NTR
      ACQUISITION CO.

    


    PROMISSORY
      NOTE

     

    
      	
              $3,000,000

            	
              New
                York, New York

            
	 	
              November
                2, 2007

            


    

    


    FOR
      VALUE
      RECEIVED, the undersigned, NTR ACQUISITION CO., a Delaware corporation
      (“Borrower”),
      promises to pay to the order of OCCIDENTAL
      PETROLEUM INVESTMENT CO.,
      a
      California company, (“Lender”),
      on
      the earlier of (i) November 1, 2008 and (ii) such date as Lender purchases
      Series A Senior Convertible Preferred Stock, par value $0.0001, of Borrower,
      (A)
      the principal sum of THREE MILLION DOLLARS ($3,000,000), or such lesser amount
      as is equal to the aggregate unpaid principal amount of all loans made by Lender
      to Borrower under this Note (the “Principal”),
      and
      (B) interest on such Principal, as set forth below. 

    


    Interest
      on this promissory note (“Note”)
      shall
      be calculated for the quarterly periods ending on March 15, June 15, September
      15 and December 15 of each year (“Interest
      Calculation Period”)
      (commencing on the date of this Note and continuing until the unpaid Principal
      and accrued but unpaid interest have been paid in full) at a rate per annum
      equal to 9.0%. Interest shall be calculated based on the average Principal
      balance, on the basis of a 360-day year for the actual number of days (including
      the first day but excluding the last day) elapsed during the Interest
      Calculation Period. Interest
      for each Interest Calculation Period shall be due and payable on the last day
      of
      such Interest Calculation Period (with the first payment payable on December
      15,
      2007). Payment of interest due on or before September 15, 2008 may be effected
      by delivery of a new promissory note (an “Additional
      Note”)
      in the
      same form as this Note and in a principal amount equal to the interest amount
      then due. If interest is not paid in cash on or before the date due, Borrower
      shall be deemed to have delivered an Additional Note in payment thereof without
      further action of Borrower or Lender unless the interest payment date with
      respect to such payment falls after September 15, 2008. Any amount of Principal
      of, or interest on, this Note which is not paid (in cash or by the delivery
      or
      deemed delivery of Additional Notes) on or before the date due (whether upon
      valid demand, by acceleration or otherwise), shall bear interest from the date
      when due until paid, and shall be payable on demand, at a rate per annum equal
      to 11.0%. The rate of interest payable on this Note shall in no event exceed
      the
      maximum rate of interest permitted by applicable law.

     

    Whenever
      any payment to be made under this Note shall be due on a day which is not a
      Business Day, then such payment shall be made on the next succeeding Business
      Day. Any such extension of time shall in each case (other than in the case
      of
      regular accruals of interest) be included in the computation of interest under
      this Note. 

    


    All
      payments and prepayments made under this Note shall be applied first to interest
      on the aggregate unpaid Principal balance of this Note and any Additional Note
      deemed delivered pursuant hereto and then to the aggregate unpaid Principal
      balance of this Note and any Additional Note deemed delivered pursuant hereto.
      

     

    
      
         

      

      
         

        
          

        

      

      
         

      

    

     

    This
      Note
      evidences (i) the amount of the aggregate unpaid Principal balance owed from
      time to time by the Borrower to the Lender hereunder and under any Additional
      Note that the Borrower is deemed to have delivered pursuant hereto, and (ii)
      the
      amount of any interest accruing hereunder on such aggregate unpaid Principal
      balance and, under any Additional Note deemed to have been delivered pursuant
      hereto, on the aggregate unpaid Principal balance thereof. In the event that,
      at
      the date hereof, or at any time thereafter, no such amount shall be owed by
      the
      Borrower to the Lender under this Note, this Note shall, nevertheless, remain
      in
      full force and effect. 

     

    The
      Borrower may prepay this Note in whole or in part at any time without premium
      or
      penalty. This Note may not be amended or modified except by an instrument in
      writing signed by the Borrower and the Lender. Borrower may not delegate its
      obligations under this Note without the prior written consent of Lender, which
      consent shall not be unreasonably withheld or delayed. 

