AmericanDG
      Energy Inc.

    


    8%
      Senior Convertible Debentures Due 2011

    Subscription
      Agreement

    


    Dear
      Sir
      or Madam:

    


    1. Subscription.
      The
      undersigned, intending to be legally bound, irrevocably subscribes for and
      agrees to purchase the aggregate U.S. dollar amount of the 8% Senior Convertible
      Debentures Due 2011 (each a “Debenture” and collectively, the “Debentures”), of
      American DG Energy Inc., a Delaware corporation (the “Company”), indicated on
      the signature page hereof, on the terms and conditions described herein and
      in
      the Debenture. 

    


    The
      undersigned herewith delivers to the Company the consideration (“Purchase
      Price”) required to purchase the Debenture subscribed for hereunder by wire
      transfer funds payable to: American DG Energy Inc., 85 First Avenue, Waltham,
      MA
      02451. The minimum subscription is for $100,000 unless otherwise determined
      in
      the discretion of the Company. Capitalized terms not otherwise defined in this
      Agreement have the meanings specified in the Debenture. 

    


    2. Investor
      Representations, Warranties and Covenants.
      The
      undersigned hereby acknowledges, represents and warrants to, and agrees with
      the
      Company as follows:

    


    (a) The
      undersigned is acquiring the Debenture for the undersigned’s own account as
      principal, for investment purposes only, and not with a view to, or for, resale
      or distribution of all or any part of the Debenture or any shares of the
      Company’s Common Stock, par value $.001 per share, issued upon conversion of the
      Debenture (the “Underlying Shares”)(the “Debenture and the Underlying Shares are
      collectively referred to herein as the “Securities”), and no other person has a
      direct or indirect beneficial interest in the Securities;

    


    (b) The
      undersigned acknowledges its understanding that the offering and sale of the
      Debentures is intended to be exempt from registration under the Securities
      Act
      of 1933, as amended (the “Securities Act”), by virtue of Sections 4(2) of the
      Securities Act and Rule 505 of Regulation D (“Regulation D”) promulgated
      thereunder and Section 4(6) of the Securities Act, and, in furtherance thereof,
      the undersigned represents and warrants to and agrees with the Company that
      the
      undersigned has the financial ability to bear the economic risk of the
      undersigned’s investment, has adequate means for providing for the undersigned’s
      current needs and contingencies and has no need for liquidity with respect
      to
      the undersigned’s investment in the Debenture.

    


    (c) The
      undersigned is an “accredited investor” as defined in Rule 501(a) of Regulation
      D under the Securities Act; 

    


    (d) The
      undersigned:

    


    (1) The
      undersigned understands and has evaluated the risks of a purchase of the
      Debenture;

    


    (2) has
      been
      given the opportunity to ask questions of and receive answers from the Company
      concerning the terms and conditions of the offering of the Debentures, and
      has
      been given the opportunity to obtain such information as the undersigned has
      deemed necessary regarding the Company, the Debenture or the Underlying Shares
      to the extent that the Company possesses such information or can acquire it
      without unreasonable effort;


    
      
         

      

      
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    (3) has
      not
      relied on any oral representation, warranty or information in connection with
      the offering of the Debentures by the Company, or any officer, employee, agent
      or affiliate of the Company;

    


    (4) has
      determined that the Debenture is a suitable investment for the undersigned
      and
      that at this time the undersigned can bear a complete loss of the undersigned’s
      investment therein;

    


    (5) has
      such
      knowledge and experience in financial and business matters that the undersigned
      is capable of evaluating the merits and risks of the undersigned’s investment in
      the Debenture;

    


    (e)If
      the
      undersigned is a corporation, limited liability company, partnership, trust,
      qualified plan or other entity, it is authorized and qualified to become a
      holder of the Securities, and the person signing this Subscription Agreement
      on
      behalf of such entity has been duly authorized to do so;

    


    (f) Any
      information which the undersigned has heretofore furnished and herewith
      furnishes to the Company with respect to the undersigned’s financial position
      and business experience is correct and complete as of the date of this Agreement
      and if there should be any material change in such information prior to issuance
      to the undersigned of the Debenture, the undersigned will immediately furnish
      such revised or corrected information to the Company;

    


    (g) The
      foregoing acknowledgments, representations, warranties and agreements shall
      survive the closing at which the Debenture is issued;

    


    (h) The
      undersigned acknowledges that the undersigned has not purchased the Debenture
      as
      a result of any general solicitation or general advertising; and 

    


    (i) The
      undersigned’s overall commitment to investments which are not readily marketable
      is not disproportionate to the undersigned’s net worth, and the undersigned’s
      investment in the Debenture and will not cause such overall commitment to become
      excessive.

