N.M. Att'y. Gen. v. N.M. Pub. Regulation Comm'n. , 2015 NMSC 32 ( 2015 )


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    New Mexico Compilation
    Commission, Santa Fe, NM
    '00'05- 10:12:03 2015.11.03
    IN THE SUPREME COURT OF THE STATE OF NEW MEXICO
    Opinion Number: 2015-NMSC-032
    Filing Date: September 28, 2015
    Docket No. S-1-SC-34768
    NEW MEXICO ATTORNEY GENERAL,
    Appellant,
    v.
    NEW MEXICO PUBLIC REGULATION COMMISSION,
    Appellee,
    and
    SOUTHWESTERN PUBLIC SERVICE
    COMPANY, OCCIDENTAL PERMIAN LTD.,
    and COALITION FOR CLEAN AFFORDABLE ENERGY,
    Intervenors-Appellees.
    APPEAL FROM THE NEW MEXICO PUBLIC REGULATION COMMISSION
    Hector H. Balderas, Attorney General
    P. Cholla Khoury, Assistant Attorney General
    Santa Fe, NM
    for Appellant
    New Mexico Public Regulation Commission
    Margaret Caffey-Moquin
    Santa Fe, NM
    for Appellee
    Hinkle Shanor, LLP
    Jeffrey L. Fornaciari
    Dana S. Hardy
    Santa Fe, NM
    1
    Xcel Energy Services, Inc.
    Stephen Fogel
    Austin, TX
    for Intervenor Southwestern Public Service Company
    Gallagher & Kennedy, P.A.
    Anthony J. Trujillo
    Germaine R. Chappelle
    Santa Fe, NM
    Thompson & Knight, LLP
    Phillip G. Oldham
    Austin, TX
    for Intervenor Occidental Permian, Ltd.
    Charles F. Noble
    Santa Fe, NM
    for Intervenor Coalition for Clean Affordable Energy
    Cuddy & McCarthy, LLP
    Rebecca Dempsey
    Santa Fe, NM
    PNM Resources, Inc.
    Benjamin Phillips
    Albuquerque, NM
    for Amicus Curiae Public Service Company of New Mexico
    OPINION
    CHÁVEZ, Justice.
    {1}     The Public Regulation Commission (PRC) granted Southwestern Public Service
    Company’s (SPS) application to (1) include a prepaid pension asset in its rate base in order
    for SPS to earn a return on this asset, and (2) obtain a renewable energy cost rider to recover
    approximately $22 million of renewable energy procurement costs from those customers
    who do not have a legislatively imposed limit on their renewable energy costs (non-capped
    customers). The Attorney General appeals the PRC’s final order granting SPS’s application,
    arguing that the approved rates are unjust and unreasonable because the inclusion of the
    entire prepaid asset in the rate base is not supported by substantial evidence, and the PRC
    2
    acted contrary to law in allowing SPS to recover the aforementioned renewable energy costs
    from non-capped customers. We affirm the PRC because (1) SPS is entitled to earn a
    reasonable rate of return on the investor-funded prepaid pension asset, and (2) SPS may
    recover its renewable energy costs in excess of the large customer cap from non-capped
    customers because such a recovery mechanism is the only viable method of cost recovery
    that is consistent with the purposes of the Renewable Energy Act, NMSA 1978, §§ 62-16-1
    to -10 (2004, as amended through 2011).
    I.     THE INCLUSION OF SPS’S PREPAID PENSION ASSET IN THE RATE
    BASE
    {2}      SPS applied to the PRC to include a prepaid pension asset in its rate base to allow
    its shareholders, who funded the asset, to receive a corresponding return on their investment.
    By including this prepaid pension asset in the rate base, the asset is treated as a capital
    investment, allowing SPS to recover the asset as an expense, thereby increasing SPS’s
    revenue requirement. See Joseph P. Tomain, Symposium Article, “Steel in the Ground”:
    Greening the Grid with the iUtility, 39 Envtl. L. 931, 945-46 (2009) (providing and
    discussing the rate making formula, which sets the amount of money utilities may receive
    for their investments and expenses). Importantly, inclusion of an investment asset in the rate
    base does not enable investors to recover the value of their investment, but instead only
    allows investors to earn a return on the asset. See 
    id. (noting that
    utilities generally recover
    the value of an investment by treating the depreciation of the asset as an operating expense).
    {3}      The parties agree that a prepaid pension asset is the amount by which investor
    contributions to a pension trust and earnings on these contributions exceed pension expenses.
    S. Co. Servs., Inc., 122 FERC ¶ 61,218, at *62235, 
    2008 WL 630079
    , slip copy at 5 (FERC
    2008) (order on tariff filing), order clarified by 128 FERC ¶ 61,276, 
    2009 WL 3043950
    (slip
    copy) (FERC 2009); In re Delmarva Power & Light Co., 
    2014 WL 3964914
    , slip copy at 18,
    315 P.U.R. 4th 10 (Del. P.S.C. 2014) (“A prepaid pension asset occurs when the
    accumulated contributions and growth in the pension plan exceed the accumulated expenses
    associated with the pension obligations.”). For example, SPS’s expert stated that if the
    annual pension contribution over a five-year period is $100 and the annual pension expense
    over the same period is only $90, at the end of the five-year period, the prepaid pension asset
    would be $50 ($100 x 5 - $90 x 5), plus any return on the $50 prepaid pension asset.
    “Conversely, when [accrued expenses] exceed[] contributions to [a] fund, a prepaid pension
    liability accrues.” See In re Sw. Pub. Serv. Co., 
    2008 WL 4226018
    n.256, slip copy at 114
    (NMPRC) (final order partially adopting recommended decision), order clarifying final
    order sub nom. 
    2008 WL 9888273
    (slip copy) (NMPRC 2008). The SPS expert also stated
    that the prepaid pension asset is an artifact of timing; over a long period, pension
    contributions and pension expenses may even out, but over short and intermediate periods
    there will surely be differences, which are recorded as either prepaid pension assets or
    pension liabilities.
    {4}    SPS’s expert testified that pension contributions and expenses differ because the
    3
    federal Employee Retirement Income Security Act of 1974, 29 U.S.C. §§ 1001-1461 (2011),
    and the Internal Revenue Code, 26 U.S.C. §§ 1-59 (2012), dictate how much the utility must
    contribute to its employee pension program, whereas the Financial Accounting Standards
    Board promulgates codified accounting standards1 that govern how pension expenses are
    determined. The expert continued by testifying that as a result of these differing federal and
    industry standards, pension contribution and expense calculations utilize different
    assumptions, attribution methods, and periods of time over which the costs are required to
    be recognized. SPS’s expert stated that these dissimilarities often result in differing annual
    contribution and expense amounts. When mandated contributions and income earned on the
    contributions exceed expenses, a prepaid pension asset accrues. See S. Co. Servs., Inc., 122
    FERC ¶ 61,218, at *62235, 
    2008 WL 630079
    , slip copy at 5; see also In re Delmarva Power
    & Light Co., 
    2014 WL 3964914
    , slip copy at 18.