     

    If
      any of
      the following events, acts or occurrences shall occur and be
      continuing:

     

    (i)
      default in the payment when due (in cash or by delivery or deemed delivery
      of an
      Additional Notes) of any amount owing by the Borrower under this Note in respect
      of principal of, or interest on, the Notes;

     

    (ii)
      any
      representation or warranty on the part of the Borrower contained in the Series
      A
      Senior Convertible Preferred Stock Purchase Agreement dated as of even date
      herewith between the Borrower and the Lender (the “SPA”)
      shall
      at any time prove to have been incorrect when made, deemed made or
      reaffirmed;

     

    (iii)
      the
      Borrower shall default in the performance or observance of any term, covenant,
      condition or agreement on its part to be performed or observed under this Note
      or the SPA and such default continues unremedied for thirty (30) days;


     

    (iv)
      either (a) the Borrower shall generally fail to pay, or admit in writing its
      inability to pay, its debts as they become due, or shall voluntarily commence
      any case or proceeding or file any petition under any bankruptcy, insolvency
      or
      similar law or seeking dissolution, liquidation or reorganization or the
      appointment of a receiver, trustee, custodian or liquidator for itself or a
      substantial portion of its property, assets or business or to effect a plan
      or
      other arrangement with its creditors, or shall file any answer admitting the
      jurisdiction of the court and the material allegations of any involuntary
      petition filed against it in any bankruptcy, insolvency or similar case or
      proceeding, or shall be adjudicated bankrupt, or shall make a general assignment
      for the benefit of creditors, or shall consent to, or acquiesce in the
      appointment of, a receiver, trustee, custodian or liquidator for itself or
      a
      substantial portion of its property, assets or business, or (b) corporate action
      shall be taken by the Borrower for the purpose of effectuating any of the
      foregoing; or

     

    
      
         

      

      
        2

        
          

        

      

      
         

      

       

    

    (v)
      involuntary proceedings or an involuntary petition shall be commenced or filed
      against the Borrower under any bankruptcy, insolvency or similar law or seeking
      the dissolution, liquidation or reorganization of the Borrower or the
      appointment of a receiver, trustee, custodian or liquidator for the Borrower
      or
      of a substantial part of the property, assets or business of the Borrower,
      or
      any writ, judgment, warrant of attachment, execution or similar process shall
      be
      issued or levied against a substantial part of the property, assets or business
      of the Borrower, and such proceedings or petition shall not be dismissed, or
      such writ, judgment, warrant of attachment, execution or similar process shall
      not be released, vacated or fully bonded, within sixty (60) days after
      commencement, filing or levy, as the case may be;

     

    then,
      and
      in any such event, all Principal, interest or other sums then accrued or owing
      by the Borrower under this Note shall become and be immediately due and payable,
      without presentment, demand, protest or notice of any kind, all of which are
      hereby expressly waived by the Borrower.

    


    Payments
      of the Principal of, interest on, and any other sums owing under this Note
      shall
      be made in such coin or currency of the United States of America as at the
      time
      of payment is legal tender for the payment of public and private debts. All
      such
      payments shall be made at such place or places and in such manner as may be
      specified by the Lender to the Borrower in writing.

    


    In
      addition to, and not in limitation of, any rights which the Lender may have
      under this Note, any agreement or applicable law, the Borrower agrees, subject
      only to any limitation imposed by applicable law, to pay all expenses, including
      reasonable attorneys’ fees and legal expenses, paid or incurred by the Lender in
      endeavoring to collect any amounts payable hereunder which are not paid when
      due, whether by acceleration or otherwise.

    


    All
      notices, demand and other communications required or permitted by this Note
      to
      be given to, or made upon, the Borrower or the Lender shall be in writing and
      shall be personally delivered or sent by registered or certified mail, postage
      prepaid, return receipt requested, or by telecopier, to the following address
      of
      the Borrower or the Lender, as the case may be, or to such other address with
      respect to the Borrower or the Lender as the Borrower or the Lender shall notify
      the other in writing:

    


    
      	
              If
                to the Borrower: 

            	
              NTR
                Acquisition Co.

            
	 	
              100
                Mill Plain Road

            
	 	
              Suite
                320

            
	 	
              Danbury,
                CT 06811

            


    

     

    
      
         

      

      
        3

        
          

        

      

      
         

      

    

     

    
      	
              If
                to the Lender: 

            	
              Occidental
                Petroleum Investment Co.

            
	 	
              10889
                Wilshire Boulevard

            
	 	
              Los
                Angeles, California 90024

            
	 	
              Attention:
                Vice President - Business Development;
                Treasurer

            


    

    


    Each
      such
      notice, demand or other communication shall be in writing and shall be deemed
      to
      be given for the purposes of this Note on the day on which such notice, demand
      or other communication is delivered or sent to the intended recipient thereof
      in
      accordance with the provisions of this Note.

