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May 24, 2026
May 24, 2026
The article reports that CAISO’s Extended Day-Ahead Market (EDAM) officially launched on 1 May 2026, beginning with PacifiCorp as its first participant, and is being positioned as a day-ahead counterpart to the long-running Western Energy Imbalance Market (WEIM). CAISO says WEIM has delivered $8.5 billion in financial benefits since 2014, and EDAM is meant to extend the same logic of wide-area optimization, resource diversity, and economic dispatch into next-day planning. In the interview, CAISO CEO Elliot Mainzer says the new market should improve both reliability and affordability by giving operators better visibility into next-day system conditions. He also makes clear that batteries are expected to be central participants, with access to the full range of market products including day-ahead energy scheduling, frequency regulation, frequency response, and imbalance reserves.
The piece emphasizes that batteries are especially well suited to EDAM because the day-ahead structure lets operators optimize around the Western grid’s familiar duck curve—charging when midday solar pushes prices down and discharging into the evening peak when demand and prices rise. Mainzer says CAISO expects batteries to play an important role not only in California but across the broader western U.S., where non-California WEIM balancing authorities already have 8,500MW of battery capacity on their systems. The article also notes that EDAM includes safeguards to prevent one balancing authority from being put at risk by excessive exports, requires each participant to prove day-ahead resource sufficiency, and is designed to handle differing state greenhouse-gas policies without distorting market signals. Overall, the article presents EDAM as a more forward-looking and more deeply optimized regional market in which battery storage is likely to become one of the key flexibility tools.
