{"document":{"slug":"filing-20260918-5397","title":"Protest of Sierra Club et al. re Midcontinent Independent System Operator, Inc.'s 08/28/2026 filing","issued":"2026-09-18","accession":"20260918-5397","docket":"ER26-3650-000","group":"MISO filings","filer":"Sierra ClubNatural Resources Defense CouncilEnvironmental Law and Policy Center ,Clean Wisconsin ,UNION OF CONCERNED SCIENTISTS ,Sustainable FERC Project ,Fresh Energy ,","kind":"filing","file":"sources/originals/20260918-5397_01.pdf","url":"https://sustainableferc.org/wp-content/uploads/2026/10/ER26-3650-Protest-of-Public-Interest-Organizations-MISO-Interconnection-Requirements-for-Large-Loads.pdf","sha256":"ef2bd68b7446322ee2ff61ab0086034691416f4f0eaee2dbbfdbe342c924dcd9","pages":30,"tokens":9540,"emptyPages":[]},"pages":[{"page":1,"startToken":0,"endToken":250,"text":"1 \n \nUNITED STATES OF AMERICA \nBEFORE THE \nFEDERAL ENERGY REGULATORY COMMISSION \n  \nMidcontinent Independent \n ) \nDocket No. ER26-3650-000 \nSystem Operator, Inc. \n ) \n  \n \nPROTEST OF SIERRA CLUB, NATURAL RESOURCES DEFENSE COUNCIL, \nENVIRONMENTAL LAW AND POLICY CENTER, CLEAN WISCONSIN, UNION OF \nCONCERNED SCIENTISTS, SUSTAINABLE FERC PROJECT, AND FRESH ENERGY \n \nPursuant to Rule 211 of the Federal Energy Regulatory Commission’s Rules of Practice \nand Procedure,1 Sierra Club, Natural Resources Defense Council, Environmental Law and Policy \nCenter, Clean Wisconsin, Union of Concerned Scientists, Sustainable FERC Project, and Fresh \nEnergy (collectively Public Interest Organizations, or “PIOs”) protest the August 28, 2026 filing \nof the Midcontinent Independent System Operator, Inc. (“MISO”) proposing Interconnection \nReliability Requirements for Large Loads (“IRR Filing”).2  \nI. \nIntroduction \nPIOs support enforceable requirements that prevent large loads from imposing avoidable \nreliability costs on other customers, causing increased reliability risk, or triggering reliability \nviolations. MISO’s filing, however, does not meet that goal. MISO has submitted tariff revisions \nthat give at least 30 gigawatts (“GW”) of large load, though likely more, an unrestricted ability to \nramp at eye-watering speeds and trip offline unexpectedly, causing voltage and frequency \ninstability. Some amount of large load is also free to take these actions without providing \nadvanced notice to MISO, and without MISO even having insight into the load configuration or \noperating capabilities. What requirements do exist would be hampered by limited enforcement \n \n1 18 C.F.R. § 385.211. \n2 MISO’s Interconnection Reliability Requirements for Large Loads, Docket No. ER26-3650, Accession \nNo. 20260828-5278 (Aug. 28, 2026) [hereinafter “IRR Filing”]."},{"page":2,"startToken":250,"endToken":608,"text":"2 \n \nability, as MISO proposes to put most of the critical restrictions of the IRR Filing in Business \nPractices Manuals (“BPMs”). Ultimately, MISO’s proposed tariff revisions are not just and \nreasonable. The Commission should reject them.  \nII. \nArgument \n \nA. \nThe Commission should not allow broad exemptions from reliability \nrequirements for existing and planned large loads. \n \nMISO proposes two broad categories of large loads which will receive automatic \nexemptions from some or all of the proposed reliability requirements: 1) large loads with a \nService Commencement Date on or prior to December 4, 2026 will be entirely exempt from any \nreliability requirements (a status MISO designates as “Fully Exempt”), and 2) large loads \nassociated with transmission projects either approved for MTEP 2026 or submitted for EPR \nreview prior to June 18, 2026 will be exempt from ride-through and ramp requirements (a status \nMISO designates as “Partially Exempt”).3 In this filing, MISO does not quantify the amount of \nload that will be subject to each of these exemption categories, but in MISO’s August 12, 2026 \nLarge Load Working Group, MISO staff estimated that a jaw-dropping 30 GW of then-existing \nor proposed load would fall into one of these two categories and thus be exempt from some or all \nrequirements.4 \nMISO’s proposed exemptions go far beyond what the Commission’s Show Cause Order5 \ndirected, represent a broad cost shift from large loads to other MISO customers, and threaten \n \n3 IRR Filing, Tab A Tariff Redline at 37A(II). MISO also proposed a third category of exemptions from \nride-through requirements which MISO would be permitted to grant at its discretion. IRR Redline at \n37(A)(II)(2)(b)(ii). PIOs also have significant concerns with this third category of exemptions, see infra \n11-12, 19-20, but discuss it separately as it is not an automatic exemption. \n4 See Declaration of Andrew Siebenaler, Attachment A, at 1. As Mr. Siebenaler explains, this amount \nwould represent roughly 20% of MISO’s peak summer demand with the new large loads in-service, or \nmore than 24% of its current peak summer demand. Id at 3. \n5 Midcontinent Indep. Sys. Operator, Inc., 195 FERC ¶ 61,212 (June 18, 2026)."},{"page":3,"startToken":608,"endToken":923,"text":"3 \n \nreliability in the region and across the Eastern Interconnect. Moreover, MISO’s proposal to allow \na portion of exempted load to retain broad exemptions even when there are material \nmodifications to the load creates a Grand Canyon-sized loophole that could allow unknown \namounts of large load to ignore reliability requirements. On these bases alone, MISO’s IRR \nFiling is not just and reasonable and should be rejected.  \n1. \nCategorically exempting some large loads from reliability requirements \ncreates reliability concerns. \n \nThe North American Electric Reliability Corporation (“NERC”) has identified the \nnumerous reliability challenges that large loads in general, and computational loads particularly, \ncan cause in bulk power system operation and planning.  \nMISO stated in the August 12, 2026, Large Load Working Group that approximately 30 \nGW of large load would be exempted from reliability requirements. But MISO has not shared, \neither in this filing or in the stakeholder process, how much load it expects to be online as of \nDecember 4, 2026 and thus fully exempted from requirements, how much load it expects to be \npartially exempted, how much of the exempted load is computational load, or, critically, if MISO \nhas conducted any studies or analysis of the reliability impact of its proposed exemptions. \nWithout this information, MISO cannot meet its burden of showing that its filing is just and \nreasonable. And there are numerous reasons to think that this significant amount of at least 30 \nGW of exempt load could cause reliability concerns. \n \nNERC recognizes that many computational loads ramp at a rate beyond what spinning \ngenerators can provide.6 Without quantifying the amount of large load that will be subject to \n \n6 NERC, Characteristics and Risks of Emerging Large Loads: Large Loads Task Force White Paper at 19 \n(July 2025), available at: https://www.nerc.com/globalassets/who-we-are/standing-\ncommittees/rstc/3_doc_white-paper-characteristics-and-risks-of-emerging-large-\nloads.pdf?_sp=75c20315-b4f2-4253-8dbd-1241008d09d2 [hereinafter “Characteristics and Risks of \nLarge Loads”]."},{"page":4,"startToken":923,"endToken":1347,"text":"4 \n \nexemptions and comparing it to the amount of battery ramp capacity in MISO,7 it is entirely \npossible that MISO will permit operation of more fast ramping inverter-based load without ramp \nlimitations than fast ramping generation exists in MISO’s markets. This deficit is especially dire \nas MISO has recognized that its current reserve product construct might not result in all reserve \nproducts being deliverable.8 And moreover, ramp rates for computational load may exceed what \ngenerators that offer into the ramp market are obligated to offer.9 Allowing an unknown amount \nof computational load to operate without ramp limits could result in load shed or system collapse \nif generators cannot ramp to match demand.10 Such an outcome would not be just and \nreasonable. \n \nSimilarly, NERC has found that computational loads can pose significant threats to \nsystem frequency and voltage stability if they are not properly configured to ride through minor \ndisturbances. Computational load tripping offline (referred to by NERC as “customer initiated \nload reduction” or “CILR” events) can increase the impacts of a disturbance or even lead to \ncascading power outages. These concerns are not hypothetical. PJM