Kentucky Municipal Energy Agency v. FERC ( 2022 )


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  •  United States Court of Appeals
    FOR THE DISTRICT OF COLUMBIA CIRCUIT
    Argued February 14, 2022               Decided August 5, 2022
    No. 19-1236
    KENTUCKY MUNICIPAL ENERGY AGENCY, ET AL.,
    PETITIONERS
    v.
    FEDERAL ENERGY REGULATORY COMMISSION,
    RESPONDENT
    KENTUCKY UTILITIES COMPANY AND LOUISVILLE GAS AND
    ELECTRIC COMPANY,
    INTERVENORS
    Consolidated with 19-1237, 20-1282, 20-1326, 20-1452,
    20-1459, 21-1013, 21-1025
    On Petitions for Review of Orders of the
    Federal Energy Regulatory Commission
    Latif M. Nurani argued the cause for municipal petitioners.
    With him on the briefs were Thomas C. Trauger and David E.
    Pomper.
    2
    Paul D. Clement argued the cause for petitioners
    Louisville Gas and Electric Company and Kentucky Utilities
    Company. With him on the briefs were Erin E. Murphy and
    Julie M.K. Siegal.
    Scott Ray Ediger, Attorney, Federal Energy Regulatory
    Commission, argued the cause for respondent. With him on
    the brief were Matthew R. Christiansen, General Counsel, and
    Robert H. Solomon, Solicitor.
    Before:     HENDERSON, TATEL*, and MILLETT, Circuit
    Judges.
    Opinion for the Court filed by Circuit Judge MILLETT.
    MILLETT, Circuit Judge: In 1998, the Federal Energy
    Regulatory Commission approved the merger of two electrical
    grid operators, Louisville Gas & Electric Company and
    Kentucky Utilities Company. To protect customers from the
    merger’s potential anticompetitive effects, the Commission
    required the combined company (collectively, “Louisville
    Utilities”) to join a then-new regional electrical grid
    organization, the Midwest Independent Transmission System
    Operator, Inc. (“MISO”). MISO would act like a free trade
    zone, allowing customers to buy power from generators across
    the region without having to pay multiple grid operators
    redundant fees to transmit electricity. By removing those
    redundant charges—known as “pancaked rates”—MISO
    membership would give Louisville Utilities customers access
    to more options for buying competitively priced power.
    *
    Judge Tatel assumed senior status after this case was argued
    and before the date of this opinion.
    3
    In 2006, the Commission granted Louisville Utilities’
    request to leave MISO on the condition that it continue to
    depancake rates for a group of municipal customers in its
    wholesale market. Louisville Utilities complied with the
    Commission’s order through an agreement called Schedule
    402.
    Twelve years later, Louisville Utilities asked the
    Commission to end its depancaking responsibilities under
    Schedule 402. Most of the customers protected by Schedule
    402 objected.
    The Commission largely approved the request on the
    ground that sufficient competition in electricity sales existed to
    provide Louisville Utilities customers alternative competitive
    sources for electricity even without depancaking. The
    Commission ended its analysis there without considering other
    effects of the modified merger order, like increased prices.
    At the same time, the Commission took steps to protect
    customers that had reasonably relied on depancaking under
    Schedule 402 in their contracting and investing decisions.
    A group of customers previously protected by Schedule
    402 (collectively, “Municipal Customers”) and Louisville
    Utilities both have petitioned for review of the Commission’s
    orders. Municipal Customers argue that the Commission
    should not have greenlit the end of depancaking and that it
    insufficiently protected customers’ reliance interests. Taking
    a different view, Louisville Utilities argues that the
    Commission’s remedy to shield customers from the end of
    depancaking was impermissibly broad.
    We vacate the Commission’s decision to end depancaking
    under Schedule 402. While the Commission adequately
    supported its conclusion that customers would continue to
    4
    enjoy a competitive market without depancaking, it was
    arbitrary for the agency to completely ignore the significant
    effect that duplicative charges would have on customer rates.
    We also conclude that the Commission’s decisions protecting
    reliance interests were reasonable, with two exceptions.
    As a result, we grant the petitions for review in part and
    vacate and remand the challenged orders in part.
    I
    A
    1
    The Federal Power Act tasks the Federal Energy
    Regulatory Commission with regulating the sale and
    transmission of wholesale electricity in interstate commerce.
    See 
    16 U.S.C. § 824
    ; FERC v. Electric Power Supply Ass’n,
    
    577 U.S. 260
    , 264 (2016). Under Section 203 of the Act,
    public utilities must seek Commission approval for certain
    mergers to ensure that they are “consistent with the public
    interest[.]” 16 U.S.C. § 824b(a)(1), (4).
    When deciding if a merger is in the public interest, the
    Commission considers “both the preservation of economic
    competition * * * and the various policies reflected in the
    statutes specific to energy regulation.” Wabash Valley Power
    Ass’n, Inc. v. FERC, 
    268 F.3d 1105
    , 1115 (D.C. Cir. 2001)
    (citation omitted). The main goal of the Federal Power Act is
    “to encourage the orderly development of plentiful supplies of
    electricity * * * at reasonable prices.” 
    Id.
     (quoting NAACP v.
    Federal Power Comm’n, 
    425 U.S. 662
    , 670 (1976)).
    Under Section 203(b), the Commission may condition its
    approval of utility mergers on “such terms and conditions as it
    5
    finds necessary or appropriate to secure” the public interest.
    16 U.S.C. § 824b(b). The agency also has the power to adjust
    merger conditions “from time to time for good cause * * * as it
    may find necessary or appropriate” and to ensure they are
    consistent with the public interest. Id.; see Westar Energy,
    Inc., 
    164 FERC ¶ 61060
    , ¶ 15 (2018); see also 
    id.
     at ¶ 15 n.24.
    2
    At the turn of this century, the Commission issued a series
    of orders to make electricity markets more competitive by
    providing wholesale buyers greater access to competing power
    plants. See Transmission Access Policy Study Group v.
    FERC, 
    225 F.3d 667
    , 682, 699 (D.C. Cir. 2000), aff’d sub nom.
    New York v. FERC, 
    535 U.S. 1
     (2002).
    As part of its reforms, the Commission addressed a barrier
    to competition known as “rate pancaking.” Wabash Valley
    Power Ass’n, 
    268 F.3d at 1116
    . Grid operators typically
    charge fees to ferry electricity to a neighboring transmission
    network, like a state levying tolls to drive on its highways.
    When an electricity customer wishes to buy power from a plant
    located on another grid it may face pancaked rates—
    transmission fees “stacked on top of one another[,]” Louisville
    Gas & Elec. Co. v. FERC, 
    988 F.3d 841
    , 844 (6th Cir. 2021),
    “much like the total tolls paid when driving on a route that
    includes both the Pennsylvania and New Jersey turnpikes[,]”
    Wabash Valley Power Ass’n, 
    268 F.3d at 1116
    . The
    Commission has concluded that pancaked rates weaken
    competition by making it more expensive for customers to buy
    power from generators on other grids. See Louisville Gas, 988
    F.3d at 844; see also Regional Transmission Orgs., 
    65 Fed. Reg. 810
    , 915 (Jan. 6, 2000).
    In part to reduce rate pancaking, the Commission prodded
    utilities to band together to form organizations known as
    6
    independent system operators or regional transmission
    organizations. These independent entities run grids on behalf
    of grid owners and charge customers standardized, non-
    duplicative fees to transmit electricity across their network.
    See Louisville Gas, 988 F.3d at 844; Midwest Indep.
    Transmission Sys. Operator, Inc., 
    104 FERC ¶ 61105
    , ¶ 29
    (2003).
    In light of those reforms, the Commission overhauled its
    approach to reviewing electricity mergers under Section 203.
    In 1996, the Commission announced that it would analyze
    whether a proposed merger is in the public interest by
    “generally” considering its effect on three factors—
    competition, rates, and regulation. See Inquiry Concerning
    the Commission’s Merger Policy Under the Federal Power Act,
    Policy Statement, 
    61 Fed. Reg. 68,595
    , 68,596 (Dec. 30, 1996)
    (“Merger Statement”); see also 
    id. at 68,597
    ; 
    18 C.F.R. § 2.26
    .
    On the competition factor, the Commission assesses
    whether the merger will significantly increase concentration in
    any market. See Merger Statement, 61 Fed. Reg. at 68,596.
    To do this, the Commission requires merging parties to identify
    products they each sell, customers that might be affected by the
    merger, and other suppliers that can compete to serve those
    customers. See id. at 68,600–68,601. The merging parties
    identify potential rivals by analyzing how much it would cost
    alternative suppliers to generate electricity and get it to
    customers and whether suppliers can physically access enough
    transmission capacity to deliver the energy. Id. at 68,601.
    The agency considers a generator a potential competitor to the
    merging parties if it can deliver the electricity to a relevant
    customer at a price that is no more than five percent above the
    market rate. See id. at 68,607 & n.6; see also 
    18 C.F.R. § 33.3
    (c)(4).
    7
    If a merger is projected to significantly increase a market’s
    concentration, the agency will investigate its competitive
    effects more closely. Merger Statement, 61 Fed. Reg. at
    68,608; cf. United States v. Philadelphia Nat’l Bank, 
    374 U.S. 321
    , 363 (1963). Applicants may mitigate competitive harms
    to some degree by joining an independent operator that can
    allow more power plants to compete and reduce market
    concentration by preventing rate pancaking. See Merger
    Statement, 61 Fed. Reg. at 68,601; see also id. at 68,609–
    68,610, 68,616.
    As for the second prong of its public-interest test, the
    Commission analyzes whether the merging parties have taken
    sufficient steps to ensure that the merger will not increase
    customers’ rates. See Merger Statement, 61 Fed. Reg. at
    68,603. Applicants “bear[] the burden of proof to demonstrate
    that the[ir] customer[s] will be protected” from rate hikes. Id.
    So the agency requires applicants to propose “ratepayer
    protection mechanisms” in case the transaction’s “expected
    benefits do not materialize.” Id.
    The third factor, which assesses how a merger will affect
    the relationship between the Commission’s regulatory
    jurisdiction and that of state authorities, is not at issue in this
    case.
    B
    1
    In 1997, two utilities in Kentucky, Louisville Gas &
    Electric Company and Kentucky Utilities Company, sought
    Commission approval to merge. See Louisville Gas and Elec.
