EX-4.2






TWENTIETH SUPPLEMENTAL INDENTURE FOR

ADDITIONAL SUBSIDIARY GUARANTEES




Twentieth Supplemental Indenture (this “Supplemental Indenture for Additional
Guarantees”), dated as of May 8, 2009, among Reliant Energy Services Texas, LLC, Reliant Energy
Texas Retail LLC, NRG Texas C&I Supply LLC and Langford Wind Power, LLC (each a “Guaranteeing
Subsidiary” and together the “Guaranteeing Subsidiaries”), each an indirect subsidiary of NRG
Energy, Inc., a Delaware corporation (the “Company”), the Company, the existing guarantors set
forth on the signature page hereto (the “Existing Guarantors”) 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 second supplemental indenture (the “Second Supplemental Indenture”), dated as of February 2,
2006, among the Company, the Guarantors named therein and the Trustee, providing for the original
issuance of an aggregate principal amount of $2,400 million of 7.375% Senior Notes due 2016 (the
“Initial Notes”), and, subject to the terms of the Indenture, future unlimited issuances of 7.375%
Senior Notes due 2016 (the “Additional Notes,” and together with the Initial Notes, the “Notes”), a
fourth supplemental indenture, dated as of March 14, 2006, among the Company, the Existing
Guarantors party thereto and the Trustee (the “Fourth Supplemental Indenture”), a sixth
supplemental indenture, dated as of April 28, 2006, among the Company, the Existing Guarantors
party thereto and the Trustee (the “Sixth Supplemental Indenture”), an eighth supplemental
indenture, dated as of November 13, 2006, among the Company, the Existing Guarantors party thereto
and the Trustee (the “Eight Supplemental Indenture”), an eleventh supplemental indenture, dated as
of July 19, 2007, among the Company, the Existing Guarantors party thereto and the Trustee (the
“Eleventh Supplemental Indenture”), a fourteenth supplemental indenture, dated as of August 28,
2007, among the Company, the Existing Guarantors and the Trustee (the “Fourteenth Supplemental
Indenture”) and a seventeenth supplemental indenture, dated as of April 28, 2009 among the Company,
the Existing Guarantors and the Trustee (together with the Base Indenture, the Second Supplemental
Indenture, the Fourth Supplemental Indenture, the Sixth Supplemental Indenture, the Eighth
Supplemental Indenture, the Eleventh Supplemental Indenture, and the Fourteenth Supplemental
Indenture, the “Indenture”);



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



WHEREAS, pursuant to Section 4.17 of the Second 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 Subsidiaries, 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 Indenture.



2. Agreement to be Bound; Guarantee. The Guaranteeing Subsidiaries hereby become parties to
the Second Supplemental Indenture as Guarantors 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 Subsidiaries hereby agree to be bound by all of the provisions of the Second
Supplemental Indenture applicable to a Guarantor and to perform all of the Obligations and
agreements of a Guarantor under the Second Supplemental Indenture. In furtherance of the
foregoing, the Guaranteeing Subsidiaries shall be deemed Guarantors for purposes of Article 10 of
the Second 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 Subsidiaries 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.



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.



Guaranteeing Subsidiary:



RELIANT ENERGY SERVICES TEXAS, LLC.



By: /s/ Christopher S. Sotos

Name: Christopher S. Sotos

Title: Treasurer





RELIANT ENERGY TEXAS RETAIL, LLC



By: /s/ Christopher S. Sotos

Name: Christopher S. Sotos

Title: Treasurer





NRG TEXAS C&I SUPPLY LLC



By: /s/ Christopher S. Sotos

Name: Christopher S. Sotos

Title: Treasurer





LANGFORD WIND POWER, LLC



	 	 	 
	By: /s/ Christopher S. Sotos

	Name:

Title:

	 	Christopher S. Sotos

Treasurer






Issuer:



NRG ENERGY, INC.



	 	 	 
	By: /s/ Christopher S. Sotos

	Name:

Title:

	 	Christopher S. Sotos

Vice President & 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


LAKE ERIE PROPERTIES INC.


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 CEDAR BAYOU DEVELOPMENT COMPANY,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 LLC


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 TEXAS HOLDING INC.


NRG TEXAS POWER 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 LP, 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/ Christopher S. Sotos

Name: Christopher S. Sotos

Title: Treasurer





GCP FUNDING COMPANY, LLC

TEXAS GENCO LP, LLC



By: /s/ Christopher S. Sotos

Name: Christopher S. Sotos

Title: Manager





NRG SOUTH TEXAS LP

By: Texas Genco GP, LLC, its General Partner



By: /s/ Christopher S. Sotos

Name: Christopher S. Sotos

Title: Vice President & Treasurer





TEXAS GENCO SERVICES, LP

By: New Genco GP, LLC, its General Partner



By: /s/ Christopher S. Sotos

Name: Christopher S. Sotos

Title: Vice President & Treasurer





NRG CONSTRUCTION LLC



By: /s/ Rachel Smith

Name: Rachel Smith

Title: Treasurer







Attest:



	 	 	 
	/s/ Tanuja M. Dehne

	Name:

Title:

	 	Tanuja M. Dehne

Corporate Secretary






LAW DEBENTURE TRUST COMPANY OF NEW YORK,



as Trustee



By: /s/ James D. Heaney

Name: James D. Heaney

Title: Managing Director