WEIM video commemorates 10 years of benefits, growth and success
When the California Independent System Operator (ISO) started the Energy Imbalance Market in November 2014, it was a relatively modest undertaking with PacifiCorp as the only other participant.
Today, as it celebrates a decade of growth and success, it is known as the Western Energy Imbalance Market (WEIM) and has 22 participants spanning 11 states and representing about 80 percent of electricity demand in the Western U.S. Along the way, the real-time electricity market has realized financial, reliability and environmental benefits that have exceeded early expectations and – as of the end of September – saw cumulative economic benefits exceeding $6.25 billion.
To commemorate the WEIM’s 10-year anniversary, a number of market participants recently talked about its impact in a video premiered at the ISO’s 2024 Stakeholder Symposium, where evolving Western electricity markets was one of the topics explored by a variety of energy experts.
“As we transition to ever greater amounts of renewable, clean energy, affordability and reliability are top priorities,” Maria Pope, president and CEO of Portland General Electric, says while kicking off the video testimonials. “Through the coordination across the West and the leadership of CAISO, the success of (the WEIM) is game changing.”
Industry leaders featured in the video say the WEIM has been even more successful than they anticipated when their companies decided to join.
And they expect even greater benefits starting in 2026 when the ISO launches its Extended Day-Ahead Market (EDAM), where many more energy transactions occur.
“The EDAM would bring the benefits of a fully integrated grid to an even larger market, which is good news for customers and the environment,” predicts Steven D. Powell, president and CEO of Southern California Edison. “Increasing collaboration with our regional partners through the WEIM and EDAM will help all of us deliver a more resilient, clean and affordable energy future.”
The WEIM manages energy imbalances throughout the West by transferring electricity between participants in 15-minute and 5-minute intervals throughout the day. The EDAM will build on the WEIM’s success by expanding the commitment of least-cost generation made a day in advance across the market’s broad geographic footprint, unlocking far greater efficiencies and value. Market coordination also helps reduce greenhouse gas emissions by finding excess clean power that would otherwise go unused and moving it across the West.
Since its establishment in 2015, the Western Energy Markets Governing Body has played an increasingly pivotal role in market design evolution, proving its members as trusted, independent decision makers amid significant market transformation. This cooperative structure with the ISO Board of Governors has fostered a productive relationship, and we expect continued evolution towards fully independent governance for the regional markets.
On the operational side, the WEIM’s success over the past decade has also evolved through operational experience, input and collaboration from participants, demonstrating the advantages of leveraging load and resource diversity – and transmission connectivity – across what has become a more interconnected and united region.
In each of the past three years, different parts of the market were able to send energy to areas experiencing tight supplies due to extreme weather events, helping to maintain reliability market-wide.
In September 2022, when California sweltered through an extended period of record-setting heat that pushed demand to unprecedented levels, the ISO balancing authority received much-needed energy transfers from the Pacific Northwest, which was not as hot, and kept the power flowing throughout the 10-day event.
During the last two summers, when Arizona and other states in the Desert Southwest endured their own extreme heat waves, California helped utilities there meet demand by exporting some of the abundant solar resources it enjoys during the day.
And then in January 2024, when the Pacific Northwest and Rocky Mountain states were experiencing unusually severe winter weather during the long Martin Luther King Jr. holiday weekend, market exports, including WEIM transfers from California and the Southwest, helped meet demand across the region. During this critical period, the ISO became a net exporter for all hours of the day and market participants were also able to depend on wheel-through transactions across the ISO system.
Kathy Anderson, Idaho Power’s Senior Manager for Transmission and Markets, talks in the WEIM anniversary video of how market flexibility helped her utility keep the lights on this past summer.
“The summer of 2024 was the second hottest in our history. In addition to the heat, we continue to see rapid growth in our area and Idaho Power set a new all-time peak demand in July. We were able to buy and import lower-cost power during the day through the market from areas that had abundant solar. This enabled us to save water and shift our hydro generation to later in the day when loads reached their highest point and this flexibility is a significant benefit on those hot days.”
Rounding out the featured energy leaders, Rebecca Wagner, former Nevada Public Utilities Commissioner and vice-chair of the WEM Governing Body, concluded with these final words:
“We had models before saying what the expectations were but we’ve really exceeded all expectations, and that success is the result of all the hard work of stakeholders, market participants and ISO staff.”
Happy anniversary WEIM.