    


    3. Investor
      Awareness.
      The
      undersigned acknowledges that:

    


    (a) No
      federal or state agency has passed upon the Securities or made any finding
      or
      determination as to the fairness of this investment;

    


    (b) There
      is
      no established market for the Securities of and no assurance has been given
      that
      any public market for them will develop;

    


    (c) The
      Securities may not be sold, pledged or otherwise transferred, except as may
      be
      permitted under the Securities Act and applicable state securities laws pursuant
      to registration or exemption therefrom; and accordingly, the undersigned may
      be
      required to bear the financial risks of an investment in the Securities for
      an
      indefinite period of time;

    


    (d) The
      undersigned consents to (i) the placing of a legend substantially in the form
      set forth below on the certificates representing the Underlying Shares stating
      that the Underlying Shares have not been registered and setting forth the
      restriction on transfer contemplated hereby, and (ii) the placing of a stop
      transfer order on the books of the Company with respect to the
      Securities.


    
      
         

      

      
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    “The
      shares represented by this certificate have not been registered under the
      Securities Act of 1933, as amended. These shares have been acquired for
      investment and not with a view to distribution or resale and may not be sold,
      mortgaged, pledged, hypothecated or otherwise transferred without an effective
      registration statement for such sales under the Securities Act of 1933, or
      an
      opinion of counsel for the corporation that registration is not required under
      such Act. 

    


    The
      shares represented by this certificate are also subject to the provisions of
      a
      certain Investor Rights Agreement dated ________, 2006 and may not be
      transferred except in accordance with the provisions of that
      agreement.”

    


    4. Miscellaneous.

    


    (a) Indemnity.
      The
      undersigned agrees to indemnify and hold harmless the Company, its affiliates,
      directors, officers, employees, agents and controlling persons (the Company
      and
      each such person being an “Indemnified Party”), from and against any and all
      losses, claims, damages, liabilities and expenses whatsoever (including, but
      not
      limited to, any and all expenses whatsoever reasonably incurred investigating,
      preparing or defending against any litigation commenced or threatened or any
      claim whatsoever), joint or several, as incurred, to which such Indemnified
      Party may become subject under any applicable United States federal or state
      law
      or the laws of any other domestic or foreign jurisdiction, or otherwise, and
      related to or arising out of or based upon any false representation, warranty
      or
      acknowledgment, or breach or failure by the undersigned to comply with any
      covenant or agreement made by the undersigned herein or in any other document
      furnished by the undersigned to any of the foregoing in connection with this
      transaction.

    


    (b) Modification.
      Except
      as otherwise provided herein, neither this Agreement nor any provisions hereof
      shall be modified, discharged or terminated except by an instrument in writing
      signed by the party against whom any waiver, change, discharge or termination
      is
      sought.

    


    (c) Binding
      Effect.
      Except
      as otherwise provided herein, this Agreement shall be binding upon and inure
      to
      the benefit of the parties and their heirs, executors, administrators,
      successors, legal representatives and assigns. If the undersigned is more than
      one person, the obligation of the undersigned shall be joint and several and
      the
      agreements, covenants, representations, warranties and acknowledgments herein
      contained shall be deemed to be made by and be binding upon each such person
      and
      his heirs, executors, administrators and successors.

    


    (d) Entire
      Agreement.
      This
      instrument contains the entire agreement of the parties and there are no
      representations, warranties, acknowledgments, covenants or other agreements
      except as stated or referred to herein.

    


    (e) Assignability.
      This
      Agreement is not transferable or assignable by the undersigned.