    Co., 
    82 FERC ¶ 61308
    , at 2 (1998) (“1998 Merger Order”)
    (Joint Appendix (“J.A.”) 2). Each company owned power
    plants and operated its own electrical grid. Kentucky Utilities
    8
    Company also sold wholesale power to twelve cities in
    Kentucky on a long-term basis. 
    Id.
     at 3–4 & n.7 (J.A. 3–4).1
    The Commission found that, by removing Louisville Gas
    & Electric as a rival, the merger would substantially increase
    concentration in the wholesale energy market faced by
    Kentucky Utilities Company’s long-term municipal customers.
    See 1998 Merger Order, at 15 (J.A. 15). The Commission
    nevertheless concluded that this factor did not weigh against
    merger approval, in part because it required the merging parties
    to join MISO, an independent grid operator. See 
    id. at 19
     (J.A.
    19). That would benefit the municipal customers because
    MISO would eliminate pancaked rates on its grid, giving them
    a wider range of power plants from which to purchase
    electricity at competitive rates. 
    Id.
     The Commission said
    that if the merged company tried to leave MISO, the agency
    would “evaluate that request in light of its impact on
    competition” in the market faced by Kentucky Utilities
    Company’s long-term wholesale power customers. 
    Id.
     (In
    this opinion, we refer to this group as Louisville Utilities’
    wholesale customers).
    The Commission then turned to the merger’s effects on
    rates. It found that the merging parties’ proposed ratepayer
    protections—which included a commitment to pass along
    1
    These customers were the Kentucky cities of Barbourville,
    Bardstown, Bardwell, Benham, Berea College, Corbin, Falmouth,
    Frankfort, Madisonville, Nicholasville, Paris, and Providence. See
    1998 Merger Order, at 3–4 n.7 (J.A. 3–4). The Commission
    referred to these cities as “requirements customers[,]” 
    id. at 3
     (J.A.
    3), which means that Kentucky Utilities Company generally
    “under[took] a relatively open-ended commitment to provide” them
    enough electricity to meet their needs. Regulation of Electricity
    Sales-for-Resale and Transmission Service, 
    50 Fed. Reg. 23,445
    ,
    23,446 (June 4, 1985).
    9
    merger-related savings and hold certain customer rates steady
    for five years—were adequate. See 1998 Merger Order, at
    20–21 (J.A. 20–21).
    2
    Seven years after the merger, the combined company,
    Louisville Utilities, sought the Commission’s permission to
    exit MISO. See Louisville Gas & Elec. Co., 
    114 FERC ¶ 61282
    , ¶ 1 (2006) (“2006 Withdrawal Order”) (J.A. 88–89).
    Several of Louisville Utilities’ wholesale customers, as
    well as other municipalities on the utility’s grid or seeking to
    join it, opposed the request. Some of them were particularly
    concerned that if Louisville Utilities left MISO, they would
    face higher, pancaked rates when purchasing power from
    MISO. See Louisville Gas, 988 F.3d at 845.
    Among those opposing Louisville Utilities’ request were
    two Kentucky municipal agencies, the Electric Plant Board of
    the City of Paducah and the Electric Plant Board of the City of
    Princeton. These cities had a dog in the fight because both had
    decided, in late 2004 and early 2005, to leave their prior grid
    and connect to Louisville Utilities’ transmission lines. In
    2005, Paducah and Princeton created the Kentucky Municipal
    Power Agency to secure electricity by investing in Prairie
    State, a new coal plant to be connected to the MISO grid. (In
    this opinion, we generally refer to Princeton, Paducah, and
    Kentucky Municipal Power Agency together as “P&P.”)
    According to P&P’s consultant at the time, the Prairie State
    investment was, “in effect, an option agreement[,]” giving P&P
    the “right, but not the obligation,” to buy a five percent stake
    in the Prairie State project. J.A. 1236 (Affidavit of Brown D.
    Thornton).
    10
    If Louisville Utilities left MISO, P&P and several other
    municipalities would face the prospect of paying pancaked
    rates to obtain power from that grid. So they negotiated with
    Louisville Utilities to avoid those charges.         Louisville
    Utilities, recognizing that it was “counter-intuitive at [that]
    time to contemplate that [the Commission] would permit [it] to
    establish new rate pancakes[,]” agreed not to charge these
    customers duplicative rates for electricity shipped to or from
    MISO, so long as MISO did the same in return. J.A. 451
    (February 2006 Term Sheet § 1); see also 2006 Withdrawal
    Order ¶¶ 99–100 (J.A. 125–126).             In exchange, the
    municipalities agreed to withdraw their challenge to Louisville
    Utilities’ exit from MISO. J.A. 455 (February 2006 Term
    Sheet § 7); 2006 Withdrawal Order ¶ 16 (J.A. 95).
    The following month, the Commission allowed Louisville
    Utilities to leave MISO, subject to one condition relevant here.
    See 2006 Withdrawal Order ¶ 4 (J.A. 90). Louisville
    Utilities’ depancaking proposal depended on MISO agreeing to
    reciprocally depancake its own charges. But the Commission
    was concerned that MISO might not do so, leaving Louisville
    Utilities’ wholesale customers stuck paying pancaked rates.
    See id. ¶ 111 (J.A. 129–130). So the Commission directed
    Louisville Utilities to “shield” its wholesale customers from
    “any re-pancaking of rates” for power shipments between its
    grid and MISO, no matter what MISO chose to do. Id.
    ¶¶ 112–113 (J.A. 130); see also id. ¶ 118 (J.A. 132–133). In
    other words, Louisville Utilities was under an obligation to
    make customers in that market whole should MISO decide to
    charge pancaked fees.
    Ultimately, Louisville Utilities negotiated Schedule 402, a
    new agreement with those municipalities already on or
    planning to join its grid. See J.A. 557. Schedule 402
    protected several groups from pancaked rates with MISO: (i)
    11
    Louisville Utilities’ current and future wholesale power
    customers, (ii) Owensboro Municipal Utilities (“Owensboro”),
    an entity that used Louisville Utilities’ grid but was not a long-
    term wholesale customer, and (iii) a group of municipal
    agencies including P&P. See J.A. 557 (Schedule 402).
    Schedule 402’s depancaking provisions were designed “to
    implement the Section 203 [merger] mitigation requirements
    ordered by the Commission” in the 1998 Merger Order and the
    2006 Withdrawal Order. J.A. 559 (Schedule 402 § 1.a.v).
    In November 2006, the Commission approved the
    agreement. See Louisville Gas & Elec. Co., 
    166 FERC ¶ 61206
    , ¶ 8 & n.19 (2019) (“March 2019 Order”) (J.A. 220–
    221).
    Here is how depancaking worked under Schedule 402.
    When a customer imported power from MISO, Louisville
    Utilities refunded the customer’s “transmission and ancillary
    services charges” for the electricity to reach the
    MISO/Louisville Utilities border.            See J.A. 557–558
    (Schedule 402, at 1; 
    id.
     § 1.a.i). When a customer shipped
    power from Louisville Utilities’ grid to MISO, the company
    waived its own corollary charges for ferrying the electricity to
    the MISO border. See J.A. 558–559 (Schedule 402 § 1.a.ii).
    Louisville Utilities’ depancaking responsibilities were limited
    to those fees “where both [MISO] and [Louisville Utilities]
    provide and charge for corresponding services” that are
    “incurred to transmit electricity to” either the MISO or the
    Louisville Utilities border. J.A. 558–559 (Schedule 402
    § 1.a.iv, 1.a.i–ii); see also Louisville Gas, 988 F.3d at 847.
    With depancaking now ensured by Schedule 402, P&P
    finalized its investment in Prairie State in 2007, which it
    financed by borrowing more than $525 million. P&P also
    signed 50-year contracts to source electricity from a
    12
    hydroelectric project being built partially on the MISO grid.
    See Louisville Gas & Elec. Co., 
    168 FERC ¶ 61152
    , ¶ 95
    (2019) (“2019 Rehearing Order”) (J.A. 302); Louisville Gas &
    Elec. Co., 
    173 FERC ¶ 61164
    , ¶ 22 (2020) (“November 2020
    Order”) (J.A. 435–436). In statements to bondholders,
    Princeton and Paducah have said that they hold ownership
    interests in the hydropower project. See NEW ISSUE BOOK
    ENTRY, KENTUCKY MUNICIPAL POWER AGENCY 146, 189
    (Aug. 22, 2019), http://www.kmpa.us/wp-content/uploads/202
    0/12/KMPA-2019A-O.S..pdf, (last accessed July 26, 2022).
    3
    For more than a decade after the merger, most of
    Louisville Utilities’ wholesale power customers relied on it for
    virtually all of their electricity needs, forgoing the opportunity
    to buy power from other utilities on the MISO grid at
    depancaked rates. See March 2019 Order ¶ 75. But after
    Louisville Utilities told one of those customers in 2012 that it
    would soon stop selling it electricity, all twelve municipalities
    began considering other power sources. In April 2014, most
    of the municipalities told Louisville Utilities that they would
    buy power from other suppliers starting in 2019. Eleven
    municipalities then jointly created the Kentucky Municipal
    Energy Agency (“Energy Agency”) to allow them to buy
    electricity collectively. Energy Agency ran a competitive
    process to sign up suppliers, including some located in MISO,
    to provide power for most of its members starting in 2019. In
    this opinion, we refer to Energy Agency and its members
    collectively as “Energy Agency.”2
    2
    The members of Energy Agency are the Kentucky cities, or
    municipal power agencies representing the cities, of Barbourville,
    13
    C
    1
    In 2018, Louisville Utilities asked the Commission for
    permission to end its depancaking responsibilities under
    Schedule 402. The company argued that independent grids
    and new generators had boomed in the 20 years after the
    merger, creating robust competition for wholesale power and
    obviating the need for depancaking. Municipal Customers
    opposed the request. They argued that ending depancaking
    would increase their rates, block access to competitive markets,
    and unfairly interfere with business plans they had made in
    reliance on depancaking continuing.3
    In March 2019, a divided Commission conditionally
    granted Louisville Utilities’ request to halt depancaking. See
    March 2019 Order ¶ 2 (J.A. 218). The Commission held that,
    under Section 203 of the Federal Power Act, the only relevant
    question was whether depancaking was still needed to mitigate
    the merger’s harm to competition for Louisville Utilities’
    wholesale customers. See 
    id.