recently narrowly averted \nblackouts when 3.8 GW of load–a mere tenth of the load MISO proposes to exempt–tripped \noffline instantaneously.11 The region required more than ten minutes to recover, which is thirty \n \n7 MISO currently does not allow wind or solar resources to provide ramping services. See MISO Tariff, \nDefinitions - U, Up and Down Ramp Capability Qualified Resource (defining resources qualified to \nprovide up and down ramp capabilities as “[a] Generation Resource that is not a Dispatchable Intermittent \nResource…”). As such, inverter-based ramp resources are limited to battery energy storage systems. \n8 MISO Market Subcommittee, Enhance Reserve Deliverability for DA and RT Market (MSC-2026-2) \nSlidedeck at 27 (July 9, 2026), available at:  \nhttps://cdn.misoenergy.org/20260709%20MSC%20Item%2012%20Enhance%20Reserve%20Deliverabili\nty%20for%20DA%20and%20RT%20Market%20(MSC-2026-2)767388.pdf. \n9 See MISO Tariff, Module C, § 40.2.5.e, “Values in Offers” (requiring that reserve product offers “shall \nreflect the actual known physical capabilities and characteristics of the Generation Resources and/or \nDemand Response Resources - Type II on which the Offer is based…”); NERC, Characteristics and Risks \nof Large Loads at 19 (noting that many generators cannot match computational load ramp rates). \n10 NERC, Characteristics and Risks of Large Loads at 19. \n11 Devin Leith-Yessian, “Va. Data Center Ride-through Performance Faulted for July Voltage \nDisturbance,” RTO Insider (Aug. 12, 2026), available at: https://www.rtoinsider.com/138974-va-data-"},{"page":5,"startToken":1347,"endToken":1750,"text":"5 \n \ntimes longer than what is typically acceptable.12 And in Texas, ERCOT recorded 26 instances of \ncomputational load CILR events of at least 100 MW between January 2023 and September \n2025.13 MISO does not present any studies or assurances that the final amount of load which will \nbe Partially or Fully Exempt from ride through requirements will not pose a threat to reliability. \nAllowing a distinct class of load to cause reliability violations and to shift the cost of mitigation \nto all other load is not just and reasonable.14   \nThe reliability concerns associated with these broad exemptions are exacerbated by \nMISO’s decision to exempt load with an in-service date before December 4, 2026 from all \nreliability requirements, including informational requirements.15 As NERC explains, “[w]ithout \nthe proper data to simulate and characterize large loads, grid planners and operators will be \nunable to accurately model large loads, leading to inaccurate analysis of BPS reliability and \nuninformed decisions when planning and operating the grid.”16 Notably, NERC recognizes that \ndata sharing is critical not just at the interconnection stage, which will have already passed by the \neffective date of the tariff, but also at the commissioning and operations stage.17 The result is that \n \ncenter-ride-through-performance-faulted-july-voltage-disturbance/; See also Declaration of Andrew \nSiebenaler, Attachment A, at 3. \n12 Declaration of Andrew Siebenaler, Attachment A, at 3. \n13 NERC, Incident Review Voltage-Sensitive Crypto Load Reductions at 2, available at: \nhttps://www.nerc.com/globalassets/our-work/reports/event-reports/incident_review_considering_voltage-\nsensitive_crypto_load_reductions.pdf.  \n14 See, e.g., PJM Interconnection, L.L.C.,193 FERC ¶ 61,217, at P 186 (2025) (finding that PJM’s behind \nthe meter generation tariff provisions were unjust and unreasonable because the tariff did not provide any \nprotections against the costs of maintaining sufficient resources to serve large loads with behind the meter \ngeneration being shifted onto other customers). \n15 IRR Filing, Tab A Tariff Redline at 37A(II)(2)(a) (exempting Fully Exempt large loads “from all \nrequirements set forth in this Section 37A”). \n16 NERC, Risk Mitigation for Emerging Large Loads, Large Loads Working Group Reliability Guideline \nat 1 (May 2026), available at: https://www.nerc.com/globalassets/our-\nwork/guidelines/reliability/RG_Risk-Mitigation-For-Emerging-Large-Loads.pdf [hereinafter “Risk \nMitigation for Large Loads”]; See also id. at 6 (“Accurate dynamic models of large load facilities are \nrequired to understand reliability implications and potential mitigations.”). \n17 Id. at 1."},{"page":6,"startToken":1750,"endToken":2065,"text":"6 \n \n“MISO will not be capable of evaluating and mitigating the reliability risk of computational \nloads on its system if it exempts significant amounts of large load from information sharing \nrequirements,” and that there is an “imminent reliability risk to the MISO footprint.”18  \nMISO’s exemption scheme threatens significant reliability concerns, and, as a result, the \nIRR Filing is not just and reasonable. \n2. \nCategorically exempting some loads improperly shifts costs. \nAs discussed above, large loads create significant impacts on system resource needs. \nComputational load can ramp at extreme rates, cause frequency disturbances, and impact system \nvoltage. Uncertainty around large load characteristics and operating parameters can also increase \nthe risk of short term load forecasting errors, which, in turn, increases the risk of under- or over-\nscheduling and dispatching generation resources.19 To the extent these concerns are able to be \nmitigated outside of reliability requirements for the large loads, mitigation will result in \nincreased costs for other MISO customers. Over-scheduling of generation resources and clearing \nmore ramp resources can mitigate some concerns associated with insufficient ramp but will \nresult in higher energy and ancillary services clearing prices for all customers, even though the \nissues themselves are caused by the exempted large loads alone. Similarly, voltage issues can be \nmitigated to some extent by installing static VAR devices or synchronous condensers.20 But the \ncosts for these interventions would not be allocated to the cost-causing large loads that \nnecessitated the interventions.  \nThe Commission and courts have long held that a just and reasonable rate must meet the \n“cost-causation” principle.21 The principle requires that “all approved rates must reflect to some \n \n18 Declaration of Andrew Siebenaler, Attachment A, at 4. \n19 NERC, Characteristics and Risks of Large Loads at 18.  \n20 NERC, Risk Mitigation for Emerging Large Loads at 26. \n21 El Paso Elec. Co. v. FERC, 76 F.4th 352, 357 (5th Cir. 2023)."},{"page":7,"startToken":2065,"endToken":2394,"text":"7 \n \ndegree the costs actually caused by the customer who must pay them”22 To implement the \nprinciple, courts and the Commission “compar[e] the costs assessed against a party to the \nburdens imposed or benefits drawn by that party.”23 To meet the cost causation principle, and for \nthe IRR Filing to be just and reasonable, large loads must pay for any reliability costs they \nimpose on the transmission system. \nPIOs recognize that MISO intends to submit a 205 filing in November addressing \n“transparency concerning the Network Upgrade costs and cost shift concerns.”24 Such a filing \nmight ameliorate the cost shift concerns discussed here. But that filing is not before the \nCommission, and, taken alone, the IRR Filing violates the cost causation principle. PIOs note \nmany of MISO’s 205 filings in response to the Show Cause Order will likely only be just and \nreasonable when considered in context with the other filings. PIOs therefore suggest that the \nCommission direct MISO to clarify whether it would be better able to meet the spirit of the Show \nCause Order if it had leave to amend its filing schedule and present all 205 filings in response to \nthe Show Cause Order jointly. PIOs also note that having tariff revisions in response to the Show \nCause Order filed in the Show Cause docket under the auspices of a 206 proceeding might allow \nfor more rapid tariff development by allowing the Commission the opportunity to rectify the \nissues noted in this protest. \n \n22 City of Lincoln v. FERC, 89 F.4th 926, 930 (D.C. Cir. 2024) (cleaned up). \n23 Midwest ISO Transmission Owners v. FERC, 373 F.3d 1361, 1368 (D.C. Cir. 2004).  \n24 Midcontinent Indep. Sys. Operator, Inc., et al., Motion of the Midcontinent Independent System \nOperator, Inc. and the MISO Transmission Owners to Hold Proceeding in Abeyance and Request for \nShortened Comment Period and Expedited Treatment, Docket No. EL26-70, Accession No. 20260803-\n5249, at 12 (Aug. 8, 2026)."