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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UNITED STATES OF AMERICA 
BEFORE THE 
FEDERAL ENERGY REGULATORY COMMISSION 
  
Midcontinent Independent 
 ) 
Docket No. ER26-3650-000 
System Operator, Inc. 
 ) 
  
 
PROTEST OF SIERRA CLUB, NATURAL RESOURCES DEFENSE COUNCIL, 
ENVIRONMENTAL LAW AND POLICY CENTER, CLEAN WISCONSIN, UNION OF 
CONCERNED SCIENTISTS, SUSTAINABLE FERC PROJECT, AND FRESH ENERGY 
 
Pursuant to Rule 211 of the Federal Energy Regulatory Commission’s Rules of Practice 
and Procedure,1 Sierra Club, Natural Resources Defense Council, Environmental Law and Policy 
Center, Clean Wisconsin, Union of Concerned Scientists, Sustainable FERC Project, and Fresh 
Energy (collectively Public Interest Organizations, or “PIOs”) protest the August 28, 2026 filing 
of the Midcontinent Independent System Operator, Inc. (“MISO”) proposing Interconnection 
Reliability Requirements for Large Loads (“IRR Filing”).2  
I. 
Introduction 
PIOs support enforceable requirements that prevent large loads from imposing avoidable 
reliability costs on other customers, causing increased reliability risk, or triggering reliability 
violations. MISO’s filing, however, does not meet that goal. MISO has submitted tariff revisions 
that give at least 30 gigawatts (“GW”) of large load, though likely more, an unrestricted ability to 
ramp at eye-watering speeds and trip offline unexpectedly, causing voltage and frequency 
instability. Some amount of large load is also free to take these actions without providing 
advanced notice to MISO, and without MISO even having insight into the load configuration or 
operating capabilities. What requirements do exist would be hampered by limited enforcement 
 
1 18 C.F.R. § 385.211. 
2 MISO’s Interconnection Reliability Requirements for Large Loads, Docket No. ER26-3650, Accession 
No. 20260828-5278 (Aug. 28, 2026) [hereinafter “IRR Filing”].

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ability, as MISO proposes to put most of the critical restrictions of the IRR Filing in Business 
Practices Manuals (“BPMs”). Ultimately, MISO’s proposed tariff revisions are not just and 
reasonable. The Commission should reject them.  
II. 
Argument 
 
A. 
The Commission should not allow broad exemptions from reliability 
requirements for existing and planned large loads. 
 
MISO proposes two broad categories of large loads which will receive automatic 
exemptions from some or all of the proposed reliability requirements: 1) large loads with a 
Service Commencement Date on or prior to December 4, 2026 will be entirely exempt from any 
reliability requirements (a status MISO designates as “Fully Exempt”), and 2) large loads 
associated with transmission projects either approved for MTEP 2026 or submitted for EPR 
review prior to June 18, 2026 will be exempt from ride-through and ramp requirements (a status 
MISO designates as “Partially Exempt”).3 In this filing, MISO does not quantify the amount of 
load that will be subject to each of these exemption categories, but in MISO’s August 12, 2026 
Large Load Working Group, MISO staff estimated that a jaw-dropping 30 GW of then-existing 
or proposed load would fall into one of these two categories and thus be exempt from some or all 
requirements.4 
MISO’s proposed exemptions go far beyond what the Commission’s Show Cause Order5 
directed, represent a broad cost shift from large loads to other MISO customers, and threaten 
 
3 IRR Filing, Tab A Tariff Redline at 37A(II). MISO also proposed a third category of exemptions from 
ride-through requirements which MISO would be permitted to grant at its discretion. IRR Redline at 
37(A)(II)(2)(b)(ii). PIOs also have significant concerns with this third category of exemptions, see infra 
11-12, 19-20, but discuss it separately as it is not an automatic exemption. 
4 See Declaration of Andrew Siebenaler, Attachment A, at 1. As Mr. Siebenaler explains, this amount 
would represent roughly 20% of MISO’s peak summer demand with the new large loads in-service, or 
more than 24% of its current peak summer demand. Id at 3. 
5 Midcontinent Indep. Sys. Operator, Inc., 195 FERC ¶ 61,212 (June 18, 2026).

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reliability in the region and across the Eastern Interconnect. Moreover, MISO’s proposal to allow 
a portion of exempted load to retain broad exemptions even when there are material 
modifications to the load creates a Grand Canyon-sized loophole that could allow unknown 
amounts of large load to ignore reliability requirements. On these bases alone, MISO’s IRR 
Filing is not just and reasonable and should be rejected.  
1. 
Categorically exempting some large loads from reliability requirements 
creates reliability concerns. 
 
The North American Electric Reliability Corporation (“NERC”) has identified the 
numerous reliability challenges that large loads in general, and computational loads particularly, 
can cause in bulk power system operation and planning.  
MISO stated in the August 12, 2026, Large Load Working Group that approximately 30 
GW of large load would be exempted from reliability requirements. But MISO has not shared, 
either in this filing or in the stakeholder process, how much load it expects to be online as of 
December 4, 2026 and thus fully exempted from requirements, how much load it expects to be 
partially exempted, how much of the exempted load is computational load, or, critically, if MISO 
has conducted any studies or analysis of the reliability impact of its proposed exemptions. 
Without this information, MISO cannot meet its burden of showing that its filing is just and 
reasonable. And there are numerous reasons to think that this significant amount of at least 30 
GW of exempt load could cause reliability concerns. 
 
NERC recognizes that many computational loads ramp at a rate beyond what spinning 
generators can provide.6 Without quantifying the amount of large load that will be subject to 
 
6 NERC, Characteristics and Risks of Emerging Large Loads: Large Loads Task Force White Paper at 19 
(July 2025), available at: https://www.nerc.com/globalassets/who-we-are/standing-
committees/rstc/3_doc_white-paper-characteristics-and-risks-of-emerging-large-
loads.pdf?_sp=75c20315-b4f2-4253-8dbd-1241008d09d2 [hereinafter “Characteristics and Risks of 
Large Loads”].

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exemptions and comparing it to the amount of battery ramp capacity in MISO,7 it is entirely 
possible that MISO will permit operation of more fast ramping inverter-based load without ramp 
limitations than fast ramping generation exists in MISO’s markets. This deficit is especially dire 
as MISO has recognized that its current reserve product construct might not result in all reserve 
products being deliverable.8 And moreover, ramp rates for computational load may exceed what 
generators that offer into the ramp market are obligated to offer.9 Allowing an unknown amount 
of computational load to operate without ramp limits could result in load shed or system collapse 
if generators cannot ramp to match demand.10 Such an outcome would not be just and 
reasonable. 
 