    {5}     The expert witness also testified that utilities cannot legally withdraw any funds from
    pension trusts except to pay pension benefits and expenses. See S. Co. Servs., Inc., 122
    FERC ¶ 61,218, at *62235, 
    2008 WL 630079
    , slip copy at 5. However, SPS customers
    benefit from a prepaid pension asset because the earnings on this asset are deemed to be
    income for SPS, which reduces the amount of revenue it must collect from its customers.
    See Ind. Office of Util. Consumer Counselor v. Ind. Mich. Power Co., 
    7 N.E.3d 1025
    , 
    2014 WL 934350
    , at *12 (Ind. Ct. App. 2014) (memorandum decision) (non-precedential). The
    following hypothetical offered by SPS’s testifying expert illustrates the indirect benefit SPS
    customers receive.
    [S]uppose that in a given year the utility had a revenue requirement of $300,
    and that it expected to earn a 6% return on the pension fund. The $3.00
    return on [a hypothetical] $50 prepaid pension asset (0.06 x $50) . . . would
    be credited against the revenue requirement, so that the utility could only
    collect $297 from its customers through [the] rates. Thus, the revenue
    requirement is reduced by $3.00 as a result of the prepaid pension asset.
    SPS customers therefore would benefit from rate reductions generated by the prepaid
    pension asset, but SPS would not earn a return on the prepaid pension asset if the asset is not
    included in SPS’s rate base.
    {6}    In this case, the New Mexico jurisdictional share2 of SPS’s prepaid pension asset is
    1
    Companies must follow Financial Accounting Standards Board codified accounting
    standards to comply with generally accepted accounting principles.
    2
    SPS operates in other states besides New Mexico. For the relevant time period,
    SPS’s total prepaid pension asset, on a total company basis, was approximately $179.7
    million. The amount of this asset attributable to New Mexico is approximately $36.9
    million.
    4
    approximately $36.9 million. According to SPS, this asset resulted in $1.7 million in
    earnings that effectively reduced SPS’s pension expense by $1.7 million, which reduced
    SPS’s revenue requirement by the same amount. SPS sought “to include the net amount of
    its prepaid pension asset of approximately $22 million” in the rate base to earn a return on
    its $22 million (the $36.9 million asset minus a $14.9 million tax deferred asset).
    {7}     In a recommended decision, the PRC hearing examiner concluded that because the
    prepaid pension asset reduced the pension expense by $1.7 million, that $1.7 million should
    be included in the rate base for recovery. The PRC hearing examiner did not recommend
    that the $22 million net prepaid pension asset amount be included in the rate base. SPS
    disagreed with this recommendation, contending that the examiner’s proposal would enable
    “SPS [to] earn a return only on the amount of the reduction in the cost of service rather than
    on the amount of the asset that resulted in the reduction.”
    {8}      The PRC also disagreed with the hearing examiner. In its final order, the PRC
    authorized the inclusion of the net amount of the prepaid asset in SPS’s rate base because
    doing so “recognizes that ratepayers benefit from the prepaid pension asset and that the
    utility should earn a return on the prepaid pension asset in order for the utility to recover its
    full cost of service.” The Attorney General appeals, arguing that substantial evidence does
    not support the inclusion of the entire prepaid pension asset within the rate base.
    A.      Standard of Review
    {9}     In determining whether a PRC final order is supported by substantial evidence, we
    review the whole record, “view[ing] the evidence in the light most favorable to the decision
    made by the [PRC].” PNM Gas Servs. v. N.M. Pub. Util. Comm’n (In re PNM Gas Servs.),
    2000-NMSC-012, ¶ 4, 
    129 N.M. 1
    , 
    1 P.3d 383
    (internal quotation marks and citation
    omitted). “ ‘Substantial evidence’ [is] such relevant evidence as a reasonable mind might
    accept as adequate to support a conclusion.” Rinker v. State Corp. Comm’n,
    1973-NMSC-021, ¶ 5, 
    84 N.M. 626
    , 
    506 P.2d 783
    . “The supreme court shall have no power
    to modify the action or order appealed from [(in this case, a PRC final order)], but shall
    either affirm or annul and vacate the same.” NMSA 1978, § 62-11-5 (1982). “The [PRC]
    is vested with considerable discretion in determining whether a rate to be received and
    charged is just and reasonable.” Hobbs Gas Co. v. N.M. Pub. Serv. Comm’n,
    1980-NMSC-005, ¶ 4, 
    94 N.M. 731
    , 
    616 P.2d 1116
    . A party challenging a PRC final order
    has the burden of establishing that the order is “arbitrary and capricious, not supported by
    substantial evidence, outside the scope of the agency’s authority, or otherwise inconsistent
    with law.” N.M. Indus. Energy Consumers v. N.M. Pub. Regulation Comm’n,
    2007-NMSC-053, ¶ 13, 
    142 N.M. 533
    , 
    168 P.3d 105
    (internal quotation marks and citation
    omitted).
    B.      The Prepaid Pension Asset
    {10}    The Attorney General contends that only the earnings generated by the prepaid
    5
    pension asset should be included in the rate base because this is the amount by which the
    ratepayers have benefitted, or the amount by which the utility’s revenue requirement is
    reduced. The Attorney General argues that only $1.7 million should be included in the rate
    base, whereas the PRC’s final order enables SPS to include $22 million in the rate base,
    which is the net amount of its prepaid pension asset. In resolving this issue, we explain the
    rationale for electric utility regulation.
    {11} Electric utilities are regulated because their industry has natural monopoly
    characteristics. Joseph P. Tomain, The Persistence of Natural Monopoly, 16 Nat. Resources
    & Env’t. 242, 242 (2002). In natural monopoly settings, both the benefits and the possibility
    of competition are limited. Omega Satellite Prods. Co. v. City of Indianapolis, 
    694 F.2d 119
    , 126 (7th Cir. 1982). If the electric industry was a competitive free-for-all, different
    companies would attempt to build separate electric grids and sign up customers as quickly
    as possible to reduce their average costs of business more rapidly than their rivals. See 
    id. This competitive
    process would last until a single company was left standing “because until
    a company serves the whole market it will have an incentive to keep expanding in order to
    lower its average costs.” 
    Id. Thus, until
    a single company wins, competition within the
    electric industry would produce wasteful duplicate grids that would needlessly raise average
    costs for consumers. See id.; Tomain, The Persistence of Natural 
    Monopoly, supra, at 242
    (“A specific service area needs only one set of electric . . . wires—the investment in any
    other set of wires is wasteful.”). To avoid wasteful duplication, a government may choose
    to give one firm a monopoly within a service area “in exchange [for] a commitment to
    provide reasonable service at reasonable rates.” Omega Satellite Prods. 
