By Robert Mullin

Idaho Power on Wednesday signed an agreement with CAISO to become the sixth utility to join the western Energy Imbalance Market (EIM).

The Boise-based company, which serves about 525,000 customers in southern Idaho and a portion of eastern Oregon, expects an April 2018 start date, pending approval from federal and state regulators.

Inclusion of Idaho Power would bring an additional 4,800 miles of transmission into the EIM while improving the market’s access to an area of Wyoming that renewable developers — including EIM member PacifiCorp — seek to tap for wind projects intended to serve the West Coast.

“The market already has proven itself to increase network efficiency, lower costs and encourage cleaner energy into the power grid,” CAISO CEO Steve Berberich said in a statement. “With each new entrant, the market will only multiply those benefits.”

CAISO launched the EIM in November 2014 in partnership with the Portland-based PacifiCorp, which operates more than 16,000 miles of transmission spanning 10 states. Unlike in an RTO, the EIM’s transmission-owning entities retain operational control over their assets, while member generators participate in the real-time market on a voluntary basis.

Nevada-based NV Energy joined the EIM in December 2015, broadening the market’s footprint and filling a transmission gap between load centers in California and generating resources located in the PacifiCorp East (PACE) balancing area. (See NV Energy has Smooth EIM Integration, CAISO Says.)

“With the entry of NV Energy, [CAISO] transfer capacity with PACE has gone from around 200 MW to 571 MW,” Eric Hildebrandt, CAISO director of market monitoring, said during an April 6 Regional Issues Forum held in Portland. “This has really been a game changer.”

Idaho Power’s membership could provide a similar — if more limited — enhancement to the market. The utility’s service territory sits adjacent to both the NV Energy and PACE balancing areas, providing increased transfer capability with the remote northeastern corner of PACE, the wind-rich area of western Wyoming.

Although wind developers see the region as a promising source of wind exports, transmission constraints — and California’s restrictions on renewable imports not delivered directly into an in-state balancing area — have impeded development of large-scale projects to serve California. Idaho’s entry into the EIM, along with possible ISO membership for PacifiCorp, could open the door for development as CAISO’s boundary effectively extends eastward, expanding RPS eligibility for a larger pool of resources.

In a deal that seemed to anticipate yesterday’s announcement, Idaho Power and PacifiCorp last year swapped $43 million in Idaho and Wyoming transmission assets, reallocating ownership of lines and equipment designed to move power westward from the massive Jim Bridger coal-fired generating plant. One result of the deal: PacifiCorp gained access to an additional 200 MW of “dynamic service” out of western Wyoming, short-term transfer capability that facilitates integration of variable renewable resources. For its part, Idaho Power expected the new arrangement to boost its transmission revenues, reducing the company’s revenue requirement from ratepayers.

Two other Northwest utilities will precede Idaho Power into the EIM. Washington-based Puget Sound Energy is scheduled to join this October, followed by Portland General Electric in October 2017.