     ¶¶ 38–42 (J.A. 232–234).
    Under that approach, as long as the customers would “have
    access to a sufficient number of competitive suppliers” without
    depancaking, the Commission would deem the merger
    “consistent with the public interest[.]” 
    Id. ¶ 42
     (J.A. 234). In
    adopting that test, the Commission concluded that it could
    ignore the effect restoring pancaking would have on other,
    Bardwell, Benham, Berea, Corbin, Falmouth, Madisonville,
    Owensboro, Paris, and Providence, along with the Frankfort Electric
    and Water Plant Board.
    3
    Several other parties also contested Louisville Utilities’
    proposal, but their claims are not before us.
    14
    long-established public-interest factors for mergers, such as
    rates. 
    Id. ¶ 44
     (J.A. 234–235).
    Analyzing only the effect on competition, the Commission
    found that depancaking was no longer necessary. See March
    2019 Order ¶ 68 (J.A. 245–246). Though pancaking would
    reduce the number of competitive suppliers in the market to
    some degree, the Commission focused on both record evidence
    of extensive competition between generators and economic
    analyses performed by Municipal Customers’ and Louisville
    Utilities’ experts. See 
    id.
     ¶¶ 67–69 (J.A. 244–246).
    The Commission held, though, that it “would not be
    consistent with the public interest” for Louisville Utilities to
    pancake rates when its customers had made business decisions
    based on the reasonable assumption that they would be
    protected from such duplicative costs. See March 2019 Order
    ¶ 79 (J.A. 250). The Commission found that the members of
    Energy Agency had reasonably relied on depancaking when
    contracting for energy from MISO-based suppliers. 
    Id.
     ¶¶ 74–
    80 (J.A. 248–250). So the Commission created a “transition
    mechanism” to protect Energy Agency’s reliance interests.
    
    Id. ¶ 74
     (J.A. 248–249).        Under that mechanism, the
    Commission directed Louisville Utilities to continue
    depancaking rates for a time-limited period confined to the
    “initial term” of “power purchase agreement[s]” entered into
    by Energy Agency when Schedule 402 depancaking was still
    in effect.    
    Id. ¶ 82
     (J.A. 251).      An initial term, the
    Commission said, meant the agreement duration “before any
    extensions[.]” 
    Id.
     ¶ 82 n.126 (J.A. 251). The Commission
    did not include P&P in the transition mechanism because it
    found it was “outside the [Louisville Utilities] market[.]” 
    Id.
    ¶ 81 & n.125 (J.A. 250–251).
    15
    Commissioner LaFleur dissented. She contended that the
    evidence of current-day market competition was insufficient to
    show that ending depancaking was in the public interest. See
    March 2019 Order ¶¶ 1–3 (LaFleur, Comm’r, dissenting) (J.A.
    260–261).
    2
    In April 2019, the Municipal Customers sought rehearing.
    Louisville Utilities did not. While that request was still
    pending, Louisville Utilities filed a proposed update to
    Schedule 402 to comply with the March 2019 Order. The
    Commission issued two more orders in response to those
    filings.
    a
    As relevant here, the Municipal Customers’ rehearing
    request argued that the Commission erred by (i) failing to
    consider the effect that removing depancaking would have on
    rates, (ii) concluding that the Louisville Utilities’ market would
    be sufficiently competitive without depancaking, (iii)
    excluding P&P from the transition mechanism, and (iv)
    limiting the transition mechanism to power purchase
    agreements, rather than all of the customers’ financial
    commitments made in reliance on depancaking.
    The Commission granted the Municipal Customers’
    request in part. See 2019 Rehearing Order ¶ 14 (J.A. 270). It
    first reaffirmed its decision to ignore the effect ending
    depancaking would have on rates. 
    Id.
     ¶¶ 25–35 (J.A. 273–
    278).     The agency recognized that it had previously
    considered the effect modifying merger conditions would have
    on all three of its typical Section 203 public-interest factors—
    competition, rates, and regulation. 
    Id.
     ¶¶ 32–35 (J.A. 277–
    278) (citing Louisville Gas & Elec. Co., 
    137 FERC ¶ 61195
    16
    (2011)). So the Commission announced that it was now
    “clarify[ing]” that its public-interest analysis of requests to
    modify merger conditions “is limited to addressing the effect
    of the modification on the public interest factor that [first] led
    the Commission to impose the condition[.]” 
    Id. ¶ 35
     (J.A.
    278).
    The Commission then reversed its decision to exclude
    P&P from the depancaking transition mechanism. See 2019
    Rehearing Order ¶ 109 (J.A. 306–307). The agency found
    that P&P is in the Louisville Utilities market and had sourced
    power while relying on depancaking. 
    Id.
    Finally, the Commission expanded the scope of Louisville
    Utilities’ depancaking responsibilities to include all contracts
    entered into by one of the Municipal Customers before the
    March 2019 Order in reliance on depancaking continuing.
    See 2019 Rehearing Order ¶ 110 (J.A. 307). That included
    “long-term financial commitments, such as * * * transmission
    service” contracts reserving the use of MISO’s wires to
    transmit electricity, so long as such agreements were used to
    carry power that was purchased before the March 2019 Order.
    
    Id. ¶ 111
     (J.A. 307). The Commission also directed the
    company to depancake P&P’s fees associated with importing
    power from Prairie State, its partially owned coal plant on the
    MISO grid. 
    Id. ¶ 112
     (J.A. 307).
    b
    In a separate order, the Commission rejected Louisville
    Utilities’ proposed transition mechanism to replace Schedule
    402, making three additional determinations relevant here.
    See Louisville Gas & Elec. Co., 
    168 FERC ¶ 61151
     (2019)
    (“2019 Transition Mechanism Order”).
    17
    First, the Commission rejected Louisville Utilities’
    argument that it would have been unreasonable for P&P to rely
    on depancaking when investing in Prairie State. See 2019
    Transition Mechanism Order ¶¶ 31–36 (J.A. 321–322).
    Louisville Utilities argued that P&P made that investment
    decision in 2005, after it was already on notice that Louisville
    Utilities was leaving MISO and before the parties had agreed
    to Schedule 402. 
    Id. ¶ 32
    . (J.A. 321). The Commission
    disagreed, finding that P&P only made a definitive Prairie State
    investment after Louisville Utilities had committed to
    depancaking in 2006, around the time the utility proposed
    leaving MISO. 
    Id. ¶ 33
     (J.A. 321). The Commission added
    that it was always “likely” that Louisville Utilities would only
    be allowed to leave MISO on the condition that it continue
    some form of depancaking. 
    Id. ¶ 35
     (J.A. 322). So P&P
    reasonably relied on pancake-free access to MISO when
    securing Prairie State power. 
    Id.
     ¶¶ 31–36 (J.A. 321–322).
    Second, the Commission directed Louisville Utilities to
    depancake fees associated with some contracts the company
    had omitted from its transition mechanism, including
    agreements several customers had made with generators
    outside of the MISO grid. See 2019 Transition Mechanism
    Order ¶¶ 39–42 (J.A. 324–325).
    Third, the Commission determined that Louisville
    Utilities’ depancaking obligation extended to three MISO
    fees—known as Schedules 26, 26-A, and 45—that the utility
    had depancaked under Schedule 402. See 2019 Transition
    Mechanism Order ¶¶ 57, 62 (J.A. 330, 332). The Commission
    explained that the transition remedy was meant to temporarily
    extend Schedule 402, and so Louisville Utilities had to
    depancake MISO fees associated with services that
    “correspond[]” to those for which Louisville Utilities also
    18
    charged. 
    Id. ¶ 62
     (J.A. 332) (citation omitted); see also 
    id. ¶ 79
     (J.A. 337).
    3
    The Municipal Customers and Louisville Utilities sought
    rehearing as to both the 2019 Rehearing Order and the 2019
    Transition Mechanism Order. The Commission responded
    with two more orders.
    In its second rehearing order, the Commission agreed to
    lessen Louisville Utilities’ depancaking responsibilities in two
    ways. See Louisville Gas & Elec. Co., 
    172 FERC ¶ 61227
    (2020) (“Second Rehearing Order”).
    First, the Commission held that Louisville Utilities only
    had to depancake rates and fees pertaining to Prairie State for
    ten years, rather than for the duration of the power agreements’
    open-ended terms. See Second Rehearing Order ¶¶ 43–44
    (J.A. 363–364). The Commission recognized that, unlike
    other power purchase agreements covered by the transition
    mechanism, P&P’s ownership right to Prairie State electricity
    had no clear end. 
    Id.
     So absent the ten-year cap, requiring
    depancaking for the term of the contracts could commit
    Louisville Utilities to provide that relief indefinitely, which
    would go beyond the term-limited reliance the Commission
    meant to protect. 
    Id.
    Second, the Commission reversed itself and held that
    Louisville Utilities need not depancake fees related to the
    Municipal Customers’ purchase of power from generators
    outside of MISO. See Second Rehearing Order ¶ 61 (J.A.
    371–372). The Commission reasoned that the transition
    mechanism only required Louisville Utilities to depancake fees
    that would have been protected under Schedule 402—in other
    words, those incurred to shuttle power to or from MISO. 
    Id.
    19
    ¶¶ 61–62 (J.A. 371–372). So charges related to contracts with
    generators outside of MISO should not be covered. See 
    id.
    As for the rehearing petition addressed to the 2019
    Transition Mechanism Order, the Commission largely
    reaffirmed its initial decision. Louisville Gas & Elec. Co., 
    173 FERC ¶ 61164
     (2020) (“Transition Rehearing Order”). As
    relevant here, the Commission bolstered its decision to order
    Louisville Utilities to depancake the MISO fee known as
    Schedule 45 for covered agreements, citing evidence that
    Louisville Utilities charges corresponding fees. See 
    id.
     ¶¶ 66–
    67 & n.117 (J.A. 407–408).
    4
    Louisville Utilities and Municipal Customers filed for
    rehearing as to both the Second Rehearing Order and the
    Transition Rehearing Order. The Commission rejected the
    requests. See November 2020 Order ¶ 22 (2020) (J.A. 435–
    436).
