WECC Reliability Study Requests Byron Woertz, Manager—System Adequacy Planning W ESTERN E LECTRICITY C OORDINATING C OUNCIL

Overview Summary of reliability assessment activities in 2015 Sample study case report Process and opportunities for developing the 2016 work plan 2 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

2015 TEPPC Study Program Data Bases 2024 Common Case 2026 Common Case 10-Year (PCM) Studies 2024 Common Case “Core Cases”Other Cases 20-Year (CapEx) Studies LTPT Enhancements 2034 Reference Case 20-Year Study Cases Round Trip Base functionality Enhanced functionality Issue-Based Analyses Flexibility Assessment Energy-Water- Climate Change Nexus Clean Power Plan Planning for Uncertainty 3 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

Summary Observations 10-Year Cases – No unserved load – Path flows affected differently – High renewable energy  dump energy – Incremental load usually served by coal or gas – Carbon price assumptions are significant – Coal retirements require significant discussion 4 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

Summary Observations (cont.) Priorities for Infrastructure – Uncertainties in planning – Expected future grid – Need for increased collaboration – Continue investigation of Variable Energy Resource integration – Operational flexibility needs – Potential gas-electric interface issues 5 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

Summary Observations (cont.) Priorities for Policy – Clean Power Plan resource mix changes – Effects of DER technologies and policies – Transmission utilization impacts of legislation and regulations (CA AB 350, CPP), EV adoption) – Coal fleet flexibility and retirements – System flexibility to accommodate VERs – Impacts of expanded EIM 6 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

WECC 10-Year Planning Process Key Concern Define the Question Focus Question How might the Western Interconnection need to change in the next years to be able to reliably serve load with available resources? 10-Year Study Cases Where might we see congestion based on given load, resource and topology parameters? Common Case Expected future 10 years from base year 7 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

10-Year Study Results Inputs Defined by Requestor Congestion Differs from “Utilization” Some Paths Designed for High Utilization Most Heavily Utilized U75 > 50% ORU90 > 20% ORU99 > 5% 8 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

Primary Results for Today Generation Changes vs CC Overall Findings Path Flow Changes vs CC 9 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

PC-21: Coal Retirement Key Question: How will transmission flows and congestion be affected in the West in a study case that approaches the 2024 trajectory of reducing carbon emissions to 80% below the 2005 levels by 2050? Assumptions: Retirement of several coal-fired generators Additional renewable resources and EE Additional gas-fired generation Additional energy storage 10 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

PC-21 Generation Changes Source 2024 Gen, TWh PC-21 Gen, TWh Increase (Decrease) Energy Storage Steam - Coal (123.8) Combined Cycle Combustion Turbine Solar Wind Dump Energy W ESTERN E LECTRICITY C OORDINATING C OUNCIL Source2024 GenPC-21 Increase (Decrease) Production Cost (1,000s) (0.6) CO 2 (MMTon)363277(86)

PC-21 Heavily Utilized Paths 12 W ESTERN E LECTRICITY C OORDINATING C OUNCIL P52 Silver Peak-Control P60 Inyo-Control P83 Montana Alberta Tie Line Path75%90%99% P60 Inyo-Control 115 kV Tie38%25%18% P52 Silver Peak- Control 55 kV34%23%0% P83 Montana Alberta Tie Line20%11%7%

PC-21 Findings Generation Increased Energy from CC and CT Increased Energy from Remaining Coal Units Increased Renewable energy— 18% to 23% Transmission Congestion on Path 83 (Alberta to Montana) High utilization on Path 52 and 60— controllable Other Findings No Unserved Load Decreased Production Cost Decreased CO2 but less than goal 13 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

PC21 CO 2 Reduction 14 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

2016 Study Request Process 15 W ESTERN E LECTRICITY C OORDINATING C OUNCIL 2016 JanFebMarAprMayJunJulAugSepOctNovDec 2016 TEPPC Considers Summary Transmission Planning Assessment Report 12/13/2016 TEPPC Decision on Requests for Reconsideration 6/10/2016 Requests for Reconsideration Due 5/12/2016 TEPPC Considers Approval of Study Program 4/12/2016 Draft Study Program Posted 4/5/2016 Study Request Window Jan 1 – Jan 31 Study Program Development Feb 1 – Mar 31 Analysis and Reporting Apr 1 – Dec 31 Summary Report Development Oct 1 – Dec 31

Contact Information Byron Woertz Manager – System Adequacy Planning (801) W ESTERN E LECTRICITY C OORDINATING C OUNCIL