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                                                                    Exhibit 4.12

                              ACCEPTABLE GUARANTEE

            This GUARANTEE AGREEMENT (this "Guarantee"), dated as of March 30,
2000 between NRG Energy, Inc., a corporation duly organized and validly existing
under the laws of Delaware (the "Guarantor"), and The Chase Manhattan Bank, as
Bond Trustee (the "Bond Trustee") on behalf of Holders of the Bonds.

                                    RECITALS

            1. NRG South Central Generating LLC (the "Issuer") and Louisiana
Generating LLC (with respect to certain sections) have entered into the
Indenture dated as of March 30, 2000 with the Bond Trustee (the "Indenture").

            2. In order to fund the Debt Service Reserve Account so that the
obligations of the Issuer under Article 6 of the Indenture shall be released,
and for other good and valuable consideration, the receipt and sufficiency of
which are acknowledged, the Guarantor has agreed to guarantee the payment of the
Guaranteed Obligation (as defined below).

            Accordingly, the Guarantor agrees with the Bond Trustee as follows:

                                    ARTICLE 1
                                   DEFINITIONS

            Unless otherwise defined, all capitalized terms used in this
Guarantee shall have the meanings given in the Indenture. The rules of
interpretation set forth in Article 1 of the Indenture shall apply to this
Guarantee.

                                    ARTICLE 2
                                    GUARANTEE

            2.01 The Guarantee. The Guarantor absolutely, unconditionally and
irrevocably guarantees to the Trustee on behalf of the Holders of the Bonds and
their respective successors and assigns the prompt payment of up to the Debt
Service Reserve Required Balance (as such amount may be reduced or increased
from time to time, the "Guaranteed Obligation") upon receipt of a written
request from the Issuer therefor.

            The Guarantor further agrees that it will promptly pay the amount
specified in such written notice, but in no event more than the Guaranteed
Obligation, on the date of receipt of such written notice. The delivery of such
notice by the Depositary Bank to the Guarantor in accordance with Section 6.6 of
the Indenture shall constitute sufficient demand on the Guarantor to make the
payment specified in such notice.

            2.02 Obligations Unconditional. The obligations of the Guarantor
under Section 2.01 are absolute, unconditional and irrevocable, irrespective of
any actual or asserted lack of value, genuineness, validity, regularity or
enforceability of the obligations of the Issuer under the Indenture, any other
Transaction Document or any other agreement or instrument

                     NRG South Central Generating Indenture
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referred to therein, or any substitution, release or exchange of any other
guarantee of or security for the Guaranteed Obligation, and, to the fullest
extent permitted by Applicable Law, irrespective of any other circumstance
whatsoever that might otherwise constitute a legal or equitable discharge or
defense of a surety or guarantor, it being the intent of this Article 2 that the
obligations of the Guarantor under this Guarantee shall be absolute and
unconditional, under any and all circumstances.

            Subject to Section 2.01, the Guarantor expressly waives diligence,
presentment, demand of payment, protest and all notices whatsoever, and any
requirement that the Bond Trustee or any Holder exhaust any right, power or
remedy or proceed against the Issuer, the Subsidiary Guarantor or any Additional
Guarantor under the Indenture or any other Transaction Document or any other
agreement or instrument referred to therein, or against any other Person under
any other guarantee of, or security for, any of the Guaranteed Obligation.

            2.03 Instrument for the Payment of Money. The Guarantor acknowledges
that this guarantee constitutes instrument for the payment of money only, and
consents and agrees that the Bond Trustee or any Holder, at its sole option, in
the event of a dispute by such Guarantor in the payment of any moneys due
hereunder, shall have the right to bring motion-action under New York CPLR
Section 3213.

            2.04 Reduction of Guaranteed Obligation. The Guaranteed Obligation
shall be reduced automatically in accordance with Section 6.6(d) of the
Indenture and the Depositary Bank shall promptly provide to the Guarantor notice
of such reduction. Contemporaneous with the giving of such notice, the Bond
Trustee shall annotate this Guarantee to reflect the Guaranteed Obligation as so
reduced.

                                    ARTICLE 3
                         REPRESENTATIONS AND WARRANTIES

            The Guarantor represents and warrants that:

            3.01 Power and Authority. The Guarantor has the corporate power and
authority to (i) execute and deliver this Guarantee and perform its obligations
hereunder, (ii) to conduct its business as currently conducted and (iii) to own
its property.

            3.02 Valid Existence. The Guarantor is duly organized and is validly
existing under and pursuant to the laws of the jurisdiction of its organization
and is qualified to do business and is in good standing in all jurisdictions
necessary for it to conduct its business and own its property except where the
failure to so qualify or be in good standing would not reasonably be expected to
result in a Material Adverse Effect.

            3.03 Due Authorization. The execution, delivery and performance by
the Guarantor of this Guarantee have been duly authorized by all necessary
corporate action, and do not and shall not require any further consents or
approvals which have not been obtained, or violate any provision of any
Applicable Law or breach any agreement presently in effect with respect to or
binding on the Guarantor or its properties except where such violations or
breach would not reasonably be expected to result in a Material Adverse Effect.

                     NRG South Central Generating Indenture
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            3.04 Binding Obligation. This Guarantee is a legal, valid and
binding obligation of the Guarantor, enforceable against it in accordance with
its terms, except as such enforceability may be limited in each case by
bankruptcy, insolvency, fraudulent conveyance, reorganization, moratorium or
similar laws affecting the enforceability of creditors' rights generally (and-to
the possible judicial application of foreign laws or governmental action
affecting the rights of creditors generally) and except as such enforceability
is subject to the application of general principles of equity (regardless of
whether the issue of enforceability is considered in a proceeding in equity or
at law), including without limitation (i) the possible unavailability of
specific performance, injunctive relief or any other equitable remedy and (ii)
concepts of materiality, reasonableness, good faith and fair dealing.

