PROMISSORY
      NOTE

     

     

    
      	$75,000.00  	As of July 27, 2007
	 	Houston,
              Texas



     

    Tremisis
      Energy Acquisition Corporation II (“Maker”) promises to pay to the order of
      Lawrence S. Coben (“Payee”) the principal sum of Seventy Five Thousand Dollars
      and No Cents ($75,000.00) in lawful money of the United States of America,
      on
      the terms and conditions described below.

     

    1.  Principal.
      The
      principal balance of this Note shall be repayable on the earlier of (i) July
      27,
      2008 or (ii) the date on which Maker consummates an initial public offering
      of
      its securities.

     

    2.  Interest.
      No
      interest shall accrue on the unpaid principal balance of this Note.

     

    3.  Application
      of Payments.
      All
      payments shall be applied first to payment in full of any costs incurred in
      the
      collection of any sum due under this Note, including (without limitation)
      reasonable attorneys’ fees, then to the payment in full of any late charges and
      finally to the reduction of the unpaid principal balance of this
      Note.

     

    4.  Events
      of Default.
      The
      following shall constitute Events of Default:

     

    (a)  Failure
      to Make Required Payments.
      Failure
      by Maker to pay the principal of this Note within five (5) business days
      following the date when due.

     

    (b)  Voluntary
      Bankruptcy, Etc.
      The
      commencement by Maker of a voluntary case under the Federal Bankruptcy Code,
      as
      now constituted or hereafter amended, or any other applicable federal or state
      bankruptcy, insolvency, reorganization, rehabilitation or other similar law,
      or
      the consent by it to the appointment of or taking possession by a receiver,
      liquidator, assignee, trustee, custodian, sequestrator (or other similar
      official) of Maker or for any substantial part of its property, or the making
      by
      it of any assignment for the benefit of creditors, or the failure of Maker
      generally to pay its debts as such debts become due, or the taking of corporate
      action by Maker in furtherance of any of the foregoing.

     

    (c)  Involuntary
      Bankruptcy, Etc.
      The
      entry of a decree or order for relief by a court having jurisdiction in the
      premises in respect of maker in an involuntary case under the Federal Bankruptcy
      Code, as now or hereafter constituted, or any other applicable federal or state
      bankruptcy, insolvency or other similar law, or appointing a receiver,
      liquidator, assignee, custodian, trustee, sequestrator (or similar official)
      of
      Maker or for any substantial part of its property, or ordering the winding-up
      or
      liquidation of its affairs, and the continuance of any such decree or order
      unstayed and in effect for a period of 60 consecutive days.

     

    
      
         

      

      
         

        
          

        

      

      
         

      

    

     

    5.  Remedies.

     

    (a)  Upon
      the
      occurrence of an Event of Default specified in Section 4(a), Payee may, by
      written notice to Maker, declare this Note to be due and payable, whereupon
      the
      principal amount of this Note, and all other amounts payable thereunder, shall
      become immediately due and payable without presentment, demand, protest or
      other
      notice of any kind, all of which are hereby expressly waived, anything contained
      herein or in the documents evidencing the same to the contrary
      notwithstanding.

     

    (b)  Upon
      the
      occurrence of an Event of Default specified in Sections 4(b) and 4(c), the
      unpaid principal balance of, and all other sums payable with regard to, this
      Note shall automatically and immediately become due and payable, in all cases
      without any action on the part of Payee.

     

    6.  Waivers.
      Maker
      and all endorsers and guarantors of, and sureties for, this Note waive
      presentment for payment, demand, notice of dishonor, protest, and notice of
      protest with regard to the Note, all errors, defects and imperfections in any
      proceedings instituted by Payee under the terms of this Note, and all benefits
      that might accrue to Maker by virtue of any present or future laws exempting
      any
      property, real or personal, or any part of the proceeds arising from any sale
      of
      any such property, from attachment, levy or sale under execution, or providing
      for any stay of execution, exemption from civil process, or extension of time
      for payment; and Maker agrees that any real estate that may be levied upon
      pursuant to a judgment obtained by virtue hereof, on any writ of execution
      issued hereon, may be sold upon any such writ in whole or in part in any order
      desired by Payee.

     

    7.  Unconditional
      Liability.
      Maker
      hereby waives all notices in connection with the delivery, acceptance,
      performance, default, or enforcement of the payment of this Note, and agrees
      that its liability shall be unconditional, without regard to the liability
      of
      any other party, and shall not be affected in any manner by any indulgence,
      extension of time, renewal, waiver or modification granted or consented to
      by
      Payee, and consents to any and all extensions of time, renewals, waivers, or
      modifications that may be granted by Payee with respect to the payment or other
      provisions of this Note, and agree that additional makers, endorsers,
      guarantors, or sureties may become parties hereto without notice to them or
      affecting their liability hereunder.

     

    8.  Notices.
      Any
      notice called for hereunder shall be deemed properly given if (i) sent by
      certified mail, return receipt requested, (ii) personally delivered, (iii)
      dispatched by any form of private or governmental express mail or delivery
      service providing receipted delivery, (iv) sent by telefacsimile or (v) sent
      by
      e-mail, to the following addresses or to such other address as either party
      may
      designate by notice in accordance with this Section:

     

    If
      to
      Maker:

    


    Tremisis
      Energy Acquisition Corporation II

    11622
      Monica Street

    Houston,
      Texas 77024

    Attn.:
      Chief Executive Officer

     

    
      
         

      

      
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    If
      to
      Payee:

    


    Lawrence
      S. Coben

    11622
      Monica Street

    Houston,
      Texas 77024  

    


    Notice
      shall be deemed given on the earlier of (i) actual receipt by the receiving
      party, (ii) the date shown on a telefacsimile transmission confirmation, (iii)
      the date on which an e-mail transmission was received by the receiving party’s
      on-line access provider (iv) the date reflected on a signed delivery receipt,
      or
      (vi) two (2) Business Days following tender of delivery or dispatch by express
      mail or delivery service.

     

    9.  Construction.
      This
      Note shall be construed and enforced in accordance with the domestic, internal
      law, but not the law of conflict of laws, of the State of New York.

     

    10.  Severability.
      Any
      provision contained in this Note which is prohibited or unenforceable in any
      jurisdiction shall, as to such jurisdiction, be ineffective to the extent of
      such prohibition or unenforceability without invalidating the remaining
      provisions hereof, and any such prohibition or unenforceability in any
      jurisdiction shall not invalidate or render unenforceable such provision in
      any
      other jurisdiction.

     

    IN
      WITNESS WHEREOF, Maker, intending to be legally bound hereby, has caused this
      Note to be duly executed by its Chief Executive Officer the day and year first
      above written.

     

    
      	 	 	 
	 	
              TREMISIS ENERGY ACQUISITION 

              CORPORATION II

            
	 
 	 
 	 
 
	
            	By:  	 
	 	
              

              Name:
                Lawrence S. Coben

              Title:
                Chief Executive Officer

            


    

    


    
      
         

      

      
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