    
      
         

      

      
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    (f) Governing
      Law and Forum.
      Notwithstanding
      the place where this Agreement may be executed by any of the parties hereto,
      all
      the terms and provisions hereof shall be construed in accordance with and
      governed by the laws of the Commonwealth of Massachusetts, without giving effect
      to its conflict of law principles. Any dispute which may arise out of or in
      connection with this Agreement shall be adjudicated before a court located
      in
      Middlesex County, Massachusetts and the parties hereby submit to the exclusive
      jurisdiction of the courts of the Commonwealth of Massachusetts located in
      Boston, Massachusetts and of the federal courts in Boston, Massachusetts with
      respect to any action or legal proceeding commenced by any party, and
      irrevocably waive any objection they now or hereafter may have respecting the
      venue of any such action or proceeding brought in such a court or respecting
      the
      fact that such court is an inconvenient forum, relating to or arising out of
      this Agreement or any acts or omissions relating to the sale of the Shares,
      and
      the undersigned consents to the service of process in any such action or legal
      proceeding by means of registered or certified mail, return receipt requested,
      in care of the address set forth below or such other address as the undersigned
      shall furnish in writing to the Company. In the event any such action is
      brought, whether at law or in equity, then the prevailing party shall be paid
      its reasonable attorney's fees, expenses and disbursements arising out of such
      action. The undersigned hereby waives trial by jury in any action or proceeding
      involving, directly or indirectly, any matter (whether sounding in tort,
      contract, fraud or otherwise) in any way arising out of or in connection with
      this Agreement or the Holder’s purchase of the Shares.

    


    


    


    


    


    


    


    


    


    [The
      balance of this page has been intentionally left blank.]


    
      
         

      

      
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    ALL
      SUBSCRIBERS MUST COMPLETE THIS PAGE

    


    


    The
      undersigned acknowledges that this subscription shall not be effective unless
      accepted by the Company as indicated below. 

    


    Date
      of
      Subscription: ______________, 2006

    
      	 	 	 
	
              Original
                Principal Amount of Debentures subscribed for: U.S. 

            	
              $
                

            	
                
                

            


    

    


    
      	 	 	 
	
               
                

            
	
              Exact
                Name in Which Title is to be Held

            	 	 
	 	 	 
	
               
                

            	 	
               
                

            
	
              Name
                of Subscriber (Print)

            	 	
              Name
                of Additional Subscriber

            
	 	 	 
	 	 	 
	
               
                

            	 	
               
                

            
	
              Address

            	 	
              Address

            
	 	 	 
	 	 	 
	
               
                

            	 	
               
                

            
	
              City,
                State, Zip Code, Country

            	 	
              City,
                State, Zip Code, Country

            
	 	 	 
	
               
                

            	 	
               
                

            
	
              Telephone
                Number

            	 	
              Telephone
                Number

            
	 	 	 
	
               
                

            	 	
               
                

            
	
              Social
                Security, Tax ID Number 

            	 	
              Social
                Security, Tax ID Number

            
	 	 	 
	
               
                

            	 	
               
                

            
	
              Signature
                of Subscriber

            	 	
              Signature
                of Additional Subscriber

            


    

    


    


    


    


    THIS
      SUBSCRIPTION IS ACCEPTED BY THE COMPANY ON THE 1ST DAY OF APRIL,
      2006.

    


    
      	 	
              AmericanDG
                Energy Inc.

            
	 	 	 
	 	 	 
	 	
              By:
                

            	
               
                

            
	 	 	 
	 	
              Name:
                Anthony S. Loumidis

            
	 	
              Title:
                Chief Financial Officer

            


    

    


    


    


    



    
      
         

      

      
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    AmericanDG
      Energy Inc.

    


    8%
      Senior Convertible Debenture Due 2011

    Investor
      Rights Agreement

    


    To
      the
      purchaser of a Debenture (as such term is defined below) of AmericanDG Energy
      Inc., a Delaware corporation (the "Company"), identified on the signature page
      of this Agreement.

    


    Dear
      Sir
      or Madam:

    


    This
      will
      confirm that in consideration of your purchase of the Debenture, the Company
      covenants and agrees with you as follows:

    


    1. Certain
      Definitions.
      As used
      in this Agreement, the following terms shall have the following respective
      meanings:

    


    “2006
      Private Placement”
shall
      mean the private placement of the Debentures conducted by the Company commencing
      March 13, 2006.

    


    "Commission"
      shall
      mean the Securities and Exchange Commission, or any other federal agency at
      the
      time administering the Securities Act.