    Co., 694 F.2d at 126
    .
    {12} Electric utility regulation consequently reflects a compact between utilities and the
    public. See Jersey Cent. Power & Light Co. v. Federal Energy Regulatory Comm’n (FERC),
    
    810 F.2d 1168
    , 1189 (D.C. Cir. 1987) (Starr, J., concurring). A utility is given a monopoly
    over a service area, and in exchange accepts government regulation of its business, including
    price regulation. 
    Id. Under this
    arrangement, utility investors obtain a stability in earnings
    that would likely be unattainable in less regulated industries, while “ratepayers are afforded
    universal, non-discriminatory service and protection from monopolistic profits.” 
    Id. {13} Regulators
    attempt to set prices that mimic market conditions and ensure that utilities
    are “profitable enough to attract capital investment.” Tomain, “Steel in the 
    Ground,” supra, at 945
    . The following rate making formula traditionally determines utility revenues to be
    received from ratepayers: R = O + (V - d)r, where
    R represents the utility’s revenue requirement—that is, the amount of money
    the utility needs to stay in business. O represents the utility’s prudently
    incurred expenses. In short, ratepayers reimburse the utility for its
    expenditures dollar for dollar. The utility’s rate base is represented by (V -
    d), which stands for the value of a utility’s capital investment minus
    depreciation, which is returned to the utility as expenses. Finally, r
    6
    represents the rate of return on the rate base.
    
    Id. at 945-46.
    {14} The utility’s rate base—the total amount of investment made by a utility to provide
    its service—is determined by adding the utility’s investment in physical properties to its
    working capital. Cent. La. Elec. Co. v. La. Pub. Serv. Comm’n, 
    373 So. 2d 123
    , 129 (La.
    1979). Thus, a utility can include physical properties such as a power plant, see, e.g., Hobbs
    Gas Co., 1980-NMSC-005, ¶ 6, and working capital—operating funds essential to pay for
    current obligations—in its rate base. Gov’t of Guam v. Fed. Mar. Comm’n, 
    329 F.2d 251
    ,
    256 (D.C. Cir. 1964); Ariz. Pub. Serv. Co., 5 FERC ¶ 63,038, at *65179, 
    1978 WL 16416
    ,
    slip copy at 2 (FERC 1978) (defining working capital as “the money which a utility puts up
    to finance the services provided until it is compensated by customers”).
    {15}    In the context of utility regulation, working capital
    does not include the total liquid funds with which the business is conducted.
    It is not the property which the business has; that is, it is not the excess of
    current assets over current liabilities. Working capital, rather, is an
    allowance for the sum which the company needs to supply from its own
    funds for the purpose of enabling it to meet its current obligations as they
    arise and to operate economically and efficiently.
    Gov’t of 
    Guam, 329 F.2d at 256
    (internal quotation marks and citation omitted). As a result,
    only utility contributions, not ratepayer contributions, can be properly included in the rate
    base as working capital. For example, if a utility were to prepay for natural gas with investor
    funds, the utility should expect to receive a reasonable return on its investment. Zia Nat.
    Gas Co. v. N.M. Pub. Util. Comm’n (In re Zia Nat. Gas Co.), 2000-NMSC-011, ¶ 22, 
    128 N.M. 728
    , 
    998 P.2d 564
    . Conversely, if ratepayers have paid in advance for the natural gas,
    the utility would have no expectation of a return because its capital was not used to buy the
    natural gas. 
    Id. {16} A
    utility can include prepayments for pension expenses in its rate base “because the
    utility is out-of-pocket for such costs until they are recovered from ratepayers and is
    therefore entitled to recover its cost of financing such prepaid expenses.” S. Co. Servs., Inc.,
    122 FERC ¶ 61,218, at *62235, 
    2008 WL 630079
    , slip copy at 5. For example, in the
    context of prepaid pension assets, income earned on the pension fund is reported under
    generally accepted accounting principles as a reduction to the utility’s pension expense. 
    Id. “If that
    reduction in pension expense is used in determining a utility’s rates, there will be a
    corresponding reduction in the amounts collected from ratepayers.” 
    Id. Under these
    circumstances, the utility must finance the reduction because it cannot use the income from
    the pension trust to pay other current obligations; as a result, the utility is allowed to recover
    the costs of financing the reduction by including the pension income in the rate base. See
    
    id. The Attorney
    General’s position is that the utility can only recover the costs of financing
    7
    the reduction of the utility’s revenue requirement, i.e., the utility can only earn a return from
    the pension income generated by the prepaid pension asset.
    {17} However, a utility may not only be out-of-pocket for reductions in its revenue
    requirement resulting from pension fund earnings. A utility may also be out-of-pocket for
    investor-funded contributions that are in excess of pension expenses. Basically, when a
    utility supplies working capital to fund contributions in excess of pension expenses to create
    an income-producing prepaid pension asset, the utility finances the cost of the entire prepaid
    pension asset. See, e.g., In re Rocky Mountain Power, 
    2014 WL 7526282
    , at *14 ¶¶ 52, 53,
    *36 (Wyo. P.S.C. 2014) (noting that a “prepaid pension asset represents [a utility’s]
    contributions to its pension . . . plans in excess of what is expensed to that time” and the
    utility “finances the asset with a combination of debt and equity financing”).
    {18} Other jurisdictions have allowed utilities to recover the financing costs of the net
    prepaid pension asset by including the asset in the rate base as a component of working
    capital. See, e.g., Ind. Office of Util. Consumer Counselor, 
    7 N.E.3d 1025
    , 
    2014 WL 934350
    , at *12 (upholding a regulatory determination that a prepaid pension asset be
    included in the rate base because the “asset amounted to working capital that benefited the
    ratepayers by reducing the total pension costs needed in [the utility’s] revenue
    requirement”); In re Rocky Mountain Power, 
    2014 WL 7526282
    , at *14, *36 (finding
    persuasive a utility’s argument that it should recover the financing costs of its prepaid
    pension asset by including the asset in the rate base to enable the utility to earn a return on
    that asset). But see In re Pub. Util. Comm’n of Or., 
    2015 WL 4710466
    , at *7 (Or. P.U.C.
    2015) (affirming a “long-standing policy of allowing a utility to recover its pension
    contributions [only as an] expense and reject[ing] the . . . Utilities’ proposal to include their
    current prepaid pension assets in rate base”).
    {19} On appeal, the Attorney General does not argue as a matter of law that the prepaid
    pension asset cannot be included in the rate base. The Attorney General’s only evidentiary
    challenge is that inclusion of the net prepaid pension asset will result in ratepayers paying
    more to SPS than the benefit ratepayers have enjoyed from the pension fund earnings. We
    interpret the Attorney General’s argument to be that SPS did not prove how much of the net
    prepaid pension asset resulted in consumers paying $1.7 million less to SPS. We disagree.
