LA JOLLA, Calif. — The dispute over how CAISO’s Extended Day-Ahead Market will allocate congestion revenues to market participants might induce a sense of déjà vu among Western electricity sector stakeholders who have closely followed the development of the region’s day-ahead markets.
Last year, a January deep freeze that put much of the Northwest on the brink of rolling blackouts set off a heated debate between supporters of EDAM and SPP’s Markets+. That dispute centered on how CAISO allocated the revenues it collected from the transmission congestion stemming from the weather event. That controversy became a kind of proxy for the competition between the two markets. (See NW Cold Snap Dispute Reflects Divisions over Western Markets.)
A similar development appears to be playing out this spring, even as most Western utilities already have settled on which day-ahead market they will join — although a handful remain uncommitted. The dispute is over the rules by which EDAM will allocate congestion revenues when a constraint in one EDAM balancing authority area produces “parallel” — or loop — flows that result in congestion in a neighboring BAA.
The issue came to light after PacifiCorp in January filed a revised Open Access Transmission Tariff with FERC to reflect the utility’s participation in EDAM, scheduled to begin in 2026.
Shortly after the OATT filing, Vancouver, British Columbia-based energy trader Powerex — a PacifiCorp transmission customer that has committed to joining SPP’s Markets+ — released a paper pointing to what it called a “design flaw” in EDAM because the market’s rules do not offer “a financial hedge that returns the day-ahead congestion charges on a delivery path back to the entities with firm transmission rights on that delivery path” — as required by FERC. (See Powerex Paper Sparks Dispute over EDAM ‘Design Flaw’.)
CAISO and PacifiCorp initially responded sharply, calling Powerex’s paper “misinformed and inflammatory,” but the ISO in March kicked off an “expedited” stakeholder initiative to address the issue after other Western entities filed similar complaints in the FERC docket for the OATT (ER25-951).
The issue was the key agenda item at an April 2 in-person meeting of the Western Energy Markets Body of State Regulators (BOSR), held in La Jolla at the site of the joint spring conference of the Committee on Regional Electric Power Cooperation and Western Interconnection Regional Advisory Body (CREPC-WIRAB).
Speaking to the BOSR, Anna McKenna, CAISO vice president of market design and analysis, emphasized that while the ISO is moving quickly to address stakeholder concerns, it disputes the contention that the market’s existing congestion revenue framework is inherently flawed. (See Fast-paced Effort will Address EDAM Congestion Revenue Issue.)
“I know that there’s been a perception out there that, because we started an initiative, we’re admitting that there’s some fundamental flaw in the EDAM design. We wholeheartedly disagree,” McKenna said.
McKenna said the new initiative is “revisiting” what CAISO thought was just and reasonable in light of FERC’s approval of the EDAM tariff in December 2023.
“And, by the way, what we have in EDAM is something that’s been in place for 10 years now under [CAISO’s Western Energy Imbalance Market]. … So there was really no change in how that congestion revenue is going to be allocated in EIM and EDAM,” although there will be different implications for the day-ahead market, she noted.
MISO Monitor Weighs in
McKenna delivered her presentation a few days after a new twist in the dispute, when Powerex on March 28 filed additional comments with FERC in the PacifiCorp OATT docket.
The comments included expert testimony from David Patton, president of Potomac Economics, which serves as the Independent Market Monitor for MISO and ERCOT and provides monitoring services for ISO-NE and NYISO.
“All other organized markets provide financial transmission rights that correspond to all of the constraints that are priced in the markets’ LMPs, which is the basis for the congestion costs charged to customers,” Patton wrote. “In sharp contrast, PacifiCorp proposes to only provide a hedge for congestion associated with constraints on PacifiCorp’s system, and no hedge for congestion costs associated with all other constraints in EDAM.”
Patton contended PacifiCorp “has proposed an unprecedented and ultimately unreasonable treatment of its firm transmission service and the customers that have purchased it.” He said the proposal is “clearly inferior to both the financial transmission rights RTOs and ISOs provide their firm transmission customers and to the physical scheduling rights firm transmission customers receive in non-market areas … under the pro forma OATT.”
Patton warned that the lack of “effective” congestion hedges could increase long-term grid reliability risks by deterring investments by “risk-averse market participants.” He said PacifiCorp “could meet the requirement for transmission service that is consistent with or superior to the pro forma OATT, despite the incomplete nature of the current EDAM design,” by submitting a revised OATT that preserves the ability of the utility’s customers to opt out of EDAM “and schedule the use of their firm transmission service ahead” of that market.
In an email to RTO Insider, PacifiCorp spokesperson Omar Granados said the utility “is proceeding toward the implementation of the approved EDAM design in 2026 and continuing to work with market participants and other stakeholders to implement those design features to maximize benefits for participants and support grid reliability. PacifiCorp will engage with stakeholders in the pending FERC proceeding and the CAISO stakeholder process on congestion to address any questions or concerns.”
Patton’s testimony also criticized EDAM itself, saying “the design of EDAM substantially deviates from the design of other day-ahead markets in how congestion costs are collected and distributed back to the EDAM participants.”
“It is highly problematic and somewhat misguided to allocate congestion revenue based on where the transmission facility is located rather than based on the sources and sinks where the congestion revenues are actually collected,” he added.
But Patton also acknowledged that EDAM is not like the other markets he monitors because it does not include other elements of an RTO, such as consolidation of balancing authority areas and transmission service providers.
At the BOSR meeting, McKenna said EDAM provides a “unique” design in that it does not force transmission owners to turn over control of their lines to the market operator, allowing each to determine how to spread congestion revenue allocations among transmission users.
She also argued that implementing a financial instrument such as congestion revenue rights would not solve the problem of which BAA receives revenues stemming from congestion caused by parallel flows.
McKenna expressed confidence in CAISO’s ability to address the issue.
“We’re not unique in that every RTO and every ISO has had to make many filings that impact its markets over the years. That is the nature of markets: learn, react, form, and you proactively address things,” she said.
“I think it’s a good point you made: that markets are not static and continue to evolve as we identify potential improvements or changes — and that’s good, because we get to keep our jobs,” New Mexico Public Regulation Commissioner and BOSR Chair Gabriel Aguilera said.
Henrik Nilsson contributed to reporting in this article.