Similarly, NERC has found that computational loads can pose significant threats to 
system frequency and voltage stability if they are not properly configured to ride through minor 
disturbances. Computational load tripping offline (referred to by NERC as “customer initiated 
load reduction” or “CILR” events) can increase the impacts of a disturbance or even lead to 
cascading power outages. These concerns are not hypothetical. PJM recently narrowly averted 
blackouts when 3.8 GW of load–a mere tenth of the load MISO proposes to exempt–tripped 
offline instantaneously.11 The region required more than ten minutes to recover, which is thirty 
 
7 MISO currently does not allow wind or solar resources to provide ramping services. See MISO Tariff, 
Definitions - U, Up and Down Ramp Capability Qualified Resource (defining resources qualified to 
provide up and down ramp capabilities as “[a] Generation Resource that is not a Dispatchable Intermittent 
Resource…”). As such, inverter-based ramp resources are limited to battery energy storage systems. 
8 MISO Market Subcommittee, Enhance Reserve Deliverability for DA and RT Market (MSC-2026-2) 
Slidedeck at 27 (July 9, 2026), available at:  
https://cdn.misoenergy.org/20260709%20MSC%20Item%2012%20Enhance%20Reserve%20Deliverabili
ty%20for%20DA%20and%20RT%20Market%20(MSC-2026-2)767388.pdf. 
9 See MISO Tariff, Module C, § 40.2.5.e, “Values in Offers” (requiring that reserve product offers “shall 
reflect the actual known physical capabilities and characteristics of the Generation Resources and/or 
Demand Response Resources - Type II on which the Offer is based…”); NERC, Characteristics and Risks 
of Large Loads at 19 (noting that many generators cannot match computational load ramp rates). 
10 NERC, Characteristics and Risks of Large Loads at 19. 
11 Devin Leith-Yessian, “Va. Data Center Ride-through Performance Faulted for July Voltage 
Disturbance,” RTO Insider (Aug. 12, 2026), available at: https://www.rtoinsider.com/138974-va-data-

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times longer than what is typically acceptable.12 And in Texas, ERCOT recorded 26 instances of 
computational load CILR events of at least 100 MW between January 2023 and September 
2025.13 MISO does not present any studies or assurances that the final amount of load which will 
be Partially or Fully Exempt from ride through requirements will not pose a threat to reliability. 
Allowing a distinct class of load to cause reliability violations and to shift the cost of mitigation 
to all other load is not just and reasonable.14   
The reliability concerns associated with these broad exemptions are exacerbated by 
MISO’s decision to exempt load with an in-service date before December 4, 2026 from all 
reliability requirements, including informational requirements.15 As NERC explains, “[w]ithout 
the proper data to simulate and characterize large loads, grid planners and operators will be 
unable to accurately model large loads, leading to inaccurate analysis of BPS reliability and 
uninformed decisions when planning and operating the grid.”16 Notably, NERC recognizes that 
data sharing is critical not just at the interconnection stage, which will have already passed by the 
effective date of the tariff, but also at the commissioning and operations stage.17 The result is that 
 
center-ride-through-performance-faulted-july-voltage-disturbance/; See also Declaration of Andrew 
Siebenaler, Attachment A, at 3. 
12 Declaration of Andrew Siebenaler, Attachment A, at 3. 
13 NERC, Incident Review Voltage-Sensitive Crypto Load Reductions at 2, available at: 
https://www.nerc.com/globalassets/our-work/reports/event-reports/incident_review_considering_voltage-
sensitive_crypto_load_reductions.pdf.  
14 See, e.g., PJM Interconnection, L.L.C.,193 FERC ¶ 61,217, at P 186 (2025) (finding that PJM’s behind 
the meter generation tariff provisions were unjust and unreasonable because the tariff did not provide any 
protections against the costs of maintaining sufficient resources to serve large loads with behind the meter 
generation being shifted onto other customers). 
15 IRR Filing, Tab A Tariff Redline at 37A(II)(2)(a) (exempting Fully Exempt large loads “from all 
requirements set forth in this Section 37A”). 
16 NERC, Risk Mitigation for Emerging Large Loads, Large Loads Working Group Reliability Guideline 
at 1 (May 2026), available at: https://www.nerc.com/globalassets/our-
work/guidelines/reliability/RG_Risk-Mitigation-For-Emerging-Large-Loads.pdf [hereinafter “Risk 
Mitigation for Large Loads”]; See also id. at 6 (“Accurate dynamic models of large load facilities are 
required to understand reliability implications and potential mitigations.”). 
17 Id. at 1.

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“MISO will not be capable of evaluating and mitigating the reliability risk of computational 
loads on its system if it exempts significant amounts of large load from information sharing 
requirements,” and that there is an “imminent reliability risk to the MISO footprint.”18  
MISO’s exemption scheme threatens significant reliability concerns, and, as a result, the 
IRR Filing is not just and reasonable. 
2. 
Categorically exempting some loads improperly shifts costs. 
As discussed above, large loads create significant impacts on system resource needs. 
Computational load can ramp at extreme rates, cause frequency disturbances, and impact system 
voltage. Uncertainty around large load characteristics and operating parameters can also increase 
the risk of short term load forecasting errors, which, in turn, increases the risk of under- or over-
scheduling and dispatching generation resources.19 To the extent these concerns are able to be 
mitigated outside of reliability requirements for the large loads, mitigation will result in 
increased costs for other MISO customers. Over-scheduling of generation resources and clearing 
more ramp resources can mitigate some concerns associated with insufficient ramp but will 
result in higher energy and ancillary services clearing prices for all customers, even though the 
issues themselves are caused by the exempted large loads alone. Similarly, voltage issues can be 
mitigated to some extent by installing static VAR devices or synchronous condensers.20 But the 
costs for these interventions would not be allocated to the cost-causing large loads that 
necessitated the interventions.  
The Commission and courts have long held that a just and reasonable rate must meet the 
“cost-causation” principle.21 The principle requires that “all approved rates must reflect to some 
 
18 Declaration of Andrew Siebenaler, Attachment A, at 4. 
19 NERC, Characteristics and Risks of Large Loads at 18.  
20 NERC, Risk Mitigation for Emerging Large Loads at 26. 
21 El Paso Elec. Co. v. FERC, 76 F.4th 352, 357 (5th Cir. 2023).

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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 principle, and for 
the IRR Filing to be just and reasonable, large loads must pay for any reliability costs they 
impose on the transmission system. 
PIOs recognize that MISO intends to submit a 205 filing in November addressing 
“transparency concerning the Network Upgrade costs and cost shift concerns.”24 Such a filing 
might ameliorate the cost shift concerns discussed here. But that filing is not before the 
Commission, and, taken alone, the IRR Filing violates the cost causation principle. PIOs note 
many of MISO’s 205 filings in response to the Show Cause Order will likely only be just and 
reasonable when considered in context with the other filings. PIOs therefore suggest that the 
Commission direct MISO to clarify whether it would be better able to meet the spirit of the Show 
Cause Order if it had leave to amend its filing schedule and present all 205 filings in response to 
the Show Cause Order jointly. PIOs also note that having tariff revisions in response to the Show 
Cause Order filed in the Show Cause docket under the auspices of a 206 proceeding might allow 
for more rapid tariff development by allowing the Commission the opportunity to rectify the 
issues noted in this protest. 
 
