ER26-3650-000 · 2026-09-18 · Sierra ClubNatural Resources Defense CouncilEnvironmental Law and Policy Center ,Clean Wisconsin ,UNION OF CONCERNED SCIENTISTS ,Sustainable FERC Project ,Fresh Energy ,

Protest of Sierra Club et al. re Midcontinent Independent System Operator, Inc.'s 08/28/2026 filing

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Topics in the text: Cost allocation · Reliability and curtailment · Filing procedure

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Opening text

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1 UNITED STATES OF AMERICA BEFORE THE FEDERAL ENERGY REGULATORY COMMISSION Midcontinent Independent ) Docket No.
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I. Introduction

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I.
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Introduction

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ER26-3650, Accession No. 20260828-5278 (Aug. 28, 2026) [hereinafter “IRR Filing”]. 2 ability, as MISO proposes to put most of the critical restrictions of the IRR Filing in Business Practices Manuals (“BPMs”).
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II. Argument

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II.
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A. The Commission should not allow broad exemptions from reliability

printed heading · Topic match: Cost allocation

FERC, 76 F.4th 352, 357 (5th Cir. 2023). 7 degree the costs actually caused by the customer who must pay them”22 To implement the principle, courts and the Commission “compar[e] the costs assessed against a party to the burdens imposed or benefits drawn by that party.”23 To meet the cost causation…
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B. The Commission should ensure harmonization of MISO and NERC

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MISO proposes to make its tariff effective as of December 4, 2026, a mere 27 days before NERC will file its standards, and many of the requirements will not be applicable until September 1, 2027.51 Under MISO’s current proposed exemption framework, it is unlikely many, if any, large loads would be…
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C. MISO improperly defers critical details for each requirement to BPMs.

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The Commission determines which terms must be in the tariff, as opposed to a BPM, pursuant to the rule of reason.
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III. Conclusion

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III.
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Conclusion

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Conclusion MISO’s IRR Filing creates broad, dangerous exemptions to reliability requirements that MISO proposes to inappropriately house in BPMs.
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CERTIFICATE OF SERVICE

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Dated this 18th day of September, 2026. /s/ Jonah Baskin Jonah Baskin Associate Attorney Sierra Club Environmental Law Program 50 F St.
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Attachment A

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Attachment A 1 Declaration of Andrew Siebenaler I, Andrew Siebenaler, declare as follows:
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I. Introduction

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I.
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Introduction

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I am an electrical engineer and the Managing Consultant - Transmission at Energy Futures Group.
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II. Purpose of Declaration

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I am familiar with MISO’s proposed reliability requirements and the proposed application of the requirements. 9.
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III. Analysis

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III.
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A. Recent events which inform my understanding of the impact of data centers on the reliability of

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Recent events which inform my understanding of the impact of data centers on the reliability of transmission systems. 12.
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B. Contextual comparison of 30,000 MW to MISO’s current peak demand.

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Contextual comparison of 30,000 MW to MISO’s current peak demand. 15.
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C. My opinion of MISO’s proposed exemptions.

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In my professional opinion, MISO’s August 28th filing creates reliability risks by exempting approximately 30,000 MW of large load from reliability requirements.
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IV. Conclusion

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IV.
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Conclusion

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In conclusion, under the exemptions proposed by MISO to the reliability requirements for large loads, a magnitude of load equivalent to roughly one-quarter of MISO’s current summer peak, or equivalent to the combined summer peak demand of LRZs 1 and 2, is at risk of operating in unexpected ways, or…
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