**Exhibit 4.18**

** **

**SECONDSUPPLEMENTAL INDENTURE ADDITIONAL SUBSIDIARY GUARANTEES**

SECOND SUPPLEMENTAL INDENTURE(this “*Supplemental Indenture for AdditionalGuarantees*”), dated as of September 21, 2006, amongReliant Energy Power Supply, LLC (the “*GuaranteeingSubsidiary*”), a subsidiary of Reliant Energy, Inc. (or its permittedsuccessor), a Delaware corporation (the “*Company*”),the Company, the other Guarantors (as defined in the Indenture referred toherein) and Wilmington Trust Company, as trustee under the indentures referredto below (the “*Trustee*”).

**WITNESSETH**

WHEREAS, the Company has heretofore executed anddelivered to the Trustee a senior indenture (the “*Base Indenture*”), dated as of December 22, 2004, between theCompany and the Trustee, as amended by a first supplemental indenture (the *“Supplemental Indenture”* and, together with the BaseIndenture, the *“Indenture”*), dated as ofDecember 22, 2004, among the Company, the Guarantors named therein and theTrustee, providing for the original issuance of an aggregate principal amountof $750.0 million of 6.75% Senior Secured Notes due 2014 (the “*Initial Note*s”), and, subject to the termsof the Supplemental Indenture, future unlimited issuances of 6.75% SeniorSecured Notes due 2014 (the “*AdditionalNotes*,” and together with the Initial Notes, the “*Notes*”);

WHEREAS, the Indenture provides that under certaincircumstances the Guaranteeing Subsidiary shall execute and deliver to theTrustee a supplemental indenture pursuant to which the Guaranteeing Subsidiaryshall unconditionally guarantee all of the Company’s Obligations under theNotes and the Indenture (the “*Note Guarantee*”);and

WHEREAS, pursuant to Section 9.01 of the Supplemental Indenture,the Trustee, the Company and the other Guarantors are authorized to execute anddeliver this Supplemental Indenture for Additional Guarantees.

NOW THEREFORE, in consideration of the foregoing andfor good and valuable consideration, the receipt of which is herebyacknowledged, the Guaranteeing Subsidiary, the Trustee, the Company and theother Guarantors mutually covenant and agree for the equal and ratable benefitof the Holders of the Notes as follows:

1.             *Capitalized Terms*.  Unless otherwise defined in this SupplementalIndenture for Additional Guarantees, capitalized terms used herein withoutdefinition shall have the meanings assigned to them in the Supplemental Indenture.

2.             *Agreement to be Bound;Guarantee*.  The GuaranteeingSubsidiary hereby becomes a party to the Supplemental Indenture as a Guarantorand as such will have all of the rights and be subject to all of theObligations and agreements of a Guarantor under the Indenture.  The Guaranteeing Subsidiary hereby agrees tobe bound by all of the provisions of the Supplemental Indenture applicable to aGuarantor and to perform all of the Obligations and agreements of a Guarantorunder the Supplemental Indenture.  Infurtherance of the foregoing, the Guaranteeing Subsidiary shall be deemed aGuarantor for purposes of Article 12 of the Supplemental Indenture, including,without limitation, Section 12.02 thereof.

 

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3.             ***NEW YORK LAW TO GOVERN*. THE INTERNAL LAW OF THE STATE OF NEW YORK SHALL GOVERN AND BE USED TOCONSTRUE THIS SUPPLEMENTAL INDENTURE FOR ADDITIONAL GUARANTEES BUT WITHOUTGIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THATTHE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY.**

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

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

6.             *The Trustee*.  The Trustee shall not be responsible in anymanner whatsoever for or in respect of the validity or sufficiency of thisSupplemental Indenture for Additional Guarantees or for or in respect of therecitals contained herein, all of which recitals are made solely by theGuaranteeing Subsidiary and the Company.

7.             *Ratification of Indenture;Supplemental Indenture for Additional Guarantees Part of Indenture*.  Except as expressly amended hereby, theIndenture 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 AdditionalGuarantees shall form a part of the Indenture for all purposes, and everyHolder of Notes heretofore or hereafter authenticated and delivered shall bybound hereby.

