CAISO Welcomes New Participants To Energy Imbalance Market


After months of intensive testing, Phoenix-based Arizona Public Service (APS) and Puget Sound Energy (PSE) of Washington state successfully began full participation in the western Energy Imbalance Market (EIM) on Saturday, Oct. 1.

The California Independent System Operator (CAISO), which launched the EIM in 2014 and manages it, says the real-time wholesale power market enables participating utilities to buy low-cost energy available across eight western states.

CAISO says the EIM uses the grid operator’s state-of-the-art software to automatically analyze western grid needs and find the lowest-cost generation to meet demand every five minutes. The EIM also helps with renewables integration, and participating utilities can access low-cost renewable energy in other western states in real time to offset power generated from local energy plants. In fact, CAISO recently touted the renewables benefits of the EIM.

APS and PSE join NV Energy, which serves 90% of Nevada, and PacifiCorp, which has customers in six states, as part of the EIM.

“Participating in a market that enables APS to buy and sell power closer to when electricity is consumed will result in meaningful economic savings to customers through lower production costs and better integration of renewable resources like solar,” said Tammy McLeod, vice president of resource management for APS, in a statement. “We are always looking for ways to operate more efficiently and cost-effectively, and we believe the EIM provides us that opportunity.”

In a separate statement, David Mills, PSE’s vice president of energy operations, said, “The CAISO EIM marks the beginning of a fundamental shift in how new energy markets can be deployed to mitigate a number of operational and policy challenges here in the Pacific Northwest.

“Puget Sound Energy anticipates that our involvement in the EIM will provide enhanced system reliability, promote the efficient integration of renewable resources, assist in decarbonizing the grid by averting the curtailment of renewable resources and provide benefits to our customers,” added Mills.

CAISO says future EIM participants include Portland General Electric, which is scheduled to enter the market in October 2017, and Idaho Power, which plans to enter the market in April 2018.

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