    II
    Municipal Customers—that is, Energy Agency and
    P&P—timely petitioned for review of the Commission’s
    orders, as did Louisville Utilities. We have jurisdiction under
    16 U.S.C. § 825l(b).
    We review the Commission’s orders “under the arbitrary-
    and-capricious standard, and we will uphold the [agency’s]
    factual findings if they are supported by substantial evidence.”
    ESI Energy, LLC v. FERC, 
    892 F.3d 321
    , 329 (D.C. Cir. 2018)
    (citation omitted). “Substantial evidence is such relevant
    evidence as a reasonable mind might accept as adequate to
    support a conclusion, and requires * * * less than a
    preponderance of evidence[.]” South Carolina Pub. Serv.
    20
    Auth. v. FERC, 
    762 F.3d 41
    , 54 (D.C. Cir. 2014) (per curiam)
    (internal quotation marks and citations omitted).
    III
    Municipal Customers challenge the Commission’s orders
    on two fronts. First, they argue that the Commission erred by
    permitting Louisville Utilities to pancake rates because (i) the
    Commission lacked substantial evidence to find that the market
    would remain competitive without depancaking, and (ii) the
    Commission arbitrarily excluded from its public-interest
    analysis the effect ending depancaking would have on rates.
    Second, they contend that the Commission’s transition
    mechanism insufficiently protected certain customers’ reliance
    interests.
    Louisville Utilities comes at the Commission’s decisions
    from a different direction. It argues that, under agency
    precedent, P&P could not reasonably have relied on
    depancaking and so should not have been shielded from any
    pancaked charges going forward. Louisville Utilities also
    objects to being required to depancake three specific MISO
    fees, along with fees associated with P&P’s hydroelectric
    project until 2057.
    We hold that while the Commission reasonably found that
    sufficient competition would survive the return of pancaking,
    it was arbitrary and capricious for the agency to ignore the
    effect pancaking would have on rates. And while the agency’s
    transition mechanism is reasonably justified for the most part,
    we conclude that the Commission inadequately explained two
    aspects of its orders.
    21
    A
    1
    Municipal Customers contend that the Commission lacked
    substantial evidence to find that sufficient wholesale power
    competition would continue even with the return of pancaking
    and its attendant rate increases.
    The question, though, is not whether, on this record,
    reasonable minds could have reached a different conclusion on
    that question. It is only whether substantial evidence
    supported the Commission’s conclusion and whether it
    reasonably explained its decision.        The Commission’s
    decision clears that bar. See Environmental Action, Inc. v.
    FERC, 
    939 F.2d 1057
    , 1064 (D.C. Cir. 1991) (“[I]t is within
    the scope of the agency’s expertise to make [a reasonable]
    prediction about the market it regulates, and a reasonable
    prediction deserves our deference notwithstanding that there
    might also be another reasonable view.”).
    The Commission grounded its decision in several relevant
    sources of data. Together, they provide substantial evidence
    that sufficient competition exists among companies able to sell
    power to wholesale customers on the Louisville Utilities grid,
    and that competition will continue even after the return of
    pancaked rates on power coming from MISO. See March
    2019 Order ¶¶ 68–73 (J.A. 245–248); 2019 Rehearing Order
    ¶¶ 58–77 (J.A. 288–295).
    First, the Commission found that MISO-based generators
    can offer prices that are competitive with Louisville Utilities’
    rates even with pancaking. See March 2019 Order ¶¶ 69–70
    (J.A. 246–247); 2019 Rehearing Order ¶ 62 & n.87 (J.A. 289).
    The Commission cited a report from Municipal Customers’
    own expert, who forecast that Energy Agency’s MISO-based
    22
    suppliers will charge rates that are only 2.5% higher, on
    average, than Louisville Utilities after accounting for
    pancaking. See March 2019 Order ¶ 70 (J.A. 246–247).
    That sufficed, the Commission explained, because it “considers
    [electricity] that can be delivered into a market at a price that is
    no more than five percent above the [market] price * * * to be
    competitive[.]” 
    Id.
     (J.A. 246) (citing 
    18 C.F.R. § 33.3
    (c)(4));
    see also Merger Statement, 61 Fed. Reg. at 68,607 & n.6.
    The Commission’s conclusion was bolstered by a
    competing forecast from Louisville Utilities’ expert, who
    predicted that Energy Agency’s rates from MISO would be
    7.8% cheaper on average than Louisville Utilities’ offerings
    even with pancaking. See March 2019 Order ¶ 69 (J.A. 246).
    Second, the Commission found that competitive sources
    of electrical power exist outside MISO that will be unaffected
    by the end of depancaking. The agency determined that 65%
    of the capacity secured by Energy Agency was sourced from
    generators outside of MISO. (Capacity is a measure of the
    total electricity that a contracted power plant can produce.)
    See March 2019 Order ¶ 71 (J.A. 247); 2019 Rehearing Order
    ¶¶ 64–65 (J.A. 290). Transmission fees from those plants are
    not depancaked under Schedule 402, so the Commission
    concluded that new pancaked rates “would have no effect on
    whether suppliers located in [such] markets remain
    competitive[.]” March 2019 Order ¶ 71 (J.A. 247).
    Third, the Commission found that the number of
    generators that could profitably sell to the Louisville Utilities
    grid had increased substantially since 1998. At the time of the
    merger, there were only four to seven competitive potential
    wholesale energy suppliers for the grid. See March 2019
    Order ¶ 72 & n.118 (J.A. 247–248). According to a
    Louisville Utilities expert that the Commission credited, more
    23
    than 100 suppliers could competitively sell to the grid in 2018,
    with available capacity to meet Municipal Customers’ needs
    “several times over[.]” J.A. 593 (Prepared Testimony of Julie
    R. Solomon); 2019 Rehearing Order ¶ 74 (J.A. 294).
    Relatedly, the Commission found that the expansion of
    independent power grids had transformed the market for
    wholesale power since 1998. At the time of the merger,
    Louisville Gas & Electric’s and Kentucky Utilities Company’s
    grids were surrounded by several small networks, limiting the
    number of plants customers could buy from at competitive
    rates. See March 2019 Order ¶ 73 (J.A. 248). Now
    Louisville Utilities’ neighbors include some of the largest
    independent grids on the continent—MISO and PJM
    Interconnection, L.L.C.—giving those customers ready access
    to independent power suppliers. See id. ¶ 73 (J.A. 248); J.A.
    656 (grid map).
    Finally, the Commission found an active and healthy
    wholesale energy market on the Louisville Utilities grid. See
    March 2019 Order ¶ 68 (J.A. 245). Energy Agency received
    proposals to replace Louisville Utilities as a power supplier
    from between 38 and 59 different companies. Id. So
    Louisville Utilities now faces far more rivals than it did at the
    time of the merger. Id.
    Municipal Customers beg to differ. To start, they argue
    that the Commission lacked data on the competitiveness of
    offers made to Energy Agency, and so it could not rely on those
    offers to show a robust wholesale power market. Plus, the
    proposals were made with depancaking in place and so, the
    Customers argue, gave little information about what would
    happen once that protection ended.
    Neither claim succeeds. As the Commission explained,
    its evidence about the competitiveness of MISO-based offers
    24
    came from Municipal Customers’ own expert. See 2019
    Rehearing Order ¶¶ 62–63 (J.A. 289); March 2019 Order ¶ 69
    (J.A. 246). And his forecasted rates accounted for the end of
    depancaking. See J.A. 1001–1002 (Surrebuttal Affidavit of
    John F. Painter) (finding that “the imposition of pancaked
    transmission charges would be projected to increase” Energy
    Agency’s power supply costs from MISO to “2.5% above
    [Louisville Utilities’ rates]”).4
    Next, Municipal Customers assert that Louisville Utilities’
    market concentration analysis measured only potential
    suppliers and not actual market participants. In their view,
    that made it irrational for the Commission to treat the presence
    of more than 100 potential suppliers as evidence of actual
    competition.
    The Commission adequately weighed this concern. It
    recognized that not all potential suppliers would offer to sell
    Municipal Customers electricity. See 2019 Rehearing Order
    ¶¶ 74–75 (J.A. 294). But the agency reasonably found the
    sheer number of large and competitive rivals would make for a
    sufficiently robust market, even if not all of the suppliers
    competed. See id.; see also March 2019 Order ¶ 72 (J.A.
    247–248).
    Lastly, the Municipal Customers contend that the
    Commission ignored the relative paucity of potential sellers
    during peak periods of energy demand. The Commission
    4
    Municipal Customers assert that the Commission conceded
    that their expert’s analysis does not accurately reflect prices absent
    depancaking. The Commission did no such thing. It simply
    summarized Municipal Customers’ argument. See 2019 Rehearing
    Order ¶ 47 n.68 (J.A. 282) (“[Municipal Customers] contend that
    [their expert’s analysis] is not representative of available prices from
    suppliers located in MISO without [depancaking.]”).
    25
    answered that contention too. It acknowledged that pancaking
    would reduce the number of rival sellers in the market. See
    March 2019 Order ¶ 67 (J.A. 244); 2019 Rehearing Order ¶ 71
    (J.A. 293). But the Commission found that, even at the
    summer peak when the market is most concentrated, “there
    would remain at least 100” competitive sellers after the end of
    depancaking. March 2019 Order ¶ 72 (J.A. 247); see also
    J.A. 593–595 (Solomon Test.). And “[m]any of these are
    relatively large suppliers[,] and the total amount of supply [is]
    several times larger than the total [needs] of all [Louisville
    Utilities] customers.” March 2019 Order ¶ 72 (J.A. 247–
    248). That range of rivals ably supported the Commission’s
    conclusion that pancaking would leave enough competition in
    its wake.5
    In short, the Commission’s conclusion that sufficient
    competition would continue after depancaking was based on
    substantial evidence from which it drew sensible inferences
    employing its expert knowledge of electricity markets. That
    is “the kind of reasonable agency prediction * * * to which we
    ordinarily defer.” Arkansas Elec. Energy Consumers v.
    FERC, 
    290 F.3d 362
    , 370 (D.C. Cir. 2002) (citation omitted).
    2
    Municipal Customers further contend that it was arbitrary
    for the Commission to ignore completely the effect pancaking
    would have on customer rates.
