APS and PSE Begin Participation in Western EIM

by | Oct 5, 2016


On October 1, three energy traders from Arizona Public Service (APS) sat in front of 24 computer screens and successfully completed their first transaction as a participant in the western regional Energy Imbalance Market (EIM) operated by the California Independent System Operator (CAL-ISO).

Both Puget Sound Energy (PSE) of Washington State and APS announced last spring that they were preparing to join the western EIM this month.

The California Independent System Operator (ISO) and PacifiCorp launched the regional EIM on November 1, 2014. Since then, participants – including PacifiCorp and NV Energy – have realized combined benefits of over $88 million.

The EIM enables utilities across the western region to buy and sell energy more efficiently, significantly reducing the cost of keeping the lights on. APS said it expects to save between $7 million and $18 million a year for its ratepayers through market participation. PSE’s customers could save between $18 million to $30 million a year, according to findings of a benefits study performed in 2014 by consultants Energy + Environmental Economics (E3).

In the case of APS, while the utility’s power plants will continue to be the first and primary source of energy to meet customer demand, the difference between participating in the EIM over the traditional, less flexible energy markets is that the EIM automatically will find the most efficient energy resources available, if APS decides to buy or sell power in the marketplace, according to CAL-ISO.

“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,” commented APS Vice President of Resource Management Tammy McLeod.

“The ISO Energy Imbalance Market will help us deliver the reliability and savings that are important to our electric customers,” said David Mills, Puget Sound Energy’s vice president of Energy Operations. “

Currently, the EIM automatically dispatches least-cost energy in real time in Arizona,California, Oregon, Washington, Nevada, Utah, Idaho and Wyoming. General Electric is scheduled to join the EIM in 2017, followed by Idaho Power in 2018.

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