Avista Utilities, Tacoma Power join Western Energy Imbalance Market

Avista Utilities Inc. and Tacoma Power Co. have joined the California ISO-managed Western Energy Imbalance Market, or EIM.

Tacoma Power and Avista Utilities, a subsidiary of Avista Corp., are the first two of four utilities scheduled to join the real-time electricity exchange market in 2022, the California ISO said in a March 2 news release. The Bonneville Power Administration and Tucson Electric Power Co. plan to become active participants in the EIM later in 2022. In January, Bonneville said it would delay its entry into the EIM by two months, from March 2 to May 3.

Once all four utilities join, EIM will have 19 members that serve nearly 77% of electricity demand in the Western U.S., CAISO said.

"[Avista Utilities and Tacoma Power's] participation during this dynamic time in the evolution of the Western energy landscape will offer meaningful benefits to their customers through enhanced operational efficiencies and the integration of clean energy resources into the power grid," CAISO President and CEO Elliot Mainzer said in the news release.

Avista Utilities serves more than 400,000 customers in Washington and Idaho. Tacoma Power serves nearly 200,000 customers in the Tacoma, Wash., area.