BHE Montana, an energy producer, operator and services provider that began participating in the California ISO's Western Energy Imbalance Market (WEIM) in 2026, has formally committed to joining the California ISO-managed Extended Day-Ahead Market (EDAM) in 2028.
With the execution of its implementation agreement, BHE Montana becomes the eighth balancing authority to formally commit to participating in EDAM, further expanding the market’s regional footprint and benefits, CAISO said.
"The Extended Day-Ahead Market will allow BHE Montana to participate in a broader regional marketplace that helps power producers and transmission providers plan and schedule energy resources one day in advance,” the Montana energy provider said in a news release. “By coordinating with a larger network of participants across the West, BHE Montana will improve access to affordable energy supplies, make more efficient use of transmission infrastructure, and enhance overall system reliability.”
EDAM launched successfully on May 1, 2026, with PacifiCorp’s East and West balancing authority areas and the ISO. Portland General Electric is scheduled to begin trading energy in the day-ahead market in October.
"Since going live, EDAM has delivered a range of positive outcomes, including efficient price formation, interregional trade, and strong resource sufficiency results across the participating balancing areas, which has been a boost to summer reliability," CAISO said.
Regional reliability has also been strengthened by the addition to the grid of about 36,000 megawatts (MW) of new resources in California since 2020, including more than 17,000 MW of battery storage capacity. This has enabled significant exports from the ISO footprint during what has been a record-setting summer for peak demand in the Western Interconnection, the grid operator said.
“It’s exciting to see BHE Montana committed to both the real-time and day-ahead markets,” said Elliot Mainzer, the ISO’s president and CEO. “As EDAM continues to grow, more communities across the West will benefit from a proven platform that enhances reliability and supports affordability.”
The real-time and day-ahead electricity markets "use proven, state-of-the-art technology to find and deliver the lowest-cost resources across a broad geographic region to meet power needs and manage congestion on transmission lines to maintain grid reliability," CAISO said.
In its first two months, EDAM delivered $11.38 million in cost savings, shared among PacifiCorp East, PacifiCorp West and the ISO balancing authority area.
At the same time, the real-time Western Energy Imbalance Market, which launched in 2014, saw its cumulative cost savings top $9 billion last quarter. EDAM is projected to deliver even greater savings as new participants join the market and its geographic footprint expands, the grid operator said.
When BHE Montana joined WEIM in May of this year, the company said participation in the real-time market enables the utility to coordinate and operate its assets and services for the benefit of its customers while supporting continued economic growth in Montana and throughout the greater Rocky Mountain region.
