Dive Brief:

• Arizona Public Service Co. completed its first trade on Oct. 1 as part of the Western regional Energy Imbalance Market, believing its participation will save customers between $7 million and $18 million annually.
• APS began considering entering the EIM last year; the California Independent System Operator and PacifiCorp launched the regional market in the fourth quarter of 2014.
• Market participants have benefited by almost $90 million since the market launched, officials claim. Puget Sound Energy has also recently entered the market.

Dive Insight:

The Western market has faced issues, but it is slowly growing in scale and currently dispatches least-cost energy in real time in California, Oregon, Washington, Nevada, Utah, Idaho and Wyoming. Along with APS, Puget Sound launched its participation this month. Portland General Electric (PGE) is scheduled to join the EIM in 2017 followed by Idaho Power in 2018. 

“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,” Tammy McLeod, vice president of Resource Management for APS, said in a statement.

The Western market allows utilities to buy and sell power in increments as small as five minutes, which APS said helps to capture "efficiencies that are not possible with traditional hour-ahead trading practices."

The utility's own power plants will continue to be its primary energy resource, but said EIM access gives the utility access to more efficient ones.

CAISO President Steve Berberich said market participants have seen considerable benefits since its launch in 2014. “Broader utility participation across the West means increased access to diverse resources which translates into benefits for customers," he said.”