Slide 1: 2027 Electric and Natural Gas IRPs TAC Meeting No. 1 Agenda
2027 Electric and Natural Gas Integrated Resource Plans Technical Advisory Committee Meeting No. 1 Agenda Tuesday, September 23, 2025 Virtual Meeting – 2:00 pm to 4:00 pm Pacific Time Topic Staff Introductions John Lyons TAC Overview of Responsibilities and Proposed Changes to Public Participation J
Slide 2: Introductions and 2027 Electric & Gas Integrated Resource Planning
Introductions and 2027 Electric & Gas Integrated Resource Planning TAC 1 – September 23, 2025
Slide 3: Introduction
Introduction 2027 Gas and Electric IRPs – TAC 1 2
Slide 4: Agenda
Agenda • TAC overview of responsibilities and proposed changes to public participation – James Gall • Avista electric and gas demand and service territory overview – Jacob Heimbigner and Michael Brutocao • Work Plan and IRP Process Review – Lori Hermanson • 2025 All-Source RFP update – Ryan Finesilv
Slide 5: Meeting Guidelines
Meeting Guidelines • IRP team is in office Monday – Wednesday; also available by email, phone and Teams for questions and comments • Stakeholder feedback responses shared with TAC at meetings, in Teams and in Appendix • Working IRP data posted to Teams • All TAC meetings will be virtual on Teams • D
Slide 6: Virtual TAC Meeting Reminders
Virtual TAC Meeting Reminders • Please mute mics unless speaking or asking a question • Raise hand or use the chat box for questions or comments • Respect the pause • Please try not to speak over the presenter or a speaker • Please state your name before commenting for the note taker • This is a pub
Slide 7: Integrated Resource Planning
Integrated Resource Planning • Required by Idaho, Oregon, and Washington* every other year • Washington requires IRP every four years and update at two years • Oregon requires an annual IRP update • Guides Avista’s gas and electric resource strategy over the next twenty years • Current and projected
Slide 8: Integrated Electric & Gas Resource Planning
System Integrated Electric & Gas Resource Planning James Gall, Manager Resource Analysis 7
Slide 9: Spectrum of Public Participation
Spectrum of Public Participation 8
Slide 10: TAC Responsibilities & Expectations
TAC Responsibilities & Expectations • Participate in any way you would like. • Be courteous to parties with different opinions. • Ask questions, be willing to share comments and opinions in any way you feel comfortable. • Provide ideas for scenarios, topics, or even information on planning assumptio
Slide 11: Avista's Obligation to the TAC
Avista’s Obligation to the TAC • Hold public meetings, provide opportunity to answer questions and take input both in writing and during meetings. • Provide data and models on the TAC team’s site (where not confidentially protected). • Provide all written comments/questions with responses when filin
Slide 12: Avista's Obligation to the TAC (Continued)
Avista’s Obligation to the TAC (Continued) • We will consider input, we may not agree, but we may use input for scenarios or to further educate Avista or the TAC during the process. • Agendas will clearly indicate the jurisdiction, fuel type, and if the material is IRP or System Planning (i.e., DPAG
Slide 13: Organizational Changes
Organizational Changes Energy Resources & Integrated Planning Generation Integrated Production & Environmental Planning & Energy Supply Substation Affairs Clean Energy Support Resource System Analysis Planning Clean Energy 12
Slide 14: IRP Planning Team Members
IRP Planning Team Members IRP Planning Team- James Gall System Planning- John Gross • Michael Brutocao, Natural Gas Planning Mgr. Electric • Jacob Heimbigner, Resource Planning Analyst • Amber Blackstock, Principal Engineer • Lori Hermanson, Sr. Power Supply Analyst • Mike Bosshardt, Engineer • Mike
Slide 15: Why Combine Public Processes?
Why Combine Public Processes? • Current Public Process Advisory Groups Group Members • Electric IRP (Electric TAC) Electric 189 Gas 86 • Gas IRP (Gas TAC) DPAG 47 • Distribution Planning Advisory Group (DPAG) Total 322 • Energy Efficiency Advisory Group (EEAG) Combined 264 • Energy Assistance Adviso
Slide 16: What is Changing and What is not?