    We hold that some or all of a prepaid pension asset should be included in the rate base to the
    extent that the evidence evinces that the asset was investor-funded, as opposed to ratepayer-
    funded.3 See In re Potomac Elec. Power Co., 
    2008 WL 516553
    , slip copy at 29, 263 P.U.R.
    3
    Because utilities may only include in the rate base investor-funded, prepaid pension
    assets, we emphasize that “shareholder contributions do not solely drive prepaid pension
    asset balances.” In re Pub. Util. Comm’n of Or., 
    2015 WL 4710466
    , at *8 (Or. P.U.C. 2015)
    . For example, during “periods of high economic growth, a prepaid pension asset balance
    will increase even with no shareholder contributions,” 
    id., presumably because,
    among other
    reasons, existing funds within a pension trust can earn unexpectedly high returns. See, e.g.,
    8
    4th 1 (D.C. P.S.C.) (finding that “investor-supplied cash contributions have resulted in an
    asset from which [utility] customers receive a tangible benefit in the form of reduced pension
    expenses” and including the prepaid pension asset in the rate base), adhered to on denial of
    reconsideration sub nom. 
    2008 WL 4831456
    (slip copy) (D.C. P.S.C. 2008); In re N. Ill. Gas
    Co., 
    2005 WL 2445944
    , slip copy at 23 (Ill. C.C. 2005) (noting that a prepaid pension asset
    “was created by ratepayer-supplied funds, not by shareholder-supplied funds,” and finding
    that the “prepaid pension asset should be eliminated from rate base”); In re Zia Nat. Gas
    Co., 2000-NMSC-011, ¶ 22 (noting that only investor-supplied working capital may be
    included in the rate base); In re Cent. Tel. Co. of Tex., 19 Tex. P.U.C. Bull. 929, 
    1993 WL 595464
    , slip copy at 13 (Tex. P.U.C. 1993) (concluding that conversely, when ratepayer-
    supplied money overfunds a pension plan, investors are not entitled to “earn a return on the
    prepaid pension asset because [this] . . . would have the effect of charging ratepayers again
    for amounts they have already paid”). Similarly, while a prepaid pension asset may be
    included in the rate base, prepaid pension liability must be subtracted from the rate base.
    See, e.g., In re Ky.-Am. Water Co., 
    1997 WL 34863470
    , slip copy at 10 (Ky. P.S.C. 1997)
    (noting that although pension liabilities can be utilized to reduce the rate base, if “a pension
    asset is created, then the asset should be included as a rate base addition”), opinion modified
    on denial of reh’g sub nom. In re Adjustment of the Rates of Ky.-Am. Water Co., 
    1997 WL 34863471
    (slip copy) (Ky. P.S.C. 1997).
    {20} The evidence indicates that SPS has a net prepaid pension asset of approximately $22
    million. The evidence also indicates that including $22 million of the net prepaid pension
    asset in the rate base would generate approximately $2.5 million in revenue for SPS, which
    exceeds the $1.7 million by which SPS asserts the pension expense was reduced. SPS
    maintains that its actual annual pension expense is $5.36 million, but the $1.7 million return
    on the prepaid pension asset reduced the pension expense to $3.66 million.
    {21} Although the Attorney General is correct to make an evidentiary contention, the
    premise of its argument is incorrect. Utilities are able to recover the costs of financing their
    business operations through the inclusion of investor-supplied working capital in the rate
    base. See In re Zia Nat. Gas Co., 2000-NMSC-011, ¶ 22. In his written testimony, Gene H.
    Wickes stated that “[t]he portion of the prepaid pension asset due to these contributions has
    therefore come exclusively from shareholder capital and should be included in rate base.”
    It is uncontested that SPS investors made contributions to the pension fund that are required
    by law. These contributions exceeded expenses and generated earnings that effectively
    In re Cent. Tel. Co. of Tex., 19 Tex. P.U.C. Bull. 929, 
    1993 WL 595464
    , slip copy at 13
    (Tex. P.U.C. 1993) (noting that because a utility failed to “accurately predict that its pension
    fund would experience favorable investment results and that there would be reductions in
    benefit levels, the [utility’s] pension fund was subsequently overfunded” through rates
    collected earlier from ratepayers). In short, simply placing a prepaid pension asset in the rate
    base allows utilities to earn returns on amounts that are not shareholder contributions. See
    In re Pub. Util. Comm’n of Or., 
    2015 WL 4710466
    , at *8.
    9
    reduced SPS’s—and consequently the ratepayers’—pension expense. Had the ratepayers
    advanced the contributions to the pension fund, their contributions would not have been
    included in the rate base. See In re N. Ill. Gas Co., 
    2005 WL 2445944
    , slip copy at 14.
    However, because the ratepayers did not make the contributions, the investors, not the
    ratepayers, absorbed the cost of funding the pension program, and therefore the net prepaid
    pension asset was properly included in the rate base. See, e.g., In re Pub. Serv. Co. of Colo.,
    
    1993 WL 494141
    , slip copy at 17, 148 P.U.R. 4th 1 (Colo. P.U.C. 1993) (“In order to
    compensate investors for the additional funds they supply to meet the higher contribution
    levels, the resulting prepaid assets are an appropriate addition to rate base.”); In re Potomac
    Elec. Power Co., 
    2008 WL 4831456
    , slip copy at 3 (concluding that inclusion of an investor-
    supplied prepaid pension asset in the rate base is supported by substantial evidence because
    “the earnings on the prepaid pension asset will reduce the annual [utility] expense, thus
    benefiting customers by reducing the revenue requirement”); Ind. Office of Util. Consumer
    Counselor, 
    7 N.E.3d 1025
    , 
    2014 WL 934350
    , at *12 (upholding a regulatory determination
    that a prepaid pension asset amounted to working capital that should be included in the rate
    base).
    {22} We note, however, that contributions to pension funds should be scrutinized to ensure
    that utility investments are “used and useful” so as to inure to the benefit of consumers. See
    N.M. Indus. Energy Consumers v. N.M. Pub. Serv. Comm’n, 1986-NMSC-059, ¶ 29, 
    104 N.M. 565
    , 
    725 P.2d 244
    (internal quotation marks omitted) (noting that the “ ‘used and
    useful’ concept is but one factor among many to be considered by the [PRC] in its rate base
    analysis”). Utilities should not voluntarily overfund their pension funds simply to earn a
    favored rate of return. In re Appalachian Power Co., 
    2011 WL 2150661
    , slip op. at 27, 288
    P.U.R. 4th 185 (W. Va. P.S.C. 2011) (“Prepayments should be subject to the same review
    as any other investment or expense of a utility. Inclusion of prepayments in rate base should
    not be used for a utility to find a convenient place to deposit funds and then expect to earn
    a return on those funds.”). On the other hand, mandatory contributions to pension funds are
    useful. Such contributions may benefit customers by generating an income-earning prepaid
    pension asset to reduce pension expenses, see, e.g., In re Potomac Elec. Power Co., 
    2008 WL 516553
    , slip copy at 29, and also fund the pension programs that make it possible for
    the utility to attract and retain highly-skilled workers. See, e.g., In re Advice Letter No. 830
    - Gas of Pub. Serv. Co. of Colo., 
    2013 WL 5799983
    , at *46-47 (Colo. P.U.C.).
