TAS Follow-up Webinar Historical Year Energy Shape Compromise for 2026 Common Case December 14, 2015 Jim Filippi- TAS Chair Tom Miller- TAS Vice Chair W ESTERN E LECTRICITY C OORDINATING C OUNCIL

Agenda Welcome- Introduction (Jim) WECC Anti-trust statement (WECC Staff) Background from last TAS Meeting (Tom) Proposed Compromise for 2026 Common Case (Kevin) Discuss stakeholder need/timing for complete 2008 data in addition to Proposed Compromise data” (Jim) – Process for preparing a proposal for 2008 data, if desired TAS Vote (Jim) Wrap-up (Jim) 2 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

Background PURPOSE: is to discuss, consider, and vote on a proposed compromise in the choice of energy shapes for use in the TEPPC 2026 Common Case. FOLLOW-UP: to the TEPPC/TAS discussions on the 2008 vs energy shapes where TEPPC reaffirmed TAS's majority vote to use year 2009 while encouraging TAS to find a compromise on the choice of year to use for load, hydro, solar, and wind energy shapes to use in the construction of the TEPPC 2026 Common Case. PROCESS – Kevin Harris consulted with Northwest planners and developed proposed compromise – Reached out to Key Stakeholders and Experts to gain support OBJECTIVE: of the compromise proposal is to adjust NW hydro generation levels to be more typical and in better alignment with Northwest Region planning needs, while maintaining overall data integrity of the 2026 Common Case GOAL: Development of 2026 Common Case useful to all planning regions 3

Compromise Proposal Overview Kevin Harris (Columbia-Grid) 4

Concern BPA and the Council use 2008 for normal PNW Hydro 2009 does not capture summer Hydro generation in the PNW The primary area of concern between 2009 and 2008 is the summer (Jun-Aug) 5

Compromise All Hourly shapes based on 2009 data (Including PNW Hydro) Monthly generation for dispatchable Hydro generation (PLF/HTC): – Based on 2009 for all areas except the PNW – For the PNW its based on 2009 except for Jun-Aug where 2008 data will be used 6

Impact to PNW Hydro Using 2009 for fixed hourly shapes results in no change to approximately 30% of PNW Hydro generation The increase in PNW dispatchable generation ~2,033 aMW Jun- Aug 7

Discussion 8

Need for Complete 2008 Data Discuss stakeholder need/timing for complete 2008 data in addition to Proposed Compromise data” – Process for preparing a proposal for 2008 data, if desired 9

TAS Vote Compromise PROPOSAL: For months of June-August, for Northwest hydro only, adjust monthly energies so that Northwest hydro energies from 2009 to come in line with 2008 historical levels. For all remaining load and energy shapes use 2009 data as determined at TAS and TEPPC. The issue to be voted on will be either – 1) to accept the compromise as presented at the webinar or – 2) to reject the compromise and use year 2009 energy shapes as was previously approved by majority vote of TAS and reaffirmed by TEPPC. 10

Wrap-up TAS Vote Result Need/timing for Complete 2008 Data Next Steps Other? Close Meeting 11