22 City of Lincoln v. FERC, 89 F.4th 926, 930 (D.C. Cir. 2024) (cleaned up). 
23 Midwest ISO Transmission Owners v. FERC, 373 F.3d 1361, 1368 (D.C. Cir. 2004).  
24 Midcontinent Indep. Sys. Operator, Inc., et al., Motion of the Midcontinent Independent System 
Operator, Inc. and the MISO Transmission Owners to Hold Proceeding in Abeyance and Request for 
Shortened Comment Period and Expedited Treatment, Docket No. EL26-70, Accession No. 20260803-
5249, at 12 (Aug. 8, 2026).

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3. The IRR Filing does not make clear when load modifications remove exemptions.  
As written, the IRR Filing is impermissibly vague with regards to how modifications will 
impact a large load’s exemption status.25 The proposed tariff provisions state that “[a] Large 
Load that has a Service Commencement Date on or prior to December 4, 2026, shall be exempt 
from all requirements set forth in this Section 37A with respect to the portion of the Large Load 
that has procured Transmission Service as of the Service Commencement Date.”26 But MISO 
never defines what constitutes a “portion” of a large load. Would replacing equipment with 
identical operating characteristics create a new portion of the large load? Would changing the 
operating characteristics of existing equipment constitute a new portion of a load? What of 
installing wholly new equipment while ensuring that the total maximum demand of the large 
load does not change? 
At earlier points in the stakeholder process, MISO indicated an intent to have “any 
modification or series of modifications to the Large Load that results in a cumulative increase in 
Demand of 25 MW or more” subject the incremental load to all applicable requirements of 
Section 37A.27 If that is still MISO’s intended policy, the proposed tariff submitted will not 
implement it. As discussed above, for Fully Exempt loads, the IRR Filing states that “[a]ny 
 
25 The Commission has regularly held that unclear tariff terms are unjust and unreasonable. See Boston 
Edison Co., 98 FERC ¶ 61,292, at P 21 (2002) (“The Commission also has an interest in ensuring that 
tariffs clearly, completely and unambiguously identify services, rates and terms and conditions. The 
Commission thus frequently rejects proposed tariff language as unclear. It is the responsibility of the 
applicant to demonstrate that its proposed tariff achieves these objectives.”); see also Dominion Energy 
Mktg. v. ISO New Eng., Inc., 155 FERC ¶ 61,121, at P 17 (“We find that ISO-NE’s existing Tariff is 
unclear as to whether new incremental capacity and existing capacity at the same generating station must 
submit a composite offer in order to participate in the [Forward Capacity Auction]. As a result of this lack 
of clarity, the Tariff fails to provide adequate notice of what the requirement is and, thus, we find the 
Tariff is unjust and unreasonable.”).  
26 IRR Filing, Tab A Tariff Redline at 37A(II)(2)(a). 
27MISO, Large Load Interconnection Reliability Requirements (LLWG) Slidedeck at 12 (July 21, 2026), 
available at: 
https://cdn.misoenergy.org/20260727%20LLWG%20Item%2003%20Interconnection%20Reliability%20
Requirements%20(LLWG-2026-3)_Presentation770291.pdf.

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modification or series of modifications to a Load that meets the MTEP/EPR Condition, which 
results in a cumulative increase of 25 MW or more in Transmission Service for such Load and 
with a Service Commencement Date after December 4, 2026, shall be subject to subsection 
(2)(b) below.”28 But the IRR Filing does not state what happens for any modification or 
modifications to the load that does not meet the MTEP/EPR condition. Notably, that would 
include any modifications to the load which are proposed after December 4, 2026.29 And while 
Partially Exempt status applies to a “Large Load, or a portion of a Large Load” that meets the 
MTEP/EPR Condition, 37A(II)(2)(b) does not contain a MW threshold or other criteria that 
spells out what would result in a “portion” of a large load being considered distinct.30  
Even if MISO were to add clarifying language stating that an addition of 25 MW or more 
to a load creates a new “portion” of a large load subject to the full reliability requirements, 
MISO’s proposal would not be just and reasonable. Merely using a MW threshold to describe 
changes to large loads would allow significant marginal costs to be imposed on the system by 
Fully Exempt loads. As MISO explained, different load has different reliability risks, with 
computational load imposing significant ramp and ride through concerns that non-computational 
load does not impose.31 If a new “portion” of a large load is only created when a load increases 
its maximum demand, a large load steel mill could convert to an AI data center of the same 
maximum demand while retaining full exemption from reliability requirements. And what is 
more, MISO would have no visibility into the change in operational characteristics before it 
occurred because the obligation to note “[a]ny changes to the characteristics of a Large Load 
 
28 IRR Filing, Tab A Tariff Redline at 37A(II)(2)(a). 
29 Id. at 37A(II)(1). 
30 Id. at 37A(II)(2)(b). 
31 IRR Filing, Transmittal Letter at 11.

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and/or Large Load Equipment, including any changes to the modeling details for the Large 
Load” is a requirement from which Fully Exempt loads are exempt.32 
4. It is not clear how a portion of a large load can comply with the requirements. 
Even if the tariff provided an explanation of what constitutes a new “portion” of a large 
load that was both clear and just and reasonable, the tariff is not sufficiently clear regarding how 
only a portion of a large load can comply with the requirements while the rest is exempted in 
whole or in part. Take, for example, Section 37A.1, which requires that the Transmission 
Customer provide MISO with “one-line diagrams, and a description of the electrical 
characteristics of the Large Load for all Large Load Equipment.”33 If a Fully Exempt large load 
develops a non-exempt portion, how would a Transmission Customer be able to provide 
diagrams of all large load equipment, while simultaneously respecting the exemption provision? 
Similarly, 37A.2 requires “verified and complete electrical models of the Large Load.”34  
If a Fully Exempt or Partially Exempt large load adds a non-exempt portion behind the 
same point of withdrawal, it is impossible to verify if the portion of the load subject to the ride-
through requirements of Section 37A.6 met its requirements to stay connected during a voltage 
or frequency disturbance while the exempt portion of the same load tripped offline. Or consider a 
500 MW facility consisting of a 250 MW exempt portion and a 250 MW non-exempt portion 
behind the same meter. If the facility as a whole ramped at a rate of 250 MW per second, how 
would MISO determine which “portion” of the facility ramped and if the ramp limits were 
violated? Similar questions arise regarding the Large Load Audit Rights in Section 37A.8. MISO 
will have no way to confirm if a large load is inappropriately withholding data contrary to the 
 
32 IRR Filing, Tab A Tariff Redline at 37A.1; see also IRR Filing, Tab A Tariff Redline at 37A(II)(2)(a) 
(exempting Fully Exempt loads from all requirements). 
33 Id. at 37A.1 (emphasis added). 
34 Id. at 37A.2 (emphasis added).