What is Changing and What is not? • What is changing? • IRP website will be updated to reflect changes. • Assumptions and modeling for electric/gas IRP will be aligned. • Meeting invites will be to all Gas, Electric, and DPAG participants as new combined “Technical Advisory Committee” or TAC • TAC m
Slide 17: Integrated System Plan Goals
Integrated System Plan Goals • Dynamic capacity expansion model between gas, electric, and impacts to delivery system. • Build off previous PRiSM model • Enhance PRiSM to include gas stochastic inputs • Model electric delivery system needs where generation “may” solve a need • Opportunity to add EE
Slide 18: Energy Efficiency, Demand Response, and Long-term Load Forecasting
Energy Efficiency, Demand Response, and Long-term Load Forecasting • CADMUS Group selected to conduct the Conservation Potential Assessment (CPA). • Energy Efficiency, • Demand Response, • Long-term Load Forecast (Gas/Electric), and • Non-Pipe Alterative Study. • Will support the 2027 and 2029 IRP p
Slide 19: Avista Electric Demand & Service Territory Overview
Avista Electric Demand & Service Territory Overview Technical Advisory Committee Meeting No. 1 – September 23, 2025 Jacob Heimbigner, Resource Planning Analyst
Slide 20: Electric Generation Capability and Service Territory
Electric Mi Natural Gas Electric and Natural Gas Hydroelectric {ENERATION CAPABILITY ]ON CAPABILITY (MN) © Coyote Springs 2 (Boardman, OR) 322.0 © Kettle Falls Combustion Turbine (Kettle Fall, WA) x.n..6.9 @ Rathdrum Combustion Turbines (Rathdrum, ID) ..n. 166.5 @ Northeast Combustion Turbines (Spok
Slide 21: Electric Customers (System)
Electric Customers (System) 3
Slide 22: Average Annual and Peak Electric Load
Average Annual and Peak Electric Load Curtailed Load All time peak load, 1,889 MW Summer 2021 4
Slide 23: Avista's 2024 Supply Mix
Avista’s 2024 Supply Mix 5 (Source: 2024 Annual Report) Nameplate Base
Slide 24: Energy Resources 2024 (GWh)
Energy Resources 2024 (GWh) 6
Slide 25: Hourly Load vs. Hourly Renewable Generation 2024
7 Percentage of Load 20% 40% 60% 80% 100% 120% 160% 180% 200% 140% 0% 0% 2% 5% 7% 10% 12% 15% 17% 20% 22% 24% 27% 29% 32% 34% 37% 39% 42% 44% 47% 49% 51% 54% 56% 59% Percentage of Hours 61% 64% 66% 69% 71% 73% 76% 78% 81% 83% 86% 88% 91% 93% 95% 98% Hourly Load vs. Hourly Renewable Generation 2024
Slide 26: Transmission
Transmission Owned Transmission 115kV 1,600 Line Owned Transmission 230kV 700 Line Owned Transmission 500kV 500 Line Distribution Lines _— 19,900 AIVISTA
Slide 27: Natural Gas System & Customer Overview
Natural Gas System & Customer Overview TAC 1 – September 23, 2025 Michael Brutocao, Natural Gas Planning Manager
Slide 28: Optional footer for data sources, etc.
2 Optional footer for data sources, etc.
Slide 29: Natural Gas Customers
Natural Gas Customers Firm Customer Load • Firm Customers (Dekatherms) • Residential • Commercial • Industrial • Interruptible Customers • Transport Firm Customers 3 Values are for calendar year 2024.
Slide 30: Weather and Natural Gas Demand
Weather and Natural Gas Demand • Heating Degree Day (HDD) • Calculated as the larger of 0 and 65 - Daily Average Temperature • Example: If the daily average temperature is 50 degrees, there are 15 HDDs • Demand for natural gas is seasonal • Peak Day – day with highest demand • Avista experienced con
Slide 31: 2027 System Resource Planning Workplan
2027 System Resource Planning Workplan Technical Advisory Committee Meeting No. 1 – September 23, 2025 Lori Hermanson, Senior Resource Planning Analyst
Slide 32: TAC 1 - September 23, 2025 (today)
TAC 1 - September 23, 2025 (today) • TAC feedback on process changes, methods and assumptions • Integrated System Plan • Merging of DPAG and TAC • Avista Demand and Service Territory Overview • RFP update (WA/ID Electric) • Action Items and Commission Recommendations Overview 2
Slide 33: TAC 2 - October 21, 2025
TAC 2 - October 21, 2025 • 2026-2029 CEIP Update (WA Elec) • Available Resource Options/OBBBA (All IRP) • Policy Considerations (OBBB, Other Building Codes, Elimination of Block Grants) (All IRP) • Portfolio and Market Scenarios and Sensitivities for 2027 IRP (All IRP) • Modeling Methodology and Com
