME streamline • PRIME plume rise • Height used to calculate turbulence • BPIP-PRM • Cavity plume amplification problem PRIME2 Model Evaluation
  45. 45. Conclusions • PRIME2 includes a superior theory to account for building downwash effects for rectangular and streamlined structures. • Inconsistencies may be due to other parts of the model • Work from EPA ORD complements the work performed by PRIME2. • Plan is to continue EPA collaboration to address model improvements to AERMOD related to building downwash. PRIME2 Model Evaluation
  46. 46. Sergio A. Guerra, PhD Ron Petersen, PhD, CCM sergio.guerra@ghd.com rpetersen@petersenresearch.com Office: + 720 974 0935 Mobile:+1 970 690 1344 PRIME2 Model Evaluation
  47. 47. www.ghd.com PRIME2 Model Evaluation

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