},{"page":8,"startToken":2394,"endToken":2822,"text":"8 \n \n3. The IRR Filing does not make clear when load modifications remove exemptions.  \nAs written, the IRR Filing is impermissibly vague with regards to how modifications will \nimpact a large load’s exemption status.25 The proposed tariff provisions state that “[a] Large \nLoad that has a Service Commencement Date on or prior to December 4, 2026, shall be exempt \nfrom all requirements set forth in this Section 37A with respect to the portion of the Large Load \nthat has procured Transmission Service as of the Service Commencement Date.”26 But MISO \nnever defines what constitutes a “portion” of a large load. Would replacing equipment with \nidentical operating characteristics create a new portion of the large load? Would changing the \noperating characteristics of existing equipment constitute a new portion of a load? What of \ninstalling wholly new equipment while ensuring that the total maximum demand of the large \nload does not change? \nAt earlier points in the stakeholder process, MISO indicated an intent to have “any \nmodification or series of modifications to the Large Load that results in a cumulative increase in \nDemand of 25 MW or more” subject the incremental load to all applicable requirements of \nSection 37A.27 If that is still MISO’s intended policy, the proposed tariff submitted will not \nimplement it. As discussed above, for Fully Exempt loads, the IRR Filing states that “[a]ny \n \n25 The Commission has regularly held that unclear tariff terms are unjust and unreasonable. See Boston \nEdison Co., 98 FERC ¶ 61,292, at P 21 (2002) (“The Commission also has an interest in ensuring that \ntariffs clearly, completely and unambiguously identify services, rates and terms and conditions. The \nCommission thus frequently rejects proposed tariff language as unclear. It is the responsibility of the \napplicant to demonstrate that its proposed tariff achieves these objectives.”); see also Dominion Energy \nMktg. v. ISO New Eng., Inc., 155 FERC ¶ 61,121, at P 17 (“We find that ISO-NE’s existing Tariff is \nunclear as to whether new incremental capacity and existing capacity at the same generating station must \nsubmit a composite offer in order to participate in the [Forward Capacity Auction]. As a result of this lack \nof clarity, the Tariff fails to provide adequate notice of what the requirement is and, thus, we find the \nTariff is unjust and unreasonable.”).  \n26 IRR Filing, Tab A Tariff Redline at 37A(II)(2)(a). \n27MISO, Large Load Interconnection Reliability Requirements (LLWG) Slidedeck at 12 (July 21, 2026), \navailable at: \nhttps://cdn.misoenergy.org/20260727%20LLWG%20Item%2003%20Interconnection%20Reliability%20\nRequirements%20(LLWG-2026-3)_Presentation770291.pdf."},{"page":9,"startToken":2822,"endToken":3169,"text":"9 \n \nmodification or series of modifications to a Load that meets the MTEP/EPR Condition, which \nresults in a cumulative increase of 25 MW or more in Transmission Service for such Load and \nwith a Service Commencement Date after December 4, 2026, shall be subject to subsection \n(2)(b) below.”28 But the IRR Filing does not state what happens for any modification or \nmodifications to the load that does not meet the MTEP/EPR condition. Notably, that would \ninclude any modifications to the load which are proposed after December 4, 2026.29 And while \nPartially Exempt status applies to a “Large Load, or a portion of a Large Load” that meets the \nMTEP/EPR Condition, 37A(II)(2)(b) does not contain a MW threshold or other criteria that \nspells out what would result in a “portion” of a large load being considered distinct.30  \nEven if MISO were to add clarifying language stating that an addition of 25 MW or more \nto a load creates a new “portion” of a large load subject to the full reliability requirements, \nMISO’s proposal would not be just and reasonable. Merely using a MW threshold to describe \nchanges to large loads would allow significant marginal costs to be imposed on the system by \nFully Exempt loads. As MISO explained, different load has different reliability risks, with \ncomputational load imposing significant ramp and ride through concerns that non-computational \nload does not impose.31 If a new “portion” of a large load is only created when a load increases \nits maximum demand, a large load steel mill could convert to an AI data center of the same \nmaximum demand while retaining full exemption from reliability requirements. And what is \nmore, MISO would have no visibility into the change in operational characteristics before it \noccurred because the obligation to note “[a]ny changes to the characteristics of a Large Load \n \n28 IRR Filing, Tab A Tariff Redline at 37A(II)(2)(a). \n29 Id. at 37A(II)(1). \n30 Id. at 37A(II)(2)(b). \n31 IRR Filing, Transmittal Letter at 11."},{"page":10,"startToken":3169,"endToken":3540,"text":"10 \n \nand/or Large Load Equipment, including any changes to the modeling details for the Large \nLoad” is a requirement from which Fully Exempt loads are exempt.32 \n4. It is not clear how a portion of a large load can comply with the requirements. \nEven if the tariff provided an explanation of what constitutes a new “portion” of a large \nload that was both clear and just and reasonable, the tariff is not sufficiently clear regarding how \nonly a portion of a large load can comply with the requirements while the rest is exempted in \nwhole or in part. Take, for example, Section 37A.1, which requires that the Transmission \nCustomer provide MISO with “one-line diagrams, and a description of the electrical \ncharacteristics of the Large Load for all Large Load Equipment.”33 If a Fully Exempt large load \ndevelops a non-exempt portion, how would a Transmission Customer be able to provide \ndiagrams of all large load equipment, while simultaneously respecting the exemption provision? \nSimilarly, 37A.2 requires “verified and complete electrical models of the Large Load.”34  \nIf a Fully Exempt or Partially Exempt large load adds a non-exempt portion behind the \nsame point of withdrawal, it is impossible to verify if the portion of the load subject to the ride-\nthrough requirements of Section 37A.6 met its requirements to stay connected during a voltage \nor frequency disturbance while the exempt portion of the same load tripped offline. Or consider a \n500 MW facility consisting of a 250 MW exempt portion and a 250 MW non-exempt portion \nbehind the same meter. If the facility as a whole ramped at a rate of 250 MW per second, how \nwould MISO determine which “portion” of the facility ramped and if the ramp limits were \nviolated? Similar questions arise regarding the Large Load Audit Rights in Section 37A.8. MISO \nwill have no way to confirm if a large load is inappropriately withholding data contrary to the \n \n32 IRR Filing, Tab A Tariff Redline at 37A.1; see also IRR Filing, Tab A Tariff Redline at 37A(II)(2)(a) \n(exempting Fully Exempt loads from all requirements). \n33 Id. at 37A.1 (emphasis added). \n34 Id. at 37A.2 (emphasis added)."},{"page":11,"startToken":3540,"endToken":3883,"text":"11 \n \nterms of the tariff, or if data is not subject to audit rights because it is associated with the portion \nof the load which is Fully Exempt. \nUltimately, some, although not all, of these issues could be mitigated with clear \ndefinitions on what constitutes a new portion of a large load, and requirements that new portions \nbe separately metered with separate telemetry and data recording equipment than any other \nportion. But such provisions are not in the tariff IRR Filing MISO submitted.35 Accordingly, \nMISO’s filing is not just and reasonable. \n5. \nThe discretionary ride-through exemption for projects submitted between \nJune 19, 2026, and October 31, 2026 will create a speculative submission \nrush. \n \nMISO proposes to create a third category of discretionary exemptions from ride through \nrequirements if a large load has “not met the MTEP/EPR Condition but has submitted Load \nassociated with a transmission project to the Transmission Provider for EPR on or after June 19, \n2026, but on or before October 31, 2026.”36 While PIOs raise broader concerns with the \nprovision below,37 the provision is also problematic in that it will encourage large load \ndevelopers to submit speculative load interconnection requests in the hope of taking advantage of \nthe time-limited exception. Whatever the justification of providing exemptions for projects that \nhave already taken concrete steps to interconnect, allowing projects to seek exemptions until \nOctober 31, 2026 is only likely to fuel speculative load requests. The Commission found in the \nShow Cause Order “that there may be speculative transmission service requests by Eligible \nCustomers on behalf of large loads that could result in cost shifting among transmission \n \n35 The Commission has previously found that metering requirements must be filed in RTO tariffs, \npursuant to the rule of reason. See Order No. 2222, Participation of Distributed Energy Resource \nAggregations in Markets Operated by Regional Transmission Organizations and Independent System \nOperators, Docket No. RM18-9, 172 FERC ¶ 61,247, at P 271 (2020). \n36 IRR Filing, Tab A Tariff Redline at 37A(II)(2)(b)(ii). \n37 See infra at 19-20."