Four Western utility executives participating in a webinar hosted by the Energy Bar Association presented their reasoning for why they ultimately chose either SPP’s Markets+ or CAISO’s Extended-Day-Ahead Market (EDAM), with some eyeing the creation of a full regional transmission organization in the future.

Representatives from Portland General Electric, Bonneville Power Administration, Public Service Company of New Mexico and Salt River Project participated in the Aug. 28 webinar about the development of wholesale markets in the West.

PGE and PNM have committed to joining EDAM, which is scheduled to go live in spring 2026, and are integrating processes with the day-ahead market alternative.

The utilities’ choices boiled down to, among other things, customer affordability and reliability.

Pam Sporborg, director of transmission and market strategy at PGE, pointed to production cost models showing EDAM would provide greater economic benefits than Markets+. The CAISO markets’ contiguous footprint also “offers us good resource diversity, helping to balance many different geographic regions.”

PNM joined for similar reasons, noting the utility delivers significant wind and solar power to California. (See PNM Signs Agreement to Join CAISO’s EDAM.)

“Being in a separate market from that would create huge operational challenges,” said Kelsey Martinez, director of regional markets and transmission strategy at PNM.

Although PNM’s decision to join EDAM means there will be market seams with SRP, Arizona Public Service and El Paso Electric, seams with California would be too costly, Martinez said. However, “we do want to ultimately have the option to be on a path to an RTO.”

“I think it needs to definitely remain optional,” she added. “Given our resource diversity with California and our wind shape and the future of our system, we see the benefits of having California footprints in an RTO eventually, and realizing more and more incremental benefits that way. So, we do think that’s an important option for us in the future.”

Sporborg, meanwhile, said the West likely will see an “incremental advancement” that captures the benefits of an RTO in a way unique to the region.

Sporborg is co-chair of the West-Wide Governance Pathways Initiative Launch Committee. The Launch Committee, consisting of members from several Western states, was formed with the task of establishing an independent RO to oversee CAISO’s WEIM and EDAM.

The Pathways model can help capture the “benefits that we see in the RTO environment, but in a uniquely Western way that is developed ground up from the stakeholders and really targets the specific benefit that we’re looking for within the overall market construct in a way that we can hopefully avoid some of the pitfalls and stagnation that we see in some of the Eastern markets,” Sporborg said.

‘Primary Platform’

Meanwhile, BPA and SRP chose to join Markets+ based on a few other benefits, the utilities’ representatives said during the webinar.

Specifically, resource adequacy requirements, an independent governance model and the greenhouse gas accounting mechanism were some of the factors that led BPA to join Markets+ in May following a lengthy public process, said Nita Zimmerman, acting vice president of bulk marketing at the agency. (See BPA Chooses Markets+ over EDAM.)

“We expect day-ahead markets to be the primary platform for wholesale electricity transitions in the West, especially with some states requiring utilities to transition to RTOs,” Zimmerman said. “And based on our experience as a later entrant to the Western [Energy Imbalance Market], BPA believes that early [day-ahead market] adoption … will better meet customer and stakeholder objectives, because the first years of a market greatly influence development and maturation of the market design.”

For SRP, an important aspect was “having a pathway to an RTO,” said Josh Robertson, director of energy market strategy at SRP.

“That’s really the next logical step here,” Robertson said. “I think we are adding some complexity by doing a day-ahead market and not an RTO, and we’re potentially leaving some things on a table. There are issues with moving to an RTO, surely, but we want to make sure that there’s a pathway to doing that.”

Markets+ has a viable path to a full-fledged RTO, given its independent board and governance structure, Robertson said.

“We did not see that path very viable with the CAISO market,” he added.