Western EIM’s new participants successfully begin testing stage

Arizona Public Service and Puget Sound Energy fully enter market Oct. 1

In preparation for full entry into the western Energy Imbalance Market (EIM) this October, the California Independent System Operator (ISO) today initiated the operations testing stage with Arizona Public Service (APS) and Puget Sound Energy (PSE).

Over the next several weeks, the EIM’s newest participants and the ISO will operate under real conditions but transactions will not be financially binding until October 1. The parallel operations will give system engineers, grid operators and market managers a test period to ensure systems are performing as expected and to make adjustments if needed.  

“The EIM has been successful in saving tens of millions of dollars by leveraging the generation and transmission capacity across the West, with a larger geographic region to optimize,” said Steve Berberich, ISO President and CEO. “The addition of APS and PSE will create more opportunities to produce additional benefits, including improved integration of renewable energy.”  

Phoenix-based APS and PSE of Bellevue, WA, will join PacifiCorp and NV Energy in the only real-time energy market in the West, serving customers in eight states. Portland General Electric is scheduled to enter the market in October 2017 while Idaho Power will begin participation in the spring of 2018. 

Launched on Nov. 1, 2014, the EIM has produced benefits totaling $88 million by more efficiently using low-cost electricity to serve demand and reducing the energy reserves individual utilities must carry. The EIM also has saved 125,739 metric tons of carbon emissions since its launch by using 302,836 megawatt-hours of excess renewable energy to offset fossil fuel generation. These benefits are expected to grow as other utilities join the EIM. 

Click here for more information on the EIM, including quarterly benefit reports and participant profiles.

Steven Greenlee | sgreenlee@caiso.com 

Anne Gonzales | agonzales@caiso.com 

California ISO Media Hotline |  888.516.6397

250 Outcropping Way  |  Folsom, California 95630  |  www.caiso.com

The California ISO provides open and non-discriminatory access to one of the largest power grids in the world. The vast network of high-voltage transmission power lines is supported by a competitive energy market and comprehensive grid planning. Partnering with about a hundred clients, the nonprofit public benefit corporation is dedicated to the continual development and reliable operation of a modern grid that operates for the benefit of consumers.  Recognizing the importance of the global climate challenge, the ISO is at the forefront of integrating renewable power and advanced technologies that will help meet a sustainable energy future efficiently and cleanly.



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The addition of APS and PSE will create more opportunities to produce additional benefits, including improved integration of renewable energy.
Steve Berberich, ISO President and CEO