},{"page":12,"startToken":3883,"endToken":4207,"text":"12 \n \ncustomers, which may lead to unjust and unreasonable increases in jurisdictional transmission \nrates” in MISO.38 Because the IRR Filing creates even more incentives to submit such \nspeculative transmission service requests, the filing is unjust and unreasonable.  \n6. \nIt is ambiguous if MISO would be able to subject exempted large loads to \nrequirements before they cause reliability issues. \n \nThe reliability impacts discussed above could create significant reliability risks in the \nMISO system. And while the proposed tariff language does allow MISO to subject otherwise \nexempt or partially exempt load to reliability requirements, the proposed tariff, as drafted, is \nambiguous regarding whether MISO is able to impose the requirements before the large load has \ncaused reliability issues. The proposed tariff provides that MISO may subject otherwise exempt \nor partially exempt load to a reliability requirement if MISO “determines that operation of a \nLarge Load results in a material adverse effect on Transmission System reliability.”39 Instead of \nusing language that would clearly allow imposition of reliability requirements if MISO \ndetermines that operation of a large load may result in adverse reliability impacts, MISO’s \nproposed tariff provision makes it unclear if MISO can impose any reliability requirements until \nafter a large load operates in a manner that “results” in a material adverse impact on reliability.  \nDisturbingly, Ms. Li’s testimony also suggests MISO would only be allowed to impose \nrequirements after a large load has impacted reliability. Ms. Li testified that MISO’s so-called \ntransition framework “preserv[es] MISO’s ability to address demonstrated material adverse \nimpacts to Transmission System reliability.”40 To the extent the tariff allows otherwise exempted \nor partially exempted large loads to cause reliability issues while MISO’s hands are tied, it is \n \n38 Midcontinent Indep. Sys. Operator, Inc., 195 FERC ¶ 61,212, at P 80. \n39 IRR Filing, Tab A Tariff Redline at 37A(II)(3). \n40 IRR Filing, Tab C, Prepared Direct Testimony of Beibei Li at 23 (emphasis added) [hereinafter “Li \nTestimony”]."},{"page":13,"startToken":4207,"endToken":4556,"text":"13 \n \nunjust and unreasonable. And to the extent the provision does not do so and is simply vague, it \nalso must be revised.41 \nMISO’s IRR Filing also fails to account for how it will handle cases where two or more \nlarge loads operating alone would not, individually, result in a material adverse impact on \nreliability, but where a large loads’ behavior interacting  with another large load would result in a \nmaterial adverse impact on reliability. MISO’s tariff fails to spell out how MISO will decide \nwhich reliability requirements it will require of which load, and how it will allocate compliance \nobligations amongst the relevant loads. \n7. The IRR Filing as drafted both explicitly exempts and explicitly does not exempt a \ncategory of large loads from reliability requirements.  \n \nMISO’s IRR Filing, as written, contains contradictory language regarding the compliance \nobligations of large loads with a Service Commencement Date on or prior to December 4, 2026, \nbut that did not require associated transmission upgrades in an MTEP cycle or submit a project \nfor EPR review. The proposed tariff revisions state in section 37A(II)(2)(a) that “[a] Large Load \nthat has a Service Commencement Date on or prior to December 4, 2026, shall be exempt from \nall requirements set forth in this Section 37A with respect to the portion of the Large Load that \nhas procured Transmission Service as of the Service Commencement Date.” The proposed tariff \nrevisions state in Section 37A(II)(2)(c) that “[a] Large Load, or a portion of a Large Load, that \ndoes not meet the MTEP/EPR Condition shall be subject to all applicable requirements set forth \nin this Section 37A.” Section 37A(II)(1) states that “Load associated with a transmission project \nshall be defined as meeting the ‘MTEP/EPR Condition’ if the project has either: (a) been \napproved by the Transmission Provider Board in MTEP 2026, or a prior MTEP; or, (b) been \nsubmitted to the Transmission Provider for Expedited Project Review (EPR) on or prior to June \n \n41 See Boston Edison Co., 98 FERC ¶ 61,292, at P 21 (2002)."},{"page":14,"startToken":4556,"endToken":4883,"text":"14 \n \n18, 2026, in accordance with Attachment FF of the Tariff.” Together, these three provisions \ncreate situations that might define a load as both exempt and not exempt. Loads that predated the \nMISO MTEP process, or loads that interconnected before December 4, 2026 but did not require \nan associated transmission upgrade in the MTEP to interconnect, will both have not met the \nMTEP/EPR Condition and thus “be subject to all applicable requirements set forth in this Section \n37A” per Section 37A(II)(2)(c), and also have had “a Service Commencement Date on or prior \nto December 4, 2026,” and thus “shall be exempt from all requirements set forth in this Section \n37A” pursuant to Section 37A(II)(2)(a). Because there is not a proviso giving primacy to either \nSection 37A(II)(2)(c) or Section 37A(II)(2)(a), some loads might be both exempt and non-\nexempt. While these contradictory terms are undoubtedly a drafting error, the resulting \nimpossibly conflicting provisions render the tariff proposal, as filed, unjust and unreasonable.  \n8. MISO’s filing goes far beyond what was directed in the Show Cause Order. \na. The Show Cause Order envisioned compliance glide paths for existing \nand late-stage development large loads, not wholesale exemptions. \n \n \nMISO justifies its exemptions by pointing to language in the Commission’s Show Cause \nOrder directing MISO to propose reasonable implementation periods “to ensure minimal \ndisruption to [] existing commercial arrangements” and to propose mechanisms to allow \nproposed projects “a reasonable amount of time to finalize ongoing agreements that are nearing \ncompletion.”42 MISO improperly reads the Show Cause Order. The Show Cause Order directs \nMISO to “propose a reasonable implementation period to ensure minimal disruption to such \nexisting commercial arrangements.”43 The direction to have an implementation period implies a \nperiod after which implementation will be completed and all loads will be subject to new tariff \n \n42 Midcontinent Indep. Sys. Operator, Inc.,195 FERC ¶ 61,212, at P 5. \n43 Id."