CAISO and SPP have made “significant progress” on adapting existing tools to tackle seams between the two entities’ respective day-ahead markets, according to a CAISO representative.

Anna McKenna, vice president of market design and analysis at CAISO, discussed seams between SPP’s Markets+ and the ISO’s Extended Day-Ahead Market (EDAM) during a technical session at the WECC quarterly meeting on Dec. 9.

CAISO’s EDAM and SPP’s Markets+ are scheduled to go live in 2026 and 2027, respectively. One concern with having two separate day-ahead markets is the potential for friction at the borders of the two markets as entities join one market or the other. These seams arise from differing policies and separate dispatch between neighboring markets, which can result in additional costs for transferring energy across the boundary. (See ‘Islanded’ BAs Face Tough Choices in Western Market Future, Experts Say.)

CAISO has met with SPP, transmission owners and providers, and other partners in the West to discuss seams, according to McKenna. She said those discussions are in the early stages, noting that system reliability is the overarching principle as EDAM evolves.

Still, SPP and CAISO’s joint work as Western reliability coordinators (RCs) can help, McKenna said.

“Significant progress has been made in adapting some of the RC-based tools,” McKenna said. “And one you might have heard about is the enhanced curtailment calculator.

“This is a pretty powerful tool for us to be able to use in the Western Interconnection, so that we can ascertain what curtailments might have to happen on the system, should limits be exceeded, in a collaborative and coordinated and reliable manner. This will be foundational for some of the discussions we’ll have on the market side as to how we deal with these challenges coming up with the seams.”

The West has a history of collaboration and already has in place “a series of robust network models, real-time data sharing with each other and state estimators that we rely on,” McKenna added.

“We want to maintain and continue to use these tools as part of our engagement in the seams discussions,” McKenna said. “And of course, these things have to evolve over time. But we’re hopeful that with the work that we’ve done in the West and collaborative nature of how we do business in the interconnection will drive and will guide those discussions.”

‘Come Together and Find Solutions’

Meanwhile, SPP has launched separate efforts, including the Markets+ Seams Working Group (MSWG) and other working groups as it develops the market. At the direction of the Markets+ Participant Executive Committee, the MSWG in 2024 began developing the Seams Strategy and Roadmap, designed to identify focus areas for policies and governing documents related to seams issues with neighboring areas.

SPP also is expanding its RTO into the Western Interconnection, and the plan is to optimize Markets+ with the RTO in 2028, Carrie Simpson, vice president of markets at SPP, said during the WECC meeting.

SPP is “committed to working on seams,” Simpson said. The RTO wants to help “coordinate transfers amongst different parties, whether it’s EDAM, [Western Energy Imbalance Market], CAISO, Markets+” or non-market participants, Simpson added.

SPP plans to host a symposium on Western seams in Tempe, Ariz., on Feb. 26. (See SPP Markets+ Cruising Through Early Development.)

A recent report by FERC urged Western electricity industry stakeholders to get ahead of seams before the launches of Markets+ and EDAM. The paper highlighted seams coordination in the Eastern Interconnection. (See FERC Report Urges West to Address Looming Market Seams Issues.)

McKenna noted that solutions in Eastern markets are not necessarily compatible with the reality in the West.

“We think there’s going to have to be some extraordinary and important efforts between, not just the market operator to market operator, but those who are within these markets, such as the transmission owners, the transmission providers, the balancing areas,” McKenna said. “We all have to come together and find solutions.”