    


    "Common
      Stock"
      shall
      mean the Common Stock, $.001 par value per share, of the Company, as constituted
      as of the date of this Agreement.

    


    “Conversion
      Shares”
shall
      mean shares of Common Stock issued upon conversion of the
      Debentures.

    


    “Debentures”
shall
      mean the 8% Senior Convertible Debentures Due 2011 of the Company issued
      pursuant to the Subscription Agreement.

    


    "Exchange
      Act"
      shall
      mean the Securities Exchange Act of 1934, as amended, or any similar federal
      statute, and the rules and regulations of the Commission thereunder, all as
      the
      same shall be in effect at the time.

    


    “Holder”
shall
      mean each purchaser of a Debenture pursuant to the Subscription Agreement and
      each transferee of such securities or any Registrable Securities to whom any
      such securities or Registrable Securities are transferred in compliance with
      Section 2 of this Agreement.

    


    “Qualified
      Offering”
shall
      mean the Company’s first firm commitment underwritten public offering of its
      Common Stock registered under the Securities Act.

    


    “Qualified
      Registration”
shall
      mean the registration of the Company’s securities on Form 10 pursuant to Section
      12(b) or 12(g) of the Exchange Act.

    


    “Outstanding
      Options”
shall
      have the meaning set forth in Section 10.

    


    "Registration
      Expenses"
      shall
      mean the expenses so described in Section 6.

    


    "Registrable
      Securities"
      shall
      mean the Conversion Shares or any shares issued upon any stock split, stock
      dividend, recapitalization or similar event with respect to such Conversion
      Shares, excluding Conversion Shares which have been (a) registered under the
      Securities Act pursuant to an effective registration statement filed thereunder
      and disposed of in accordance with the registration statement covering them,
      or
      (b) publicly sold pursuant to Rule 144 under the Securities
      Act.


    
      
         

      

      
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    "Securities
      Act"
      shall
      mean the Securities Act of 1933, as amended, or any similar federal statute,
      and
      the rules and regulations of the Commission thereunder, all as the same shall
      be
      in effect at the time.

    


    "Selling
      Expenses"
      shall
      mean the expenses so described in Section 6.

    


    “Subscription
      Agreement”
shall
      mean the Subscription Agreement dated as of ______, 2006 with respect to your
      purchase of the Debentures 

    


    2. Restrictions
      on Transfer.
      (a) The
      Holder agrees not to make any disposition of all or any portion of the
      Registrable Securities unless and until:

    


    (i) there
      is
      then in effect a registration statement under the Securities Act covering such
      proposed disposition and such disposition is made in accordance with such
      registration statement; or

    


    (ii) (A) the
      transferee has agreed in writing to be bound by the terms of this Agreement,
      (B) the Holder shall have notified the Company of the proposed disposition
      and shall have furnished the Company with a detailed statement of the
      circumstances surrounding the proposed disposition, and (C) if reasonably
      requested by the Company, the Holder shall have furnished the Company with
      an
      opinion of counsel, reasonably satisfactory to the Company, that such
      disposition will not require registration of such shares under the Securities
      Act. 

    


    (b) Notwithstanding
      the provisions of subsection (a) above, no such restriction shall apply to
      a
      transfer by a Holder that is (A) a partnership transferring to its partners
      or former partners in accordance with partnership interests, (B) a
      corporation transferring to a wholly-owned subsidiary or a parent corporation
      that owns all of the capital stock of the Holder, (C) a limited liability
      company transferring to its members or former members in accordance with their
      interest in the limited liability company, (D) a Holder transferring to its
      affiliated venture capital fund or (E) an individual transferring to the
      Holder’s family member or trust for the benefit of an individual Holder;
provided
      that in
      each case the transferee will agree in writing to be subject to the terms of
      this Agreement to the same extent as if he were an original Holder
      hereunder.