},{"page":15,"startToken":4883,"endToken":5295,"text":"15 \n \nprovisions. The Commission has employed similar implementation period approaches before, \nwhen applying reliability standards to inverter based resources.44 \nA reading of the Show Cause Order that would direct MISO to indefinitely exempt some \nlarge loads from reliability requirements also fails to read the Show Cause Order as a whole. The \nShow Cause Order repeatedly emphasized the need for MISO to ensure large loads pay for the \ncosts they impose on the system. The Commission found that “MISO’s Tariff appears to be \nunjust and unreasonable because it lacks adequate mechanisms to mitigate the risk of cost \nshifting among transmission customers, which may result in unjust and unreasonable rates for \ntransmission service.”45 As discussed above, allowing some loads to dodge reliability \nrequirements will shift costs on to other customers.46 If the Commission had intended to direct \nMISO to indefinitely exempt some large loads from reliability requirements, it would have said \nso in the Show Cause Order. MISO’s design here is not required by prior Commission orders. \nb. MISO does not justify why existing large loads would face disrupted \ncommercial arrangements from information and modeling requirements. \nEven if the Show Cause Order could be interpreted to direct for existing and near-\ncompletion large loads to receive exemptions from some reliability requirements, MISO does not \njustify why it exempts existing large loads from all reliability requirements. Specifically, MISO \n \n44 See N. Am. Elec. Reliability Corp.,190 FERC ¶ 61,098, at PP 12 (approving the NERC standard), 7 \n(“NERC describes its proposed implementation plan for Reliability Standards PRC-028-1 and PRC-002-5 \nas ‘a risk-based, phased-in compliance approach’ that would require generator owners to implement \ndisturbance monitoring equipment by no later than 2030.”) (2025); Accession Number: 20241104-5220 at \nexhibit B (describing the phased-in implementation plan). \n45 Midcontinent Indep. Sys. Operator, Inc., 195 FERC ¶ 61,212, at P 66. See also id., (See, Comm’r, \nconcurring at 9) (“As we move forward, I’ll be looking to ensure cost-recovery agreements contain fair \nand transparent measures to ensure the right costs get on the right bills.”); id (Chang, Comm’r, concurring \nat 6 (“While individual states have been exploring or using various approaches to protect retail customers \nagainst unjustified cost shifts, the Commission to date has not initiated any proactive exploration of how \nto protect wholesale customers against unjustified cost shifts. I am laser-focused on this issue because we \nshould not create unjustified costs for consumers in our efforts to connect and serve large loads.”). \n46 See supra at 6-7."},{"page":16,"startToken":5295,"endToken":5628,"text":"16 \n \ndoes not justify why complying with information and modeling requirements in Sections 37A.1-\n37A.2 would cause more than a de minimis disruption to existing commercial relationships. \nInstituting the modeling and information requirements would not require installation of any new \nequipment or facilities. And the Commission has previously found it just and reasonable to make \ngeneration resources, including existing generation resources with signed Generator \nInterconnection Agreements, provide similar information.47 MISO does not show that excluding \nsome large loads from the reporting requirements of 37A.1 and 37A.2 is just and reasonable. \nB. \nThe Commission should ensure harmonization of MISO and NERC \nrequirements. \n \nThe Commission has directed NERC to develop large load reliability standards by the \nend of the year.48 While PIOs appreciate that the Show Cause Order directed MISO to develop \nreliability standards within a more compressed timeline than the NERC standards,49 in light of \nthe Commission’s subsequent order directing NERC to develop reliability standards, the \nCommission should allow MISO to  propose reliability standards which can be harmonized with \nthe standards NERC will submit to the Commission. Harmonizing MISO’s reliability \nrequirements with NERC’s requirements from the start, rather than MISO developing standards \nit might need to revise to comply with NERC requirements, is preferable on two fronts: first, \nwhile MISO regularly focuses on implementing reliability standards, NERC has special expertise \nin developing reliability standards. Second, if MISO’s standards are not in line with NERC \nstandards, large load developers and owners might plan for MISO standards, and then be forced \n \n47 See N. Am. Elec. Reliability Corp.,190 FERC ¶ 61,098 (2025). \n48 Order Directing the North American Electric Reliability Corporation To File Reliability Standard(S) \nPertaining to Computational Load Integration, 196 FERC ¶ 61,031 (2026). \n49 Midcontinent Indep. Sys. Operator, Inc., 195 FERC ¶ 61,212, at P 64 (discussing preliminary finding \nregarding the need for reliability standards), 196 FERC ¶ 61,133 at 9 (directing that responses to the show \ncause order be submitted by November 16, 2026)."},{"page":17,"startToken":5628,"endToken":5970,"text":"17 \n \nto make costly or disruptive updates to standards after load sites have already been designed or \ndeveloped.  \nMISO recognizes the value of harmonizing NERC and MISO standards in its filing, but \navers that “[w]hile NERC processes are underway to develop industry wide guidelines, the \nMISO region cannot wait to put in place needed interconnection reliability requirements to \nreliably integrate these near-term Large Loads.”50 While this may be true as a matter of MISO \nmeeting the directive of the Show Cause Order, harmonizing MISO and NERC standards would \nnot significantly delay implementation of reliability requirements. MISO proposes to make its \ntariff effective as of December 4, 2026, a mere 27 days before NERC will file its standards, and \nmany of the requirements will not be applicable until September 1, 2027.51 Under MISO’s \ncurrent proposed exemption framework, it is unlikely many, if any, large loads would be subject \nto MISO’s reliability requirements before NERC’s requirements are finalized and approved. \nLarge loads that begin service as of December 4 are fully exempt from all reliability \nrequirements in MISO’s proposal, and any large loads that come online between December 4 and \nDecember 31 would presumably have been subject to the MTEP/EPR condition and therefore \nonly be subject to Large Load Information and Basic Facility Data Requirements, Large Load \nModeling Requirements, and Large Load Audit Rights. Moreover, submitting the IRR Filing \nnow does not provide large load developers significant additional time to plan around \ncompliance requirements as compared to waiting to harmonize with NERC requirements. As Ms. \nLi notes, MISO’s Business Practices Manual (“BPM”) development timeline has been extended \n \n50 IRR Filing, Transmittal Letter at 3. \n51 Large Load Information and Basic Facility Data Requirements, Large Load Modeling Requirements, \nLarge Load Ride-Through Requirements, Large Load Ramp Requirements, and Large Load Audit Rights \napply as of the effective date of the tariff. Large Load Telemetry Requirements, Large Load Forecast Data \nRequirements, and Large Load Phasor Measurement Unit Requirements are not applicable until \nSeptember 1, 2027. See generally IRR Filing, Tab A Tariff Redline."},{"page":18,"startToken":5970,"endToken":6279,"text":"18 \n \nto December 2026.52 Because MISO has (improperly) decided to place core reliability \nrequirements in the BPMs, large load developers might not even have a month’s notice between \na final picture of MISO’s reliability requirements and NERC’s requirements. Altogether, the \nminimal delay associated with harmonizing MISO and NERC standards would make the \ntemporary imposition of MISO standards that will likely need revision unjust and unreasonable. \nThe Commission should reject the IRR filing on this basis, and make updated findings in the \nShow Cause docket directing MISO to file revised reliability requirements that harmonize with \nNERC requirements by the end of January 2027.  \nC. \nMISO improperly defers critical details for each requirement to BPMs. \n \nMISO’s filing defers significant, core elements of its reliability requirements in each \ncategory of requirement to its BPMs. MISO leaves far more than “implementation details” to the \nBPMs, and in doing so has proposed an unjust and unreasonable tariff. \nThe Commission determines which terms must be in the tariff, as opposed to a BPM, \npursuant to the rule of reason. “The rule of reason requires utilities to file only those practices \nthat affect rates and service significantly, that are realistically susceptible of specification, and \nthat are not so generally understood in any contractual arrangement as to render recitation \nsuperfluous.”53 “The tariff need not include mere implementation details.”54 MISO’s tariff \nprovisions, as proposed, do not comport with the rule of reason. For ease of navigating each of \nthese inappropriate referrals of substantive tariff provisions to the BPMs, PIOs have organized \ninappropriate deferral of reliability requirements to the BPM by section: \n \n52 IRR Filing, Li Testimony at 39. \n53 City & Cnty. of San Francisco v. FERC, 24 F.4th 652, 661 (D.C. Cir. 2022) (cleaned up). \n54 Hecate Energy Greene Cnty. 3 LLC v. FERC, 72 F.4th 1307, 1312 (D.C. Cir. 2023)."},{"page":19,"startToken":6279,"endToken":6574,"text":"19 \n \n1. 