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

2. Overview Study Description › Scope › Input assumptions › Study qualifications Study Results › Details Generation Paths Other Observations 2 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

3. Study Description 3 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

4. Study Description - Purpose Model a scenario that approaches the 2024 trajectory of reducing carbon emissions to 80% below the 2005 levels by 2050. 4 W ESTERN E LECTRICITY C OORDINATING C OUNCIL 248 in 2024

5. 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 5 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

6. 6 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

7. PC21 Coal Retirements by State/Province 7 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

8. Replacement Sources 8 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.

9. 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. 9 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

10. Results 10 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

11. Dump Energy ReservesNomogramsCostDeliverableConstraints 11 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.

12. 12 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

13. Category Change – Estimated/Actual 13 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

14. 14 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

15. Generation Comparison 15 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

16. Difference in Annual Energy - WECC 16 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

17. 2024 CO 2 PC21 Coal Retirement Case 17 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

18. Generation Change by State and Fuel 18 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

19. 19 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

20. 20 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.

21. WECC Paths 21 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

22. Top 15 Heavily Utilized in PC21 22 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

23. Comparison of Net Annual Flow – Top 15 U90 23 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

24. Path 8 24 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.

25. Path 65+66 (COI plus PDCI) 25 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

26. Path 27 26 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.

27. Path 46 27 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

28. More Results 28 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

29. WECC Peak Week 29 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

30. WECC Peak Hour – PC21 30 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

31. WECC Early April 31 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

32. Dump Energy 4/7/24 – PC21 32 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

33. Peak hour on April 2 – WECC PC21 33 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

34. California Peak Week 34 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

35. California Early April 35 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.

36. 36 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

37. 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 37 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

38. 38 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