    


    (c) Each
      certificate representing Registrable Securities shall be stamped or otherwise
      imprinted with legends substantially similar to the following (in addition
      to
      any legend required under applicable state securities laws):

    


    “THE
      SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE
      SECURITIES ACT OF 1933, AS AMENDED. THESE SHARES HAVE BEEN ACQUIRED FOR
      INVESTMENT AND NOT WITH A VIEW TO DISTRIBUTION OR RESALE AND MAY NOT BE SOLD,
      MORTGAGED, PLEDGED, HYPOTHECATED OR OTHERWISE TRANSFERRED WITHOUT AN EFFECTIVE
      REGISTRATION STATEMENT FOR SUCH SALES UNDER THE SECURITIES ACT OF 1933, OR
      AN
      OPINION OF COUNSEL FOR THE CORPORATION THAT REGISTRATION IS NOT REQUIRED UNDER
      SUCH ACT. 

    


    THE
      SHARES REPRESENTED BY THIS CERTIFICATE ARE ALSO SUBJECT TO THE PROVISIONS OF
      A
      CERTAIN INVESTOR RIGHTS AGREEMENT DATED ________, 2006 AND MAY NOT BE
      TRANSFERRED EXCEPT IN ACCORDANCE WITH THE PROVISIONS OF THAT
      AGREEMENT.”


    
      
         

      

      
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    (d) The
      Company shall be obligated to reissue promptly unlegended certificates at the
      request of the Holder if the Company has completed its Qualified Offering and
      the Holder shall have obtained an opinion of counsel (which counsel may be
      counsel to the Company) reasonably acceptable to the Company to the effect
      that
      the securities proposed to be disposed of may lawfully be so disposed of without
      registration, qualification and legend.

    


    (e) Any
      legend endorsed on an instrument pursuant to applicable state securities laws
      and the stop-transfer instructions with respect to such securities shall be
      removed upon receipt by the Company of an order of the appropriate blue sky
      authority authorizing such removal.

    


    3. Required
      Registration.
       The
      Company shall use its best efforts to file within one hundred twenty (120)
      days
      following the closing of a Qualified Offering or a Qualified Registration,
      and
      use its best efforts to cause to become effective under the Securities Act,
      a
      registration statement covering the sale of the Registrable Securities, and
      shall take all action necessary to qualify the Registrable Securities under
      state “blue sky” laws as hereinafter provided. The Company shall be entitled to
      include in any registration statement referred to in this Section 3 shares
      of
      Common Stock to be sold by the Company for its own account. 

    


    4. Registration
      Procedures.
      Whenever the Company is required by the provisions of Section 3 to use its
      best
      efforts to effect the registration of any Registrable Securities under the
      Securities Act, the Company will, as soon as reasonably possible:

    


    (a) prepare
      and file with the Commission a registration statement on Form S-1 or such other
      form of general applicability satisfactory to Company with respect to such
      securities and use its best efforts to cause such registration statement to
      become and remain effective for the period of the distribution contemplated
      thereby (determined as hereinafter provided);

    


    (b) prepare
      and file with the Commission such amendments and supplements to such
      registration statement and the prospectus used in connection therewith as may
      be
      necessary to keep such registration statement effective until the earliest
      to
      occur of (i) the date that all of the securities registered thereunder have
      been
      sold pursuant thereto, (ii) the third anniversary of the date of the final
      closing of the Offering, or (iii) until, by reason of Rule 144(k) under the
      Securities Act or any other rule of similar effect, the securities registered
      thereunder are no longer required to be registered for the sale thereof by
      the
      Holder without restriction. 

    


    (c) furnish
      to each seller of Registrable Securities and to each underwriter, if any, such
      number of copies of the registration statement and the prospectus included
      therein (including each preliminary prospectus) as such persons reasonably
      may
      request in order to facilitate the public sale or other disposition of the
      Registrable Securities covered by such registration statement;

    


    (d) use
      its
      best efforts to register or qualify the Registrable Securities covered by such
      registration statement under the securities or "blue sky" laws of such
      jurisdictions as the sellers of the Shares and the Registrable Securities or,
      in
      the case of an underwritten public offering, the managing underwriter reasonably
      shall request, provided,
      however,
      that
      the Company shall not for any such purpose be required to qualify generally
      to
      transact business as a foreign corporation in any jurisdiction where it is
      not
      so qualified or to consent to general service of process in any such
      jurisdiction;

    


    (e) use
      its
      best efforts to list the Registrable Securities covered by such registration
      statement with any securities exchange on which the Common Stock of the Company
      is then listed; and


    
      
         

      

      
        -8-

        
          

        

      

      
         

      

    


    


    


    (f) make
      available for inspection by each seller of Registrable Securities, any
      underwriter participating in any distribution pursuant to such registration
      statement, and any attorney, accountant or other agent retained by such seller
      or underwriter, all financial and other records, pertinent corporate documents
      and properties of the Company, and cause the Company's officers, directors
      and
      employees to supply all information reasonably requested by any such seller,
      underwriter, attorney, accountant or agent in connection with such registration
      statement.