    {23} We conclude that the Attorney General has failed to meet its burden of showing that
    the PRC’s inclusion of the entire prepaid pension asset was unreasonable or unlawful for
    lack of substantial evidence. See In re PNM Gas Servs., 2000-NMSC-012, ¶ 4.
    II.    THE LAWFULNESS OF THE RENEWABLE PORTFOLIO STANDARDS
    RIDER
    A.     SPS’s Recovery of Renewable Energy Procurement Costs from Non-Capped
    Customers
    10
    {24} The Attorney General also contends that the PRC acted contrary to law when it
    approved SPS’s renewable energy cost rider because the rider sought to recover renewable
    energy costs from non-capped customers, customers who are not subject to a legislatively
    imposed limit on their renewable energy costs. We review issues of law de novo. N.M.
    Attorney Gen. v. N.M. Pub. Regulation Comm’n, 2013-NMSC-042, ¶ 10, 
    309 P.3d 89
    .
    However, “[w]hen an agency that is governed by a particular statute construes or applies that
    statute, [we] will [accord] some deference to the agency’s interpretation.” 
    Id. ¶ 12
    (internal
    quotation marks and citations omitted). We will reverse the agency’s interpretation of a
    statute if it is unreasonable or unlawful. 
    Id. {25} The
    resolution of this issue necessitates a discussion of the Renewable Energy Act,
    §§ 62-16-1 to -10. As a preface to our discussion of this issue, some background on
    renewable energy promotion is warranted.
    {26} Under the traditional rate formula, utilities receive a reasonable rate of return for
    capital project investments such as power plants. See Tomain, “Steel in the 
    Ground,” supra, at 946
    . Utilities consequently have an incentive to invest in capital projects, see 
    id., and “prefer
    low-risk, conventional technologies that can be built quickly instead of long-term,
    innovative technologies that would be riskier.” Virginia R. Hildreth, Comment, Renewable
    Energy Subsidies and the GATT, 14 Chi. J. Int’l L. 702, 707 (2014). As a result,
    “government assistance is often key to encourage investment in industries like renewable
    energy.” 
    Id. Such encouragement
    is desirable because there are numerous benefits to
    renewable energy such as “lessened dependence on foreign fossil fuel supplies, heightened
    national security, overall cleaner air, and local and rural job creation.” Shelley Welton,
    From the States Up: Building a National Renewable Energy Policy, 17 N.Y.U. Envtl. L.J.
    987, 995 (2008); see also Brent M. Haddad & Paul Jefferiss, Forging Consensus on National
    Renewables Policy: The Renewables Portfolio Standard and the National Public Benefits
    Trust Fund, 12 The Elec. J. 68, 69 (Mar. 1999) (listing benefits of renewable energy).
    {27} Renewable portfolio standards are among the most popular methods of encouraging
    renewable energy development. See Lincoln L. Davies, State Renewable Portfolio
    Standards: Is There A “Race” and Is It “To the Top”?, 3 San Diego J. Climate & Energy
    L. 3, 10 (2011-2012). These standards mandate that utilities incorporate renewable energy
    sources into their electric generation portfolios, 
    id. at 13,
    and frequently enable utilities to
    purchase renewable energy credits4 to satisfy the mandates of renewable portfolio standards.
    
    Id. at 11.
    A renewable portfolio standard therefore combines “both a potentially inflexible
    regulatory directive and the malleable tool of economic trading,” 
    id. at 10,
    to “inject an
    element of economic efficiency into [renewable portfolio standard] schemes.” 
    Id. at 11.
    {28}   Under the Renewable Energy Act, New Mexico has a renewable portfolio standard
    4
    Renewable energy credits “typically represent the production of one megawatt hour
    (‘MWh’) of renewables-fueled electricity.” 
    Davies, supra, at 11
    .
    11
    that both mandates the incorporation of renewable energy sources into electric generation
    portfolios and allows for the purchase of renewable energy certificates (credits) to satisfy the
    mandates. Sections 62-16-4 to -5. Pursuant to this renewable portfolio standard, before the
    proceedings in this case, the evidence indicates that SPS received PRC approval to (1)
    purchase the outputs of two New Mexico wind farms, (2) pay incentives encouraging
    customers to install solar and biomass generation systems, (3) obtain renewable energy
    credits from various sources, and (4) purchase solar photovoltaic systems.
    {29} The controversy over the permissibility of SPS’s proposed rider arises from a
    disagreement as to how renewable energy costs are allocated between different rate classes.
    In utility regulation, customers are often divided into different classes that are charged
    different rates. II Leonard Saul Goodman, The Process of Ratemaking 964-65 (1998). The
    creation of rate classes involves the consideration of various factors such as alternate fuel
    capability and types of customer, which can be classified as residential, commercial, or
    industrial. 
    Id. at 965.
    Differential rates can be utilized to implement various policies.
    Tomain, “Steel in the 
    Ground,” supra, at 946
    -47.
    {30} In this case, cost allocation has been utilized to address a problem that is incidental
    to the promotion of renewable energy generation. The use of renewable energy tends to
    raise energy costs relative to the consumption of fossil fuels. See 
    Hildreth, supra, at 716
    (“The technology needed for renewable energy tends to be more expensive than traditional
    fuel sources.”); Trevor D. Stiles, Renewable Resources and the Dormant Commerce Clause,
    4 Envtl. & Energy L. & Pol’y J. 34, 43-44, 45 (2009) (numerically illustrating how there is
    a “vast price discrepancy between renewable energy sources and fossil fuel sources for
    energy generation”). The prospect of “overly high renewable implementation costs” has
    prompted concern that commercial and large industrial customers may leave the utility
    system or exit states that implement prohibitively expensive renewable energy promotion
    plans. California Commissioner Seeks Consideration of Shale Gas, 4054 PUR Util. Reg.
    News 1, 1 (Jan. 20, 2012). These large customers may have the capacity to self-generate
    their energy needs or simply close their plants in areas where energy costs are high. See
    Charles G. Stalon & Reinier H.J.H. Lock, State-Federal Relations in the Economic
    Regulation of Energy, 7 Yale J. on Reg. 427, 449 (1990). When these large customers are
    driven from the utility system, utility rates have to be raised even further for remaining
    customers, which exacerbates the potential for other customer exits. See 
    id. In light
    of the
    potential for large customers to exit the grid, the Legislature enacted Section 62-16-4(A)(2),
    which limits the annual amount large customers can be charged for renewable energy
    procurement. The PRC calls this limit the “large customer cap.” Accordingly, costs that
    exceed the large customer cap may be called “large customer cap costs.”
