1. PC21 Coal Retirement Study TAS/TEPPC – Nov. 2015 W ESTERN E LECTRICITY C OORDINATING C OUNCIL WECC System Adequacy Planning

2. Study Requestors Center for Energy Efficiency and Renewable Technologies (CEERT) Natural Resource Defense Council (NRDC) PacifiCorp (PAC)* State and Provincial Steering Committee (SPSC) Scenario Planning Steering Group (SPSG) Western Grid Group (WGG) Western Interconnection Regional Advisory Body (WIRAB) 2 W ESTERN E LECTRICITY C OORDINATING C OUNCIL *PAC later withdrew from study request when scope was changed to indefinitely postpone a reliability analysis.

3. Overview Study Description › Scope › Input assumptions › Study qualifications Study Results › Details Generation Paths Other Observations 3 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

4. Study Description 4 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

5. Study Description - Purpose Model a scenario that approaches the 2024 trajectory of reducing carbon emissions to 80% below the 2005 levels by 2050. 5 W ESTERN E LECTRICITY C OORDINATING C OUNCIL 248 in 2024

6. Study Description - Assumptions Modeling assumptions include: – Retirement of several high CO 2 intensity coal-fired generators based on vintage and location – Addition of renewable resources (wind + solar) – Additional energy efficiency – Addition of gas-fired generation – Addition of energy storage resources – More details on next slides 6 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

7. 7 ABAZCACOMTUTWY Battle River 4,5 [537] Apache 2,3 [350] ACE Cogen [103] Comanche 1,2 [660] Colstrip 1,2,3 [1354] Huntington 1,2 [909] Dave Johnston 1-4 [762] Genesse 2 [390] Cholla 1,3 [387] Argus 8,9 [50] Craig 1,2 [863] Intermountain 1,2 [1800] Jim Bridger 1,2,3 [1581] Sheerness 1,2 [780] Coronado 1 [380] Casterville [1] Hayden 1,2 [446] NM KUCC 1-4 [175] Naughton 1,2 [357] Sundance 3 [362] H.W. Sundt 4 [156] Fellow [1] M Drake 5,6,7 [254] Four Corners 4,5 [1540] Sunnyside [53] Neil Simpson 2 [80] Navajo 2,3 [1500] Jackson Valley [21] Nucla 1-4 [100] Wygen 1,2 [180] Lassen [22] R D Nixon 1 [208] NVWA Wyodak [340] Mt Poso [35] N Valmy 2 [268] Centralia 2 [688] Phillips Carbon [16] TS Power 1 [227] Portland Cement [28] Port of Stockton [44] PC21 Additional Coal Retirements

8. 8 W ESTERN E LECTRICITY C OORDINATING C OUNCIL ABAZCACOMTUTWY Battle River 3 [148] Cholla 2 [262] RioBravo Jasm [35] Arapahoe 3,4 [153] JE Corette [153] Carbon 1,2 [172] Neil Simpson 1 [18] HR Milner [144] Four Corners 1-3 [560] Cherokee 3 [152] Osage 1-3 [30] Sundance 1,2 [576] Navajo 1 [750] Lamar 4,6 [38] NM Valmont 5 [184] San Juan 2,3 [839] WN Clark 1,2 [40] NVWA Reid Gardner 1-4 [587] Centralia 1 [688] Valmy 1 [254] OR Boardman [610] PC01 Common Case Coal Retirements [6418 MW]

9. PC21 Coal Retirements by State/Province 9 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

10. Replacement Sources 10 W ESTERN E LECTRICITY C OORDINATING C OUNCIL The Retired MWh represents the energy produced by the PC21 retired coal resources in the 2024 v1.5 common case. The EE energy was modeled as a load reduction and resulted in a total reduction of about 1700 GWh.

11. Study Qualifications Path Ratings: The WECC paths associated with a few of the retired generators and their replacements would likely need to be re- rated through the path rating process. No changes in path or branch ratings were assumed for this study. Constraints: Other operating constraints and nomograms were also not modified. Flexibility Reserves: The flexibility reserve adders for each reserve area are derived from the loads and amount of variable generation. The flexibility reserve adders were not recalculated for this study. Resource Adequacy: A check of the peak planning reserve margins was not done. System Stability: Tests of system stability were not conducted. 11 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

12. Results 12 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

13. Dump Energy ReservesNomogramsCostDeliverableConstraints 13 W ESTERN E LECTRICITY C OORDINATING C OUNCIL Generation that is chosen by the PSM model for commitment and dispatch for a least-cost solution may be dumped if its dispatch will break a modeling constraint regarding generation, transmission, reserves, and/or nomograms.

14. 14 W ESTERN E LECTRICITY C OORDINATING C OUNCIL From New Gen 0 269,923 0 0 0 2,409,645 1,801,747 0 0 Load side 0 0 0 18,820,604 38,636,263 61,938,182 629,356 -1,731,070

15. Category Change – Estimated/Actual 15 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

16. 16 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

17. Generation Comparison 17 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

18. Difference in Annual Energy - WECC 18 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

19. 2024 CO 2 PC21 Coal Retirement Case 19 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

20. Generation Change by State and Fuel 20 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

21. 21 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

22. 22 W ESTERN E LECTRICITY C OORDINATING C OUNCIL This was the only replacement ES unit that had any significant operation. The others didn’t seem to reach the price thresholds.

23. WECC Paths 23 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

24. Top 15 Heavily Utilized in PC21 24 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

25. Comparison of Net Annual Flow – Top 15 U90 25 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

26. PC-21 Heavily Utilized Paths 26 W ESTERN E LECTRICITY C OORDINATING C OUNCIL P52 Silver Peak-Control P60 Inyo-Control P83 Montana Alberta Tie Line Path75%90%99% P60 Inyo-Control 115 kV Tie38%25%18% P52 Silver Peak- Control 55 kV34%23%0% P83 Montana Alberta Tie Line20%11%7%

27. Path 8 27 W ESTERN E LECTRICITY C OORDINATING C OUNCIL The retirement of the base load generation at Colstrip 1,2,3 had an impact on the Path 8 flows. It is also possible that the path rating would be reduced.

28. Path 65+66 (COI plus PDCI) 28 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

29. Path 27 29 W ESTERN E LECTRICITY C OORDINATING C OUNCIL In the past a nomogram has been used to define a relationship between generation and path 27 flows. The nomogram was not modified to specify how the replacement generation in Utah would be treated with respect to southern California.

30. Path 46 30 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

31. More Results 31 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

32. WECC Peak Week 32 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

33. WECC Peak Hour – PC21 33 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

34. WECC Early April 34 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

35. Dump Energy 4/7/24 – PC21 35 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

36. Peak hour on April 2 – WECC PC21 36 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

37. California Peak Week 37 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

38. California Early April 38 W ESTERN E LECTRICITY C OORDINATING C OUNCIL The gaps between the demand and generation represent energy imports. The hours where the generation exceeds the demand represents exports.

39. 39 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

40. Observations The PC21 study had no unserved load. PC21 CO 2 was 29 million metric tons short of goal Overall energy from PC01 CC and CT units increased Overall energy from remaining coal units increased Share of annual energy from renewable resources is 23.1% in PC21 vs. 17.7% in PC01 Poor performance of PC21 pump storage projects except for project added in SRP area 40 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

41. 41 W ESTERN E LECTRICITY C OORDINATING C OUNCIL Contact Stan Holland Western Electricity Coordinating Council Senior Engineer stan@wecc.biz (801) 883-6858 Stan Holland Western Electricity Coordinating Council Senior Engineer stan@wecc.biz (801) 883-6858