The Western Transmission Expansion Coalition plans to publish its 10-year outlook for Western transmission needs in February 2026 and has begun outlining the 20-year plan, according to Energy Strategies, which is developing the report.
The WestTEC effort, jointly facilitated by the Western Power Pool (WPP) and WECC, will address long-term interregional transmission needs across the Western Interconnection. The goal is to produce transmission portfolios for 10- and 20-year planning horizons. (See WestTEC Tx Study on Track Despite Delays.)
The 10-year outlook is slated for release in February 2026, pending approval from the WestTEC Steering Committee, said John Muhs, senior consultant with Energy Strategies, during a WestTEC Regional Engagement Committee meeting Dec. 11.
The 10-year report will include a six-page summary, a 20-page report and technical appendices with supplemental data and methodology, according to presentation slides.
“The study work itself is largely done pending approval,” Muhs said. “But the 20-year is further behind — it’s earlier on in the study process.”
The goal for the 20-year plan is to have a report in front of the WestTEC Steering Committee by September 2026, Muhs said.
The consulting firm has begun developing the 20-year reference case nodal models and hypothesis map. Energy Strategies is using the 10-year models as a starting point to develop the production cost model and system reliability assessment, according to the slides.
Energy and Environmental Economics (E3) will provide data on expected electricity demand by 2045, which Energy Strategies will use to develop area-level load profiles for the 20-year reference case with feedback from the WestTEC Assessment and Technical Taskforce (WATT).
Based on data from E3 and the 10-year outlook, Energy Strategies is mapping out how the transmission system could look in 20 years, according to the slides.
The main objective of WestTEC is to create an “actionable” transmission study by conducting integrated planning analysis across the Western Interconnection.
The study horizons focus on evaluating transmission requirements in 2035 and 2045, with the goal of prioritizing “flexible and scalable transmission solutions for nearer-term needs to help better position the system for efficient long-run expansion,” the study plan reads.
The effort has support from stakeholders across the Western region. For example, WATT members include representatives from the Bonneville Power Administration, Western Area Power Administration, Powerex, Northwest Power and Conservation Council, and more.
In June, CAISO cited WestTEC as one of the factors influencing its interregional transmission planning, saying it will use the information to help identify opportunities it will emphasize, either by itself or in collaboration with other entities. (See Inland Wind, WestTEC to Guide CAISO Interregional Planning.)
Energy Strategies will present “a much more finalized version and set of results” of the 20-year outlook during WPP’s all-committee meeting in January, Muhs said.