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terms of the tariff, or if data is not subject to audit rights because it is associated with the portion 
of the load which is Fully Exempt. 
Ultimately, some, although not all, of these issues could be mitigated with clear 
definitions on what constitutes a new portion of a large load, and requirements that new portions 
be separately metered with separate telemetry and data recording equipment than any other 
portion. But such provisions are not in the tariff IRR Filing MISO submitted.35 Accordingly, 
MISO’s filing is not just and reasonable. 
5. 
The discretionary ride-through exemption for projects submitted between 
June 19, 2026, and October 31, 2026 will create a speculative submission 
rush. 
 
MISO proposes to create a third category of discretionary exemptions from ride through 
requirements if a large load has “not met the MTEP/EPR Condition but has submitted Load 
associated with a transmission project to the Transmission Provider for EPR on or after June 19, 
2026, but on or before October 31, 2026.”36 While PIOs raise broader concerns with the 
provision below,37 the provision is also problematic in that it will encourage large load 
developers to submit speculative load interconnection requests in the hope of taking advantage of 
the time-limited exception. Whatever the justification of providing exemptions for projects that 
have already taken concrete steps to interconnect, allowing projects to seek exemptions until 
October 31, 2026 is only likely to fuel speculative load requests. The Commission found in the 
Show Cause Order “that there may be speculative transmission service requests by Eligible 
Customers on behalf of large loads that could result in cost shifting among transmission 
 
35 The Commission has previously found that metering requirements must be filed in RTO tariffs, 
pursuant to the rule of reason. See Order No. 2222, Participation of Distributed Energy Resource 
Aggregations in Markets Operated by Regional Transmission Organizations and Independent System 
Operators, Docket No. RM18-9, 172 FERC ¶ 61,247, at P 271 (2020). 
36 IRR Filing, Tab A Tariff Redline at 37A(II)(2)(b)(ii). 
37 See infra at 19-20.

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customers, which may lead to unjust and unreasonable increases in jurisdictional transmission 
rates” in MISO.38 Because the IRR Filing creates even more incentives to submit such 
speculative transmission service requests, the filing is unjust and unreasonable.  
6. 
It is ambiguous if MISO would be able to subject exempted large loads to 
requirements before they cause reliability issues. 
 
The reliability impacts discussed above could create significant reliability risks in the 
MISO system. And while the proposed tariff language does allow MISO to subject otherwise 
exempt or partially exempt load to reliability requirements, the proposed tariff, as drafted, is 
ambiguous regarding whether MISO is able to impose the requirements before the large load has 
caused reliability issues. The proposed tariff provides that MISO may subject otherwise exempt 
or partially exempt load to a reliability requirement if MISO “determines that operation of a 
Large Load results in a material adverse effect on Transmission System reliability.”39 Instead of 
using language that would clearly allow imposition of reliability requirements if MISO 
determines that operation of a large load may result in adverse reliability impacts, MISO’s 
proposed tariff provision makes it unclear if MISO can impose any reliability requirements until 
after a large load operates in a manner that “results” in a material adverse impact on reliability.  
Disturbingly, Ms. Li’s testimony also suggests MISO would only be allowed to impose 
requirements after a large load has impacted reliability. Ms. Li testified that MISO’s so-called 
transition framework “preserv[es] MISO’s ability to address demonstrated material adverse 
impacts to Transmission System reliability.”40 To the extent the tariff allows otherwise exempted 
or partially exempted large loads to cause reliability issues while MISO’s hands are tied, it is 
 
38 Midcontinent Indep. Sys. Operator, Inc., 195 FERC ¶ 61,212, at P 80. 
39 IRR Filing, Tab A Tariff Redline at 37A(II)(3). 
40 IRR Filing, Tab C, Prepared Direct Testimony of Beibei Li at 23 (emphasis added) [hereinafter “Li 
Testimony”].

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unjust and unreasonable. And to the extent the provision does not do so and is simply vague, it 
also must be revised.41 
MISO’s IRR Filing also fails to account for how it will handle cases where two or more 
large loads operating alone would not, individually, result in a material adverse impact on 
reliability, but where a large loads’ behavior interacting  with another large load would result in a 
material adverse impact on reliability. MISO’s tariff fails to spell out how MISO will decide 
which reliability requirements it will require of which load, and how it will allocate compliance 
obligations amongst the relevant loads. 
7. The IRR Filing as drafted both explicitly exempts and explicitly does not exempt a 
category of large loads from reliability requirements.  
 
MISO’s IRR Filing, as written, contains contradictory language regarding the compliance 
obligations of large loads with a Service Commencement Date on or prior to December 4, 2026, 
but that did not require associated transmission upgrades in an MTEP cycle or submit a project 
for EPR review. The proposed tariff revisions state in section 37A(II)(2)(a) that “[a] Large Load 
that has a Service Commencement Date on or prior to December 4, 2026, shall be exempt from 
all requirements set forth in this Section 37A with respect to the portion of the Large Load that 
has procured Transmission Service as of the Service Commencement Date.” The proposed tariff 
revisions state in Section 37A(II)(2)(c) that “[a] Large Load, or a portion of a Large Load, that 
does not meet the MTEP/EPR Condition shall be subject to all applicable requirements set forth 
in this Section 37A.” Section 37A(II)(1) states that “Load associated with a transmission project 
shall be defined as meeting the ‘MTEP/EPR Condition’ if the project has either: (a) been 
approved by the Transmission Provider Board in MTEP 2026, or a prior MTEP; or, (b) been 
submitted to the Transmission Provider for Expedited Project Review (EPR) on or prior to June 
 
41 See Boston Edison Co., 98 FERC ¶ 61,292, at P 21 (2002).

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18, 2026, in accordance with Attachment FF of the Tariff.” Together, these three provisions 
create situations that might define a load as both exempt and not exempt. Loads that predated the 
MISO MTEP process, or loads that interconnected before December 4, 2026 but did not require 
an associated transmission upgrade in the MTEP to interconnect, will both have not met the 
MTEP/EPR Condition and thus “be subject to all applicable requirements set forth in this Section 
37A” per Section 37A(II)(2)(c), and also have had “a Service Commencement Date on or prior 
to December 4, 2026,” and thus “shall be exempt from all requirements set forth in this Section 
37A” pursuant to Section 37A(II)(2)(a). Because there is not a proviso giving primacy to either 
Section 37A(II)(2)(c) or Section 37A(II)(2)(a), some loads might be both exempt and non-
exempt. While these contradictory terms are undoubtedly a drafting error, the resulting 
impossibly conflicting provisions render the tariff proposal, as filed, unjust and unreasonable.  
8. MISO’s filing goes far beyond what was directed in the Show Cause Order. 
a. The Show Cause Order envisioned compliance glide paths for existing 
and late-stage development large loads, not wholesale exemptions. 
 