                                    ARTICLE 4
                                  MISCELLANEOUS

            4.01 Notices. All notices required or permitted under the terms and
provisions of this Guarantee shall be in writing (including by telex or fax) in
the English language delivered to the intended recipient. Any such notice shall
be effective when received if given in accordance with the provisions of Section
12.5 of the Indenture to the address set out beneath such party's signature to
this Guarantee.

            4.02 Severability. If any provision hereof is invalid, illegal or
unenforceable in any jurisdiction, then to the fullest extent permitted by law,
(i) the other provisions hereof shall remain in full force and effect in such
jurisdiction and shall be liberally construed in favor of the Bond Trustee and
the Holders in order to carry out the intentions of the parties hereto as nearly
as may be possible and (ii) the invalidity, illegality or unenforceability of
any provision hereof in any jurisdiction shall not affect the validity, legality
or enforceability of such provision in any other jurisdiction.

            4.03 Benefit of Guarantee. This Guarantee shall be binding upon and
inure to the benefit of the Guarantor, the Bond Trustee, the Holders and their
respective successors, transferees and assigns.

            4.04 Language. The language of this Guarantee is the English
language and no translation made or to be made hereof shall have any legal
validity.

            4.05 Governing Law. This Guarantee shall be governed by, and
construed in accordance with, the laws of the State of New York applicable to
agreements made and to be performed entirely within the State of New York,
without regard to principles of conflicts of law thereof (other than Section
5-1401 of the New York General Obligations Law) to the extent the application of
such principles would cause the application of the laws of any other
jurisdiction.

            4.06 Further Assurances. The Guarantor shall execute and deliver all
such instruments and take all such actions as may be reasonably necessary to
effectuate fully the purposes of this Guarantee.

            4.07 Term. This Guarantee shall terminate upon the earlier to occur
of indefeasible payment in full of the Guaranteed Obligation and reduction of
the Guaranteed Obligation to zero.

                     NRG South Central Generating Indenture
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            4.08 Amendments. Except as otherwise expressly provided in this
Guarantee, any provision of this Guarantee may be amended or modified only by an
instrument in writing signed by the parties hereto.

            4.09 Submission to Jurisdiction and Venue. Any legal action or
proceeding against the Guarantor with respect to this Guarantee shall be brought
and enforced in the U.S. state or federal courts located in the Borough of
Manhattan, The City of New York, New York, and, by execution and delivery of
this Guarantee, the Guarantor irrevocably accepts for itself and in respect of
its property, generally, irrevocably and unconditionally, the jurisdiction of
the aforesaid courts. A judgment, after exhaustion of all available appeals, in
any such action or proceeding shall be conclusive and binding upon the Guarantor
and may be enforced in any other jurisdiction by a suit upon such judgment, a
certified copy of which shall be conclusive evidence of the judgment.

            4.10 Appointment of Process Agent. The Guarantor irrevocably
designates, appoints and empowers CT Corporation System, with offices on the
date of this Guarantee at 111 Eighth Avenue, New York, New York 10011, as its
designee, appointee and agent with respect to any action or proceeding to
receive, accept and acknowledge for and on its behalf, and in respect of its
property, service of any and all legal process, summons, notices and documents
which may be served in any such action or proceeding and agrees that the failure
of any such agent to give any advice of any service of process to it shall not
impair or affect the validity of such service or of any judgment based thereon.
If for any reason such designee, appointee and agent shall cease to be available
to act as such, the Guarantor shall designate a new designee, appointee and
agent in the United States on the terms and for the purposes of this provision
reasonably satisfactory to the Trustee. The Guarantor further irrevocably
consents to the service of process out of any of the aforementioned courts in
any such action or proceeding by the mailing of copies thereof by registered or
certified mail, postage prepaid, to it, at its address set forth below, such
service to become effective 30 days after such mailing. Nothing in this
Guarantee shall affect the right of the Trustee to serve process or to commence
legal proceedings or otherwise proceed against the Guarantor in any other
jurisdiction in any other manner permitted by law. The Guarantor waives
irrevocably, to the extent permitted by law, any objection to the laying of
venue in New York, New York, and any claim of inconvenient forum in respect of
any such action in New York, New York to which it might otherwise be entitled in
any actions arising out of or based on this Guarantee.

                     NRG South Central Generating Indenture

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      IN WITNESS WHEREOF, each party has caused this Guarantee to be duly
executed and delivered by its officer thereto duly authorized as of the date
first above written.

NRG Energy, Inc.
Guarantor


By: /s/ Craig A. Mataczynski
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Title: Senior Vice President
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Address:  1221 Nicollet Mall
          Suite 700
          Minneapolis, Minnesota 55403

Attention: Vice President and General Counsel
Telephone: (612) 373-5300
Telecopy:  (612) 373-5392
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THE CHASE MANHATTAN BANK,
not in its individual capacity, but solely
as Bond Trustee


By: /s/ Annette M. Marsula
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       Annette M. Marsula
Title: Vice President
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Address:   The Chase Manhattan Bank
           Capital Markets Fiduciary Services
           450 W. 33rd Street, 15th Floor
           New York, New York 10001

Attention: Annette Marsula
           International and Project Finance Group
Telephone: (212) 946-7557
Telecopy:  (212) 946-8177