Slide 34: TAC 3 - November 20, 2025
TAC 3 - November 20, 2025 • Future Climate Analysis (All IRP) • CCA/CPP Overview and Joining New Markets (WA Elec/Gas, OR Gas) • Carbon Sequestration (All IRP) • CPP Compliance (OR Gas) • Natural Gas-fired Heat Pump Technology (WA/ID/OR Gas) • Washington Non-Pipe Alternatives (NPAs) (WA Gas) 4
Slide 35: TAC 4 - January 21, 2026
TAC 4 - January 21, 2026 • Market Overview and Price Forecast (WA/ID/OR Gas) • Wholesale Electric Price Forecast (WA/ID Elec) • Sub-hourly Modeling (WA/ID Elec) • DER Forecast Impact on Distribution System (WA Dist) • Cost of Carbon (SCC, Allowances, CCI) 5
Slide 36: TAC 5 - February 20, 2026
TAC 5 - February 20, 2026 • New Resource Options (WA/ID Elec) • Wholesale Price Forecast – Deterministic (All Elec) • New Resource Options (All Gas) • Liquified Natural Gas Analysis (All Gas) • Electrification Assumptions and Scenarios (All Gas) 6
Slide 37: TAC 6 - March 16, 2026
TAC 6 - March 16, 2026 • Wholesale Price Forecast – Stochastic (WA/ID Elec) • Wholesale Market Price Scenarios (WA/ID Elec) • RFP Update (WA/ID Elec) • Economic Forecast and 5-yr Load Forecast (All IRP) 7
Slide 38: TAC 7 - April 15, 2026
TAC 7 - April 15, 2026 • Energy Efficiency Savings Since 2025 IRP (OR Gas) • Hybrid Heat Pump Program Update (OR Gas) • Gas Avoided Cost (WA/ID/OR Gas) • Long-run Load Forecast (All IRP) • End-use Load Forecast (All IRP) 8
Slide 39: TAC 7 - April 20, 2026
TAC 7 - April 20, 2026 • Conservation Potential Assessment (WA/ID/OR Elec/Gas) • Demand Response Potential Assessment (WA/ID/OR Elec/Gas) 9
Slide 40: TAC 8 - May 15, 2026
TAC 8 - May 15, 2026 • IRP Generation Option Transmission Planning Studies (WA/ID Transmission) • Distribution System Planning within the IRP (WA/ID Distribution) • Transmission Project Example Evaluation (WA/ID Transmission) • Gas Distribution Update (Gas) • Natural Gas Availability & Resiliency (G
Slide 41: TAC 9 - May 27, 2026
TAC 9 - May 27, 2026 • CEIP Update (WA Elec) • CETA Interim/Energy Compliance Report (WA Elec) • Load Forecast (All IRP) 11
Slide 42: TAC 10 - June 15, 2026
TAC 10 - June 15, 2026 • Technical Modeling Workshop • PRiSM model tour (All IRP) • Aurora Resource Adequacy model tour (WA/ID Elec) • New Resource Cost model tour (All IRP) 12
Slide 43: TAC 11 - July 15, 2026
TAC 11 - July 15, 2026 • Load & Resource Balance and Methodology (WA/ID Elec) • Loss of Load Probability (WA/ID Elec) • WRAP Update (WA/ID Elec) 13
Slide 44: TAC 12 - August 17, 2026
TAC 12 - August 17, 2026 • Preferred Resource Strategy Results (All IRP) • Oregon Non-Pipe Alternatives (NPA) (OR Gas) • IRP/Progress Report Outlines (All IRP) • Next Steps 14
Slide 45: TAC 13 - September 17, 2026
TAC 13 - September 17, 2026 • Portfolio Scenario Analysis (All IRP) • Avoided Cost (WA/ID Elec) • Resource Adequacy Results (WA/ID Elec) • Customer Benefit Indicator Forecast and Results/Energy Burden (WA Elec/Gas, OR Gas) • Final Report Overview and Comment Plan (All IRP) • Action Items (All IRP) 1
Slide 46: TAC 14 - October 7, 2026
TAC 14 - October 7, 2026 • Electric Transmission & Distribution 5-yr Plan (WA/ID Elec) 16
Slide 47: Other Key Dates
Other Key Dates • Oct 15, 2026 – Draft Electric IRP Released to TAC • Nov TBD 2026 – Virtual Public Meeting • Noon-1pm • 6-7pm • Jan 1, 2027 – Final Electric IRP Filed • Feb 15, 2027 – Draft Gas IRP Released to TAC • Apr 1, 2027 – Final Gas IRP Filed 17
Slide 48: 2025 All Source Request for Proposal Update
2025 All Source Request for Proposal Update Technical Advisory Committee Meeting No. 1 – September 23, 2025 Ryan Finesilver, Resource Marketing Manager
Slide 49: All Source RFP Resource Request
All Source RFP Resource Request Winter Capacity: 105 MW 2027-2029; + 310 MW by 2030 Summer Capacity: 135 MW 2027-2029; + 290 MW by 2030 Up to 200 aMW of renewable or non-emitting resources Demand Response: At least 5 MW 2
Slide 50: Design and Selection Spans all of 2025
Design and Selection Spans all of 2025 RFP Short List Finalists IE Selected Release Selection Selected 01.13.25 05.30.25 09.2.25 ~11.21.25 UTC Initial Detailed Approval Proposals Proposals (WA POR Due 10.06.25 Process) 06.30.25 05.22.25 3
