PROMISSORY NOTE

Exhibit 10.4

PROMISSORY NOTE

FOR VALUE RECEIVED, effective as of September 22, 2006, the undersigned, PetroAlgae, LLC (the “Borrower”) DOES HEREBY PROMISE to pay to the order of XL TechGroup, Inc. (“Lender”), at its office at 1901 S. Harbor City Blvd., Suite 300, Melbourne, FL 32901, in lawful money of the United States and in immediately available funds, the principal amount of TWENTY-FIVE MILLION DOLLARS ($25,000,000), or such lesser amount as is equal to the aggregate unpaid outstanding principal amount of all Loans (as defined in that certain Capital Funding and Company Development Agreement executed between the Borrower and Lender on even date herewith, hereinafter referred to as the “Agreement”) made to the Borrower by Lender, on the earliest to occur of (a) the Borrower’s receipt of the gross proceeds of a Qualified IPO (as defined in the Agreement), (b) the sale of all or substantially all of the assets of the Borrower, or (c) August 31, 2010, together with any interest then accrued and unpaid on the aggregate principal amount of the Loans outstanding, in like money at said office. Interest shall accrue monthly on the aggregate outstanding principal amount of any Loans, and any unpaid interest thereupon, as of the last business day of such month at a rate per annum equal to the Wall Street Journal Prime Rate (as defined in the Agreement) for such month plus two hundred (200) basis points. Interest shall be calculated on the basis of a three hundred sixty day (360) year.

Any amount of principal or accrued interest owing under this Promissory Note (this “Note”) which is not paid when due, whether at stated maturity, by acceleration, or otherwise, shall bear interest from the date when due until said principal amount is paid in full, payable on demand, at a rate per annum equal at all times to fifteen percent (15%) (the “Default Rate”); provided, however, that the rate of interest payable hereunder shall not be greater than the maximum rate of interest permitted to be charged under the laws of the State of Florida. In the event that the principal amount or any accrued interest, or a portion thereof, shall not be paid within fifteen (15) days from the date such principal or accrued interest shall become due, the Borrower agrees to pay the Lender a late payment charge of five percent (5%)  on any amount so overdue and further agrees that said late payment charge shall not be considered interest but shall be for the purposes of defraying the expense of the Lender in handling such delinquent payment. The collection of such late payment charge shall in no way limit the right of the Lender to exercise its right to declare a default hereunder in accordance with the terms and conditions of this Note.

This Note is subject to the Agreement, and is secured by, and subject to, that certain Security Agreement made between Lender and Borrower as of even date herewith (the “Security Agreement”). This Note is issued together with that certain Purchase Option Agreement executed between Lender and Borrower as of even date herewith (the “Purchase Option”). If each and every one of the stipulations, agreements, terms, covenants, conditions, representations and warranties contained herein or in any other instrument or documents relating hereto, including but not limited to the Agreement, the Purchase Option, and the Security Agreement are not duly performed, complied with and abided by (each, a “Default”), the entire outstanding principal sum, together with any accrued and unpaid interest, evidenced hereby or secured by any instrument securing the payment hereof, without notice shall, at the option of the Lender (in its sole and absolute discretion) become immediately due and payable, without further notice of any kind (which is expressly waived by Borrower) and, in the event that any such amount is not immediately paid, shall bear interest thereafter at the Default Rate.

1

THE LENDER ACKNOWLEDGES AND AGREES THAT THE REPAYMENT OF THE LOANS PRIOR TO A QUALIFIED IPO AGREES THAT,