37A(I) Violations of Requirements \nSection 37A(I) discusses what happens if a large load fails to comply with the reliability \nrequirements: “Failure to comply with the requirements established in this Section 37A may \nresult in a delayed Service Commencement Date, a period of time needed for corrective action, \noperational limitations, or other remediation action(s) by Transmission Provider as may be \nnecessary to maintain Transmission System reliability. The process by which Transmission \nProvider [sic] will determine whether any such measures are appropriate, which may include the \nperiod of time during which corrective action must be undertaken, shall be as set forth in the \nBusiness Practices Manual for Large Load.”55 \n \nThe IRR Filing does not explain at all how MISO will evaluate the reliability risk \nassociated with non-compliance, or do more than vaguely reference “Transmission System \nreliability” to explain how MISO will determine what consequences result from non-compliance. \nThe process by which MISO considers penalties is clearly susceptible to specification.56 And \ngiven these “operational limitations, or other remediation action(s)” can presumably include \nactions up to and including disconnection of the load, the penalties available and how they are \nassessed makes a substantial impact on rates. Under the rule of reason, these terms should be \nincluded in a tariff, and not relegated to the BPM. \n2. 37A(II)(2)(b)(ii) Ride-Through Requirement Exemptions \nSection 37A(II)(2)(b)(ii) allows MISO to exempt large loads from ride-through \nrequirements provided the load submitted an EPR request on or after June 19, 2026, but on or \nbefore October 31, 2026. The relevant provision provides MISO may waive the ride-through \nrequirements:  \n \n55 IRR Filing, Tab A Tariff Redline at 37A(I). \n56 See, e.g., MISO Tariff, Attachment FF, Section IX. Variance Analysis."},{"page":20,"startToken":6574,"endToken":6940,"text":"20 \n \nbased upon a determination that: a) exemption from such requirements would not have an \nadverse reliability impact; and, b) compliance with such requirements would result in \nsignificant costs. The Business Practices Manual for Large Load shall set forth the \nprocess and documentation necessary for Transmission Provider to determine whether \nsuch criteria have been met.57 \n \nThis section does not meet the rule of reason. What constitutes significant costs, or at \nleast principles of how MISO will determine what constitutes significant costs, are reasonably \nsusceptible of specification. What is a significant cost, especially to a data center willing to \nspend significant amounts of money to interconnect, is not so self evident so as to be generally \nunderstood. And the exemption self-evidently significantly affects rates: the load is only eligible \nfor the waiver if compliance carries “significant costs.” The Commission should direct MISO to \nprovide a metric by which it will determine if costs are significant, or at least principles that will \nguide its determination, in its order rejecting the IRR Filing. For example, a reasonable definition \nof significant costs could be defined as the greater of either $1 million in marginal costs or 10% \nmarginal increase in cost of the total large load development cost. \n3. 37A(II)(2)(b)(iii) imposition of requirements on otherwise exempt load \nSection 37A(II)(2)(b)(iii) provides that MISO can, in certain situations, require load that \nwould have otherwise been exempt from some or all reliability requirements nonetheless comply \nwith some or all requirements. The section states that  \n[t]he process by which Transmission Provider will make [a determination that operation \nof a Large Load results in a material adverse effect on Transmission System reliability] \nand which, if any, of the requirements of this Section 37A are to be applied shall be as set \nforth in the Business Practices Manual for Large Load.58 \n \nHere too, MISO leaves too much to the BPM. While the mechanics of how MISO \ncollects information and notifies otherwise exempt load that it must meet reliability requirements \n \n57 IRR Filing, Tab A Tariff Redline at 37(A)(II)(2)(b)(ii). \n58 IRR Filing, Tab A Tariff Redline at 37(A)(II)(3)."},{"page":21,"startToken":6940,"endToken":7278,"text":"21 \n \nis properly the domain of a BPM, the tariff must contain information about how MISO will \ndetermine which requirements will apply to the load. \n4. 37A.3 Large Load Telemetry Requirements  \nSection 37A.3 concerns telemetry requirements. But the tariff filing itself defers so much \nto the BPM that significant questions of which facilities the standards will apply to, and what the \nstandards are, are unanswerable from tariff language. The proposed language provides:  \n[i]ndividual metering will be required for all Large Load and any Generation Resource(s) \nserving such Large Load that is located behind the same Point(s) of Withdrawal to the \nTransmission System as the Large Load and meeting thresholds outlined in the Business \nPractices Manual for Large Load. All telemetry shall be provided via Inter-Control \nCenter Communications Protocol (ICCP) and must meet Transmission Provider update \nrequirements as specified in the Business Practices Manual for Large Load.59 \n \nIt is impossible to tell which collocated generation must be individually metered as the \n“thresholds” for applicable generation are proposed to be located in the BPM. And what \nmetering equipment will be required is also unclear as telemetry update requirements are also \nlocated in the BPM. MISO requiring all large loads meeting certain “thresholds” to be \nindividually metered speaks to a clearly specifiable standard, and update requirements for meters \nare specifiable.60 As the Commission noted while accepting another MISO filing in June, \nmetering requirements can have “costly and burdensome” impacts on market participants by \nimpacting which meters participants can use.61 As such, these terms have a significant impact on \nrates. Because deferring these elements to the BPM would violate the rule of reason, the \nCommission should reject the IRR Filing.  \n \n59 Id. at 37A.3. \n60 See, e.g., MISO Tariff, § 38.2.5(e)(vii)(c) (requiring “[a]ll metering equipment must be capable of \nstoring a minimum of 35-days of hourly intervals for each measured value”). \n61 Midcontinent Indep. Sys. Operator, Inc., 195 FERC ¶ 61,210, at P 85 (June 18, 2026)."},{"page":22,"startToken":7278,"endToken":7614,"text":"22 \n \n5. 37A.6 Large Load Ride-Through Requirements \nSection 37A.6 concerns ride-through requirements for computational loads. As drafted, \nhowever, the section contains no discernable requirements at all:  \nA Transmission Customer taking Transmission Service on behalf of a Computational \nLoad shall be responsible for ensuring that the Computational Load remains connected to \nthe Transmission System and continue operation during voltage and frequency \ndisturbances within the performance criteria established by the Transmission Provider in \nthe Business Practices Manual for Large Load.  \n \nRide-through requirements apply at the Point(s) of Withdrawal and may include \nevaluation, testing, modeling, monitoring, and other compliance measures established by \nthe Transmission Provider in the Business Practices Manual for Large Load.62 \n \nThe IRR Filing does not specify what the requirements actually are, and states that they \n“may include evaluation, testing, modeling, monitoring, and other compliance measures,” \nleaving the actual compliance measures entirely in the BPM. Ride-through standards are capable \nof specification.63 And they have a substantial impact on rates, as MISO has stated that \nexemptions are needed in order to not disrupt commercial arrangements.64  \n6. 37A.7 Large Load Ramp Requirements \nSection 37A.7 contains ramp limitations on computational loads. Here too, MISO’s \nproposed tariff language leaves all substantive requirements to the BPM:  \nComputational Load shall be subject to up-ramp and down-ramp limits established by the \nTransmission Provider consistent with the process set forth in the Business Practices \nManual for Large Load. The Computational Load must have an effective up and down \nramp rate not exceeding the specified limit outlined in the Business Practices Manual for \nLarge Load unless otherwise directed by the Balancing Authority, Reliability \nCoordinator, or Transmission Operator.65 \n \n \n62 IRR Filing, Tab A Tariff Redline at 37A.6 \n63 See, e.g., MISO Tariff, Attachment X, Appendix 6, Article 9.7.3, “Ride Through Capability and \nPerformance” (requiring generators ride through within the “no trip zone” defined by Reliability Standard \nPRC024-3). \n64 IRR Filing, Transmittal Letter at 13-14. \n65 IRR Filing, Tab A Tariff Redline at 37A.7."