    {31} In earlier proceedings, the evidence indicates that the PRC had already approved
    SPS’s “requested procurements without any reduction to SPS’s overall [renewable portfolio
    standards] to account for large customer cap costs.” When the PRC learned that SPS’s costs
    exceeded the large customer cap, the PRC specifically approved treatment of that amount
    as a deferred cost. “A ‘deferred cost’ is one that has been paid by the [utility] but is
    12
    postponed for inclusion in rates until a future period.” I Leonard Saul Goodman, The
    Process of Ratemaking 321 (1998). This may occur, for example, when a utility “has a
    major future liability, and before collecting anything through rates, its management decides
    that the books should reflect the liability.” 
    Id. Under these
    circumstances, a utility “may
    apply for [regulator] approval to fund an account, and to reflect on its books a deferred debit
    or ‘regulatory asset,’ . . . which later can be charged to ratepayers and amortized over a
    future period.” 
    Id. Regulatory assets
    are often created to spread out the recovery of
    nonrecurring costs over a period of years so as to avoid substantial rate increases, which may
    occur if full recovery was allowed as soon as the utility made an expenditure. City of Corpus
    Christi v. Pub. Util. Comm’n of Tex., 
    51 S.W.3d 231
    , 244-45 (Tex. 2001).
    {32} SPS filed an application seeking to obtain a rider to recover approximately $22
    million of renewable energy procurement costs. Riders are surcharges applied to directly
    recover specific costs. See Chesapeake Utils. Corp. v. Del. Pub. Serv. Comm’n, 
    705 A.2d 1059
    , 1063 (Del. Super. Ct. 1997) (referring to a rider as a surcharge); Citizens Util. Bd. v.
    Ill. Commerce Comm’n, 
    651 N.E.2d 1089
    , 1102 (Ill. 1995) (“[A] rider mechanism . . .
    facilitates direct recovery of a particular cost.”). These surcharges give regulators more
    flexibility in spreading out costs charged to ratepayers over a period of time. See
    Chesapeake Utils. 
    Corp., 705 A.2d at 1063
    n.3.
    {33} Section 62-16-4(A)(1)(a)-(d) mandates that a certain percentage of a “public utility’s
    total retail sales to New Mexico customers” be comprised of renewable energy. The
    required percentage escalates over time. See 
    id. However, under
    the large customer cap
    provision of Section 62-16-4(A)(2), the renewable portfolio standards mandated in Section
    62-16-4(A)(1)
    shall be reduced, as necessary, to provide for the following specific
    procurement requirements for nongovernmental customers at a single
    location or facility, regardless of the number of meters at that location or
    facility, with consumption exceeding ten million kilowatt-hours per year
    [(capped customers)]. On and after January 1, 2006, the kilowatt-hours of
    renewable energy procured for these customers shall be limited so that the
    additional cost of the renewable portfolio standard to each customer does not
    exceed the lower of one percent of that customer’s annual electric charges or
    forty-nine thousand dollars ($49,000) [(large customer cap)].
    Section 62-16-4(A)(2). The large customer cap in Section 62-16-4(A)(2) also escalates over
    time such that capped customers can continue to be charged increasing amounts for
    renewable energy.
    {34} The evidence indicates that SPS sought to recover the renewable energy procurement
    costs that exceeded the large customer cap from non-capped customers. The Attorney
    General opposed SPS’s application, arguing that SPS could only recover its costs from large
    customers. The Attorney General argues that recovery of large customer cap costs from non-
    13
    capped customers is contrary to both Section 62-16-4(A)(2) and 17.9.572.15 NMAC, a
    regulation concerning renewable energy cost recovery. The Attorney General contends that
    Section 62-16-4(A)(2) mandates the reduction of renewable energy procurements if such
    procurements would generate costs in excess of the large customer cap. Under the Attorney
    General’s reasoning, because large customer cap costs should not have arisen as a matter of
    law, they cannot be allocated to non-capped customers.
    {35} In a supplemental recommended decision, the hearing examiner recommended that
    SPS be allowed to recover large customer cap costs from non-capped customers because
    given the cost limits on large customers, SPS’s ability to collect excess costs from large
    customers in the future would be speculative and uncertain. In a final order partially
    adopting the recommended decision (the final order), the PRC agreed with the hearing
    examiner. We affirm the PRC on this issue because its actions are consistent with Section
    62-16-4(A)(2) and the Renewable Energy Act as a whole.
    B.     Discretion to Reduce Renewable Energy Procurements
    {36} Section 62-16-4(A)(2) states that the New Mexico renewable portfolio standards
    mandate “shall be reduced, as necessary” to accommodate the large customer cap.
    According to the Attorney General, the word “shall” indicates that renewable energy
    procurement reductions are mandated whenever renewable energy procurement costs would
    otherwise exceed the large customer cap. One opposing interpretation of Section 62-16-
    4(A)(2) is that the phrase “as necessary” modifies the phrase “shall be reduced” to indicate
    that the PRC has discretion to reduce renewable energy procurements, even if large customer
    cap costs would result from such procurements. The Attorney General argues that when
    large customer cap costs arise, the PRC has discretion regarding the amount by which
    renewable energy procurement should be reduced, but not whether the renewable portfolio
    standards should be reduced. We hold that (1) Section 62-16-4(A)(2) does not mandate a
    reduction in renewable energy procurement whenever large customer cap costs arise, and
    (2) the PRC has discretion to reduce renewable energy procurement when large customer cap
    costs arise.
    {37} Our analysis begins with the plain text of the statute. Garcia v. Gutierrez,
    2009-NMSC-044, ¶ 53, 
    147 N.M. 105
    , 
    217 P.3d 591
    . In analyzing the phrase “shall be
    reduced, as necessary,” we knowledge that “shall” is a word of mandate. See Black’s Law
    Dictionary 1375 (6th ed. 1990). However, the phrase “as necessary” indicates discretion.
    Norris v. Emanuel Cty., 
    561 S.E.2d 240
    , 244 (Ga. Ct. App. 2002). Because “as necessary”
    modifies the word “shall” in Section 62-16-4(A)(2) (internal quotation marks omitted), the
    statute’s plain text indicates that when large customer cap costs arise, the PRC has discretion
    to determine whether renewable energy procurement reductions are necessary.