    5
    Municipal Customers object that the Commission erred by
    focusing only on short-term competition and by giving them the
    burden of more fully disclosing the proposals received by Energy
    Agency. Because Municipal Customers made these arguments only
    in their reply brief, they are forfeited. See Union of Concerned
    Scientists v. Department of Energy, 
    998 F.3d 926
    , 931 (D.C. Cir.
    2021).
    26
    We agree. Agencies cannot disregard important aspects
    of a problem before them. See Motor Vehicle Mfrs. Ass’n of
    U.S., Inc. v. State Farm Mut. Auto. Ins. Co., 
    463 U.S. 29
    , 43
    (1983). Because increases in electricity rates—independent
    of competition concerns—were an important consideration
    under the facts of this case, as well as under agency and judicial
    precedent, the Commission erred by backhanding the effect
    that pancaking would have on rates.
    When determining if a proposed merger is “consistent with
    the public interest,” the Commission “generally” considers its
    effect on rates. 
    18 C.F.R. § 2.26
    (b). That makes sense, as the
    public interest “encompasses” the “various policies reflected in
    the statutes specific to energy regulation[,]” including the
    encouragement of “the orderly development of plentiful
    supplies of electricity * * * at reasonable prices.” Wabash
    Valley Power Ass’n, 
    268 F.3d at 1115
     (emphasis added and
    citations omitted).
    Rate effects can have that same importance when the
    Commission evaluates supplemental merger orders under
    Section 203(b). After all, the Commission will modify a
    merger order only if the transaction will remain “consistent
    with the public interest[.]” Westar Energy, Inc., 
    164 FERC ¶ 61060
    , at ¶ 15. Importantly, this rate analysis goes beyond
    just looking at competition because, as the Commission has
    recognized, markets do not always function perfectly. See
    Merger Statement, 61 Fed. Reg. at 68,603.
    Yet here, the Commission expressly refused to even
    consider the effect ending depancaking would have on
    electricity rates. See March 2019 Order ¶ 44 (J.A. 234–235).
    The Commission held, instead, that because depancaking was
    imposed to protect competition, that was the only factor it
    needed to consider in ending the program. Id.
    27
    That “ostrich-like approach” will not do. Environmental
    Def. Fund v. FERC, 
    2 F.4th 953
    , 975 (D.C. Cir. 2021).
    Commission precedent requires it to consider how modifying a
    merger order under Section 203(b) affects the public interest,
    see Westar Energy, Inc., 
    164 FERC ¶ 61060
    , at ¶ 15, and a
    merger’s effect on rates is a central factor in the agency’s
    public-interest analysis, see 
    18 C.F.R. § 2.26
    (b). So the
    Commission could not sensibly brush off the effect of its
    supplemental order on customers’ rates. See also Emera
    Maine, 
    155 FERC ¶ 61233
    , ¶ 37 n.68 (2016).
    The refusal to look at rate effects was quite consequential
    in this case because rate hikes are not only likely—they are
    certain. All parties agree that they will happen. See March
    2019 Order ¶ 79 (J.A. 250); Louisville Utilities Intervenor Br.
    12. And both Municipal Customers and Louisville Utilities
    agree they will be material increases. Municipal Customers’
    expert estimated that if depancaking were scrapped, the
    municipalities’ rates in 2019 would increase by at least 15%,
    with one customer’s rates rising 47%. See J.A. 768 (Affidavit
    of John F. Painter (Oct. 2, 2018)). If depancaking continued,
    by contrast, Louisville Utilities forecast that the program would
    save customers at least $200 million in rate prices between
    2018 and 2028. See J.A. 550 (Direct Testimony of Tom
    Jessee). By refusing to consider the material effects of its
    order on customer rates—a factor that its own regulations
    identify as a key component of the public interest, see 
    18 C.F.R. § 2.26
    (b)—the Commission engaged in “unreasoned,
    arbitrary, and capricious decisionmaking.” Humane Soc’y of
    the United States v. Zinke, 
    865 F.3d 585
    , 606 (D.C. Cir. 2017).
    On top of that, the Commission had previously
    acknowledged the role of rates in its public-interest analysis
    when considering a different modification to a term of the
    Louisville Utilities merger.    In a 2011 decision, the
    28
    Commission determined that all three of its standard public-
    interest factors—including rate effects—were relevant and
    evaluated them when modifying another order concerned with
    this very same merger. And it did so even though the order
    being modified was, as here, originally designed to address
    only competition concerns. See Louisville Gas, 
    137 FERC ¶ 61195
    , at ¶¶ 6–7, 39 (modifying orders meant to protect
    competition only after finding that the change would have no
    “adverse impact on * * * rates or regulation”).
    The Commission and Louisville Utilities make several
    counterarguments, none of which succeeds.
    The Commission, for its part, asserts that its approach is
    supported by other Section 203(b) decisions that did not weigh
    rate effects. See 2019 Rehearing Order ¶¶ 15–16 & n.31 (J.A.
    270–271) (citing Commission orders); see also Commission
    Br. 46–47.
    Not at all. In the orders the Commission cites, the issue
    of price increases simply was not raised by any party. See
    MidAmerican Energy Holdings Co., 
    131 FERC ¶ 61004
    , ¶¶ 8–
    11 (2010) (utility stated without rebuttal that modification
    would save ratepayers money); Public Serv. Co. of New
    Mexico, 
    135 FERC ¶ 61230
    , ¶¶ 9–11 (2011) (same); PPL
    Corp., 
    153 FERC ¶ 61257
    , ¶ 22 (2015) (protestor arguing that
    modification would affect capacity, but not claiming any effect
    on rates); Westar Energy, 
    164 FERC ¶ 61060
    , at ¶¶ 13–16 (rate
    effects not at issue).6
    6
    See also Commission Br. 46 (not contesting Municipal
    Customers’ claim that “other public interest factors such as rate
    impacts were not raised” in the cited decisions) (formatting modified
    and citation omitted).
    29
    The Commission also argues that its earlier decision in
    Louisville Gas is inapposite because in that decision it was
    Louisville Utilities itself that raised the issue of rate effects, not
    the customers. 2019 Rehearing Order ¶ 33 (J.A. 277–278).
    But if rate effects are an important part of the problem, then
    they remain so regardless of which party raises the concern.
    See Spirit Airlines, Inc. v. Department of Transp., 
    997 F.3d 1247
    , 1255 (D.C. Cir. 2021). Basic fairness and rational
    decisionmaking require no less.
    Nor does it matter, as the Commission contends, that the
    Section 203(b) standard was not directly at issue in Louisville
    Gas. See 2019 Rehearing Order ¶ 33 (J.A. 277–278). The
    Commission there applied its understanding of the Section
    203(b) standard, see Louisville Gas, 
    137 FERC ¶ 61195
    , at
    ¶¶ 1, 37–39, and so created agency precedent to complement
    what its regulation and prior cases had already said, see 
    18 C.F.R. § 2.26
    (b); MidAmerican Energy Holdings Co., 
    131 FERC ¶ 61004
    , at ¶ 16.
    The Commission tried to smooth over this conflict by
    holding that the agency was now “clarify[ing]” that, for
    supplemental orders, it would only consider the particular
    public-interest factor that the order approving the merger was
    meant to address. 2019 Rehearing Order ¶ 35 (J.A. 278).
    That is of no help. To be sure, an agency may depart from
    its precedent so long as it “display[s] awareness that it is
    changing position” and shows that “the new policy is
    permissible under the statute, that there are good reasons for it,
    and that the agency believes it to be better[.]” FCC v. Fox
    Television Stations, Inc., 
    556 U.S. 502
    , 515 (2009) (emphases
    omitted).
    But even assuming the Commission’s “clarif[ication]”
    showed sufficient awareness of its changed position, the
    30
    agency failed to put its analysis where its mouth was. 2019
    Rehearing Order ¶ 35 (J.A. 278). In the very orders
    announcing this new approach, the Commission defied it.
    Rather than analyzing Louisville Utilities’ request to end
    depancaking only in terms of its effect on competition, the
    Commission went on to address other public interest goals.
    For example, the Commission tailored its remedy to address
    some customers’ reliance interests, reasoning that the “public
    interest requires” that its approval of Louisville Utilities’
    request be conditioned on protecting those interests. March
    2019 Order ¶ 74 (J.A. 248–249).
    So it seems the modification standard is not so narrow after
    all.    And nowhere did the Commission explain why
    selectively excluding rate effects from the public-interest
    analysis would make any sense.
    The Commission argues that because its rules only provide
    that it “generally consider[s]” rates under Section 203, and then
    only as to “proposed mergers[,]” it need not always weigh rate
    effects in evaluating supplemental order requests.
    Commission Br. 48–49 (emphasis added and citations
    omitted). But just because the Commission need not consider
    rates in every Section 203(b) proceeding does not mean the
    agency can ignore rate effects when they are raised and are
    significant. Because Commission rules and judicial precedent
    establish that customer rates are a cardinal consideration in
    determining whether a merger’s terms are in the public interest,
    the Commission must address rates when they are an important
    aspect of the problem before it. See 
    18 C.F.R. § 2.26
    (b);
    Wabash Valley Power Ass’n, 
    268 F.3d at 1115
    .
    Louisville Utilities, for its part, contends that because
    pancaking necessarily increases rates, analyzing rate effects
    here is a “circular inquiry that would inevitably favor keeping”
    31
    depancaking in place forever. Louisville Utilities Intervenor
    Br. 12. But Louisville Utilities’ own evidence suggested
    otherwise. A Louisville Utilities executive testified that
    depancaking reduces Municipal Customers’ rates but increases
    those of the retail and transmission customers whose bills pay
    for the program. See J.A. 551–552 (Jessee Test.); see also
    Merger Statement, 61 Fed. Reg. at 68,603 (on the rate effects
    prong, Commission will protect “wholesale ratepayers and
    transmission customers”). Beyond that, even if an inquiry into
    rates would favor keeping depancaking in place, that would not
    dictate the outcome of the Commission’s full public-interest
    determination based on all relevant factors.
    In sum, in this case, how restoring pancaking would affect
    rates was a critical part of the public-interest analysis to which
    the Commission could not close its eyes.
    Vacatur is the “normal remedy” for “unsustainable agency
    action[,]” and neither the Commission nor Louisville Utilities
    “has * * * asked the court []or given us any reason to depart
    from that standard course of action.” Brotherhood of
    Locomotive Eng’rs & Trainmen v. Federal R.R. Admin., 
    972 F.3d 83
    , 117 (D.C. Cir. 2020) (citation omitted).
