THIRD AMENDED AND RESTATED REVOLVING LINE OF CREDIT NOTE

Exhibit 10.1

THIRD AMENDED AND RESTATED
REVOLVING LINE OF CREDIT NOTE
No. AR — 5

     Lime Energy Co., a Delaware corporation (the “ Company ”), for value received, promises to pay to Advanced Biotherapy, Inc. (“ Noteholder ”), the principal amount of Four Million Five Hundred Thousand Dollars ($4,500,000) (the “ Maximum Principal Amount ”), or so much thereof as may be advanced and be outstanding, together with interest thereon, to be computed on each advance from the date of its disbursement as set forth herein. This Note is issued pursuant to that certain Amended and Restated Note Issuance Agreement dated of even date herewith, by and among the Company, Noteholder and the other lender named therein (the “ AR Note Issuance Agreement ”), and the obligation of the Noteholder to make advances is subject to the Company’s compliance with the conditions set forth in the AR Note Issuance Agreement.

     Noteholder authorizes the Company to record on the grid sheet accompanying this Note (the “ Grid Sheet ”) all advances, repayments, prepayments and the unpaid principal balance from time to time. As provided in the AR Note Issuance Agreement, all advances, repayments and prepayments on the notes issued pursuant thereto are to be made pro rata among Noteholder and the lender named therein. Noteholder agrees that, in the absence of manifest error, the record kept by the Company on the Grid Sheet shall be conclusive evidence of the matters recorded, provided that the failure of the Company to record or correctly record any amount or date shall not affect the obligation of the Company to pay the outstanding principal balance of the advances and the interest thereon in accordance with this Note.

     The following is a statement of the rights of Noteholder and the conditions to which this Note is subject, and to which Noteholder, by the acceptance of this Note, agrees:

     1.  Payment of Principal and Interest.

          1.1. Interest . The outstanding principal balance hereunder shall bear interest at the rate of seventeen percent (17%) per annum with twelve percent (12%) per annum payable in cash (the “ Current Interest ”) and the remaining five percent (5%) per annum to be capitalized (the “ Capitalized Interest ”). The Current Interest shall be payable on the first Business Day (as hereinafter defined) of each calendar quarter, commencing on January 2, 2009 and continuing until the principal balance hereunder shall have been paid in full. The Capitalized Interest shall be added to the outstanding principal balance of this Note on the first calendar day of each quarter that this Note remains outstanding (the “ Capitalized Interest ”) and shall be due and payable on the Maturity Date (as hereinafter defined) or on such other date as may be required hereby. As used herein, references to the “principal balance” shall include Capitalized Interest. For the avoidance of doubt, Capitalized Interest shall bear interest at the same interest rate and shall be payable on the same terms as principal advanced by the Noteholder. Capitalized Interest and Current Interest shall be calculated based on a 365 day year for the actual number of days elapsed. “ Business Day ” shall mean any day, other than a Saturday, Sunday, a day that is a legal holiday under the laws of the State of Illinois or any other day on which banking institutions located in Chicago, Illinois are authorized or required by law or other governmental action to close.

          1.2. Principal. The entire outstanding principal balance and all accrued and unpaid interest shall be immediately due and payable on March 31, 2009 (the “ Maturity Date ”).

          1.3. Borrowing and Repayment . The Company may from time to time during the term of this Note borrow, partially or wholly, repay its outstanding borrowings, and reborrow, subject to all of the limitations, terms and conditions of this Note; provided, however, that the total outstanding borrowings under this Note shall not at any time exceed the Maximum Principal Amount. The outstanding principal balance of this Note, together with all accrued but unpaid interest, including, without limitation, all Capitalized Interest, shall be due and payable in full on the Maturity Date.

          1.4. Business Purpose; Usury Savings Clause . This Note is being issued for business purposes. The Company and Noteholder intend to comply at all times with applicable usury laws. If at any time such laws would render usurious any amounts due under this Note under applicable law, then it is the Company’s and Noteholder’s express intention that the Company not be required to pay interest on this Note at a rate in excess of the maximum lawful rate, that the provisions of this Section 1.4 shall control over all other provisions of this Note which may be in apparent conflict hereunder, that such excess amount shall be immediately credited to the principal balance of this Note (or, if this Note has been fully paid, refunded by Noteholder to the Company), and the provisions hereof shall be immediately reformed and the amounts thereafter decreased, so as to comply with the then applicable usury law, but so as to permit the payment of the maximum amount otherwise due under this Note.

          1.5. Application of Payments . Payments by the Company shall be applied first to any and all accrued interest through the payment date and second to the unpaid principal balance.

     2.  Unused Funds Fee. The Company agrees to pay to Noteholder a fee (the “ Unused Funds Fee ”) calculated by multiplying (a) four percent (4%) times (b) the daily amount by which the Maximum Principal Amount exceeds the outstanding advances made to the Company, excluding Capitalized Interest, dividing the product by (c) 365 and then multiplying the quotient by (d) the number of days in such calendar quarter. The Unused Funds Fee shall be payable quarterly in arrears on the first Business Day of each calendar quarter for the immediately preceding calendar quarter commencing on the first such date following the date hereof, with a final payment on the Maturity Date or any earlier date on which all amounts payable hereunder become due pursuant to the terms hereof. Any Unused Funds Fee that shall not be paid by the tenth (10 ^th ) day of each calendar quarter shall accrue interest at the rate of seventeen percent (17%) per annum until paid in full together with such accrued interest.

     3.  Termination Fee. In the event, and on the date (the “ Termination Date ”), that the Company delivers written notice to Noteholder terminating the lending relationship evidenced by this Note prior to the Maturity Date, the Company agrees to pay a termination fee to the Noteholder (the “ Termination Fee ”) calculat