EX-4.3






TWELFTH SUPPLEMENTAL INDENTURE




ADDITIONAL SUBSIDIARY GUARANTEES




Supplemental Indenture (this “Supplemental Indenture for Additional Guarantees”),
dated as of July 19, 2007, among NRG Texas Power LLC (the “Guaranteeing Subsidiary”), a subsidiary
of NRG Energy, Inc. (or its permitted successor), a Delaware corporation (the “Company”), the
Company, the other Guarantors (as defined in the Indenture referred to herein) and Law Debenture
Trust Company of New York, as trustee under the indentures referred to below (the “Trustee”).



W I T N E S S E T H




WHEREAS, the Company has heretofore executed and delivered to the Trustee an indenture (the
“Base Indenture”), dated as of February 2, 2006, between the Company and the Trustee, as amended by
a ninth supplemental indenture (the “Ninth Supplemental Indenture” and, together with the Base
Indenture, the “Indenture”), dated as of November 21, 2006, among the Company, the Guarantors named
therein and the Trustee, providing for the original issuance of an aggregate principal amount of
$1,100 million of 7.375% Senior Notes due 2017 (the “Initial Notes”), and, subject to the terms of
the Ninth Supplemental Indenture, future unlimited issuances of 7.375% Senior Notes due 2017 (the
“Additional Notes,” and together with the Initial Notes, the “Notes”);



WHEREAS, the Indenture provides that under certain circumstances the Guaranteeing Subsidiary
shall execute and deliver to the Trustee a supplemental indenture pursuant to which the
Guaranteeing Subsidiary shall unconditionally guarantee all of the Company’s Obligations under the
Notes and the Indenture (the “Subsidiary Guarantee”); and



WHEREAS, pursuant to Section 4.17 of the Ninth Supplemental Indenture, the Trustee, the
Company and the other Guarantors are authorized and required to execute and deliver this
Supplemental Indenture for Additional Guarantees.



NOW THEREFORE, in consideration of the foregoing and for good and valuable consideration, the
receipt of which is hereby acknowledged, the Guaranteeing Subsidiary, the Trustee, the Company and
the other Guarantors mutually covenant and agree for the equal and ratable benefit of the Holders
of the Notes as follows:



1. Capitalized Terms. Unless otherwise defined in this Supplemental Indenture for Additional
Guarantees, capitalized terms used herein without definition shall have the meanings assigned to
them in the Ninth Supplemental Indenture.



2. Agreement to be Bound; Guarantee. The Guaranteeing Subsidiary hereby becomes a party to
the Ninth Supplemental Indenture as a Guarantor and as such will have all of the rights and be
subject to all of the Obligations and agreements of a Guarantor under the Indenture. The
Guaranteeing Subsidiary hereby agrees to be bound by all of the provisions of the Ninth
Supplemental Indenture applicable to a Guarantor and to perform all of the Obligations and
agreements of a Guarantor under the Ninth Supplemental Indenture. In furtherance of the foregoing,
the Guaranteeing Subsidiary shall be deemed a Guarantor for purposes of Article 10 of the Ninth
Supplemental Indenture, including, without limitation, Section 10.02 thereof.



3. NEW YORK LAW TO GOVERN. THE INTERNAL LAW OF THE STATE OF NEW YORK SHALL GOVERN AND BE USED
TO CONSTRUE THIS SUPPLEMENTAL INDENTURE FOR ADDITIONAL GUARANTEES BUT WITHOUT GIVING EFFECT TO
APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT THE APPLICATION OF THE LAWS OF ANOTHER
JURISDICTION WOULD BE REQUIRED THEREBY.



4. Counterparts. The parties may sign any number of copies of this Supplemental Indenture for
Additional Guarantees. Each signed copy shall be an original, but all of them together represent
the same agreement.



5. Effect of Headings. The Section headings herein are for convenience only and shall not
affect the construction hereof.



6. The Trustee. The Trustee shall not be responsible in any manner whatsoever for or in
respect of the validity or sufficiency of this Supplemental Indenture for Additional Guarantees or
for or in respect of the recitals contained herein, all of which recitals are made solely by the
Guaranteeing Subsidiary and the Company.



7. Ratification of Indenture; Supplemental Indenture for Additional Guarantees Part of
Indenture. Except as expressly amended hereby, the Indenture is in all respects ratified and
confirmed and all the terms, conditions and provisions thereof shall remain in full force and
effect. This Supplemental Indenture for Additional Guarantees shall form a part of the Indenture
for all purposes, and every Holder of Notes heretofore or hereafter authenticated and delivered
shall by bound hereby.



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IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture for
Additional Guarantees to be duly executed and attested, all as of the date first above written.



Dated: July 19, 2007




NRG Texas Power LLC




By:    /s/ Clint Freeland

Name: Clint Freeland

Title: Vice President and Treasurer





Issuer:


NRG ENERGY, INC.