    Even putting that forfeiture aside, the decision whether to
    vacate an order depends “on the seriousness of the order’s
    deficiencies * * * and the disruptive consequences of an
    interim change that may itself be changed.” Environmental
    Def. Fund, 2 F.4th at 976 (citation omitted). Considering
    those factors, we conclude that vacatur is appropriate.
    The Commission’s failure to consider an important public-
    interest factor—one that is central to the Federal Power Act’s
    purpose of “encourag[ing] the orderly development of plentiful
    supplies of electricity * * * at reasonable prices[,]” NAACP,
    
    425 U.S. at
    670—was a “major shortcoming[] that [went] to
    32
    the heart of the [agency’s] decision[,]” and so favors vacatur,
    Humane Soc’y, 865 F.3d at 614. A material effect on rates is
    not even disputed in this case, so we cannot find that there is a
    “significant possibility” that the Commission may be able to
    “find an adequate explanation for its actions on remand[,]”
    given that it must go back to the drawing table and entirely redo
    its public-interest analysis. Standing Rock Sioux Tribe v.
    Army Corps of Eng’rs, 
    985 F.3d 1032
    , 1051 (D.C. Cir. 2021)
    (formatting modified and citation omitted). Though vacatur
    may cause some disruption, that disruption seems unlikely to
    be severe, as our decision implicates in large part the same type
    of rates that are required to be depancaked in the short term
    under the transition mechanism. We therefore vacate the
    Commission’s decision to permit Louisville Utilities to end
    depancaking under Schedule 402 and remand for the agency to
    reconsider its decision in light of the direct and indirect effects
    ending depancaking would have on customers’ rates.
    B
    Both Louisville Utilities and the Municipal Customers
    separately assail the Commission’s transition mechanism. We
    review these challenges to provide the Commission guidance
    on remand, should it conclude—after considering the relevant
    factors—that ending depancaking under Schedule 402 is in the
    public interest. See National Fuel Gas Supply Corp. v. FERC,
    
    468 F.3d 831
    , 844 (D.C. Cir. 2006) (Kavanaugh, J.)
    (“provid[ing] specific guidance to FERC on what it could do
    on remand if it chose to re-promulgate” orders vacated in part
    by the court); cf. Oncor Elec. Delivery Co. v. NLRB, 
    887 F.3d 488
    , 495 (D.C. Cir. 2018).
    Louisville Utilities argues that the Commission erred in
    whom it protected—which parties qualified for the remedy.
    Then both Municipal Customers and Louisville Utilities
    33
    contend that the Commission erred in what it protected—which
    fees the agency required to be depancaked. We conclude that
    the Commission’s decision as to whom to protect was
    reasonable and mostly reach the same conclusion regarding its
    decision as to what fees to cover.
    1
    Louisville Utilities argues that the Commission should not
    have required it to continue depancaking rates for P&P. In its
    view, P&P only ever enjoyed depancaked rates because
    Louisville Utilities voluntarily chose to provide them, making
    it unreasonable for P&P to think that depancaking would
    continue indefinitely. Louisville Utilities adds that it should
    not have to depancake fees associated with Prairie State in
    particular, because P&P did not in fact rely on depancaking
    when contracting with that generator.
    Louisville Utilities is incorrect. The Commission’s
    conclusion that P&P reasonably relied on continued
    depancaking was sound, and substantial evidence supports the
    Commission’s finding that P&P committed to Prairie State in
    reliance on depancaked rates.
    a
    The Commission’s transition mechanism was designed to
    protect “customers located in the [Louisville Utilities] market
    that reasonably relied on” depancaking in contracting for
    electrical power. March 2019 Order ¶ 80 (J.A. 250). P&P fit
    that bill.
    To start, the Commission properly found that P&P is a
    customer in the Louisville Utilities market. See 2019
    Rehearing Order ¶ 109 (J.A. 306–307). Like the other parties
    whose reliance interests the Commission protected—without
    34
    protest from Louisville Utilities—P&P is on the Louisville
    Utilities grid and a potential Louisville Utilities wholesale
    power customer that was expressly protected from pancaked
    rates under Schedule 402. See March 2019 Order ¶¶ 77, 81
    (J.A. 249–251); 2019 Rehearing Order ¶ 109 (J.A. 306–307);
    Second Rehearing Order ¶ 37 (J.A. 360); cf. J.A. 593 (Solomon
    Test.) (Louisville Utilities’ expert analyzing competition
    effects of ending depancaking on P&P, among other
    customers).
    The Commission’s conclusion that P&P could reasonably
    rely on the protections of Schedule 402 was also sound because
    its depancaking provisions were designed to comply with
    earlier Commission orders, and so were not optional. See
    Second Rehearing Order ¶¶ 39–40 (J.A. 361–362); Transition
    Rehearing Order ¶¶ 45–46 (J.A. 395–397).
    Louisville Utilities insists that it was only required to
    protect those customers in its wholesale market at the time of
    the merger in 1998, and it protected other entities in Schedule
    402 only voluntarily.
    Not so. Schedule 402, which depancaked P&P’s rates
    with MISO, was by its terms “intended to implement the
    Section 203 mitigation requirements ordered by the
    Commission[.]” J.A. 559 (Schedule 402 § 1.a.v); see
    Transition Rehearing Order ¶ 45 (J.A. 395–396). And
    Louisville Utilities itself acknowledged, when first agreeing to
    protect P&P and other parties from rate pancaking that “it [was]
    counter-intuitive at [that] time to contemplate that FERC would
    permit the company to establish new rate pancakes” for the
    parties to the agreement. J.A. 450–451 (February 2006 Term
    Sheet § 1); see Second Rehearing Order ¶¶ 39–40 (J.A. 361–
    35
    362).7 So the Commission’s conclusion that P&P reasonably
    believed itself protected from pancaked rates by the
    Commission was justified.
    To be sure, the 2006 Withdrawal Order only expressly
    directed Louisville Utilities to protect its wholesale customers
    from pancaked rates with MISO. See 2006 Withdrawal Order
    ¶ 112 (J.A. 130). But the Commission reasonably found that
    Louisville Utilities agreed to depancake P&P’s rates because
    P&P was planning to join the Louisville Utilities wholesale
    market, and would then be protected by the Commission’s
    merger orders. See Second Rehearing Order ¶ 40 (J.A. 361–
    362); Transition Rehearing Order ¶¶ 45–46 (J.A. 395–397);
    1998 Merger Order, at 19 (J.A. 19) (protecting customers in
    Louisville Utilities’ wholesale market). In other words,
    Louisville Utilities agreed to Schedule 402 because it had to
    depancake rates for entities in its wholesale market subject to
    its “horizontal market power[,]” which it understood at the time
    would likely soon include P&P. 2006 Withdrawal Order
    ¶ 112 (J.A. 130); see also Second Rehearing Order ¶ 40 (J.A.
    361); cf. J.A. 583, 601 (Solomon Test.) (Louisville Utilities
    expert assessing the competitive effects of pancaking on all
    Schedule 402 customers on the company’s grid). Especially
    given our deference to the Commission’s interpretation of
    tariffs like Schedule 402, that is substantial evidence
    supporting the agency’s conclusion that Louisville Utilities did
    not voluntarily depancake P&P’s rates with MISO. See City
    7
    Cf. LG&E Energy LLC on behalf of Louisville Gas and
    Electric Co. et al., Midwest ISO Withdrawal & Independent
    Transmission Organization/Reliability Coordinator Implementation
    Filing, FERC Accession No. 20051007-4004 (Oct. 7, 2005), at 20
    (“[Louisville Utilities] seek[s] to ensure that [its] withdrawal from
    [M]ISO * * * is consistent with the Commission’s goal of
    eliminating transmission rate pancaking.”).
    36
    & County of San Francisco v. FERC, 
    24 F.4th 652
    , 660 (D.C.
    Cir. 2022).
    On top of that, in protecting P&P, the Commission was
    hewing to the March 2019 Order, to which Louisville Utilities
    never objected. See Second Rehearing Order ¶ 37 (J.A. 360).
    In that decision, the Commission required Louisville Utilities
    to temporarily depancake rates for the City of Owensboro,
    another Schedule 402 customer that was not one of Louisville
    Utilities’ wholesale clients in 1998. See March 2019 Order
    ¶ 77 (J.A. 249). Louisville Utilities tries to distinguish
    Owensboro’s coverage, asserting that the city, unlike P&P, was
    on its grid in 1998. But Owensboro indisputably was not a
    Louisville Utilities wholesale customer in 1998. That goes to
    show that the Commission found it reasonable for entities to
    rely on depancaking even if they were not Louisville Utilities
    wholesale customers at the time of the merger—a holding to
    which the company did not object when the Commission first
    adopted it in 2019. See Second Rehearing Order ¶ 37 (J.A.
    360).
    b
    The Commission also reasonably found that P&P relied on
    depancaking when it invested in Prairie State.
    Louisville Utilities argues that it was “chronologically
    impossible” for P&P to “rely on de-pancaking when deciding
    to invest in Prairie State” because it began investing in the
    generator after Louisville Utilities had announced plans to
    leave MISO and before it signed Schedule 402. Louisville
    Utilities Opening Br. 36.
    That argument misses the mark. As the Commission
    found, P&P first agreed to invest only a modest amount in
    Prairie State in February 2005, when Louisville Utilities was
    37
    still in MISO and unable to pancake rates with other parts of
    that grid. See Transition Rehearing Order ¶ 47 (J.A. 397).
    While the utility’s request to leave MISO was pending, P&P
    looked into other electricity options, recognizing that fully
    investing in a generator in MISO might be uneconomical with
    pancaked rates. See id.; see also J.A. 1240–1242 (Thornton
    Aff.). It was only after the Commission accepted Schedule
    402, with its promise of depancaking for P&P, that P&P made
    the decision to invest hundreds of millions of dollars in Prairie
    State. See Transition Rehearing Order ¶ 47 (J.A. 397); J.A.
    1235, 1239–1240 (Thornton Aff.).          That is substantial
    evidence of reliance.
