SECOND AMENDMENT TO MEMBERSHIP INTEREST PURCHASE AGREEMENT

Exhibit 10.39

SECOND AMENDMENT TO MEMBERSHIP INTEREST PURCHASE AGREEMENT

THIS SECOND AMENDMENT TO MEMBERSHIP INTEREST PURCHASE AGREEMENT (this “ Amendment ”) is made and entered into as of December 29, 2006, by and between DQE FINANCIAL CORP., a Delaware corporation (“ Seller ”), and BLUE WOLF ENERGY HOLDINGS LLC, a Delaware limited liability company (“ Purchaser ”).

RECITALS:

WHEREAS, Seller and Purchaser are parties to that certain Membership Interest Purchase Agreement dated as of November 22, 2006 relating to Montauk Energy Capital, LLC, as amended by First Amendment to Membership Interest Purchase Agreement, dated December 29, 2006 (collectively, the “ Purchase Agreement ”);

WHEREAS, Seller and Purchaser acknowledge that as of the date hereof that only $60,000,000 of the $101,837,726 of the Preliminary Purchase Price has been paid by Purchaser to Seller, through no fault of either party, but due to the delay in the wire transfer system;

WHEREAS, Purchaser has agreed to execute and deliver to Seller a demand secured promissory note in the form of Exhibit “A” attached hereto and made a part hereof (the “ Purchaser Note ”), to evidence Purchaser’s irrevocable and unconditional obligation to pay to Seller $41,837,726 (the “ Remaining Cash Purchase Price Payable ”), being the remaining portion of the Preliminary Purchase Price due from Purchaser to Seller on the date hereof; and

WHEREAS, Purchaser has received the Remaining Cash Purchase Price Payable from its lender in Citibank Account No. 376-43819-1-3-552 (the “ BWEH Funding Account ”), and Purchaser has provided Citibank, N.A. with irrevocable instructions to wire the Remaining Cash to Purchaser on January 2, 2007.

NOW, THEREFORE, in consideration of the mutual promises and covenants herein contained, the Parties, intending to be legally bound hereby, agree as follows:

1. Defined Terms . Capitalized terms used but not defined herein have the meanings ascribed to them in the Purchase Agreement.

2. Waiver of Requirement to Pay Remaining Cash Purchase Price Payable on the Closing Date . Notwithstanding anything in the Purchase Agreement to the contrary, including, but not limited to Section 2.5(b)(i) of the Purchase Agreement and subject to Purchaser’s execution and delivery of the Purchaser Note to Seller on the date hereof, the Purchaser and Seller agree that all conditions precedent to the effectiveness of purchase and sale of the Purchased Interests as of December 29, 2006 have been satisfied upon execution and delivery by Purchaser of the Purchaser Note and Purchaser and Seller hereby waive any requirement for the Remaining Cash Purchase Price Payable to be paid on the Closing Date (December 29, 2006).

3. Grant of Security Interest . In order to secure Purchaser’s obligation to pay the Remaining Cash Purchase Price Payable as evidenced by the Purchaser Note, Purchaser hereby grants to Seller a first and only lien and security interest in the BWEH Funding Account.

Purchaser further agrees and acknowledges that Purchaser has granted no other lien on, or security interest in, the BWEH Funding Account, and that all assets of Purchaser are free and clear of any liens, claims and encumbrances.

[Signature page follows]

IN WITNESS WHEREOF, the Parties have executed and delivered this Amendment as of the date first above written.

IN WITNESS WHEREOF, the Parties have executed and delivered this Amendment as of the date first above written.

EXHIBIT “A”

PURCHASER NOTE

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