 
MISO justifies its exemptions by pointing to language in the Commission’s Show Cause 
Order directing MISO to propose reasonable implementation periods “to ensure minimal 
disruption to [] existing commercial arrangements” and to propose mechanisms to allow 
proposed projects “a reasonable amount of time to finalize ongoing agreements that are nearing 
completion.”42 MISO improperly reads the Show Cause Order. The Show Cause Order directs 
MISO to “propose a reasonable implementation period to ensure minimal disruption to such 
existing commercial arrangements.”43 The direction to have an implementation period implies a 
period after which implementation will be completed and all loads will be subject to new tariff 
 
42 Midcontinent Indep. Sys. Operator, Inc.,195 FERC ¶ 61,212, at P 5. 
43 Id.

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provisions. The Commission has employed similar implementation period approaches before, 
when applying reliability standards to inverter based resources.44 
A reading of the Show Cause Order that would direct MISO to indefinitely exempt some 
large loads from reliability requirements also fails to read the Show Cause Order as a whole. The 
Show Cause Order repeatedly emphasized the need for MISO to ensure large loads pay for the 
costs they impose on the system. The Commission found that “MISO’s Tariff appears to be 
unjust and unreasonable because it lacks adequate mechanisms to mitigate the risk of cost 
shifting among transmission customers, which may result in unjust and unreasonable rates for 
transmission service.”45 As discussed above, allowing some loads to dodge reliability 
requirements will shift costs on to other customers.46 If the Commission had intended to direct 
MISO to indefinitely exempt some large loads from reliability requirements, it would have said 
so in the Show Cause Order. MISO’s design here is not required by prior Commission orders. 
b. MISO does not justify why existing large loads would face disrupted 
commercial arrangements from information and modeling requirements. 
Even if the Show Cause Order could be interpreted to direct for existing and near-
completion large loads to receive exemptions from some reliability requirements, MISO does not 
justify why it exempts existing large loads from all reliability requirements. Specifically, MISO 
 
44 See N. Am. Elec. Reliability Corp.,190 FERC ¶ 61,098, at PP 12 (approving the NERC standard), 7 
(“NERC describes its proposed implementation plan for Reliability Standards PRC-028-1 and PRC-002-5 
as ‘a risk-based, phased-in compliance approach’ that would require generator owners to implement 
disturbance monitoring equipment by no later than 2030.”) (2025); Accession Number: 20241104-5220 at 
exhibit B (describing the phased-in implementation plan). 
45 Midcontinent Indep. Sys. Operator, Inc., 195 FERC ¶ 61,212, at P 66. See also id., (See, Comm’r, 
concurring at 9) (“As we move forward, I’ll be looking to ensure cost-recovery agreements contain fair 
and transparent measures to ensure the right costs get on the right bills.”); id (Chang, Comm’r, concurring 
at 6 (“While individual states have been exploring or using various approaches to protect retail customers 
against unjustified cost shifts, the Commission to date has not initiated any proactive exploration of how 
to protect wholesale customers against unjustified cost shifts. I am laser-focused on this issue because we 
should not create unjustified costs for consumers in our efforts to connect and serve large loads.”). 
46 See supra at 6-7.

16 
 
does not justify why complying with information and modeling requirements in Sections 37A.1-
37A.2 would cause more than a de minimis disruption to existing commercial relationships. 
Instituting the modeling and information requirements would not require installation of any new 
equipment or facilities. And the Commission has previously found it just and reasonable to make 
generation resources, including existing generation resources with signed Generator 
Interconnection Agreements, provide similar information.47 MISO does not show that excluding 
some large loads from the reporting requirements of 37A.1 and 37A.2 is just and reasonable. 
B. 
The Commission should ensure harmonization of MISO and NERC 
requirements. 
 
The Commission has directed NERC to develop large load reliability standards by the 
end of the year.48 While PIOs appreciate that the Show Cause Order directed MISO to develop 
reliability standards within a more compressed timeline than the NERC standards,49 in light of 
the Commission’s subsequent order directing NERC to develop reliability standards, the 
Commission should allow MISO to  propose reliability standards which can be harmonized with 
the standards NERC will submit to the Commission. Harmonizing MISO’s reliability 
requirements with NERC’s requirements from the start, rather than MISO developing standards 
it might need to revise to comply with NERC requirements, is preferable on two fronts: first, 
while MISO regularly focuses on implementing reliability standards, NERC has special expertise 
in developing reliability standards. Second, if MISO’s standards are not in line with NERC 
standards, large load developers and owners might plan for MISO standards, and then be forced 
 
47 See N. Am. Elec. Reliability Corp.,190 FERC ¶ 61,098 (2025). 
48 Order Directing the North American Electric Reliability Corporation To File Reliability Standard(S) 
Pertaining to Computational Load Integration, 196 FERC ¶ 61,031 (2026). 
49 Midcontinent Indep. Sys. Operator, Inc., 195 FERC ¶ 61,212, at P 64 (discussing preliminary finding 
regarding the need for reliability standards), 196 FERC ¶ 61,133 at 9 (directing that responses to the show 
cause order be submitted by November 16, 2026).

17 
 
to make costly or disruptive updates to standards after load sites have already been designed or 
developed.  
MISO recognizes the value of harmonizing NERC and MISO standards in its filing, but 
avers that “[w]hile NERC processes are underway to develop industry wide guidelines, the 
MISO region cannot wait to put in place needed interconnection reliability requirements to 
reliably integrate these near-term Large Loads.”50 While this may be true as a matter of MISO 
meeting the directive of the Show Cause Order, harmonizing MISO and NERC standards would 
not significantly delay implementation of reliability requirements. 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 subject 
to MISO’s reliability requirements before NERC’s requirements are finalized and approved. 
Large loads that begin service as of December 4 are fully exempt from all reliability 
requirements in MISO’s proposal, and any large loads that come online between December 4 and 
December 31 would presumably have been subject to the MTEP/EPR condition and therefore 
only be subject to Large Load Information and Basic Facility Data Requirements, Large Load 
Modeling Requirements, and Large Load Audit Rights. Moreover, submitting the IRR Filing 
now does not provide large load developers significant additional time to plan around 
compliance requirements as compared to waiting to harmonize with NERC requirements. As Ms. 
Li notes, MISO’s Business Practices Manual (“BPM”) development timeline has been extended 
 
50 IRR Filing, Transmittal Letter at 3. 
51 Large Load Information and Basic Facility Data Requirements, Large Load Modeling Requirements, 
Large Load Ride-Through Requirements, Large Load Ramp Requirements, and Large Load Audit Rights 
apply as of the effective date of the tariff. Large Load Telemetry Requirements, Large Load Forecast Data 
Requirements, and Large Load Phasor Measurement Unit Requirements are not applicable until 
September 1, 2027. See generally IRR Filing, Tab A Tariff Redline.

18 
 
to December 2026.52 Because MISO has (improperly) decided to place core reliability 
requirements in the BPMs, large load developers might not even have a month’s notice between 
a final picture of MISO’s reliability requirements and NERC’s requirements. Altogether, the 
minimal delay associated with harmonizing MISO and NERC standards would make the 
temporary imposition of MISO standards that will likely need revision unjust and unreasonable. 
The Commission should reject the IRR filing on this basis, and make updated findings in the 
Show Cause docket directing MISO to file revised reliability requirements that harmonize with 
NERC requirements by the end of January 2027.  
C. 
MISO improperly defers critical details for each requirement to BPMs. 
 