    2
    Turning to Municipal Customers’ and Louisville Utilities’
    challenges to the Commission’s design of its reliance interest
    remedy, we generally find no error, with two exceptions.
    Because the transition remedy was designed to “protect the
    economics of the decisions made by [Municipal Customers]
    while [depancaking] was in effect[,]” the Commission ordered
    Louisville Utilities to depancake fees associated with
    agreements entered before the March 2019 Order to the same
    extent as they would have been covered under Schedule 402.
    Transition Rehearing Order ¶ 77 (J.A. 412); see 
    id.
     ¶¶ 24–25
    (J.A. 386–387).
    To ensure that the transition mechanism only covered
    “reasonabl[e]” reliance interests, the Commission only
    required continued depancaking for the “initial term” of
    covered power agreements. March 2019 Order ¶¶ 80, 82
    (J.A. 250–251); see also 2019 Rehearing Order ¶ 111 (J.A.
    307); Transition Rehearing Order ¶¶ 49, 83 (J.A. 398–399,
    415–416).
    38
    In applying those principles, the Commission made
    several choices about what types of fees were covered, which
    financial commitments to protect, and how long its remedy
    should last. Municipal Customers and Louisville Utilities
    each challenge some of those details.
    a
    Louisville Utilities argues that the Commission arbitrarily
    required it to depancake three MISO fees known as Schedules
    26, 26-A, and 45. The utility claims that it does not charge
    fees that correspond to those schedules, so MISO’s bills are not
    duplicative, leaving no pancaked rates to depancake.
    The Commission reasonably found otherwise. Schedules
    26 and 26-A are MISO’s overhead charges to customers for
    construction that benefits multiple parts of its grid. See 2019
    Transition Mechanism Order ¶ 63 (J.A. 332). As the
    Commission noted, Louisville Utilities does not similarly
    divide its grid into zones, and its building requirements are
    different. See id.; Transition Rehearing Order ¶ 64 (J.A. 405–
    406). But what matters for purposes of depancaking is that
    Louisville Utilities collects fees from its customers for the
    same basic purpose as Schedules 26 and 26–A: that is,
    building and maintaining transmission capacity. See 2019
    Transition Mechanism Order ¶ 63 (J.A. 332); Transition
    Rehearing Order ¶ 64 (J.A. 405–406). Depancaking the
    Schedule 26 and 26-A fees ensures that customers do not pay
    for that same type of overhead twice.
    As for the Schedule 45 charges, MISO uses those fees to
    pay for the costs of responding to grid reliability alerts. See
    2019 Transition Mechanism Order ¶ 64 (J.A. 332–333);
    Transition Rehearing Order ¶¶ 66–67 & n.117 (J.A. 407–408).
    The Commission found that Louisville Utilities charges fees to
    that same end. See Transition Rehearing Order ¶¶ 66–67 &
    39
    n.117 (J.A. 407–408). Though Louisville Utilities contends
    that Schedule 45 covers “discretionary and site-specific”
    responses, it has no answer to the Commission’s evidence that
    it also charges customers to address the same type of incidents.
    Louisville Utilities Opening Br. 41–42.
    Given that record, Louisville Utilities provides no basis for
    us to reject these technical and record-specific factual findings
    by the Commission. See Electric Power Supply Ass’n, 577
    U.S. at 292.
    b
    Contrary to the Municipal Customers’ objection, the
    Commission properly limited its transition mechanism to their
    preexisting agreements with entities in MISO because
    Schedule 402 itself only applied to such contracts. See Second
    Rehearing Order ¶ 61 (J.A. 371–372); Transition Rehearing
    Order ¶¶ 76, 83 (J.A. 412, 415–416).
    Though Municipal Customers contend that some
    municipalities had relied on backup energy in MISO when
    securing power outside of MISO, the Commission sensibly
    focused its remedy on the agreements that fell squarely within
    Schedule 402—that is, contracts with entities inside MISO.
    See Transition Rehearing Order ¶¶ 76, 83 (J.A. 412, 415–416).
    In doing so, the Commission reasonably declined to embroil
    itself in the intractable task of trying to discern which other
    arrangements that themselves would not have been protected
    by Schedule 402 were in some sense still reliant on it. Even if
    another decision would have been reasonable, that is the type
    of “line-drawing” that “[w]e are generally unwilling” to
    overturn unless the lines drawn are “patently unreasonable,
    having no relationship to the underlying regulatory problem.”
    ExxonMobil Gas Mktg. Co. v. FERC, 
    297 F.3d 1071
    , 1085
    40
    (D.C. Cir. 2002) (formatting modified and citation omitted).
    Municipal Customers have not shown that.
    c
    Turning to the Commission’s decision to require
    Louisville Utilities to depancake P&P’s rates tied to Prairie
    State only for ten years, Louisville Utilities says there is too
    much coverage. P&P says there is too little coverage. We
    say the Commission got it just right enough.
    P&P’s investment in Prairie State presented the
    Commission with a conundrum. P&P had counted on
    continued depancaking in investing in the Prairie State project,
    creating a reliance interest. See 2019 Rehearing Order ¶ 111
    (J.A. 307). Investing in the project—which includes a coal
    plant, a coal mine, and related facilities—took considerable
    resources. See J.A. 1285 (Prairie State Project Power Sales
    Agreement Attach. 1); Second Rehearing Order ¶ 44 (J.A.
    364).
    Yet the arrangement did not fit easily into the
    Commission’s decision to cabin the transition mechanism to
    the initial term of power purchase agreements. See Second
    Rehearing Order ¶¶ 44, 53 (J.A. 364, 368–369); March 2019
    Order ¶ 82 n.126 (J.A. 251). P&P’s arrangement with Prairie
    State lasts until all of the consortium’s relevant “obligations
    and liabilities” have been paid and the project “has been
    terminated[.]” See J.A. 1255 (Prairie State Project Power
    Sales Agreement § 101). That could be decades and decades
    down the line. Because P&P’s arrangement with Prairie State
    has no “readily apparent ‘term’”—or, rather, has an indefinite
    term—bringing the entire Prairie State arrangement into the
    transition mechanism would saddle Louisville Utilities with
    potentially perpetual depancaking duties, which the
    Commission found incompatible with the time-limited nature
    41
    of the remedy. See Second Rehearing Order ¶¶ 43–44 (J.A.
    363–364); see also id. ¶ 53 (J.A. 368).
    Balancing P&P’s reliance interests against the burden of
    indefinite mitigation, the Commission capped Prairie State-
    related depancaking to a “proxy term” of ten years. November
    2020 Order ¶ 20 (J.A. 435). For support, the Commission
    pointed to one of its earlier merger mitigation decisions,
    NextEra Energy, Inc., 
    165 FERC ¶ 61199
     (2018). See Second
    Rehearing Order ¶ 44 & n.70 (J.A. 364). In NextEra, the
    Commission found that it needed to retain a mitigation measure
    to preserve competition for only approximately ten years
    because, by that point, new generators might enter the market
    and replace the rivalry lost in the merger. See 
    165 FERC ¶ 61199
    , at ¶ 31. Similarly here, the Commission found that a
    decade would give P&P enough time to “plan for future market
    conditions[,]” and the benefit of “new entry” from other
    generators to provide energy alternatives. November 2020
    Order ¶ 20 (J.A. 435).
    Municipal Customers respond that P&P’s agreements with
    Prairie State contain a definitive end date, albeit one that “is
    not expressed as a calendar date[.]” Municipal Customers
    Opening Br. 35–36.
    That misses the point. The Commission defined an
    “initial term” to mean “the term specified in [a] power purchase
    agreement before any extensions pursuant to an evergreen
    provision or other provision[.]” March 2019 Order ¶ 82 n.126
    (J.A. 251). In that way, the Commission drew a line against
    protecting contracts if they were extended and re-extended. In
    other words, to confine the remedy to reasonable reliance
    interests for a reasonable period of time, the Commission
    “phase[d]-out the De-pancaking Mitigation,” rather than
    allowing it to continue indefinitely. Second Rehearing Order
    42
    ¶¶ 43, 67 (J.A. 363, 374); see also March 2019 Order ¶ 80 (J.A.
    250). So it made sense to set a reasonable time limit for Prairie
    State depancaking that would be fair under the circumstances.
    See Second Rehearing Order ¶¶ 43–44 (J.A. 363–364). P&P,
    for its part, never even proposed an alternative fixed timeframe
    the Commission could have used as an initial term instead.
    See J.A. 1482–1485 (Municipal Customers Rehearing Request
    as to the Transition Rehearing Order and Second Rehearing
    Order); Municipal Customers Opening Br. 33–38.
    Both Louisville Utilities and Municipal Customers
    contend that the Commission acted arbitrarily by relying on
    NextEra to select a term for Prairie State depancaking. To
    Louisville Utilities, NextEra involved the question of how long
    merger mitigation “should exist in the first place, not how long
    it should take to transition away from” it. Louisville Utilities
    Opening Br. 39 (internal quotation marks omitted). Because
    Louisville Utilities had been depancaking rates for more than a
    decade already, it argues that the Commission’s directive to
    cover Prairie State fees for ten more years was irrational.
    Municipal Customers, meanwhile, argue that NextEra
    inappositely dealt with the question of how long mitigation is
    needed to protect competition, not reliance interests, and the
    approximately ten-year mitigation term there was based on
    case-specific facts.
    Those are fair points. But not enough to displace the
    Commission’s judgment. The Commission never claimed
    that the facts of NextEra mapped onto the Prairie State situation
    perfectly. Instead, the Commission found NextEra to be a
    helpful benchmark because the approximately ten-year
    mitigation period in that case (i) gave the affected parties time
    to adjust to the new market landscape, by (ii) allowing for more
    competitive entry. See November 2020 Order ¶ 20 (J.A. 435).
    Those same considerations apply to the Commission’s
    43
    transition mechanism here. Like the affected parties in
    NextEra, P&P will now face a new market and cost
    environment; ten additional years of depancaking will give it a
    cushion to “plan accordingly.”            
    Id.
        And if there is
    “competitive new entry[,]” as the Commission predicted,
    P&P’s reliance interests may diminish as new providers lower
    the costs of switching to a new energy source. 
    Id.
