Common Case Process Jon Jensen Staff Engineer System Adequacy Planning
2 Introduction: 2026 Common Case What is it? Year 10 focused Production Cost/Economic Dispatch (SCED) Model (GridView); 8760 hours of results data Balancing Authority (BA) forecast of year 2026 load, transmission, and generation data Highlight potential generation and/or transmission reliability risks throughout Western Interconnection Use in planning studies and evaluating potential scenarios
2026 Common Case Major Assumptions 3 Resources Loads Transmission 2026 Common Case
4 Balancing Authorities
5 Dataset Building Activities LRS Submittals Utility IRPs WREZ Tool NREL Mesoscale Data Resource Portfolio SWG Resource Planners Work Group Participants LRS Submittals Modeling Enhancements MWG Loads DWG Data Improvements DWG Transmission Network SWG RPCG/CCTA WECC Staff Debugging/Validation DWG/MWG/SWG/Staff TEPPC Dataset WECC Staff Scenario Runs/Analysis/Reporting
Dataset Location www.wecc.biz/systemadequacyplanning/pages/datasets.aspx 6
Dataset Location www.wecc.biz/systemadequacyplanning/pages/datasets.aspx 7
8 2026 Common Case Results (V1.3) Annual Generation by Category (GWh) 2024 PC1 v1.5 2026 WECC V1.3 Conventional Hydro Energy Storage Steam - Coal Steam - Other Nuclear Combined Cycle Combustion Turbine IC Other DG/DR/EE - Incremental Biomass RPS Geothermal Small Hydro RPS Solar Wind 0 50,000 100,000 150,000 200,000 250,000 300,000
9 Transmission Utilization Terminology Utilization Metrics Most Heavily Utilized Congestion Negative Connotation U75: % of hours flows are 75% or more of path rating U75 > 50% OR Some Paths Designed for High Utilization U90: % of hours flows are 90% or more of path rating U90 > 20% OR U99: % of hours flows are 99% or more of path rating U99 > 5%
10 Path Utilization Most Heavily Utilized Paths - WECC_V1.2.1 Common Case U75 U90 U99 60% 50% Percent of Hours 40% 30% 20% 10% 0%
2026 Common Case Transmission Most Heavily Utilized Paths Utilization 11 P83 Montana Alberta Tie P25 PacifiCorp/PG&E P60 Inyo-Control P52 Silver Peak-Control P45 SDG&E-CFE P80 Montana Southeast Most Heavily Utilized Paths U75 U90 U99 P60 Inyo-Control 54.7% 26.9% 0.0% P52 Silver Peak-Control 42.9% 26.6% 0.0% P80 Montana Southeast 46.5% 18.7% 1.8% P83 Montana Alberta Tie 26.2% 17.8% 0.1% P45 SDG&E-CFE 15.5% 11.9% 9.8% P25 PacifiCorp/PG&E 7.5% 4.4% 2.8%
12 Study Program Transmission Expansion Planning Policy Committee (TEPPC) Study Program https://www.wecc.biz/_layouts/15/wopiframe.aspx?sourcedoc=/reliability/2016%20teppc% 202016%20Study%20Program%20-%20Approved.docx&action=default&DefaultItemOpen=1
13 Study Program Major considerations: System reliability and System Utilization Perform relevant PCM (Year 10) and Capital Expansion (Year 20) study cases, ex. High DG, Coal retirements, RPS Requested by diverse group of stakeholders, TOs, TPs, LSEs Used to guide and improve economic and operational analysis Interconnection-wide perspective on future transmission and resource adequacy needs
14 Cases
15 Cases
Study Case Results PC06 High NG Price PC07 Low NG Price
17 Overview Study Case Descriptions Impacts to Generation Commitment and Dispatch Impacts to Path Flows Key Observations
18 High and Low NG Price Studies Purpose To study the effect of increasing (and decreasing) the natural gas (NG) prices while keeping all other fuel prices at their original values. These study cases were derived from version 1.3 of the 2026 Common Case. Comparisons are made to that version.
19 High and Low NG Price Studies High NG Price (PC06) Common case NG prices increased by 50% Example: Colorado average price was increased from 4.68 $/MMBtu to 7.02 $/MMBtu Low NG Price (PC07) Common case NG prices decreased by 36% Example: Colorado average price was decreased from 4.68 $/MMBtu to 2.99 $/MMBtu Key Questions Impact to generation Impact to transmission
20 Comparison of Generation Results Most significant change is in between coal-fired generation and NG-fired generation.
21 Change in Generation by state (PC1 to PC6) The higher gas price triggered some displacement of gas-fired generation by coal-fired generation.
22 Change in Generation by state (PC1 to PC7)
23 Path 45
24 Observations
25 Change in Generation Low NG Prices had a much greater affect on generation dispatch than did High NG Prices. Low NG Price case NG-fired generation increased 28.43% (85,600 GWh) Coal-fired generation decreased 43.65% (85,000 GWh) High NG Price case Coal-fired generation increased 11.42% (22,300 GWh) NG-fired generation decreased 8.85% (26,500 GWh)
26 Production Costs/Path Flows Costs changed due to changing fuel (NG) prices not due to changes in carbon costs. Flows into California increased slightly in the High Gas Price study and decreased slightly in the Low Gas Price study.
27 Questions Jon Jensen Staff Engineer Western Electricity Coordinating Council jjensen@wecc.biz 801-819-7614