MISO’s filing defers significant, core elements of its reliability requirements in each 
category of requirement to its BPMs. MISO leaves far more than “implementation details” to the 
BPMs, and in doing so has proposed an unjust and unreasonable tariff. 
The Commission determines which terms must be in the tariff, as opposed to a BPM, 
pursuant to the rule of reason. “The rule of reason requires utilities to file only those practices 
that affect rates and service significantly, that are realistically susceptible of specification, and 
that are not so generally understood in any contractual arrangement as to render recitation 
superfluous.”53 “The tariff need not include mere implementation details.”54 MISO’s tariff 
provisions, as proposed, do not comport with the rule of reason. For ease of navigating each of 
these inappropriate referrals of substantive tariff provisions to the BPMs, PIOs have organized 
inappropriate deferral of reliability requirements to the BPM by section: 
 
52 IRR Filing, Li Testimony at 39. 
53 City & Cnty. of San Francisco v. FERC, 24 F.4th 652, 661 (D.C. Cir. 2022) (cleaned up). 
54 Hecate Energy Greene Cnty. 3 LLC v. FERC, 72 F.4th 1307, 1312 (D.C. Cir. 2023).

19 
 
1. 37A(I) Violations of Requirements 
Section 37A(I) discusses what happens if a large load fails to comply with the reliability 
requirements: “Failure to comply with the requirements established in this Section 37A may 
result in a delayed Service Commencement Date, a period of time needed for corrective action, 
operational limitations, or other remediation action(s) by Transmission Provider as may be 
necessary to maintain Transmission System reliability. The process by which Transmission 
Provider [sic] will determine whether any such measures are appropriate, which may include the 
period of time during which corrective action must be undertaken, shall be as set forth in the 
Business Practices Manual for Large Load.”55 
 
The IRR Filing does not explain at all how MISO will evaluate the reliability risk 
associated with non-compliance, or do more than vaguely reference “Transmission System 
reliability” to explain how MISO will determine what consequences result from non-compliance. 
The process by which MISO considers penalties is clearly susceptible to specification.56 And 
given these “operational limitations, or other remediation action(s)” can presumably include 
actions up to and including disconnection of the load, the penalties available and how they are 
assessed makes a substantial impact on rates. Under the rule of reason, these terms should be 
included in a tariff, and not relegated to the BPM. 
2. 37A(II)(2)(b)(ii) Ride-Through Requirement Exemptions 
Section 37A(II)(2)(b)(ii) allows MISO to exempt large loads from ride-through 
requirements provided the load submitted an EPR request on or after June 19, 2026, but on or 
before October 31, 2026. The relevant provision provides MISO may waive the ride-through 
requirements:  
 
55 IRR Filing, Tab A Tariff Redline at 37A(I). 
56 See, e.g., MISO Tariff, Attachment FF, Section IX. Variance Analysis.

20 
 
based upon a determination that: a) exemption from such requirements would not have an 
adverse reliability impact; and, b) compliance with such requirements would result in 
significant costs. The Business Practices Manual for Large Load shall set forth the 
process and documentation necessary for Transmission Provider to determine whether 
such criteria have been met.57 
 
This section does not meet the rule of reason. What constitutes significant costs, or at 
least principles of how MISO will determine what constitutes significant costs, are reasonably 
susceptible of specification. What is a significant cost, especially to a data center willing to 
spend significant amounts of money to interconnect, is not so self evident so as to be generally 
understood. And the exemption self-evidently significantly affects rates: the load is only eligible 
for the waiver if compliance carries “significant costs.” The Commission should direct MISO to 
provide a metric by which it will determine if costs are significant, or at least principles that will 
guide its determination, in its order rejecting the IRR Filing. For example, a reasonable definition 
of significant costs could be defined as the greater of either $1 million in marginal costs or 10% 
marginal increase in cost of the total large load development cost. 
3. 37A(II)(2)(b)(iii) imposition of requirements on otherwise exempt load 
Section 37A(II)(2)(b)(iii) provides that MISO can, in certain situations, require load that 
would have otherwise been exempt from some or all reliability requirements nonetheless comply 
with some or all requirements. The section states that  
[t]he process by which Transmission Provider will make [a determination that operation 
of a Large Load results in a material adverse effect on Transmission System reliability] 
and which, if any, of the requirements of this Section 37A are to be applied shall be as set 
forth in the Business Practices Manual for Large Load.58 
 
Here too, MISO leaves too much to the BPM. While the mechanics of how MISO 
collects information and notifies otherwise exempt load that it must meet reliability requirements 
 
57 IRR Filing, Tab A Tariff Redline at 37(A)(II)(2)(b)(ii). 
58 IRR Filing, Tab A Tariff Redline at 37(A)(II)(3).

21 
 
is properly the domain of a BPM, the tariff must contain information about how MISO will 
determine which requirements will apply to the load. 
4. 37A.3 Large Load Telemetry Requirements  
Section 37A.3 concerns telemetry requirements. But the tariff filing itself defers so much 
to the BPM that significant questions of which facilities the standards will apply to, and what the 
standards are, are unanswerable from tariff language. The proposed language provides:  
[i]ndividual metering will be required for all Large Load and any Generation Resource(s) 
serving such Large Load that is located behind the same Point(s) of Withdrawal to the 
Transmission System as the Large Load and meeting thresholds outlined in the Business 
Practices Manual for Large Load. All telemetry shall be provided via Inter-Control 
Center Communications Protocol (ICCP) and must meet Transmission Provider update 
requirements as specified in the Business Practices Manual for Large Load.59 
 
It is impossible to tell which collocated generation must be individually metered as the 
“thresholds” for applicable generation are proposed to be located in the BPM. And what 
metering equipment will be required is also unclear as telemetry update requirements are also 
located in the BPM. MISO requiring all large loads meeting certain “thresholds” to be 
individually metered speaks to a clearly specifiable standard, and update requirements for meters 
are specifiable.60 As the Commission noted while accepting another MISO filing in June, 
metering requirements can have “costly and burdensome” impacts on market participants by 
impacting which meters participants can use.61 As such, these terms have a significant impact on 
rates. Because deferring these elements to the BPM would violate the rule of reason, the 
Commission should reject the IRR Filing.  
 
59 Id. at 37A.3. 
60 See, e.g., MISO Tariff, § 38.2.5(e)(vii)(c) (requiring “[a]ll metering equipment must be capable of 
storing a minimum of 35-days of hourly intervals for each measured value”). 
61 Midcontinent Indep. Sys. Operator, Inc., 195 FERC ¶ 61,210, at P 85 (June 18, 2026).