By:    /s/ Clint Freeland

Name: Clint Freeland

Title: Vice President and Treasurer





Existing Guarantors:




ARTHUR KILL POWER LLC






ASTORIA GAS TURBINE POWER LLC


BERRIANS I GAS TURBINE POWER LLC


BIG CAJUN II UNIT 4 LLC


CABRILLO POWER I LLC


CABRILLO POWER II LLC


CHICKAHOMINY RIVER ENERGY CORP.


COMMONWEALTH ATLANTIC POWER LLC


CONEMAUGH POWER LLC


CONNECTICUT JET POWER LLC


DEVON POWER LLC


DUNKIRK POWER LLC


EASTERN SIERRA ENERGY COMPANY


EL SEGUNDO POWER LLC


EL SEGUNDO POWER II LLC


HANOVER ENERGY COMPANY


HOFFMAN SUMMIT WIND PROJECT, LLC


HUNTLEY IGCC LLC


HUNTLEY POWER LLC


INDIAN RIVER IGCC LLC


INDIAN RIVER OPERATIONS INC.


INDIAN RIVER POWER LLC


JAMES RIVER POWER LLC


KAUFMAN COGEN LP


KEYSTONE POWER LLC


LOUISIANA GENERATING LLC


MIDDLETOWN POWER LLC


MONTVILLE IGCC LLC


MONTVILLE POWER LLC


NEO CHESTER-GEN LLC


NEO CORPORATION


NEO FREEHOLD-GEN LLC


NEO POWER SERVICES INC.


NEW GENCO GP, LLC


NORWALK POWER LLC


NRG AFFILIATE SERVICES INC.


NRG ARTHUR KILL OPERATIONS INC.


NRG ASIA-PACIFIC, LTD.


NRG ASTORIA GAS TURBINE OPERATIONS, INC.


NRG BAYOU COVE LLC


NRG CABRILLO POWER OPERATIONS INC.


NRG CADILLAC OPERATIONS INC.


NRG CALIFORNIA PEAKER OPERATIONS LLC


NRG CONNECTICUT AFFILIATE SERVICES INC.


NRG DEVON OPERATIONS INC.


NRG DUNKIRK OPERATIONS INC.


NRG EL SEGUNDO OPERATIONS INC.


NRG GENERATION HOLDINGS, INC.


NRG HUNTLEY OPERATIONS INC.


NRG INTERNATIONAL LLC


NRG KAUFMAN LLC


NRG MESQUITE LLC


NRG MIDATLANTIC AFFILIATE SERVICES INC.


NRG MIDDLETOWN OPERATIONS INC.


NRG MONTVILLE OPERATIONS INC.


NRG NEW JERSEY ENERGY SALES LLC


NRG NEW ROADS HOLDINGS LLC


NRG NORTH CENTRAL OPERATIONS INC.


NRG NORTHEAST AFFILIATE SERVICES INC.


NRG NORWALK HARBOR OPERATIONS INC.


NRG OPERATING SERVICES, INC.


NRG OSWEGO HARBOR POWER OPERATIONS INC.


NRG POWER MARKETING INC.


NRG ROCKY ROAD LLC


NRG SAGUARO OPERATIONS INC.


NRG SOUTH CENTRAL AFFILIATE SERVICES INC.


NRG SOUTH CENTRAL GENERATING LLC


NRG SOUTH CENTRAL OPERATIONS INC.


NRG TEXAS LLC


NRG WEST COAST LLC


NRG WESTERN AFFILIATE SERVICES INC.


OSWEGO HARBOR POWER LLC


PADOMA WIND POWER, LLC


SAGUARO POWER LLC


SAN JUAN MESA WIND PROJECT II, LLC


SOMERSET OPERATIONS INC.


SOMERSET POWER LLC


TEXAS GENCO FINANCING CORP.


TEXAS GENCO GP, LLC


TEXAS GENCO HOLDINGS, INC.


TEXAS GENCO OPERATING SERVICES, LLC


VIENNA OPERATIONS INC.


VIENNA POWER LLC


WCP (GENERATION) HOLDINGS LLC


WEST COAST POWER LLC




By:    /s/ Clint Freeland

Name: Clint Freeland

Title: Treasurer





LAKE ERIE PROPERTIES INC.




By:    /s/ Clint Freeland

Name: Clint Freeland

Title: Vice President and Treasurer





GCP FUNDING COMPANY, LLC






TEXAS GENCO LP, LLC




By:    /s/ Clint Freeland  

Name: Clint Freeland

Title: Manager





NRG SOUTH TEXAS LP


By: Texas Genco GP, LLC, its General Partner




By:    /s/ Clint Freeland 

Name: Clint Freeland

Title: Vice President and Treasurer





TEXAS GENCO SERVICES, LP




By: New Genco GP, LLC, its General Partner




By:    /s/ Clint Freeland  

Name: Clint Freeland

Title: Vice President and Treasurer




Attest:



/s/ Tanuja M. Dehne 

Name: Tanuja M. Dehne

Title: Corporate Secretary





LAW DEBENTURE TRUST COMPANY OF NEW YORK,




as Trustee




By:     /s/ James D. Heaney

Name: James D. Heaney

Title: Vice President





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