On December 12, 2019, in ER20-588, MISO proposed a fundamental first step forward for the use of storage resources to maximize the reliability and efficiency of the electric system. The proposed changes to the tariff will allow a storage facility to be selected as a preferred solution to a Transmission Issue in the MTEP process like traditional transmission solutions, such as wires. The use of energy storage to serve multiple functions is of great interest to MISO and its stakeholders, responds to the expressed policy interests of the Commission, and will support the efficiency and reliability of the electric transmission system.
Since March of 2018, MISO has been working with stakeholders to develop Tariff provisions that
address enabling, evaluating, and selecting a storage facility as a transmission asset when, due to
its unique characteristics, the storage as a transmission asset (SATOA) is shown to be the preferred solution to Transmission Issues identified in the planning processes. The proposed protocol outlines the considerations required to compare the SATOA to more traditional transmission assets, including aspects unique to the storage device. Those unique features include degradation of capacity over time,
inverter-based impacts on reliability, and impacts on operating and interconnecting market
resources. This proposal to utilize energy storage as transmission-only assets reflects a fundamental
shift in how these resources are typically added to the system. This foundational first step forward reflected in the filing will not only enable the utilization of more energy storage resources, but the utilization of more energy storage functions to further enhance the robustness of the system.
MISO’s proposal includes:
• A comprehensive Tariff framework for considering SATOA as transmission
• The opportunity for SATOAs to be evaluated in MTEP and be valued like a
• Specific criteria for the evaluation of a SATOA; and
• Provisions that clarify SATOAs are not subject to the Generation Interconnection
Procedures (“GIP”) in MISO Tariff Attachment X.
Dr. Paul Dumais
CEO of Dumais Consulting with expertise in FERC regulatory matters, including transmission formula rates.