22 
 
5. 37A.6 Large Load Ride-Through Requirements 
Section 37A.6 concerns ride-through requirements for computational loads. As drafted, 
however, the section contains no discernable requirements at all:  
A Transmission Customer taking Transmission Service on behalf of a Computational 
Load shall be responsible for ensuring that the Computational Load remains connected to 
the Transmission System and continue operation during voltage and frequency 
disturbances within the performance criteria established by the Transmission Provider in 
the Business Practices Manual for Large Load.  
 
Ride-through requirements apply at the Point(s) of Withdrawal and may include 
evaluation, testing, modeling, monitoring, and other compliance measures established by 
the Transmission Provider in the Business Practices Manual for Large Load.62 
 
The IRR Filing does not specify what the requirements actually are, and states that they 
“may include evaluation, testing, modeling, monitoring, and other compliance measures,” 
leaving the actual compliance measures entirely in the BPM. Ride-through standards are capable 
of specification.63 And they have a substantial impact on rates, as MISO has stated that 
exemptions are needed in order to not disrupt commercial arrangements.64  
6. 37A.7 Large Load Ramp Requirements 
Section 37A.7 contains ramp limitations on computational loads. Here too, MISO’s 
proposed tariff language leaves all substantive requirements to the BPM:  
Computational Load shall be subject to up-ramp and down-ramp limits established by the 
Transmission Provider consistent with the process set forth in the Business Practices 
Manual for Large Load. The Computational Load must have an effective up and down 
ramp rate not exceeding the specified limit outlined in the Business Practices Manual for 
Large Load unless otherwise directed by the Balancing Authority, Reliability 
Coordinator, or Transmission Operator.65 
 
 
62 IRR Filing, Tab A Tariff Redline at 37A.6 
63 See, e.g., MISO Tariff, Attachment X, Appendix 6, Article 9.7.3, “Ride Through Capability and 
Performance” (requiring generators ride through within the “no trip zone” defined by Reliability Standard 
PRC024-3). 
64 IRR Filing, Transmittal Letter at 13-14. 
65 IRR Filing, Tab A Tariff Redline at 37A.7.

23 
 
The default ramp limit is clearly capable of specification; it is a number.66 And ramp limitations 
have a significant enough impact on rates that MISO felt it was justified to exempt some load 
from compliance to avoid disruption to commercial arrangements.67 Here too, MISO’s deferrals 
to the BPM defy the rule of reason. 
III. 
Conclusion 
 
MISO’s IRR Filing creates broad, dangerous exemptions to reliability requirements that 
MISO proposes to inappropriately house in BPMs. Each of these elements renders MISO’s filing 
unjust and unreasonable. Accordingly, the Commission should reject the filing. Instituting 
reliability requirements for large loads is critical to ensuring large load interconnection and 
operation will not result in reliability violations. The proposed standards filed simply do not live 
up to that important task. 
Respectfully submitted,                                         Dated: September 18, 2026 
 
/s/ Jonah Baskin 
Jonah Baskin 
Associate Attorney 
jonah.baskin@sierraclub.org 
 
Sierra Club Environmental Law Program 
50 F Street NW, Eighth Floor 
Washington, DC 20001 
 
/s/ Katie Duckworth 
Katie Duckworth 
Staff Attorney 
kduckworth@elpc.org 
  
Environmental Law & Policy Center 
35 E. Wacker Dr., Ste. 1600 
Chicago, IL 60601  
 
 
/s/ Lee Shaver 
Lee Shaver 
Senior Energy Analyst 
lshaver@ucs.org 
 
Union of Concerned Scientists  
200 East Randolph Street, Suite 5151 
Chicago, IL 60601 
 
 
/s/ Ciaran Gallagher  
Ciaran Gallagher, Ph.D. 
Energy & Air Manager 
cgallagher@cleanwisconsin.org 
 
Clean Wisconsin 
634 W Main St #300 
Madison, WI 53703 
 
66 NERC suggests that the ramp limit should be specified as a MW/min limit. See NERC, Risk Mitigation 
for Large Loads at n.29.  
67 IRR Filing, Transmittal Letter at 13-14.

24 
 
 
 
/s/ Anna Markowski 
Anna Markowski 
Director, Midwest 
Climate and Clean Energy 
amarkowski@nrdc.org   
 
Natural Resources Defense Council  
20 North Wacker Drive, Suite 1600  
Chicago, IL 60606  
 
 
/s/ Laura Hannah 
Laura Hannah 
Senior Advocate 
lhannah@nrdc.org   
 
Sustainable FERC Project 
Natural Resources Defense Council 
20 North Wacker Drive, Suite 1600  
Chicago, IL 60606 
/s/ Mike Schowalter 
Mike Schowalter 
Managing Director, Transmission Policy 
schowalter@fresh-energy.org 
 
Fresh Energy 
81 Seventh St. E., Suite 200 
Saint Paul, MN 55101 
(612) 433-3648

25 
 
 
CERTIFICATE OF SERVICE 
I hereby certify that I have this day served the foregoing document upon each person designated 
on the official service list compiled by the Secretary in this proceeding. 
  
Dated this 18th day of September, 2026. 
  
/s/ Jonah Baskin                      
 
Jonah Baskin  
Associate Attorney  
Sierra Club Environmental Law Program  
50 F St. NW, 8th Floor Washington, DC 20001  
(202) 556-3917  
jonah.baskin@sierraclub.org

Attachment A

1 
 
Declaration of Andrew Siebenaler 
I, Andrew Siebenaler, declare as follows: 
I. 
Introduction 
1. I am an electrical engineer and the Managing Consultant - Transmission at Energy Futures 
Group. Energy Futures Group (“EFG”) is a clean-energy consulting firm headquartered in 
Hinesburg, Vermont, with a satellite office in Canton, New York. EFG has two primary 
areas of practice.  The first is in the design, implementation, and evaluation of programs and 
policies to promote investments in efficiency, renewable energy, other distributed resources, 
and strategic electrification.  The second is in integrated resource planning. transmission 
planning and related analyses.  EFG staff have delivered projects on behalf of energy 
regulators, government agencies, utilities, and advocacy organizations in at least forty states, 
eight Canadian provinces, and several countries in Europe. 
2. I have worked for fourteen years in transmission planning roles, including at regional 
organizations, utilities and consulting firms. I have participated in the development of 
energy policy, transmission plans, and integrated resource plans (IRPs) included in local 
and regional plans covering the Midcontinent Independent System Operator (MISO), 
Southwest Power Pool (SPP), and in the state of Colorado. These efforts resulted in 
filings before utility regulatory bodies in Colorado, Michigan, Minnesota, North Dakota, 
South Dakota and Wisconsin and at the FERC. I have performed transmission planning 
analyses for reliability, system stability, nodal production cost analysis for economic 
transmission development, and served as a Subject Matter Expert in NERC transmission 
planning compliance efforts across the Mid-Continent Area Power Pool (MAPP) 
footprint. I received a Bachelor of Science Degree in Electrical and Computer 
Engineering from the University of Minnesota – Duluth in 2012.  My resume, included 
as Exhibit 1, provides additional detail regarding my professional and educational 
experience. 
3. It is my understanding, based on statements made by MISO staff and MISO stakeholders 
in the stakeholder process, and based on my reading of MISO’s proposed reliability 
requirements, that large load projects equal approximately 30,000 MW of demand, 
representing more than 24% of MISO’s stated System Peak Demand for the summer 
season as stated in the MISO Planning Year 2025-2026 Loss of Load Expectation Study 
Report,1 would be fully or partially exempt from MISO’s reliability requirements. 
4. A portion of the 30,000 MWs of large load is also exempt from requirements related 
to data collection. This lack of data collection requirement ensures reliability risks can 
only be identified once they are encountered, whereas proper application of the 
proposed requirements to all large loads could ensure proactive mitigation and 
maintained reliability.  
5. I conclude that the proposed exemptions from interconnection reliability 
requirements for large load customers represent an imminent reliability risk to the 
                                                     
1 PY 2025-2026 LOLE Study Report, MISO, available at https://cdn.misoenergy.org/PY%202025-
2026%20LOLE%20Study%20Report685316.pdf?v=20250313114401.