},{"page":23,"startToken":7614,"endToken":7874,"text":"23 \n \nThe default ramp limit is clearly capable of specification; it is a number.66 And ramp limitations \nhave a significant enough impact on rates that MISO felt it was justified to exempt some load \nfrom compliance to avoid disruption to commercial arrangements.67 Here too, MISO’s deferrals \nto the BPM defy the rule of reason. \nIII. \nConclusion \n \nMISO’s IRR Filing creates broad, dangerous exemptions to reliability requirements that \nMISO proposes to inappropriately house in BPMs. Each of these elements renders MISO’s filing \nunjust and unreasonable. Accordingly, the Commission should reject the filing. Instituting \nreliability requirements for large loads is critical to ensuring large load interconnection and \noperation will not result in reliability violations. The proposed standards filed simply do not live \nup to that important task. \nRespectfully submitted,                                         Dated: September 18, 2026 \n \n/s/ Jonah Baskin \nJonah Baskin \nAssociate Attorney \njonah.baskin@sierraclub.org \n \nSierra Club Environmental Law Program \n50 F Street NW, Eighth Floor \nWashington, DC 20001 \n \n/s/ Katie Duckworth \nKatie Duckworth \nStaff Attorney \nkduckworth@elpc.org \n  \nEnvironmental Law & Policy Center \n35 E. Wacker Dr., Ste. 1600 \nChicago, IL 60601  \n \n \n/s/ Lee Shaver \nLee Shaver \nSenior Energy Analyst \nlshaver@ucs.org \n \nUnion of Concerned Scientists  \n200 East Randolph Street, Suite 5151 \nChicago, IL 60601 \n \n \n/s/ Ciaran Gallagher  \nCiaran Gallagher, Ph.D. \nEnergy & Air Manager \ncgallagher@cleanwisconsin.org \n \nClean Wisconsin \n634 W Main St #300 \nMadison, WI 53703 \n \n66 NERC suggests that the ramp limit should be specified as a MW/min limit. See NERC, Risk Mitigation \nfor Large Loads at n.29.  \n67 IRR Filing, Transmittal Letter at 13-14."},{"page":24,"startToken":7874,"endToken":7954,"text":"24 \n \n \n \n/s/ Anna Markowski \nAnna Markowski \nDirector, Midwest \nClimate and Clean Energy \namarkowski@nrdc.org   \n \nNatural Resources Defense Council  \n20 North Wacker Drive, Suite 1600  \nChicago, IL 60606  \n \n \n/s/ Laura Hannah \nLaura Hannah \nSenior Advocate \nlhannah@nrdc.org   \n \nSustainable FERC Project \nNatural Resources Defense Council \n20 North Wacker Drive, Suite 1600  \nChicago, IL 60606 \n/s/ Mike Schowalter \nMike Schowalter \nManaging Director, Transmission Policy \nschowalter@fresh-energy.org \n \nFresh Energy \n81 Seventh St. E., Suite 200 \nSaint Paul, MN 55101 \n(612) 433-3648"},{"page":25,"startToken":7954,"endToken":8020,"text":"25 \n \n \nCERTIFICATE OF SERVICE \nI hereby certify that I have this day served the foregoing document upon each person designated \non the official service list compiled by the Secretary in this proceeding. \n  \nDated this 18th day of September, 2026. \n  \n/s/ Jonah Baskin                      \n \nJonah Baskin  \nAssociate Attorney  \nSierra Club Environmental Law Program  \n50 F St. NW, 8th Floor Washington, DC 20001  \n(202) 556-3917  \njonah.baskin@sierraclub.org"},{"page":26,"startToken":8020,"endToken":8022,"text":"Attachment A"},{"page":27,"startToken":8022,"endToken":8478,"text":"1 \n \nDeclaration of Andrew Siebenaler \nI, Andrew Siebenaler, declare as follows: \nI. \nIntroduction \n1. I am an electrical engineer and the Managing Consultant - Transmission at Energy Futures \nGroup. Energy Futures Group (“EFG”) is a clean-energy consulting firm headquartered in \nHinesburg, Vermont, with a satellite office in Canton, New York. EFG has two primary \nareas of practice.  The first is in the design, implementation, and evaluation of programs and \npolicies to promote investments in efficiency, renewable energy, other distributed resources, \nand strategic electrification.  The second is in integrated resource planning. transmission \nplanning and related analyses.  EFG staff have delivered projects on behalf of energy \nregulators, government agencies, utilities, and advocacy organizations in at least forty states, \neight Canadian provinces, and several countries in Europe. \n2. I have worked for fourteen years in transmission planning roles, including at regional \norganizations, utilities and consulting firms. I have participated in the development of \nenergy policy, transmission plans, and integrated resource plans (IRPs) included in local \nand regional plans covering the Midcontinent Independent System Operator (MISO), \nSouthwest Power Pool (SPP), and in the state of Colorado. These efforts resulted in \nfilings before utility regulatory bodies in Colorado, Michigan, Minnesota, North Dakota, \nSouth Dakota and Wisconsin and at the FERC. I have performed transmission planning \nanalyses for reliability, system stability, nodal production cost analysis for economic \ntransmission development, and served as a Subject Matter Expert in NERC transmission \nplanning compliance efforts across the Mid-Continent Area Power Pool (MAPP) \nfootprint. I received a Bachelor of Science Degree in Electrical and Computer \nEngineering from the University of Minnesota – Duluth in 2012.  My resume, included \nas Exhibit 1, provides additional detail regarding my professional and educational \nexperience. \n3. It is my understanding, based on statements made by MISO staff and MISO stakeholders \nin the stakeholder process, and based on my reading of MISO’s proposed reliability \nrequirements, that large load projects equal approximately 30,000 MW of demand, \nrepresenting more than 24% of MISO’s stated System Peak Demand for the summer \nseason as stated in the MISO Planning Year 2025-2026 Loss of Load Expectation Study \nReport,1 would be fully or partially exempt from MISO’s reliability requirements. \n4. A portion of the 30,000 MWs of large load is also exempt from requirements related \nto data collection. This lack of data collection requirement ensures reliability risks can \nonly be identified once they are encountered, whereas proper application of the \nproposed requirements to all large loads could ensure proactive mitigation and \nmaintained reliability.  \n5. I conclude that the proposed exemptions from interconnection reliability \nrequirements for large load customers represent an imminent reliability risk to the \n                                                     \n1 PY 2025-2026 LOLE Study Report, MISO, available at https://cdn.misoenergy.org/PY%202025-\n2026%20LOLE%20Study%20Report685316.pdf?v=20250313114401."},{"page":28,"startToken":8478,"endToken":8895,"text":"2 \n \nMISO footprint as well as the Eastern Interconnection due to the significant \namounts of load not being subject to reliability and data collection requirements. \nII. \nPurpose of Declaration \n8. I am familiar with MISO’s proposed reliability requirements and the proposed \napplication of the requirements.  \n9. I am also familiar with the impacts to system reliability resulting from improperly \nexempting significant amounts of large load additions. These impacts, described in more \ndetail below, were demonstrated in two separate events in northern Virgina, once on July \n22nd, 2026 and during a previous event on July 10th, 2024. These events represented \n3,800 MW and 1,500 MW, respectively, of data center demand removing themselves \nfrom the grid after a transmission fault resulted in oscillations.  \n10. In addition, I am aware that NERC issued a Level 3 Alert2 on May 4, 2026 entitled \n“Essential Action to Industry Computational Load Modeling, Studies, \nInstrumentation, Commissioning, Operations, Protection, and Control” which \ndiscusses how existing planning processes are insufficient to address risks associated \nwith computational load entities. At the time of NERC’s alert, NERC defined \ncomputational load entities as loads 20 MW or greater, connected at 60kV, and \ncontaining more than 1 MW of IT load.  \n11. The purpose of my declaration is to discuss my opinion of the reliability impact of \nMISO’s proposed exemption of approximately 30,000 MW of large loads from MISO’s \nproposed reliability requirements. \nIII. \nAnalysis \nA. Recent events which inform my understanding of the impact of data centers on the reliability of \ntransmission systems. \n12. On June 10, 2024, 1,500 MW of data center demand disconnected itself from the grid \nin Northern Virginia after an event related to the failure of a lightning arrester on a 230 \nkV transmission lines. The NERC incident report3 concluded “While this disturbance \ndid not cause significant operating issues with the grid at this location and at this time, \nas data center loads continue to grow rapidly, the risk could quickly increase” and \nrecommended the following: \na. “Require dynamic response models of large loads in their facility \ninterconnection requirements 8 Incident Review – Considering Simultaneous \nVoltage-Sensitive Load Reductions” \n                                                     \n2 NERC Alert, Essential Action to Industry Computational Load Modeling, Studies, Instrumentation, Commissioning, Operations, \nProtection, and Control, NERC (May 4, 2026) available at https://www.nerc.com/globalassets/programs/bpsa/alerts/level-3-\ncomputational-load-alert.pdf. \n3 NERC Incident Report, Incident Review Considering Simultaneous Voltage-Sensitive Load Reductions, NERC (Jan. 8, 2025) \navailable at https://www.nerc.com/globalassets/our-work/reports/event-reports/incident_review_large_load_loss.pdf."},{"page":29,"startToken":8895,"endToken":9344,"text":"3 \n \nb. “Perform studies to determine the potential magnitude of load loss for system \ndisturbances (faults)  \n• \n Study the impact that these large load losses would have on the \nsystem” \n \n13. On May 4, 2026, NERC issues its highest-level alert (Level 3). In this alert, NERC \ndetermined a set of immediate actions that NERC recommended registered entities \nshould take to reduce the risk to the Bulk Power System. These actions related to the \nmodeling, study, installed fault recording or instrumentation, commissioning, operation, \nprotection, and control of computational load. In the alert, NERC emphasized the \nreliability importance of system operators having access to robust modeling of \ncomputational loads. \n14. On July 22, 2026, a second incident in Northern Virginia occurred when 3,800 MW of \ndata center demand disconnected itself from the grid as a result of oscillations due to a \nfault on a 230 kV transmission line. This event resulted in the need for operator action to \nstabilize system conditions. Effects were reported to last in excess of ten minutes, or \nthirty times longer than is typically acceptable for recovery and damping of stability \noscillations.  \n \nB. Contextual comparison of 30,000 MW to MISO’s current peak demand. \n15. MISO’s stated peak system demand for the summer season, as stated in the Planning \nYear 2025-2026 Loss of Load Expectation Study report, is 123,576 MW. This makes \n30,000 MW more than 24% of MISO’s current peak summer demand, and 20% of \nMISO’s peak summer demand with the new large loads in-service. The Planning Year \n2025-2026 Loss of Load Expectation Study report also states that MISO’s Local \nResource Zone (LRZ) 1 2025 summer peak demand is 17,889 and LRZ 2 summer peak \ndemand is 12,694 MW, combining to 30,583 MW. When comparing to the total large \nload either fully or partially exempt from meeting reliability requirements to MISO’s \nposted peak demand data, we can see that this would be equivalent to exempting roughly \none-quarter of MISO’s 2025-2026 summer peak demand, or the entirety of both LRZs 1 \nand 2. \nC. My opinion of MISO’s proposed exemptions. \n16. In my professional opinion, MISO’s August 28th filing creates reliability risks by \nexempting approximately 30,000 MW of large load from reliability requirements. \nIncidents like those experienced on June 10, 2024 and July 22, 2026 indicate the \nimportance of applying broadly applicable ride through requirements to large loads. By \nallowing for significant amounts of load to be exempt from ride through requirements, \nMISO faces substantial risk of similar incidents impacting the MISO system.  \n17. Similarly, MISO’s filing fails to consider the immediate action called for in the May 4, \n2026 NERC Level 3 alert aimed at addressing reliability risks associated with"},{"page":30,"startToken":9344,"endToken":9540,"text":"4 \n \ncomputational loads. NERC’s recommendations noted the importance of operator \nvisibility into computational load behavior, characteristics, and configuration. In my \nprofessional opinion, MISO will not be capable of evaluating and mitigating the \nreliability risk of computational loads on its system if it exempts significant amounts of \nlarge load from information sharing requirements. Because MISO would not have this \nvisibility, I am concerned about imminent reliability risk to the MISO footprint. \nIV. \nConclusion \n18. In conclusion, under the exemptions proposed by MISO to the reliability requirements \nfor large loads, a magnitude of load equivalent to roughly one-quarter of MISO’s \ncurrent summer peak, or equivalent to the combined summer peak demand of LRZs 1 \nand 2, is at risk of operating in unexpected ways, or in ways that could cause system \ninstability. This could cause severe reliability impacts that would otherwise be \nmitigated if the exemptions were not allowed.  \n \nI declare under penalty of perjury under the laws of the United States, pursuant to 28 U.S.C. \n§ 1746, that the foregoing is true and correct to the best of my knowledge. \nExecuted on September 16, 2026, in Lakeville, Minnesota. \n \n \nAndrew Siebenaler \nManaging Consultant – Transmission \nEnergy Futures Group"}],"sections":[{"p":1,"at":0,"title":"Opening text","method":"opening text","endPage":1,"endAt":886,"startToken":0,"endToken":113},{"p":1,"at":886,"title":"I. Introduction","method":"printed heading","endPage":1,"endAt":890,"startToken":113,"endToken":114},{"p":1,"at":890,"title":"Introduction","method":"printed heading","endPage":2,"endAt":243,"startToken":114,"endToken":286},{"p":2,"at":243,"title":"II. Argument","method":"printed heading","endPage":2,"endAt":260,"startToken":286,"endToken":288},{"p":2,"at":260,"title":"A. The Commission should not allow broad exemptions from reliability","method":"printed heading","endPage":16,"endAt":656,"startToken":288,"endToken":5390},{"p":16,"at":656,"title":"B. The Commission should ensure harmonization of MISO and NERC","method":"printed heading","endPage":18,"endAt":692,"startToken":5390,"endToken":6073},{"p":18,"at":692,"title":"C. MISO improperly defers critical details for each requirement to BPMs.","method":"printed heading","endPage":23,"endAt":332,"startToken":6073,"endToken":7670},{"p":23,"at":332,"title":"III. Conclusion","method":"printed heading","endPage":23,"endAt":338,"startToken":7670,"endToken":7671},{"p":23,"at":338,"title":"Conclusion","method":"printed heading","endPage":25,"endAt":8,"startToken":7671,"endToken":7955},{"p":25,"at":8,"title":"CERTIFICATE OF SERVICE","method":"printed heading","endPage":26,"endAt":0,"startToken":7955,"endToken":8020},{"p":26,"at":0,"title":"Attachment A","method":"printed heading","endPage":27,"endAt":82,"startToken":8020,"endToken":8033},{"p":27,"at":82,"title":"I. Introduction","method":"printed heading","endPage":27,"endAt":86,"startToken":8033,"endToken":8034},{"p":27,"at":86,"title":"Introduction","method":"printed heading","endPage":28,"endAt":167,"startToken":8034,"endToken":8503},{"p":28,"at":167,"title":"II. Purpose of Declaration","method":"printed heading","endPage":28,"endAt":1535,"startToken":8503,"endToken":8710},{"p":28,"at":1535,"title":"III. Analysis","method":"printed heading","endPage":28,"endAt":1551,"startToken":8710,"endToken":8712},{"p":28,"at":1551,"title":"A. Recent events which inform my understanding of the impact of data centers on the reliability of","method":"printed heading","endPage":29,"endAt":1188,"startToken":8712,"endToken":9079},{"p":29,"at":1188,"title":"B. Contextual comparison of 30,000 MW to MISO’s current peak demand.","method":"printed heading","endPage":29,"endAt":2087,"startToken":9079,"endToken":9235},{"p":29,"at":2087,"title":"C. My opinion of MISO’s proposed exemptions.","method":"printed heading","endPage":30,"endAt":511,"startToken":9235,"endToken":9414},{"p":30,"at":511,"title":"IV. Conclusion","method":"printed heading","endPage":30,"endAt":516,"startToken":9414,"endToken":9415},{"p":30,"at":516,"title":"Conclusion","method":"printed heading","endPage":30,"endAt":1309,"startToken":9415,"endToken":9540}]}