Historical Year for 2026 Common Case Load/Hydro/Wind/Solar Shapes TAS November 2015 Meeting Tom Miller- TAS Vice Chair W ESTERN E LECTRICITY C OORDINATING C OUNCIL

Discussion 1.WECC Anti Trust Statement 2.Meeting Background and Objectives 3.Use of Load Shapes in Gridview- WECC Staff 4.California Load Attributes – Developing Criteria for Load Shapes – Peak Load Months and Heating/Cooling Days 5.Revisit 2008 vs 2009 Hydro – CA Concerns about 2008 Hydro – Northwest Load and Wind (April) 6.The Great Recession 7.Alternative Proposal (Vote at TAS Quarterly meeting) 8.Other Lessons learned and Next Steps 2 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

Background and Objectives Background – TAS Vote - Michael Bailey – Concerns Raised – Further Investigation Meeting Objectives – Overview of further investigation of Load shapes – Present and discuss rationale for alternative proposal- VOTE – Lessons Learned and next steps Meeting Success: – Provide stakeholders additional information and opportunity to discuss attributes of candidate energy shape years – Provide alternative proposal to be considered with original proposal for 2026 Common Case (Note: Vote will be done at TAS Quarterly Meeting in November) 3 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

Use of Load Shapes- Gridview Over view of Gridview Modeling Options for use of load shapes – Monthly Peak MW and Energy – Annual Peak and Energy (Uses 8760 profile)logic Issue: Need to review reported LRS data too! 4 W ESTERN E LECTRICITY C OORDINATING C OUNCIL WECC Staff to add slides for discussion

Load Criteria Development 5 W ESTERN E LECTRICITY C OORDINATING C OUNCIL What Criteria do Planning Regions Plan to? Summer Winter Peak Mw Energy Load-net wind-solar Peaks Table shows assessment of Annual Peak Month Non-Typical Peak Month Typical Peak Month

Load Criteria Development 6 W ESTERN E LECTRICITY C OORDINATING C OUNCIL 2008 California Major Load Centers June Peak not typical Conclusion: 2009 is a better representative year over 2008 regarding typical system peak months

CA Annual Cooling Days 7 W ESTERN E LECTRICITY C OORDINATING C OUNCIL Conclusion: both 2008 and 2009 are good candidate years regarding CA CDDs

Typical Northwest Wind and Loads 8 W ESTERN E LECTRICITY C OORDINATING C OUNCIL Wind: Northwest (WA+OR) WECC-Wide Stress: In California-Southwest, the system is more prone to over- generation (with high solar and low load in April). In Northwest, it is also more likely to have over-generation (with higher wind) in April than in June.

NW Hydro Data 9 W ESTERN E LECTRICITY C OORDINATING C OUNCIL Concerns Non-typical NW Hydro Monthly Shape April 2008: Below typical NW Hydro may under-state over- generation issues in the Northwest (Wind) and Southwest/California Regions (Low Load/High Solar) June 2009: late runoff and above average my “stress” flows across COI and CA 500/230kv Backbone Conclusion: 2009 better representative of typical year that has benefits for all regions to assess April stress

The Great Recession 10 W ESTERN E LECTRICITY C OORDINATING C OUNCIL Conclusion: 2009 loads more typical and reflect rebound from 2008 as peak of economic down-turn

Pros and Cons 11 W ESTERN E LECTRICITY C OORDINATING C OUNCIL PROS Annual Hydro Energy Good (Pro) CA Load Peak MonthPoor (Con) CA June Peak non-typical Good (Pro) Hydro Monthly VariationsDeviations from typical (Con) In line with typical (Pro) April NW Hydro Lower than typical NW Hydro: under represents Over-Gen (Con) Favorable for Assessing typical Over-Gen WECC- wide (Pro) June NW Hydro Non Typical (High) “Stress” on COI Favorable (Pro) CA Cooling Degree Days Good (Pro) June not typical Good (Pro) “Stress” sensitivities Good (Con) Poor (Pro) Updated NREL Wind SolarAvailable (Pro) Great Recession Peak of Economic Down-turn (Con) Recovery towards economic growth (Pro)

Proposals Original Proposal for TAS Vote: 2008 Coincident Load-Wind-Solar-Hydro New- Alternative Proposal: 2009 Coincident Load-Wind-Solar-Hydro 12 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

Lessons Learned Gridview modeling of monthly peak-MW and energy helps mitigates concern over 2008 CA June peak Issues Need to develop regional criteria for load shapes Reported load forecasts need to be vetted for use in TEPPC data-set – Implied Load Modifiers: EE, BTM-PV – Incremental Modeling: EE, BTMPV, Other – Understand underlying assumptions: economic, temperature (1 in 2) adjusted Need for WECC Staff time for load assessments 13 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

NEXT Steps 2026 Common Case Energy Shape Implementation Smart Goals discussion at Upcoming TAS Quarterly Meeting Discussion – Smart Goal: Measurable, Attainable, Relevant, Time-bound): Understanding WECC Load Forecast Data Investigate 2026 Common Case Load Forecasts Shapes TAS Process Improvements for Load Assessments 14 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

Questions or Comments 15 W ESTERN E LECTRICITY C OORDINATING C OUNCIL