Slide 51: Evaluate, Rank Proposals Independently
Evaluate, Rank Proposals Independently Financial Qualitative Evaluation Independent Evaluator Evaluation Evaluation Team Procure Power LLC Resource Planning 4
Slide 52: Selection Criteria Balances Cost and Risks
Selection Criteria Balances Cost and Risks Category Weighting (%) Financial Analysis 60 Electric Risk Factors 10 Environmental Factors 10 Price Risk 10 Risk Management 5 Social and Community 5 Total 100 5
Slide 53: Initial Proposal Summary
Initial Proposal Summary RFP Bid Summary Number of Resource Type Total Capacity (MW) Proposals Wind 18 4,054 Wind + Storage 7 1,517 Wind Wind + Natural Gas 1 904 Wind + Solar + Storage 7 2,320 Solar 7 754 Solar Solar + Storage 11 1,498 Battery 14 1,752 Storage Pumped Storage Hydro 1 134 Demand Respo
Slide 54: Navigating Externalities
Navigating Externalities Notice 2025-42 Tariffs on Concerning Executive Order 14315 of Federal tax imported July 7, 2025. credit materials availability and equipment Method for Establishing Foreign Beginning of Construction Entity of Permitting Concern Continuity Requirement 7
Slide 55: RFP Timeline
RFP Timeline October 2025 Detailed Proposals due from Short- Includes Price Refresh / Additional List Info Fourth Quarter 2025 Final Selection of Resources Contract Negotiations 8
Slide 56: Avista 2025 All Source RFP
Avista 2025 All Source RFP www.myavista.com/about- us/integrated-resource- planning/2025-all-source- rfp 9
Slide 57: Q&A Questions
Q&A Questions 10
Slide 58: Action Items Update from 2025 IRPs
Action Items Update from 2025 IRPs 2027 IRP Technical Advisory Committee No. 1 – September 23, 2025 John Lyons, Ph.D., Senior Resource Policy Analyst
Slide 59: 2025 Electric IRP Action Items and Comments
2025 Electric IRP Action Items and Comments 2
Slide 60: 2025 Electric IRP Action Items
2025 Electric IRP Action Items Company Actions: • Determine the Northeast CTs retirement date and develop a plan for replacing the lost capacity. • Pursue transmission expansion opportunities within Avista’s service territory and those connecting to Avista’s transmission system. • Develop an all-sou
Slide 61: 2025 Electric IRP Action Items
2025 Electric IRP Action Items IRP Planning Actions: • Incorporate future policy requirements regarding CETA and/or the Climate Commitment Act (CCA) implementation as directed by the Washington Commission, legislature, or voter initiatives. • Explore how end use load forecasting should or should not
Slide 62: 2025 Electric IRP Action Items
2025 Electric IRP Action Items IRP Planning Actions: • Work with the TAC to determine the best strategy for engagement, such as meeting frequency (as experimented in this IRP), along with best available technologies to facilitate communication and data availability. • Determine Avista’s resource nee
Slide 63: Idaho PUC Staff Comments Electric IRP
Idaho PUC Staff Comments Electric IRP • The Company continue to evaluate potential resource allocation methods due to the divergence in resource strategies and to keep the Commission informed about any potential changes in the resource allocation method; • The Company during the RFP process evaluate
Slide 64: Idaho PUC Staff Comments Electric IRP
Idaho PUC Staff Comments Electric IRP • The Company continue to improve the IRP reliability analysis to measure resource adequacy metrics on additional portfolios under evaluation across more years in the planning horizon; • The Company exercise caution when planning DSM programs for EE measures and
Slide 65: Washington UTC Staff Comments Electric IRP
Washington UTC Staff Comments Electric IRP Preferred Resource Strategy • Within 120 days of filing the Final 2025 IRP, issue the required all-source request for proposals to evaluate the cost-effectiveness of all resources to cover the capacity shortfall within the next four years. Load Forecast • F
Slide 66: Washington UTC Staff Comments Electric IRP
Washington UTC Staff Comments Electric IRP Resource Adequacy • Continue to participate with Western Resource Adequacy Program to aid in Avista and the region’s resource adequacy, while presumably lessening the burden on any one utility. Distributed Energy Resources • For the 2027 IRP Update, hold a
