1. Dan Beckstead Associate Staff Engineer TEPPC 2026 Common Case Load

2. 2 2024 TEPPC Common Case – Major Assumptions 2026 Common Case LoadsResourcesTransmission

3. 3 2024 TEPPC Common Case – Load Assumptions 2026 Common Case LoadsResourcesTransmission

4. 4 Dataset Building Activities Resource Portfolio SWG Loads DWG Transmission Network SWG TEPPC Dataset WECC Staff Debugging/Validation DWG/MWG/SWG/Staff Modeling Enhancements MWG Scenario Runs/Analysis/Reporting LRS Submittals Utility IRPs Resource Planners Work Group Participants WREZ Tool NREL Meso- scale Data Data Improvements DWG WECC Staff LRS Submittals DSM Task Force SCG Common Case Transmission Assumptions WECC Powerflow Case

5. 5 Provided to WECC by the BAs and forwarded to NERC and FERC as required under the FERC- approved NERC Standards Brings together the Load Serving Entities (LSEs) forecasts inside each respective BA o LSEs within each BA provide the BA with their load forecast, who in turn provides the BA forecast to WECC’s Loads and Resources Subcommittee (LRS) each year Balancing Authority Load Forecasts

6. 6 10-year forecast 1-in-2 (50% or median) forecast Specified on an annual and monthly energy (GWh) and peak (MW) basis 2010 BA forecasts provided a starting point for the 2022 TEPPC Common Case 2012 BA forecasts provided a starting point for the 2024 TEPPC Common Case 2015 BA forecast (latest) used in 2026 CC updated when possible Balancing Authority Load Forecasts

7. TEPPC Load Bubbles

8. Steps: (DWG input required) Collect LRS Submittals Submit BA forecast to LBNL LBNL to apply EE adjustments Adjusted 2024 peak and energy forecasts applied to 2005 historic hourly shapes Check Load shape distortion (Compression/Expansion) Apply Pumping Loads

9. Excessive Compression of the shape Cause: The forecasted growth in energy is a lot greater than the forecasted growth in peak for a particular month. There will be a noticeable amount of compression in the forecasted shape for a month when the monthly load factor of the forecast is a lot greater than the monthly load factor of the existing shape. Consequences: The change in the loads between peak and off-peak hours is reduced which decreases the amount of variation in the loads. Excessive compression of the shape also tends to diminish the features of the shape such as the difference in the daily peak values between weekend days and weekdays. When a shape is compressed to the extreme it becomes a flat line with no variation or features.

11. Excessive Expansion of the shape Cause: The forecasted growth in peak is a lot greater than the forecasted growth in energy for a particular month. There will be a noticeable amount of stretching in the forecasted shape for a month when the monthly load factor of the forecast is a lot less than the monthly load factor of the existing shape. Consequences: The change in the loads between peak and off-peak hours is increased which increases the amount of variation in the loads. Excessive stretching of the shape also tends to exaggerate the features of the shape such as the monthly peaks or the difference in the daily peak values between weekend days and weekdays.

13. Pumping Loads: Does TEPPC want to change pumping loads in Hydro Sensitivity cases? 2011 High Hydro Year 2001 Low Hydro Year HMTF to pick different study years?

14. Questions? Dan Beckstead Associate Staff Engineer Western Electricity Coordinating Council dbeckstead@wecc.biz (801) 819-7656