CAISO’s Extended Day-Ahead Market delivered $11 million in savings during its first two months of operation across three initial balancing authorities — PacifiCorp East, PacifiCorp West, and CAISO itself — demonstrating that regional day-ahead optimization can unlock cheaper supply and improve generation utilization across the Western grid. The market achieves this by allowing participants to trade energy a day ahead across a broader footprint, matching low-cost resources with demand more efficiently than isolated balancing areas can alone. CAISO projects these savings will grow substantially as additional utilities join, following the expansion trajectory of the Western Energy Imbalance Market.
The mechanism is straightforward: a day-ahead market gives operators visibility into next-day supply and demand across a wider region, enabling them to commit the most economic units and avoid the costly, last-minute dispatch decisions that characterize real-time balancing. For the three launch participants, this meant accessing PacifiCorp’s diverse resource mix — including Wyoming wind and Utah coal — alongside CAISO’s solar-heavy portfolio, smoothing the net-load curve and reducing curtailment. Early data suggests the market is also improving renewable integration by providing a larger geographic pool for balancing variability.
WEIM offers the clearest precedent. Launched in 2014 with PacifiCorp as its first external participant, the real-time imbalance market has since grown to include more than a dozen entities across the West and now generates hundreds of millions in annual benefits. EDAM extends that logic into the day-ahead timeframe, where unit commitment decisions carry greater financial and operational weight. The $11 million figure, while modest in absolute terms, represents proof of concept: the architecture works, the incentives align, and the value proposition scales with participation.
Several major Western utilities are evaluating EDAM entry, including Seattle City Light, Salt River Project, and NV Energy. Their decisions will hinge on transmission access, regulatory approval, and the complexity of integrating existing resource portfolios into CAISO’s market systems. FERC’s Order 2222 and ongoing transmission planning reforms could accelerate participation by lowering barriers to distributed resource aggregation and interregional coordination. The Western Resource Adequacy Program, meanwhile, adds a reliability layer that may make day-ahead market participation more attractive for load-serving entities facing tightening reserve margins.
For the broader industry, EDAM’s early results validate a thesis long held by market designers: the Western grid’s Balkanized operation leaves money and clean energy on the table. A unified day-ahead market won’t solve resource adequacy or transmission constraints on its own, but it creates a price signal that rewards flexibility and penalizes inefficiency — exactly the mechanism needed as the resource mix shifts toward weather-dependent generation. The potluck, it turns out, scales.
Read the full report at Energy Central