WEIM cumulative benefits approach $7 billion
FOLSOM, Calif. – The Western Energy Imbalance Market (WEIM) continues to demonstrate substantial value with the release of its fourth-quarter 2024 benefits report showing the regional real-time market operated by the California Independent System Operator (ISO) delivered another $374.24 million on behalf of its participants.
The quarterly tally pushes the total cumulative West-wide benefits from the decade-old market to $6.62 billion since 2014, positioning it to close in on $7 billion later this year. It also continues to emphasize the value of the ISO’s Extended Day-Ahead Market (EDAM), which promises to further build upon the benefits of WEIM for participants in the day-ahead market, where the vast majority of energy trading occurs.
The WEIM is designed to enable participants to buy and sell power in real time. With state-of-the-art technology, the market finds and delivers the lowest-cost resources to meet immediate power needs and manages congestion on transmission lines to maintain grid reliability.
EDAM’s 2026 launch will build on the proven economic, reliability and environmental benefits of WEIM by optimizing use of existing transmission and generation resources in the day-ahead timeframe across a broad western footprint.
Onboarding activities are underway with PacifiCorp and Portland General Electric, with both entities targeting joining EDAM in 2026. Two additional entities, the Balancing Authority of Northern California and the Los Angeles Department of Water and Power, have also signed agreements to join EDAM in 2027. Several additional entities have publicly indicated their intention to join EDAM, or have otherwise indicated EDAM as their preferred day-ahead market option.
WEIM currently has 21 market participants outside of the ISO which collectively represent 80% of the demand for electricity in the Western interconnection. The WEIM footprint includes portions of Arizona, California, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, Wyoming, Texas, and extends into British Columbia.
The WEIM will continue to operate as a standalone, real-time market after the launch of EDAM, with two more entities already committed to join the WEIM in 2026.
The benefits report measures cost savings to participants, including market efficiencies and environmental benefits such as displacement of more expensive generation with renewable resources. The WEIM has now helped participants avoid a total of more than 1 million metric tons of CO2 since its launch, roughly equal to emissions from 219,293 passenger cars driven for a year.
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The California Independent System Operator (ISO) is a nonprofit public benefit corporation focused on the continuous improvement and secure operation of a reliable grid for the benefit of consumers. It provides comprehensive grid planning, and ensures open, nondiscriminatory access to one of the world’s largest networks of high-voltage transmission power lines and operates a $9 billion competitive electricity market.
The ISO is at the forefront of integrating renewable power, storage systems and advanced technologies onto the grid to support state energy policies and decarbonization goals, while keeping reliability and cost effectiveness at the core of its operations and ensuring a sustainable and resilient energy future.
The Western Energy Imbalance Market (WEIM) is a real-time wholesale energy trading market that enables participants anywhere in the West to buy and sell energy when needed. Set to launch in 2026, the Extended Day-Ahead Market (EDAM) extends market operations into the day-ahead timeframe. The Western Energy Markets Governing Body, designed by regional stakeholders, shares authority with the ISO Board of Governors to advance rules specific to participation in the WEIM and the EDAM.