Letter of interest

March 21, 2007

XXX
Barranquilla, Colombia

Dear Mr. XXX:

We are pleased to convey the terms and conditions under which XXX or one or more of its subsidiaries (“Purchaser”) would acquire up to one hundred (100%) percent of the outstanding common stock of XXX (“Company”) (the “Transaction”) . Because of Purchaser’s relevant experience and understanding of the business of the Company,Purchaser is confident of its ability to consummate the Transaction quickly and efficiently.

The Transaction represents an important and exciting opportunity for the Purchaser to continue strategic efforts in the development of its energy infrastructure portfolio. Purchaser has a strong interest in the Company’s existing operations and particularly in the prospect of carrying out theproposed XXMW expansion of its generation capacity.

Purchase Price. We propose a transaction pursuant to which Purchaser would acquire up to one hundred (100%) percent of the outstanding shares of Company at a purchase price based on a Company enterprise value of US$_____. The purchase price would be payable in cash, not subject to financing. Such enterprise value includes the amount ofUS$________, which will be payable if the area where the generation assets of Company are located is granted Duty Free Zone (Zona Franca) status pursuant to applicable Colombian foreign trade regulations. Purchaser will work together with the Company towards obtaining this approval in the shortest period of time possible. We have arrived at such enterprise value for Company by using certain informationabout the business of the Company, its assets, debt and projected revenues and expenses provided to us by XXX. Such information is subject to confirmation during the proposed due diligence described below and the purchase price will be determined as a result thereof.

Principal Conditions to Consummation. In addition to the conditions to closing set forth in a definitive share purchase agreementto be negotiated and executed by Purchaser and the selling shareholders (the “Share Purchase Agreement”), Purchaser’s obligation to close the proposed Transaction would be conditioned upon the following matters:

a) satisfactory completion of due diligence by Purchaser prior to the execution of a definitive Share Purchase Agreement including, without limitation, an analysis of ForeignCorrupt Practices Act (FCPA) related issues and all legal and regulatory due diligence relating to the proposed Transaction. Subject to the obtainment of all reasonably required information and the access rights described in paragraph 5 below, Purchaser intends to complete its due diligence investigation of Company within forty five (45) days after the Effective Date (as defined in the last paragraphof this letter). An indicative list of due diligence items and required information is provided in Annex A to this letter;

b) approval of the Share Purchase Agreement by Purchaser’s Board of Directors.

Additionally, each party’s obligation to close the proposed Transaction would be conditioned upon the following matters:

x) negotiation and execution of a mutuallysatisfactory definitive Share Purchase Agreement, including appropriate representations, warranties, covenants, agreements and indemnities, and the satisfaction of all conditions contained therein; and

y) the filing and notifying of all necessary applications, documents and information with and the receipt of all approvals, consents, permits and waivers from all necessary governmentalauthorities and third parties as may be required by Colombian law or applicable agreements in order to consummate the Transaction.

3. Definitive Documentation. In connection with the Transaction, we would expect that Purchaser and the selling shareholders would enter into the Share Purchase Agreement and related documents, which would be mutually satisfactory in form and substance to the...