    {38} The next sentence in Section 62-16-4(A)(2) provides that “the kilowatt-hours of
    renewable energy procured for these customers shall be limited so that the additional cost
    of the renewable portfolio standard to each customer does not exceed” the large customer
    14
    cap. The word “shall” in this sentence is not modified by any words of discretion. The
    Attorney General apparently relies upon this lack of discretionary language to argue that
    Section 62-16-4(A)(2) mandates renewable energy procurement reductions whenever large
    customer cap costs arise. We disagree. This sentence merely precludes capped customers
    from being charged costs in excess of the statutory cap. Logically, should large customer
    cap costs arise, the PRC can ensure compliance with the statutory cap in two ways: the PRC
    can either reduce renewable energy procurement or adjust what is actually charged to capped
    customers. In adjusting what is actually charged to capped customers, the PRC “may
    authorize deferred recovery of the costs of complying with the renewable portfolio
    standard.” Section 62-16-4(A)(2). In other words, the PRC can choose not to reduce
    procurements, even when large customer cap costs arise, by deferring the excess costs for
    later recovery, so as not to charge capped customers with statutorily prohibited costs. See
    
    id. {39} A
    plain reading of Section 62-16-4(A)(2) indicates that the PRC has the authority not
    to reduce renewable energy procurements, even when large customer cap costs increase.
    This interpretation is strongly supported by a reading of the Renewable Energy Act in its
    entirety, and it should therefore be adopted. See Arnold v. State, 1980-NMSC-030, ¶ 10, 
    94 N.M. 381
    , 
    610 P.2d 1210
    (“Legislative intent is to be determined primarily from the
    language used in the Act or statute as a whole.”). Moreover, this reading acknowledges the
    difficulty of avoiding large customer cap costs.
    {40} First, the renewable portfolio standard promulgated by the Renewable Energy Act
    provides a minimum standard. See § 62-16-4(A)(1) (“[R]enewable energy shall comprise
    no less than [a given] percent of each public utility’s total retail sales to New Mexico
    customers.” (emphasis added)). The Attorney General’s reading of Section 62-16-4(A)(2)
    would have us treat the large customer cap as providing a maximum standard. This is
    problematic because mandating renewable energy procurement reductions whenever large
    customer cap costs arise would be inconsistent with Section 62-16-2(A)(5), which plainly
    states that “a public utility should have incentives to go beyond the minimum requirements
    of the renewable portfolio standard.”
    {41} Second, Section 62-16-4(A) clearly evinces a legislative intent to systematically
    increase renewable energy use in New Mexico. Section 62-16-4(A)(1) escalates renewable
    energy procurement requirements over time, while Section 62-16-4(A)(2) increases the large
    customer cap over time. Mandating renewable energy procurement reductions whenever
    large customer cap costs arise would undermine New Mexico’s ability to systematically
    increase renewable energy usage.
    {42} Third, the Attorney General’s argument is erroneously premised on the idea that
    Section 62-16-4(A)(2) was meant to protect non-capped customers from high renewable
    energy costs by banning costs in excess of the large customer cap to prevent large customer
    cap costs from being allocated to non-capped customers. We need not adopt the Attorney
    General’s interpretation of Section 62-16-4(A)(2) to protect non-capped customers from high
    15
    renewable energy costs because another statutory provision already performs this function:
    Section 62-16-4(B) mandates setting an overall reasonable cost threshold for renewable
    energy procurement.
    {43} Fourth, the Attorney General’s argument appears to assume that large customer cap
    costs can be forecast on an accurate and consistent basis so that in approving renewable
    energy procurements, the PRC can systematically avoid large customer cap costs. The
    record proper indicates otherwise. PRC approvals of renewable energy procurement are
    “based on the best information available at the time the resources were being reviewed.”
    SPS notes that how much large customer cap costs will increase depends on future
    occurrences such as the fluctuation of natural gas prices. Accordingly, the evidence
    indicates that we cannot reasonably expect that large customer cap costs can be predictably
    eliminated.
    {44} Reading the language of the Renewable Energy Act as a whole, we conclude that the
    PRC has discretion to decline to reduce renewable energy procurement, even when large
    customer cap costs arise. This authority is congruent with the statutory policy of increasing
    renewable energy use in New Mexico. Moreover, we cannot reasonably expect that either
    the PRC or utilities will be able to avoid large customer cap costs. Thus, adopting the
    Attorney General’s position that large customer cap costs have to be avoided as a matter of
    law also would be contrary to practical experience.
    C.     Section 62-16-4(A)(2) Does Not Preclude the Recovery of Large Customer Cap
    Costs from Non-Capped Customers
    {45} The PRC exercised its discretion not to reduce renewable energy procurement when
    large customer cap costs arose, which is consistent with our interpretation of Section 62-16-
    4(A)(2). It then authorized the deferral of large customer cap costs for future recovery. The
    PRC’s final order provides for the collection of large customer cap costs from non-capped
    customers. We therefore determine the permissibility of collecting large customer cap costs
    from non-capped customers.
    {46} The Attorney General does not oppose SPS’s ability to recover deferred large
    customer cap costs. It merely contends that such costs should not be recovered from non-
    capped customers, asserting that (1) enabling recovery of large customer cap costs from non-
    capped customers “violate[s] the basic ratemaking principle of cost[ ] causation,” and (2)
    Section 62-16-4(A)(2) protects non-capped customers from paying for large customer cap
    costs. We reject the Attorney General’s position as contrary to law and hold that large
    customer cap costs can be allocated to non-capped customers.
    {47} The Attorney General’s contention that allocating large customer cap costs to non-
    capped customers violates the principle of cost causation is without merit. The plain
    language of Section 62-16-4(A)(2) does not mandate that renewable energy procurement
    costs be recovered only against those customers who caused large customer cap costs.
    16
    Moreover, renewable energy procurement costs arise as a result of statutory mandate, see
    § 62-16-4(A)(1), such that neither capped nor non-capped customers can be said to cause any
    specific procurement costs.
    {48} Similarly, the Attorney General’s assertion that Section 62-16-4(A)(2) protects non-
    capped customers from large customer cap costs is unsupported by law. Its argument
    assumes that Section 62-16-4(A)(2) mandates reductions in renewable energy procurement
    whenever large customer cap costs arise to protect both capped and non-capped customers
    from high renewable energy costs. Under the Attorney General’s reasoning, rates for non-
    capped customers cannot be increased by large customer cap costs because such increases
    would deprive non-capped customers of the protections provided by Section 62-16-4(A)(2).
    We reject this reasoning because Section 62-16-4(A)(2) does not evince a legislative intent
    to protect non-capped customers. We have already held that Section 62-16-4(A)(2) does not
    mandate renewable energy procurement reductions when large customer cap costs arise. The
    Attorney General’s contention that Section 62-16-4(A)(2) precludes large customer cap costs
    to protect non-capped customers is also incorrect because nothing in Section 62-16-4(A)(2)
    addresses the interests of non-capped customers. See State v. Diamond, 1921-NMSC-099,
    ¶ 5, 
    27 N.M. 477
    , 
    202 P. 988
    (We will not insert words that are absent in a statute.). We
    conclude that Section 62-16-4(A)(2) does not preclude the allocation of large customer cap
    costs to non-capped customers.