    


    (g) In
      connection with each registration hereunder, each seller of Registrable
      Securities will furnish to the Company in writing such information with respect
      to such seller and the proposed distribution by such seller as reasonably shall
      be necessary in order to assure compliance with federal and applicable state
      securities laws.

    


    (h) In
      connection with each registration pursuant to Section 3 covering an underwritten
      public offering, the Company and the Holder agree to enter into a written
      agreement with the managing underwriter selected by the Company containing
      such
      provisions as are customary in the securities business for such an arrangement
      between such underwriter and companies of the Company's size and investment
      stature.

    


    5. Suspension
      of Use of Registration Statement.
      The
      Holder agrees that, upon receipt of any notice from the Company of (A) the
      happening of any event which makes any statements made in the registration
      statement or related prospectus filed pursuant to this Investor Rights
      Agreement, or any document incorporated or deemed to be incorporated therein
      by
      reference, untrue in any material respect or which requires the making of any
      changes in such registration statement or prospectus so that, in the case of
      such registration statement, it will not contain any untrue statement of a
      material fact or omit to state any material fact required to be stated therein
      or necessary to make the statements therein, in light of the circumstance under
      which they were made, not misleading or (B) that, in the judgment of the
      Company’s Board of Directors, it is advisable to suspend use of the prospectus
      for a discrete period of time due to pending corporate developments which are
      or
      may be material to the Company but have not been disclosed in the registration
      statement or in relevant public filings with the SEC, or (C) the SEC has issued
      a stop order suspending the effectiveness of the registration statement, such
      Holder will forthwith discontinue disposition of such Registrable Securities
      covered by such registration statement or prospectus until it is advised in
      writing by the Company that use of the applicable prospectus may be resumed,
      and
      has received copies of any additional or supplemented filings that are
      incorporated or deemed to be incorporated by reference in such prospectus.
      The
      Company shall use all reasonable best efforts to insure that the use of the
      prospectus may be resumed as soon as practicable.

    


    6. Expenses.
      All
      expenses incurred by the Company in complying with Section 3, including, without
      limitation, all registration and filing fees, printing expenses, fees and
      disbursements of counsel and independent public accountants for the Company,
      fees and expenses (including counsel fees) incurred in connection with complying
      with state securities or "blue sky" laws, fees of the National Association
      of
      Securities Dealers, Inc., transfer taxes, fees of transfer agents and
      registrars, costs of insurance and fees and disbursements of one counsel for
      the
      sellers of Registrable Securities, but excluding any Selling Expenses, are
      called "Registration Expenses". All underwriting discounts and selling
      commissions applicable to the sale of Registrable Securities are called "Selling
      Expenses".

    


    The
      Company will pay all Registration Expenses in connection with the registration
      statement under Section 3. All Selling Expenses in connection with each
      registration statement under Section 3 shall be borne by the participating
      sellers in proportion to the number of shares sold by each, or by such
      participating sellers other than the Company (except to the extent the Company
      shall be a seller) as they may agree.


    
      
         

      

      
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    7. Indemnification
      and Contribution.
      (a) In
      the event of the registration of any Registrable Securities under the Securities
      Act pursuant to Section 3, the Company will indemnify and hold harmless the
      Holder and each other seller of such Shares and Registrable Securities
      thereunder, each underwriter of such Registrable Securities thereunder and
      each
      other person, if any, who controls such seller or underwriter within the meaning
      of the Securities Act, against any losses, claims, damages or liabilities,
      joint
      or several, to which such seller, underwriter or controlling person may become
      subject under the Securities Act or otherwise, insofar as such losses, claims,
      damages or liabilities (or actions in respect thereof) arise out of or are
      based
      upon any untrue statement or alleged untrue statement of any material fact
      contained in any registration statement under which such Registrable Securities
      were registered under the Securities Act pursuant to Section 3, any preliminary
      prospectus or final prospectus contained therein, or any amendment or supplement
      thereof, or arise out of or are based upon the omission or alleged omission
      to
      state therein a material fact required to be stated therein or necessary to
      make
      the statements therein not misleading, and will reimburse each such seller,
      each
      such underwriter and each such controlling person for any legal or other
      expenses reasonably incurred by them in connection with investigating or
      defending any such loss, claim, damage, liability or action, provided, however,
      that the Company will not be liable in any such case if and to the extent that
      any such loss, claim, damage or liability arises out of or is based upon an
      untrue statement or alleged untrue statement or omission or alleged omission
      so
      made in conformity with information furnished by any such seller, any such
      underwriter or any such controlling person in writing specifically for use
      in
      such registration statement or prospectus.