2 
 
MISO footprint as well as the Eastern Interconnection due to the significant 
amounts of load not being subject to reliability and data collection requirements. 
II. 
Purpose of Declaration 
8. I am familiar with MISO’s proposed reliability requirements and the proposed 
application of the requirements.  
9. I am also familiar with the impacts to system reliability resulting from improperly 
exempting significant amounts of large load additions. These impacts, described in more 
detail below, were demonstrated in two separate events in northern Virgina, once on July 
22nd, 2026 and during a previous event on July 10th, 2024. These events represented 
3,800 MW and 1,500 MW, respectively, of data center demand removing themselves 
from the grid after a transmission fault resulted in oscillations.  
10. In addition, I am aware that NERC issued a Level 3 Alert2 on May 4, 2026 entitled 
“Essential Action to Industry Computational Load Modeling, Studies, 
Instrumentation, Commissioning, Operations, Protection, and Control” which 
discusses how existing planning processes are insufficient to address risks associated 
with computational load entities. At the time of NERC’s alert, NERC defined 
computational load entities as loads 20 MW or greater, connected at 60kV, and 
containing more than 1 MW of IT load.  
11. The purpose of my declaration is to discuss my opinion of the reliability impact of 
MISO’s proposed exemption of approximately 30,000 MW of large loads from MISO’s 
proposed reliability requirements. 
III. 
Analysis 
A. Recent events which inform my understanding of the impact of data centers on the reliability of 
transmission systems. 
12. On June 10, 2024, 1,500 MW of data center demand disconnected itself from the grid 
in Northern Virginia after an event related to the failure of a lightning arrester on a 230 
kV transmission lines. The NERC incident report3 concluded “While this disturbance 
did not cause significant operating issues with the grid at this location and at this time, 
as data center loads continue to grow rapidly, the risk could quickly increase” and 
recommended the following: 
a. “Require dynamic response models of large loads in their facility 
interconnection requirements 8 Incident Review – Considering Simultaneous 
Voltage-Sensitive Load Reductions” 
                                                     
2 NERC Alert, Essential Action to Industry Computational Load Modeling, Studies, Instrumentation, Commissioning, Operations, 
Protection, and Control, NERC (May 4, 2026) available at https://www.nerc.com/globalassets/programs/bpsa/alerts/level-3-
computational-load-alert.pdf. 
3 NERC Incident Report, Incident Review Considering Simultaneous Voltage-Sensitive Load Reductions, NERC (Jan. 8, 2025) 
available at https://www.nerc.com/globalassets/our-work/reports/event-reports/incident_review_large_load_loss.pdf.

3 
 
b. “Perform studies to determine the potential magnitude of load loss for system 
disturbances (faults)  
• 
 Study the impact that these large load losses would have on the 
system” 
 
13. On May 4, 2026, NERC issues its highest-level alert (Level 3). In this alert, NERC 
determined a set of immediate actions that NERC recommended registered entities 
should take to reduce the risk to the Bulk Power System. These actions related to the 
modeling, study, installed fault recording or instrumentation, commissioning, operation, 
protection, and control of computational load. In the alert, NERC emphasized the 
reliability importance of system operators having access to robust modeling of 
computational loads. 
14. On July 22, 2026, a second incident in Northern Virginia occurred when 3,800 MW of 
data center demand disconnected itself from the grid as a result of oscillations due to a 
fault on a 230 kV transmission line. This event resulted in the need for operator action to 
stabilize system conditions. Effects were reported to last in excess of ten minutes, or 
thirty times longer than is typically acceptable for recovery and damping of stability 
oscillations.  
 
B. Contextual comparison of 30,000 MW to MISO’s current peak demand. 
15. MISO’s stated peak system demand for the summer season, as stated in the Planning 
Year 2025-2026 Loss of Load Expectation Study report, is 123,576 MW. This makes 
30,000 MW more than 24% of MISO’s current peak summer demand, and 20% of 
MISO’s peak summer demand with the new large loads in-service. The Planning Year 
2025-2026 Loss of Load Expectation Study report also states that MISO’s Local 
Resource Zone (LRZ) 1 2025 summer peak demand is 17,889 and LRZ 2 summer peak 
demand is 12,694 MW, combining to 30,583 MW. When comparing to the total large 
load either fully or partially exempt from meeting reliability requirements to MISO’s 
posted peak demand data, we can see that this would be equivalent to exempting roughly 
one-quarter of MISO’s 2025-2026 summer peak demand, or the entirety of both LRZs 1 
and 2. 
C. My opinion of MISO’s proposed exemptions. 
16. In my professional opinion, MISO’s August 28th filing creates reliability risks by 
exempting approximately 30,000 MW of large load from reliability requirements. 
Incidents like those experienced on June 10, 2024 and July 22, 2026 indicate the 
importance of applying broadly applicable ride through requirements to large loads. By 
allowing for significant amounts of load to be exempt from ride through requirements, 
MISO faces substantial risk of similar incidents impacting the MISO system.  
17. Similarly, MISO’s filing fails to consider the immediate action called for in the May 4, 
2026 NERC Level 3 alert aimed at addressing reliability risks associated with

4 
 
computational loads. NERC’s recommendations noted the importance of operator 
visibility into computational load behavior, characteristics, and configuration. In my 
professional opinion, MISO will not be capable of evaluating and mitigating the 
reliability risk of computational loads on its system if it exempts significant amounts of 
large load from information sharing requirements. Because MISO would not have this 
visibility, I am concerned about imminent reliability risk to the MISO footprint. 
IV. 
Conclusion 
18. 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 in ways that could cause system 
instability. This could cause severe reliability impacts that would otherwise be 
mitigated if the exemptions were not allowed.  
 
I declare under penalty of perjury under the laws of the United States, pursuant to 28 U.S.C. 
§ 1746, that the foregoing is true and correct to the best of my knowledge. 
Executed on September 16, 2026, in Lakeville, Minnesota. 
 
 
Andrew Siebenaler 
Managing Consultant – Transmission 
Energy Futures Group