Exhibit 10.31

Execution Copy

SUB-ASSIGNMENT AGREEMENT

SUB-ASSIGNMENT, dated as of December 7, 2001, between THE BANK OF NEW YORK (as successor to United States Trust Company), not in its individual
capacity but solely as Collateral Agent for the Owner Lessors (as defined below), as assignee ("Collateral Agent"); EME HOMER CITY GENERATION L.P., a
Pennsylvania limited partnership, as assignor ("Homer City"); EDISON MISSION MARKETING & TRADING, INC., a California corporation
("EMMT"), as consenting party; and EDISON MISSION ENERGY FUEL SERVICES, INC., a California corporation as consenting party; ("EMEFS", and
together with EMMT, the "Consenting Parties").

W I T N E S S E T H

WHEREAS, contemporaneously herewith, Homer City will enter into a transaction pursuant to the Participation Agreements listed on Exhibit Aby and among EME Homer City, each of the Owner Lessors party thereto (the "Owner
Lessors"), Wells Fargo Bank Northwest, National Association, not in its individual capacity but solely as Owner Manager, the Owner Participant, Homer City Funding LLC, as
Lender, the Lease Indenture Trustee, the Security Agent and The Bank of New York, not in its individual capacity but solely as Bondholder Trustee (as amended, modified and supplemented and in effect
from time to time, collectively, the "Participation Agreements") whereby Homer City will sell undivided interests in its generating assets to the Owner
Lessors and the Owner Lessors will lease such undivided interests in its generating assets back to Homer City under the Facility Leases. Capitalized terms used but not defined herein shall have the
meanings assigned to them in Appendix A to the Participation Agreements.

WHEREAS,
pursuant to the Ownership and Operation Agreement, the Collateral Agent has agreed to serve as a common collateral agent for the Owner Lessors.

WHEREAS,
in consideration of the transactions contemplated by the Participation Agreements, Homer City has agreed to, and simultaneously herewith will, assign, for the term of the
Facility Site Leases, all of its rights and interest in, to and under those certain Material Project Agreements more fully described onExhibit Bhereto (the "Assigned Agreements") to the Collateral Agent for the benefit of the Owner Lessors pursuant to an assignment agreement (the
"Assignment Agreement").

WHEREAS,
for the term of the Facility Leases, the Owner Lessors have agreed to subassign all their right, title and interest in, to and under the Assigned Agreements back to Homer City.

NOW,
THEREFORE, in consideration of the representations, warranties, covenants and agreements contained herein, the parties hereto agree as follows:



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IN
WITNESS WHEREOF, the parties have signed this Sub-Assignment Agreement as of the date first above written.

|EME HOMER CITY GENERATION L.P.                                                                                                                                 |  |                                                         
|-------------------------------------------------------------------------------------------------------------------------------------------------------------- |  | --------------------------------------------------------
|By:                                                                                                                                                            |  | Mission Energy Westside, Inc.
        as General Partner
|By:                                                                                                                                                            |  | /s/ John P. Finneran                                    
|                                                                                                                                                               |  | Name:                                                   
|                                                                                                                                                               |  | Title:                                                  
|THE BANK OF NEW YORK,
        not in its individual capacity, but solely as
        Collateral Agent for the Owner Lessors                                     |  |                                                         
|By:                                                                                                                                                            |  | /s/ Christopher J. Grell                                
|                                                                                                                                                               |  | Name:                                                   
|                                                                                                                                                               |  | Title:                                                  
|EDISON MISSION MARKETING & TRADING,
        INC., a California corporation (with respect to the
        Energy Sales Agreement and NOx Agreement
        only) |  |                                                         
|By:                                                                                                                                                            |  | /s/ David C. Goss                                       
|                                                                                                                                                               |  | Name:                                                   
|                                                                                                                                                               |  | Title:                                                  
|EDISON MISSION ENERGY FUEL
        SERVICES, INC., a California corporation (with
        respect to the Fuel Supply Agreement only)                           |  |                                                         
|By:                                                                                                                                                            |  | /s/ Steven D. Eisenberg                                 
|                                                                                                                                                               |  | Name:                                                   
|                                                                                                                                                               |  | Title:                                                  

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Exhibit A        Participation Agreements

1.    The
Participation Agreement dated as of December 7, 2001 by and among EME Homer City Generation, L.P., a Pennsylvania limited partnership, as Facility Lessee;
Homer City OL1 LLC, a Delaware limited liability company, as Owner Lessor; Wells Fargo Bank Northwest, National Association, both in its individual capacity and solely as Owner Manager; General
Electric Capital Corporation, a Delaware corporation, as Owner Participant; Homer City Funding LLC, a Delaware limited liability company, as Lender; The Bank of New York (as successor to United States
Trust Company of New York), both in its individual capacity and solely as Lease Indenture Trustee; The Bank of New York (as successor to United States Trust Company of New York), both in its
individual capacity and solely as Security Agent; and The Bank of New York (as successor to United States Trust Company of New York), both in its individual capacity and solely as Bondholder Trustee.

