PacifiCorp became the first entity in the Western United States to formally commit to a regional coordinated energy market by signing an implementation agreement this week with the California ISO (CAISO) for its Extended Day-Ahead Market (EDAM). PacifiCorp is expected to begin participation in the EDAM in spring 2026.
In January, the Federal Energy Regulatory Commission (FERC) accepted changes to the CAISO tariff that enabled it to launch a Western day-ahead electricity market. The EDAM builds off of CAISO’s Western Energy Imbalance Market (WEIM), a real-time, wholesale energy market. EDAM is expected to become operational in 2026.
CAISO says participants will be able to trade in the day-ahead timeframe to realize lower costs to ratepayers from accessing the most efficient supply. The expanded market is also intended to increase reliability through greater situational awareness and allow participants to share surplus renewable energy across a broad Western footprint.
In March, Idaho Power and Portland General Electric (PGE) announced they intend to pursue participation in CAISO’s EDAM, totaling five entities indicating a preference to participate in the expanded Western market. PacifiCorp, Balancing Authority of Northern California (BANC), and Los Angeles Department of Water & Power (LADWP) had previously announced intent to join the market.
PacifiCorp, a Portland-based grid operator that serves customers in California, Idaho, Oregon, Utah, Washington, and Wyoming, was the first to publicly announce its intent to join the EDAM in December 2022 to expand on benefits it currently realizes from participation in the ISO’s real-time WEIM.
“We are excited to formalize our agreement to become a participant in the EDAM,” said Cindy Crane, chief executive officer for PacifiCorp. “A modern, coordinated day-ahead market in the West is vital to optimizing the region’s energy resources so we can continue to provide reliable and affordable power to our 2 million electricity customers across six states.”
“The momentum we are seeing for participation in the EDAM is very gratifying, and PacifiCorp’s formal commitment brings better definition to the vision of a regional dayahead electricity market,” said Elliot Mainzer, president and CEO of the ISO. “This is a major piece of a truly collaborative effort to support reliability and affordability for electricity customers by leveraging resource diversity and transmission connectivity across the footprint of the Western grid. We now look forward to continue working with additional valued partners in the West to take the next steps in a fully integrated regional market.”
The WEIM is a real-time energy market that was established by PacifiCorp and CAISO in 2014. CAISO says it has produced more than $5.6 billion in cumulative economic efficiencies and enhanced reliability across 22 entities in 11 states. The market now represents 79% of the electricity load in the Western Interconnection.
The WEIM aims to optimize the energy imbalances throughout the West by transferring energy between participants in 15-minute and 5-minute intervals throughout the day. The proposed EDAM would build on this real-time market by expanding to a high volume of resource commitments made a day in advance.
