Study Results Southwest Firmed Resource Option This slide deck contains results from the 2012 TEPPC Study Program related to the Southwest Firmed Resource Option Studies. The generation results for the associated transmission expansion projects follow immediately along with flow information for the added transmission.

Pumped Hydro Firming Modeling Goal Compare different Pumped hydro amounts in different wind conditions given various modeling techniques Compare path flows and production costs Implementation Steps Start with 2022 PC23 NW Resource Option (+12,000 GWh) 1.Increase WECC annual energy demand 8% 2.Add 12,000 GWh of renewables to NW 3.Under the purview of the added generation in a particular region, investigate how a nearby region’s pumped hydro responds based on different types of modeling 4.Investigate how the changes listed above impact path flows

Pumped Hydro Modeling Options Schedule and dispatch is optimized via independent LP Any hour available for pumping/generating based on price signals (D) Weeknight/weekend pumping, weekday generating Must-run off (D)Must-run on Dispatched against system cost curve before thermals in commitment pass 1 (D) Dispatched based on LMP after prelim dispatch #2 of thermals LP for Pumped Hydro Minimize Cost Subject to Energy conservation (observe input-output ratio) Reservoir levels Operating capacities (min/max pumping and gen) NOTE: resultant pumping/gen from each hour included in DC power flow solution as fixed/load load at bus.

Pumped Hydro Modeling Inputs Input DataUnit Cycle efficiency (output/input)% Reservoir storage limitMW Max pumping capacityMW Max capacity of genMW Operating reservey/n Determines economic behavior Currently we do not input fixed or operating O&M for pumped storage units

Add: 12,000 GWh to meet WECC RPS Add transmission Renewable Options Under High Load Firmed Cases Increase WECC-wide load 8% For these regions 3 Add: firming resource Gas Hydro Pumped storage

Increase WECC-wide load 8% 1 8% 8% increase to peak and energy 10% 10% decrease to energy Higher Load = Additional RPS Energy

Calculate ratios of planned renewables in TEPPC 2022 Common Case Do not include existing resources Do not include DG IRP and LRS data Apply ratio to study build-out of 12,000 GWh Concept: development trends are best representation of what could be added to each state More resources available than what is identified in WREZ More granular information from CPUC/CAISO Locate resources using WREZ peer-analysis tool Extrapolation Method Add 12,000 GWh to meet WECC RPS 2

10-Year Study Results PC28-1 Eldorado PS PC28-2 LEE PS Pumped Hydro

Production cost decreased $16 M (.1%) Dump energy increase d 19GWh (5.7%) Emergency Energy decreased.2% CO2 Emissions decreased.05% CA, WA, NV

Assume purchase/sale of electricity at bus where plant is located

10-Year Study Results PC28-1 Eldorado PS PC28-2 LEE PS Pumped Hydro

Production cost decreased $27 M (.15%) Dump energy increased 24 GWh (7%) Emergency Energy decreased.1% CO2 Emissions decreased 0.138% AZ, NV, CA, WA

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