2.    The
Participation Agreement dated as of December 7, 2001 by and among EME Homer City Generation, L.P., a Pennsylvania limited partnership, as Facility Lessee;
Homer City OL2 LLC, a Delaware limited liability company, as Owner Lessor; Wells Fargo Bank Northwest, National Association, both in its individual capacity and solely as Owner Manager; General
Electric Capital Corporation, a Delaware corporation, as Owner Participant; Homer City Funding LLC, a Delaware limited liability company, as Lender; The Bank of New York (as successor to United States
Trust Company of New York), both in its individual capacity and solely as Lease Indenture Trustee; The Bank of New York (as successor to United States Trust Company of New York), both in its
individual capacity and solely as Security Agent; and The Bank of New York (as successor to United States Trust Company of New York), both in its individual capacity and solely as Bondholder Trustee.

3.    The
Participation Agreement dated as of December 7, 2001 by and among EME Homer City Generation, L.P., a Pennsylvania limited partnership, as Facility Lessee;
Homer City OL3 LLC, a Delaware limited liability company, as Owner Lessor; Wells Fargo Bank Northwest, National Association, both in its individual capacity and solely as Owner Manager; General
Electric Capital Corporation, a Delaware corporation, as Owner Participant; Homer City Funding LLC, a Delaware
limited liability company, as Lender; The Bank of New York (as successor to United States Trust Company of New York), both in its individual capacity and solely as Lease Indenture Trustee; The Bank of
New York (as successor to United States Trust Company of New York), both in its individual capacity and solely as Security Agent; and The Bank of New York (as successor to United States Trust Company
of New York), both in its individual capacity and solely as Bondholder Trustee.

4.    The
Participation Agreement dated as of December 7, 2001 by and among EME Homer City Generation, L.P., a Pennsylvania limited partnership, as Facility Lessee;
Homer City OL4 LLC, a Delaware limited liability company, as Owner Lessor; Wells Fargo Bank Northwest, National Association, both in its individual capacity and solely as Owner Manager; General
Electric Capital Corporation, a Delaware corporation, as Owner Participant; Homer City Funding LLC, a Delaware limited liability company, as Lender; The Bank of New York (as successor to United States
Trust Company of New York), both in its individual capacity and solely as Lease Indenture Trustee; The Bank of New York (as successor to United States Trust Company of New York), both in its
individual capacity and solely as Security Agent; and The Bank of New York (as successor to United States Trust Company of New York), both in its individual capacity and solely as Bondholder Trustee.

5.    The
Participation Agreement dated as of December 7, 2001 by and among EME Homer City Generation, L.P., a Pennsylvania limited partnership, as Facility Lessee;
Homer City OL5 LLC, a Delaware limited liability company, as Owner Lessor; Wells Fargo Bank Northwest, National Association, both in its individual capacity and solely as Owner Manager; General
Electric Capital Corporation, a Delaware corporation, as Owner Participant; Homer City Funding LLC, a Delaware limited liability company, as Lender; The Bank of New York (as successor to United States
Trust

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Company of New York), both in its individual capacity and solely as Lease Indenture Trustee; The Bank of New York (as successor to United States Trust Company of New York), both in its individual
capacity and solely as Security Agent; and The Bank of New York (as successor to United States Trust Company of New York), both in its individual capacity and solely as Bondholder Trustee.

6.    The
Participation Agreement dated as of December 7, 2001 by and among EME Homer City Generation, L.P., a Pennsylvania limited partnership, as Facility Lessee;
Homer City OL6 LLC, a Delaware limited liability company, as Owner Lessor; Wells Fargo Bank Northwest, National Association, both in its individual capacity and solely as Owner Manager; General
Electric Capital Corporation, a Delaware corporation, as Owner Participant; Homer City Funding LLC, a Delaware limited liability company, as Lender; The Bank of New York (as successor to United States
Trust Company of New York), both in its individual capacity and solely as Lease Indenture Trustee; The Bank of New York (as successor to United States Trust Company of New York), both in its
individual capacity and solely as Security Agent; and The Bank of New York (as successor to United States Trust Company of New York), both in its individual capacity and solely as Bondholder Trustee.

7.    The
Participation Agreement dated as of December 7, 2001 by and among EME Homer City Generation, L.P., a Pennsylvania limited partnership, as Facility Lessee;
Homer City OL7 LLC, a Delaware limited liability company, as Owner Lessor; Wells Fargo Bank Northwest, National Association, both in its individual capacity and solely as Owner Manager; General
Electric Capital
Corporation, a Delaware corporation, as Owner Participant; Homer City Funding LLC, a Delaware limited liability company, as Lender; The Bank of New York (as successor to United States Trust Company of
New York), both in its individual capacity and solely as Lease Indenture Trustee; The Bank of New York (as successor to United States Trust Company of New York), both in its individual capacity and
solely as Security Agent; and The Bank of New York (as successor to United States Trust Company of New York), both in its individual capacity and solely as Bondholder Trustee.

8.    The
Participation Agreement dated as of December 7, 2001 by and among EME Homer City Generation, L.P., a Pennsylvania limited partnership, as Facility Lessee;
Homer City OL8 LLC, a Delaware limited liability company, as Owner Lessor; Wells Fargo Bank Northwest, National Association, both in its individual capacity and solely as Owner Manager; General
Electric Capital Corporation, a Delaware corporation, as Owner Participant; Homer City Funding LLC, a Delaware limited liability company, as Lender; The Bank of New York (as successor to United States
Trust Company of New York), both in its individual capacity and solely as Lease Indenture Trustee; The Bank of New York (as successor to United States Trust Company of New York), both in its
individual capacity and solely as Security Agent; and The Bank of New York (as successor to United States Trust Company of New York), both in its individual capacity and solely as Bondholder Trustee.

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Exhibit B  Assigned Agreements

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