Slide 67: Washington UTC Staff Comments Electric IRP
Washington UTC Staff Comments Electric IRP Supply-side Resources • For the 2027 IRP Update, model that the costs of power-to-gas include conversion costs necessary to repurpose existing plants. Additionally, Avista should monitor regional hydrogen storage options. • Ongoing: Use the NARUC Advanced N
Slide 68: Washington UTC Staff Comments Electric IRP
Washington UTC Staff Comments Electric IRP Clean Energy Transformation Act • For the 2027 IRP Update, continue to model the PRS to pursue the interim targets, and the 2030 and 2045 CETA targets at the lowest reasonable cost, while considering the impact of rate shock in a short period. • For the 202
Slide 69: 2025 Natural Gas IRP Action Items and Comments
2025 Natural Gas IRP Action Items and Comments 12
Slide 70: 2025 Natural Gas IRP Planning Actions – Avista
2025 Natural Gas IRP Planning Actions – Avista • Investigate options to increase natural gas availability and resiliency for existing and potential new natural gas generation without additional natural gas pipelines. • Incorporate future policy requirements regarding CETA and/or the Climate Commitme
Slide 71: Gas Action Items 2025-2026 Action Plan – Avista
Gas Action Items 2025-2026 Action Plan – Avista • Incorporate any new Customer Benefit Indicators (CBIs), targets, or directives from the 2025 Clean Energy Implementation Plan (CEIP). • Purchase Community Climate Investments for compliance to the Climate Protection Plan for years 2025, 2026, 2027, 2
Slide 72: Gas Action Items 2025-2026 Action Plan – Avista
Gas Action Items 2025-2026 Action Plan – Avista • Release an annual RFP to investigate options of acquiring the necessary amount of RNG chosen in the PRS in 2030 of 1.184 million dekatherms. • Investigate adding liquified natural gas storage to improve resiliency in the North Idaho/Eastern Spokane r
Slide 73: Idaho PUC Staff Comments – Natural Gas IRP
Idaho PUC Staff Comments – Natural Gas IRP • New Resource Modeling Software – continue evaluating results during implementation • Natural Gas Demand Forecast – update and/or expand scenarios to cover policy changes in Oregon and Washington • Natural Gas Supply Resources and Options – Canadian tariff
Slide 74: Oregon PUC Order Recommendations Natural Gas IRP
Oregon PUC Order Recommendations Natural Gas IRP • Recommendation 1: Commission acknowledge Avista’s 2025 to 2026 Action Item 1 for Avista to investigate carbon capture technologies leading up to the next IRP. • Recommendation 2: Commission acknowledge Avista’s 2025 to 2026 Action Item 2 for Avista
Slide 75: Oregon PUC Order Recommendations Natural Gas IRP
Oregon PUC Order Recommendations Natural Gas IRP • Recommendation 4: The Commission acknowledge Avista’s 2025 to 2026 Action Item 4 for Avista to engage Oregon’s stakeholders to explore additional new offerings for interruptible, transport, and low-income customers to work towards identified savings
Slide 76: Washington UTC Comments – 2025 Natural Gas IRP
Washington UTC Comments – 2025 Natural Gas IRP 1) Demonstrate how key IRP topics are extended to Avista’s customers and communities for feedback, via partnership and conversation in addition to TAC meetings. 2) Improve the communication of the IRP to more clearly convey analysis, correctly label gra
Slide 77: Washington UTC Comments – 2025 Natural Gas IRP
Wasington UTC Comments – 2025 Natural Gas IRP 3) Include a wider range of assumptions regarding demand, customer counts, and decarbonization. a) In line with primary recommendation number 2, clearly display the full range of those assumptions. b) Include at least one scenario where customer count, n
Slide 78: Washington UTC Comments – 2025 Natural Gas IRP
Wasington UTC Comments – 2025 Natural Gas IRP 4) Discuss, and include graphics exploring, the effects of the greater range of scenarios and sensitivities described in this letter. a) Any discussion of effects should consider various timelines, rate and energy burden impacts, consumption levels, and