     So while
    NextEra dealt with a different factual scenario, its principles
    have purchase here, and the Commission’s judgment in that
    regard was well within its broad remedial powers under Section
    203(b).    See Environmental Action, 
    939 F.2d at 1064
    (deferring to Commission merger condition decision because
    “agency discretion is, if anything, at [its] zenith when the action
    assailed relates to the fashioning of policies, remedies[,] and
    sanctions”) (formatting modified and citation omitted).
    Municipal Customers respond that P&P can do nothing to
    “plan” for the end of depancaking because it is irrevocably
    committed to Prairie State. Municipal Customers Opening Br.
    38 (citation omitted). But the Commission only guarded
    reasonable reliance interests, March 2019 Order ¶ 80 (J.A.
    250), and it was not unreasonable for the Commission to leave
    P&P responsible for some portion of its open-ended investment
    in Prairie State given that nothing in Schedule 402 promised
    that its depancaking would continue indefinitely. See J.A. 559
    (Schedule 402 § 1.a.v) (recognizing that parties to the
    depancaking provisions could seek changes with the
    Commission); Second Rehearing Order ¶ 53 (J.A. 368) (“[T]he
    Transition Mechanism * * * was intended to protect, for a
    limited period of time, the customers that accessed the market
    and reasonably relied on the De-Pancaking Mitigation when
    making their past power supply choices.”).
    44
    d
    Next, Louisville Utilities argues that the Commission’s
    order to depancake P&P’s rates related to a hydroelectric
    project was arbitrary. We agree.
    The Commission held that P&P should be protected from
    pancaked fees relating to a hydropower project in which it held
    an ownership stake. See November 2020 Order ¶ 22 & n.35
    (J.A. 435–436). Because P&P’s power agreements with the
    project last “until December 31, 2057, or until other conditions
    occur[,]” the Commission found that depancaking must
    continue until the end of 2057. Id. (citation omitted).
    That reasoning cannot be reconciled with the
    Commission’s determination that the transition mechanism
    was meant to extend depancaking only for a “limited period of
    time[.]” Second Rehearing Order ¶ 53 (J.A. 368). The
    Commission had just said that ten years of mitigation was
    enough to protect P&P’s similar long-term investment in
    Prairie State. See id. ¶ 44 (J.A. 364). Yet here, the
    Commission concluded that mitigation must continue for an
    additional 38 years—simply because the hydropower
    agreements contained a concrete end date of 2057. See
    November 2020 Order ¶ 22 (J.A. 435–436).
    That makes no sense. If ten years of protection suffices
    for an ownership interest that continues “indefinitely[,]”
    something in the neighborhood of ten years would seem the
    relevant timeframe to protect another exceptionally long
    investment.      Second Rehearing Order ¶ 44 (J.A. 364);
    Municipal Customers Opening Br. 36 (recognizing
    inconsistency between Commission’s hydropower holding and
    its Prairie State decision). The Commission failed to explain
    why the fact that an agreement will terminate by a date certain
    justified extending the mitigation term for nearly four decades.
    45
    Though we are deferential to the Commission’s remedial
    decisions, we cannot overlook such unexplained inconsistency.
    See Chippewa & Flambeau Improvement Co. v. FERC, 
    325 F.3d 353
    , 358 (D.C. Cir. 2003) (“A grant of discretion to an
    agency does not, of course, authorize it to make an unprincipled
    decision[.]”).
    The Commission responds that its decision was not unduly
    discriminatory because parties with “clear initial terms and
    those without clear initial terms are not similarly situated.”
    Commission Br. 70. But the agency’s mistake was not that it
    did not factually distinguish the two cases. The Commission
    simply failed to explain why that distinction matters, given that
    the point of the transition mechanism was to protect reasonable
    reliance interests for a reasonable time, not to protect those who
    happen to have tied their agreements to a calendar. See
    Second Rehearing Order ¶ 53 (J.A. 368).
    Should the Commission conclude on remand that the
    public interest supports ending depancaking under Schedule
    402, it must either better explain this aspect of the transition
    mechanism or take a fresh approach to the question.
    e
    Finally, Municipal Customers contend that the
    Commission arbitrarily declined to protect the entirety of a
    transmission reservation Energy Agency purchased from
    MISO. Here too, we find the Commission’s reasoning
    inexplicable.
    Before the March 2019 Order, Energy Agency agreed to
    an eight-year deal to reserve capacity on MISO’s wires for
    imported power. See Second Rehearing Order ¶ 49 (J.A.
    366); J.A. 1178 (Affidavit of John F. Painter (Aug. 2, 2019)).
    That capacity reservation gives Energy Agency the temporary
    46
    right to ship electricity, using MISO lines, from MISO-based
    generators to the border with Louisville Utilities. See J.A.
    1181 (2019 Painter Aff.); Louisville Gas, 988 F.3d at 845–846
    (explaining how transmission reservations work). As part of
    that agreement, Energy Agency is contractually “obligated to
    make monthly payments for the MISO * * * capacity reserved”
    regardless of how much it uses. J.A. 1173 (2019 Painter Aff.);
    see also 2019 Rehearing Order ¶ 104 & n.142 (J.A. 304–305).
    The Commission agreed that the reservation must be
    depancaked, but only so long as it is used to transmit power
    purchased before the March 2019 Order. See 2019 Rehearing
    Order ¶ 111 (J.A. 307). The agency asserted that, unlike
    power purchase agreements, a transmission reservation is “not
    a separate financial commitment that merits” independent
    protection. Second Rehearing Order ¶ 53 (J.A. 368). If
    those agreements were covered, the Commission said, Energy
    Agency could “preserve * * * de-pancaking for future power
    supply transactions not yet entered into[.]” Id. That would
    be unreasonable, according to the Commission, because
    customers now “have access to competitive power supply
    choices[.]” Id. (J.A. 368–369).
    That rationale does not make sense. The Commission
    said it would protect Municipal Customers’ commitments (i)
    that were reasonably reliant on depancaking, (ii) for a
    reasonable initial term, and (iii) that would have been protected
    under Schedule 402. See March 2019 Order ¶ 80 (J.A. 250);
    2019 Rehearing Order ¶ 111 (J.A. 307); Second Rehearing
    Order ¶ 43 (J.A. 363–364). Energy Agency’s transmission
    reservation checks each of those boxes.
    Energy Agency’s transmission reservation was
    indisputably made in reliance on depancaking, see 2019
    Rehearing Order ¶ 111 (J.A. 307), and there was unrebutted
    47
    record evidence that Energy Agency owes monthly fees for
    eight years even if its reserved capacity is unused, see J.A. 1173
    (2019 Painter Aff.); see also 2019 Rehearing Order ¶ 104 &
    n.142 (J.A. 304–305). In addition, the Commission had
    already decided that transmission reservations used to import
    power from MISO—like those at issue here—must be
    depancaked under Schedule 402. 8 On this record, the
    Commission’s holding that transmission reservations are not
    “separate financial commitment[s]” meriting independent
    protection was conclusory and inconsistent with the plain
    criteria of the transition mechanism. Second Rehearing Order
    ¶ 53 (J.A. 368).9
    That customers now enjoy a competitive power market is
    beside the point. See Second Rehearing Order ¶ 53 (J.A. 368–
    369).     If today’s competitive market obviated reliance
    interests, there would be no need for the transition mechanism
    at all. But the Commission balanced competing interests and
    explicitly concluded that reliance interests in electricity
    contracts must be protected for a reasonable period of time:
    8
    See 2019 Rehearing Order ¶ 111 & n.148 (J.A. 307) (citing
    Owensboro Mun. Utils., 
    166 FERC ¶ 61131
     (2019), rev’d, Louisville
    Gas, 988 F.3d at 843); Owensboro Mun., 
    166 FERC ¶ 61131
    , at
    ¶¶ 41–44 (requiring Louisville Utilities to depancake a Schedule 402
    customer’s “transmission reservation” in MISO); Louisville Gas,
    988 F.3d at 848 (Commission required Louisville Utilities to
    depancake a customer’s “reservation charges * * * apparently for the
    life of the contract with MISO”).
    9
    It does not matter for this decision that the Sixth Circuit later
    vacated the Commission’s order requiring Louisville Utilities to
    depancake a transmission reservation in MISO. See Louisville Gas,
    988 F.3d at 843; see also Brooklyn Union Gas Co. v. FERC, 
    409 F.3d 404
    , 406 (D.C. Cir. 2005). The Sixth Circuit’s decision was issued
    after the challenged orders, and so it cannot retroactively make
    earlier Commission decisions that did not rely on it reasonable.
    48
    “Although we have determined that there would continue to be
    a sufficient number of competitive suppliers [absent
    depancaking],” it would nevertheless “not be consistent with
    the public interest to” end depancaking “without a [remedy]
    accounting for [customers’] reliance on that mitigation.”
    March 2019 Order ¶ 79 (J.A. 250). So the Commission’s
    competition finding does nothing to justify reaching a different
    result for transmission reservations than it did for power
    purchase agreements.
    The Commission’s claim that depancaking Energy
    Agency’s entire transmission reservation would unduly extend
    its remedy to future power agreements was also baseless. See
    Second Rehearing Order ¶¶ 51–53 (J.A. 367–368). The
    Commission did not explain why Louisville Utilities could not
    depancake the portions of the reservation to which Energy
    Agency irrevocably committed before the March 2019 Order
    without covering other fees that may attend its future use.
    That amounts to a failure of reasoned decisionmaking. See
    Spirit Airlines, 997 F.3d at 1255 (“An agency is required to
    consider responsible alternatives to its chosen policy and to
    give a reasoned explanation for its rejection of such
    alternatives.”) (citation omitted).
    The Commission and Louisville Utilities argue that
    “power purchase agreements and transmission service
    reservations are different, especially in light of the
    determination that customers now have competitive supply
    choices.” Commission Br. 78; see also Louisville Utilities
    Intervenor Br. 16–17.         But that simply repeats the
    Commission’s hollow explanation for limiting its protection of
    the transmission contract that we have already found wanting.
    If the Commission chooses again to end Schedule 402
    depancaking on remand, it must come forward with a logical
    explanation for its decision here that is consistent with the
    49
    purpose and scope of the transition mechanism, or it must
    extend depancaking on reasoned terms to Energy Agency’s
    transmission contract.
    IV
    For all those reasons, we grant the petitions in part, vacate
    the challenged orders in part, and remand for further
    proceedings consistent with this opinion.
    So ordered.