    


    (b) In
      the
      event of a registration on behalf of the Holder of any of the Registrable
      Securities under the Securities Act pursuant to Section 3, the Holder, severally
      and not jointly, will indemnify and hold harmless the Company, each person,
      if
      any, who controls the Company within the meaning of the Securities Act, each
      officer of the Company who signs the registration statement, each director
      of
      the Company, each underwriter and each person who controls any underwriter
      within the meaning of the Securities Act, against all losses, claims, damages
      or
      liabilities, joint or several, to which the Company or such officer, director,
      underwriter or controlling person may become subject under the Securities Act
      or
      otherwise, insofar as such losses, claims, damages or liabilities (or actions
      in
      respect thereof) arise out of or are based upon any untrue statement or alleged
      untrue statement of any material fact contained in the registration statement
      under which such Registrable Securities was registered under the Securities
      Act
      pursuant to Section 3, any preliminary prospectus or final prospectus contained
      therein, or any amendment or supplement thereof, or arise out of or are based
      upon the omission or alleged omission to state therein a material fact required
      to be stated therein or necessary to make the statements therein not misleading,
      and will reimburse the Company and each such officer, director, underwriter
      and
      controlling person for any legal or other expenses reasonably incurred by them
      in connection with investigating or defending any such loss, claim, damage,
      liability or action, provided, however, that the Holder will be liable hereunder
      in any such case if and only to the extent that any such loss, claim, damage
      or
      liability arises out of or is based upon an untrue statement or alleged untrue
      statement or omission or alleged omission made in reliance upon and in
      conformity with information pertaining to the Holder furnished in writing to
      the
      Company by the Holder specifically for use in such registration statement or
      prospectus, and provided, further, however, that the liability of the Holder
      hereunder shall be limited to the proportion of any such loss, claim, damage,
      liability or expense which is equal to the proportion that the public offering,
      price of the shares sold by the Holder under such registration statement bears
      to the total public offering price of all securities sold thereunder, but not
      in
      any event to exceed the proceeds received by the Holder from the sale of
      Registrable Securities covered by such registration statement.

    


    (c) Promptly
      after receipt by an indemnified party hereunder of notice of the. commencement
      of any action, such indemnified party shall, if a claim in respect thereof
      is to
      be made against the indemnifying party hereunder, notify the indemnifying party
      in writing thereof, but the omission so to notify the indemnifying party shall
      not relieve it from any liability which it may have to such indemnified party
      other than under this Section 6 and shall only relieve it from any liability
      which it may have to such indemnified party under this Section 6 if and to
      the
      extent the indemnifying party is prejudiced by such omission. In case any such
      action shall be brought against any indemnified party and it shall notify the
      indemnifying party of the commencement thereof, the indemnifying party shall
      be
      entitled to participate in and, to the extent it shall wish, to assume and
      undertake the defense thereof with counsel satisfactory to such indemnified
      party, and, after notice from the indemnifying party to such indemnified party
      of its election so to assume and undertake the defense thereof, the indemnifying
      party shall not be liable to such indemnified party under this Section 6 for
      any
      legal expenses subsequently incurred by such indemnified party in connection
      with the defense thereof other than reasonable costs of investigation and of
      liaison with counsel so selected, provided,
      however,
      that,
      if the defendants in any such action include both the indemnified party and
      the
      indemnifying party and the indemnified party shall have reasonably concluded
      that there may be reasonable defenses available to it which are different from
      or additional to those available to the indemnifying party or if the interests
      of the indemnified party reasonably may be deemed to conflict with the interests
      of the indemnifying party, the indemnified party shall have the right to select
      a separate counsel and to assume such legal defenses and otherwise to
      participate in the defense of such action, with the expenses and fees of such
      separate counsel and other expenses related to such participation to be
      reimbursed by the indemnifying party as incurred.


