2024 Common Case Results Resource Adequacy

What and Why The resource adequacy check is a measure of a regions ability to meet its load requirements at time of peak using resources within each region and transmission constrained imports from neighboring regions. TEPPC uses this check to indicate if there are adequate resources in the dataset as well as a check to not over build the dataset.

List of Inputs Sub-regional coincident peak demand 2024 generation by area and resource type Targeted planning reserve margin On-peak coincident capacity value by resource type Transfer capacity that could be used to eliminate deficits High-Cost CT The approach historically used by WECC and relatively easy to implement Cannot readily simulate DR program rules (e.g., limits on hours per event) Iterative LMP-Based Approach The approach implemented last year for economic DR resources Can specify precisely which hours DR resources are called Requires a separate model outside of PROMOD and iterative runs of PROMOD with and without DR (i.e., not the most elegant approach)

2024 Generation Renewable Resources Conventional Resources As needed to meet RPS targets Conventional Resources WECC class code 0-2 resources Based on resource reconciliation efforts and stakeholder feedback OTC replacement units Arapahoe 4 to natural gas and Valmont/Cherokee units replaced with one natural gas unit

Sub-Regional Coincident Peak Demand Both summer and winter peaks Extracted from the 2024 Common Case load forecast Peak Load Lookup Name AZ-NM-NV Basin Alberta British Columbia CA-North CA-South NWPP RMPA Summer Peaks 34,652 15,554 14,340 9,034 29,397 43,067 28,053 13,465 Winter Peaks 21,724 12,421 15,795 12,296 20,357 27,738 34,337 11,202

Planning Reserve Margins LRS 2013 Power Supply Assessment Sub-Region Zones Included in Sub-RegionSummer Summer Margin Winter Margin AZ-NM-NV Arizona, New Mexico, Southern Nevada 13.6% 14.0% Basin Idaho, Northern Nevada, Utah 13.7% Alberta 12.6% 13.9% British Columbia CA-North Northern California, San Francisco, SMUD 15.0% 12.1% CA-South Southern California Edison, San Diego Gas & Electric, LADWP, Imperial Irrigation District 15.2% 11.0% NWPP Pacific Northwest, Montana 17.5% 19.2% RMPA Colorado, Wyoming 15% 15.9% LRS Power Supply Assessment Document

On-Peak Capacity Value, Summer Stakeholder input from past/current study programs Current values pending SWG feedback Summer - Percentage of Installed Capacity Available to Serve Load at Time of Peak Generation Type AZ-NM-NV Basin Alberta British Columbia CA-North CA-South NWPP RMPA Biomass RPS 100% 66% 65% Geothermal 72% 70% Small Hydro RPS 35% Solar PV 60% Solar CSP0 90% 95% Solar CSP6 Wind 10% 16% 5% Hydro Pumped Storage Coal Nuclear Combined Cycle Combustion Turbine Other Steam Other Negative Bus Load Dispatchable DSM

Available Transmission Capacity Between Subregions Based on path ratings Accounts for transmission capacity used to reassign joint ownership plants Limited so transfers do not exceed a subregion's surplus Assumed wheeling from neighboring regions only

Conventional generation added Region Gen needed after RPS additions (MW) Gen added to each region (MW) CA-SO 5336 3297.98 RMPA 694 946 Basin 650 655.2 AZ-NM-NV 948 3874 AESO 873 915.9 CA-NO 2133 1682.3 BC (Site C) 1099.8