    


    This
      Note
      and the loans evidenced hereby have been made in and shall be governed by and
      construed in accordance with the laws of the State of New York without reference
      to the choice of laws thereof. To the fullest extent permitted by applicable
      law, each party hereto (i) agrees that any claim, action or proceeding by such
      party seeking any relief whatsoever arising out of, or in connection with,
      this
      Note shall be brought only in the United States District Court for the Central
      District of California and in any California State court located in Los Angeles
      County and not in any other State or Federal court in the United States of
      America or any court in any other country, (ii) agrees to submit to the
      exclusive jurisdiction of such courts located in the State of California for
      purposes of all legal proceedings arising out of, or in connection with, this
      Note and (iii) irrevocably waives any objection which it may now or hereafter
      have to the laying of the venue of any such proceeding brought in such a court
      and any claim that any such proceeding brought in such a court has been brought
      in an inconvenient forum. If any provision of this Note or the application
      thereof is held invalid or unenforceable for any reason, the remainder of this
      Note and the application thereof will not be affected thereby, the provisions
      of
      this Note being severable in any such instance. 

     

    Except
      as
      otherwise set forth in this Note, the Borrower hereby waives diligence,
      presentment, demand, protest and notice of any kind whatsoever. The nonexercise
      by the Lender of any of its rights hereunder in any particular instance shall
      not constitute a waiver thereof in that or any subsequent instance.

     

    
      
         

      

      
        4

        
          

        

      

      
         

      

    

     

    The
      Lender understands and acknowledges that the Borrower is a recently organized
      blank check company formed for the purpose of acquiring (an “initial business
      combination”) one or more businesses or assets in the energy industry. The
      Lender further understands that (a) the Borrower’s assets consist of the cash
      proceeds of its public offering (the “IPO”)
      and
      private placements of its securities, and that substantially all of those
      proceeds have been deposited in a trust account with a third party (the
“Trust
      Account”)
      for
      the benefit of the Borrower, certain of its stockholders and the underwriters
      of
      its IPO and (b) the monies in the Trust Account may be disbursed only (i) to
      the
      Borrower in limited amounts from time to time (and in no event more than
      $3,250,000 in total) in order to permit the Borrower to pay its operating
      expenses; (ii) if the Borrower completes an initial business combination, to
      certain dissenting public stockholders, to the underwriters for the IPO in
      the
      amount of underwriting discounts and commissions they earned in the IPO but
      whose payment they have deferred, and then to the Borrower; and (iii) if the
      Borrower fails to complete an initial business combination within the allotted
      time period and liquidates, subject to the terms of the agreement governing
      the
      Trust Account, to the Borrower in limited amounts to permit the Borrower to
      pay
      the costs and expenses of its liquidation and dissolution, and then to the
      Borrower’s stockholders who purchased securities in the IPO. Unless and until
      the initial business combination occurs, the Borrower waives any right, title,
      interest or claim of any kind (any “Claim”)
      it or
      any of its affiliates have or may have in the future in or to any monies in
      the
      Trust Account and agrees not to seek recourse against the Trust Account or
      any
      funds distributed therefrom (except amounts properly released to the Borrower
      as
      described above) as a result of, or arising out of, any Claims against the
      Borrower in connection with this Note.

    


    For
      purposes of this Note, “Business
      Day”
shall
      mean each Monday, Tuesday, Wednesday, Thursday and Friday which is not a day
      on
      which banking institutions in The City of New York are authorized or obligated
      by law or executive order to close.

     

    
      
         

      

      
        5

        
          

        

      

      
         

      

    

     

    
      	
              Borrower:
                

            	NTR
              ACQUISITION CO.
	 	 	 
	 	 	 
	 	
              By:

            	
              /s/
                MARIO E. RODRIGUEZ

            
	 	 	
              Mario
                E. Rodriguez

            
	 	 	
              Chief
                Executive Officer

            
	 	 	 
	 	 	 
	
              Lender:
                

            	
              OCCIDENTAL
                PETROLEUM

              INVESMENT
                CO.

            
	 	 	 
	 	 	 
	 	
              By:
                

            	
              /s/
                TODD STEVENS

            
	 	 	
              Todd
                Stevens

            
	 	 	
              Vice
                President