Commissioner Rosner’s and Commissioner Chang’s Joint Concurrence Regarding SPP’s Capacity Accreditation Proposals under ER24-1317 and ER24-2953

Docket Nos. ER24-1317-000 | ER24-2953-000

We concur in today’s order because it approves SPP’s proposal to improve capacity accreditation techniques for all resource types, including conventional, variable, and storage resources.  

Numerous parties in this proceeding raise various methodological concerns with SPP’s proposal.  However, despite the concerns, commenters nonetheless appear to universally recognize that SPP’s proposal is an improvement over the status quo.  Given the growing urgency of the resource adequacy challenge in SPP, we are persuaded that the Commission should accept this just and reasonable improvement.

At the same time, having a capacity accreditation approach that is good enough to be just and reasonable may not be enough to meet the evolving resource adequacy challenges.  The state of the art in measuring system resource adequacy and resources’ contribution to resource adequacy is advancing rapidly as regions around the country develop analytical approaches to account for how weather variation, severe weather or system events, fuel constraints, output variability, and other factors affect the dependable capacity value of all resource types.  Notably, parties from across the spectrum identify opportunities for SPP to improve its accreditation framework.[1]  Ultimately, using a consistent ELCC-based accreditation methodology for all resource types, as several regions have implemented,[2] may be the most practical way for SPP to equitably and accurately accredit the capacity value of all resource types.

More generally, there is a growing need for the industry to coalesce around best practices for resource adequacy metrics and capacity accreditation.  The traditional method of measuring resources’ contribution to system resource adequacy only during peak load conditions is becoming increasingly inadequate.  Recent experience during events such as Winter Storms Uri and Elliott demonstrates that resource adequacy risks can be significant during all hours of the year, driven by variability of load, generation, and fuel supplies.  Thus, as regions work to incorporate fuel constraints, correlated outages, the value of interregional transmission, and other factors into their resource adequacy metrics, those lessons should be broadly shared and adopted.  Further, it has become increasingly evident that the traditional one-in-ten loss of load expectation criterion may not comprehensively capture the actual resource and energy adequacy risks that a system faces.  It would be beneficial to develop and use additional ways to measure resource and energy adequacy during different times of the year, particularly since the magnitude and the duration of loss of load events can affect customers greatly.  NERC’s recent workshop on evaluating resource contributions to reliability and capacity supply demonstrates that there is an emerging consensus on the value of probabilistic approaches[3] and the potential for industry to identify and incorporate best practices from across the country.

We encourage SPP to continue to work with its states and stakeholders to improve its capacity accreditation techniques as the state of the art advances.  Put simply, we need to continue to improve the way system operators measure and accredit contributions to resource adequacy to achieve the balance between reliability and affordability that all consumers deserve.

For these reasons, we respectfully concur.