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For Immediate Release: May 8, 2019

Folsom, Calif. – The California Independent System Operator (ISO) has signed an agreement with Tucson Electric Power (TEP), a recognized leader in renewable energy, to participate in the Western Energy Imbalance Market (EIM) beginning in April 2022.

The Western EIM has delivered substantial cost savings to participants in addition to reducing carbon emissions. Earlier this month, the ISO announced that since 2014 total gross cost benefits to EIM participants had reached $650 million. But most significantly, the $85.3 million in benefits posted last quarter had more than doubled when compared to the same time in 2018.

“For current EIM participants, the real-time market has generated meaningful economic and energy resource benefits,” said Steve Berberich, ISO President and CEO. “We are optimistic Tucson Electric Power will experience similar results and welcome their participation in the Western EIM.”

“The EIM will help TEP save money for customers by expanding our real-time access to renewable power and other low-cost energy resources across the Western grid,” said Erik Bakken, Vice President of System Operations and Environmental for TEP.

TEP estimates that participation in the EIM will generate approximately $13 million in annual energy cost savings for customers. “The EIM supports our plan to provide affordable, reliable and increasingly sustainable service to our customers,” said Michael Bowling, TEP’s Director of Wholesale Marketing.

In the EIM, participating utilities and their customers benefit when the market automatically draws on the least-cost generating option available to meet short-term variations in their customers’ power use. This also allows participants to maximize their use of renewable resources, by taking advantage of available wind and solar generation anywhere in the system while efficiently integrating their variable output with other dispatchable resources.

Current EIM participants include PacifiCorp, NV Energy of Nevada, Arizona Public Service, Puget Sound Energy of Washington, Portland General Electric, Idaho Power, Powerex, and the Balancing Authority of Northern California/Sacramento Municipal Utility District.

Other entities scheduled to begin participation include Seattle City Light and Arizona’s Salt River Project (2020); Los Angeles Department of Water and Power, Northwestern Energy of Butte, Montana, and Public Service Company of New Mexico (2021); and Avista (2022).

For more information, visit the Western EIM site at

TEP provides safe, reliable electric service to approximately 425,000 customers in Southern Arizona. For more information, visit TEP and its parent company, UNS Energy, are subsidiaries of Fortis Inc. (TSX/NYSE: FTS), which owns utilities that serve more than 3 million customers across Canada and in the United States and the Caribbean. For more information, visit

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