EXHIBIT 2.4ASSIGNMENT AGREEMENT     This Assignment (this “Assignment”) is entered into effective as of September 16, 2005(the “Effective Date”), by and between Macquarie Infrastructure Company Inc., a Delawarecorporation (“Assignor”) and Macquarie Gas Holdings LLC, a Delaware limited liabilitycompany (“Assignee”).Recitals     Macquarie Investment Holdings Inc. (“MIHI”) entered into a Purchase Agreement (the“Purchase Agreement”) dated as of August 2, 2005, as amended by a First Amendment toPurchase Agreement dated as of August 17, 2005, by and between k1 Ventures Limited, K-1 HGCInvestment, L.L.C. and MIHI; and     MIHI assigned its rights and obligations under the Purchase Agreement to Assignor pursuant tothat certain Assignment Agreement dated as of August 17, 2005 by and between MIHI and Assignor; and     Assignor has agreed to assign its rights and obligations under the Purchase Agreement toAssignee and Assignee has agreed to acquire such rights and obligations.     NOW THEREFORE, in consideration of the premises and for other good and valuable consideration,the receipt and sufficiency of which is hereby acknowledged, Assignor and Assignee hereby agree asfollows:     (1) Assignment. Effective as of the Effective Date, Assignor does hereby transfer and assignto Assignee all of Assignor’s rights and obligations under the Purchase Agreement.     (2) Assumption. Effective as of the Effective Date, Assignee hereby assumes all of theobligations of Assignor as “Buyer” under the Purchase Agreement and agrees to be bound by the termsof the Purchase Agreement.     (3) Indemnification. Assignee agrees to indemnify and hold harmless Assignor, its affiliatesand each of their respective officers, directors and employees, from and against any costs,judgments, claims, liabilities, damages, losses, penalties and expenses of any kind (includingreasonable attorneys’ fees and expenses of investigation) arising out of or relating to Assignee’srights and obligations as “Buyer” under the Purchase Agreement.     (4) Joinder Agreement. To evidence its acceptance of the assignment of all of Assignees rightsand obligations under the Purchase Agreement, and to become a party to the Purchase Agreement,Assignee agrees to execute a Joinder Agreement in the form attached to the Purchase Agreement asExhibit E.
 

 
     (5) CHOICE OF LAW. THIS ASSIGNMENT SHALL BE GOVERNED BY AND CONSTRUED, ENFORCED AND PERFORMEDIN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.     (6) Further assurances. Assignor and Assignee will promptly, upon reasonable request and atthe sole expense of the requesting party, execute and deliver all such other documents and takesuch other actions as may be reasonably necessary to effectuate the intent and provisions of thisAssignment.
 

 
     IN WITNESS WHEREOF, Assignor and Assignee each respectively has caused this Assignment to beexecuted by its undersigned officers.       ASSIGNOR:       MACQUARIE INFRASTRUCTURE COMPANY INC.  (d/b/a Macquarie Infrastructure Company (US))       By: /s/ Peter Stokes       Name: Peter Stokes  Title: Chief Executive Officer       ASSIGNEE:       MACQUARIE GAS HOLDINGS LLC       By: /s/ Peter Stokes       Name: Peter Stokes  Title: Chief Executive Officer