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Tacoma Power Joins CAISO’s Western Energy Imbalance Market

March 14, 2022

by Peter Maloney
March 14, 2022

Tacoma Power has become one of the newest members of the California Independent System Operator’s Western Energy Imbalance Market (WEIM). 

“Gaining first-hand experience with centralized markets will better prepare us to engage in regional discussions about expanding such markets to advance our service delivery in safe, reliable, affordable, environmentally-friendly ways,” Clay Norris, WEIM sponsor and power manager for Tacoma Power, said in a statement.

Publicly owned Tacoma Power serves nearly 200,000 electric customers in the Tacoma, Washington, area.

Tacoma Power was joined in its March 2 entry in the WEIM by Avista Utilities, which serves more than 400,000 electric customers in Washington and Idaho. 
While Tacoma Power and Avista are the newest members of WEIM, they are expected to be joined later this year by Bonneville Power Administration and Tucson Electric Power.

Once all four utilities have joined WEIM, the organization will have 19 members serving nearly 77 percent of electric demand in the Western United States.

The WEIM uses the latest technology to find and deliver the lowest-cost energy to its members on a regional basis. Exchanging energy supplies across a wide, multi-state region enhances reliability and provides environmental benefits through the reduction of renewable energy curtailments, leading to lower greenhouse gas emissions because excess renewable energy in one area can be deployed elsewhere potentially offsetting the use of fossil fuels, the California Independent System Operator (CAISO) said.

As more utilities join WEIM, CAISO is developing an extended day-ahead market, that will be able to handle the majority of participants’ energy transactions. That initiative is now working through a stakeholder process that began in January.

Last March, the Turlock Irrigation District and the Balancing Area of Northern California Phase 2, comprised of the Modesto Irrigation District, the City of Redding, the City of Roseville, and the Western Area Power Administration (WAPA) Sierra Nevada Region, began participating in WEIM