 

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

Dated: September 21, 2006.
|   | RELIANT ENERGY POWER SUPPLY, LLC |
|--------|----------------------------------|
|   |                             |   |
|   | By:                              | /s/ Lloyd A. Whittington |
|   | Name:                            | Lloyd A. Whittington |
|   | Title:                           | Vice President and Treasurer |
|   |                             |   |
|   | RELIANT ENERGY, INC.             |
|   |                             |   |
|   | By:                              | /s/ Andrew C. Johannesen |
|   | Name:                            | Andrew C. Johannesen |
|   | Title:                           | Vice President and Asst. Treasurer |

 

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|        | RELIANT ENERGY ASSET  MANAGEMENT, LLC      |
|--------|--------------------------------------------|
|   | RELIANT ENERGY BROADBAND,  INC.            |
|   | RELIANT ENERGY CALIFORNIA  HOLDINGS, LLC   |
|   | RELIANT ENERGY  COMMUNICATIONS, INC.       |
|   | RELIANT ENERGY COOLWATER,  INC.            |
|   | RELIANT ENERGY CORPORATE  SERVICES, LLC    |
|   | RELIANT ENERGY ELLWOOD,  INC.              |
|   | RELIANT ENERGY ETIWANDA,  INC.             |
|   | RELIANT ENERGY FLORIDA,  LLC               |
|   | RELIANT ENERGY KEY/CON  FUELS, LLC         |
|   | RELIANT ENERGY MANDALAY,  INC.             |
|   | RELIANT ENERGY NORTHEAST  GENERATION, INC. |
|   | RELIANT ENERGY NORTHEAST  HOLDINGS, INC.   |
|   | RELIANT ENERGY ORMOND  BEACH, INC.         |
|   | RELIANT ENERGY POWER  GENERATION, INC.     |
|   | RELIANT ENERGY RETAIL  HOLDINGS, LLC       |
|   | RELIANT ENERGY SABINE  (TEXAS), INC.       |
|   | RELIANT ENERGY SERVICES  DESERT BASIN, LLC |
|   | RELIANT ENERGY SERVICES  MID-STREAM, LLC   |
|   | RELIANT ENERGY SEWARD, LLC                 |
|   | RELIANT ENERGY TRADING  EXCHANGE, INC.     |
|   | RELIANT ENERGY VENTURES,  INC.             |
|   | RELIANT ENERGY WHOLESALE  GENERATION, LLC  |
|   |                                       |   |
|        | By:                                        | /s/ Andrew C. Johannesen |
|   | Name:                                      | Andrew C. Johannesen |
|   | Title:                                     | Assistant Treasurer of the corporations and limited  liability companies, and of the general partners of the limited partnerships,  listed above |

 

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|   | RELIANT ENERGY  SERVICES, INC.          |
|--------|-----------------------------------------|
|   |                                    |   |
|   | By:                                     | /s/ Andrew C. Johannesen |
|   | Name:                                   | Andrew C. Johannesen |
|   | Title:                                  | Vice President and Treasurer |
|   |                                    |   |
|   | RELIANT ENERGY RETAIL  SERVICES, LLC    |
|   | RELIANT ENERGY ELECTRIC  SOLUTIONS, LLC |
|   | RELIANT ENERGY SOLUTIONS  EAST, LLC     |
|   |                                    |   |
|   | By:                                     | /s/ Lloyd A. Whittington |
|   | Name:                                   | Lloyd A. Whittington |
|   | Title:                                  | Vice President and Treasurer of the limited liability  companies listed above |

 

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|        | RELIANT ENERGY CAPTRADES  HOLDING CORP. |
|--------|-----------------------------------------|
|   | RELIANT ENERGY SABINE  (DELAWARE), INC. |
|   |                                    |   |
|        | By:                                     | /s/ Patricia F. Genzel |
|   | Name:                                   | Patricia F. Genzel |
|   | Title:                                  | President |

 

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|        | WILMINGTON TRUST COMPANY,  as Trustee |
|--------|---------------------------------------|
|   |                                  |   |
|        | By:                                   | /s/ Michael G. Oller |
|   | Authorized Signatory                  |

 

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