    {49} The PRC had previously approved of SPS’s procurement plans. Under Section 62-
    16-6(A), “[c]osts that are consistent with commission approval of procurement plans . . .
    shall be deemed to be reasonable.” Thus, the renewable procurement costs in this case are
    reasonable as a matter of law. Because these procurement costs are reasonable, SPS is
    entitled under Section 62-16-6(A) to recover large customer cap costs. 
    Id. (“A public
    utility
    that procures or generates renewable energy shall recover, through the rate-making process,
    the reasonable costs of complying with the renewable portfolio standard.”). The evidence
    indicates that if large customer cap costs only can be collected from capped customers, 20
    years or more could elapse “before SPS even has the opportunity to collect” these
    procurement costs. Thus, as the PRC determined, the Attorney General’s proposed cost
    recovery mechanism “is speculative and uncertain, and would not provide a reasonable
    opportunity for SPS to recover [large customer cap] costs.” Forcing SPS to collect large
    customer cap costs only from capped customers would effectively disallow recovery of these
    procurement costs, contrary to the Renewable Energy Act’s guarantee that utilities can
    recover the reasonable costs of renewable energy procurement. Sections 62-16-4(A)(2) &
    -6(A).5
    5
    We also note that although the Attorney General relies on Section 62-16-4(A)(2) to
    argue for a cost recovery mechanism which SPS argues would effectively disallow its ability
    to recover large customer cap costs, such a mechanism would be contrary to the plain
    language of Section 62-16-4(A)(2), which provides that “[n]othing contained in this
    paragraph [concerning the large customer cap] shall be construed as affecting a public
    
    17 Dall. 17
    .9.572.15 NMAC Does Not Preclude the Recovery of Large Customer Cap
    Costs from Non-Capped Customers
    {50} The Attorney General contends that the “plain language” of 17.9.572.15 NMAC
    “make[s] clear that costs associated with large [capped] customers should be borne by large
    customers alone.” 17.9.572.15 NMAC is a regulatory provision concerning renewable
    energy cost recovery that references Section 62-16-4(A)(2). Our interpretation of Section
    62-16-4(A)(2) therefore informs our construction of 17.9.572.15 NMAC. We have
    previously held in this opinion that Section 62-16-4(A)(2) provides the PRC with discretion,
    not a mandate, to reduce renewable energy procurement when large customer cap costs arise,
    and does not bar the allocation of large customer cap costs to non-capped customers.
    Consistent with our interpretation of Section 62-16-4(A)(2), we hold that 17.9.572.15
    NMAC also does not bar the allocation of large customer cap costs to non-capped customers.
    {51}   17.9.572.15 NMAC provides that:
    A.      A public utility shall recover the reasonable costs of
    complying with this rule through the rate making process, including its
    reasonable interconnection and transmission costs and other costs attributable
    to acquisition and delivery of renewable energy to retail New Mexico
    customers.
    B.     Costs that are consistent with commission-approved annual
    Renewable Energy Act plans are deemed to be reasonable.
    C.       A public utility that is permitted to defer the recovery of
    renewable energy costs pursuant to commission order may, through the
    ratemaking process, recover from customers that are not subject to the rate
    impact limitations of Sections 62-16-4A(2) and 62-16-4A(3) NMSA 1978 the
    cumulative sum of those deferred amounts, plus a carrying charge on those
    amounts.
    D.     For customers that are subject to the rate impact limitations
    of Section 62-16-4A(2) NMSA 1978, a public utility may, through the
    ratemaking process, recover from those customers the cumulative sum of
    those Section 62-16-4A(2) NMSA 1978 limited deferred amounts, plus
    carrying charges on those amounts.
    E.      Any renewable energy procurement costs recovered through
    the utility’s fuel clause shall be separately identified in its monthly and
    utility’s right to recover all reasonable costs of complying with the renewable portfolio
    standard.”
    18
    annual fuel and purchased power clause adjustment filings and its
    continuation filings.
    {52} The Attorney General’s argument relies on 17.9.572.15(D) NMAC to support its
    contention that large customer cap costs can only be recovered from large customers. The
    Attorney General seems to share our understanding that large customer cap costs, which
    arise pursuant to Section 62-16-4A(2), may be deferred. Based on this understanding, the
    Attorney General assumes that the term “Section 62-16-4A(2) NMSA 1978 limited deferred
    amounts” in Subsection D is a synonym for deferred large customer cap costs. Armed with
    this assumption, the Attorney General contends that because Subsection D concerns recovery
    of costs from capped customers and only Subsection D expressly refers to recovery of
    “Section 62-16-4A(2) NMSA 1978 limited deferred amounts,” large customer cap costs can
    only be recovered from capped customers.
    {53} We reject the Attorney General’s contention. 17.9.572.15(C) NMAC states that
    whenever “[a] public utility . . . is permitted to defer the recovery of renewable energy costs
    pursuant to commission order,” the utility may recover the deferred amounts from non-
    capped customers. Subsection C therefore authorizes public utilities to recover deferred
    costs, in general, from non-capped customers. By contrast, 17.9.572.15(D) NMAC
    explicitly authorizes only the recovery of “Section 62-16-4A(2) NMSA 1978 limited
    deferred amounts” from capped customers. Thus, although 17.9.572.15(D) NMAC arguably
    provides that only “Section 62-16-4A(2) NMSA 1978 limited deferred amounts” may be
    recovered from capped customers, 17.9.572.15(C) NMAC provides that any deferred
    amounts may be recovered from non-capped customers.
    {54} We conclude that a plain reading of 17.9.572.15 NMAC indicates that deferred costs
    arising from Section 62-16-4A(2) can be recovered from both capped and non-capped
    customers. There is simply no language explicitly banning the collection of deferred large
    customer cap costs from non-capped customers. The Attorney General errs in conflating the
    issue of whether capped customers may be charged only for Section 62-16-4A(2) deferred
    amounts with whether only capped customers may be charged the aforesaid deferred
    amounts.
    III.   CONCLUSION
    {55} We affirm the PRC’s final order. We will not disturb the PRC’s finding that SPS’s
    entire prepaid pension asset was properly included in the rate base. We also hold that the
    PRC properly allocated large customer cap costs to non-capped customers to enable SPS to
    recover its reasonable renewable energy procurement costs.
    {56}   IT IS SO ORDERED.
    ____________________________________
    EDWARD L. CHÁVEZ, Justice
    19
    WE CONCUR:
    ____________________________________
    BARBARA J. VIGIL, Chief Justice
    ____________________________________
    PETRA JIMENEZ MAES, Justice
    ____________________________________
    CHARLES W. DANIELS, Justice
    ____________________________________
    TIMOTHY L. GARCIA, Judge
    Sitting by designation
    20