    
      
         

      

      
        -10-

        
          

        

      

      
         

      

    


    


    


    (d) In
      order
      to provide for just and equitable contribution to joint liability under the
      Securities Act in any case in which either (i) the Holder exercising rights
      under this Agreement, or any controlling person of the Holder, makes a claim
      for
      indemnification pursuant to this Section 6 but it is judicially determined
      (by
      the entry of a final judgment or decree by a court of competent jurisdiction
      and
      the expiration of time to appeal to the denial of the last right of appeal)
      that
      such indemnification may not be enforced in such case notwithstanding the fact
      that this Section 6 provides for indemnification in such case, or (ii)
      contribution under the Securities Act may be required on the part of any the
      Holder or any such controlling person in circumstances for which indemnification
      is provided under this Section 6; then, and in each such case, the Company
      and
      the Holder will contribute to the aggregate losses, claims, damages or
      liabilities to which they may be subject (after contribution from others) in
      such proportion so that the Holder is responsible for the portion represented
      by
      the percentage that the public offering price, if any, of its Registrable
      Securities offered by the registration statement bears to the public offering
      price, if any, of all securities offered by such registration statement, and
      the
      Company is responsible for the remaining portion; provided, however, that,
      in
      any such case, (A) the Holder will not be ruled to contribute any amount in
      excess of the public offering price, if any, of all such Registrable Securities
      offered by it pursuant to such registration statement; and (B) no person or
      entity guilty of fraudulent misrepresentation (within the meaning of Section
      11(f) of the Securities Act) will be entitled to contribution from any person
      or
      entity who was not guilty of such fraudulent misrepresentation.

    


    8. Rule
      144 Reporting . With
      a
      view to making available the benefits of certain rules and regulations of the
      Commission which may at any time permit the sale of the Registrable Securities
      to the public without registration, at all times after 90 days after the
      Qualified Offering or the Qualified Registration shall have become effective,
      the Company agrees to:

    


    (a) make
      and
      keep public information available, as those terms are understood and defined
      in
      Rule 144 under the Securities Act;

    


    (b) use
      reasonable efforts to file with the Commission in a timely manner all reports
      and other documents required of the Company under the Securities Act and the
      Exchange Act; and

    


    (c) furnish
      to the Holder forthwith upon request a written statement by the Company as
      to
      its compliance with the reporting requirements of such Rule 144 and of the
      Securities Act and the Exchange Act, a copy of the most recent annual or
      quarterly report of the Company, and such other reports and documents so filed
      by the Company as the Holder may reasonably request in availing the Holder
      of
      any rule or regulation of the Commission allowing the Holder to sell any
      Registrable Securities without registration.


    
      
         

      

      
        -11-

        
          

        

      

      
         

      

    


    


    9. “Lockup”
      Agreement.
      The
      Holder hereby agrees that such Holder shall not sell, transfer, make any short
      sale of, grant any option for the purchase of, or enter into any hedging or
      similar transaction with the same economic effect as a sale, any shares of
      Common Stock (or other securities) of the Company held by the Holder for a
      period specified by the representative of the underwriters of Common Stock
      (or
      other securities) of the Company not to exceed one hundred eighty (180) days
      following the effective date of the Company’s Qualified Offering or Qualified
      Registration

    


    10. Miscellaneous.

    


    (a) All
      covenants and agreements contained in this Agreement by or on behalf of any
      of
      the parties hereto shall bind and inure to the benefit of the respective
      successors and assigns of the parties hereto (including without limitation
      permitted transferees of any Shares or Registrable Securities), whether so
      expressed or not.

    


    (b) All
      notices, requests, consents and other communications hereunder shall be in
      writing and shall be mailed by certified or registered mail, return receipt
      requested, postage prepaid, or telexed, in the case of non-U.S. residents,
      addressed as follows:

    


    if
      to the
      Company or any other party hereto, at the address of such party set
      forth

    in
      the
      Subscription Agreement;

    


    if
      to the
      Holder, at the address of the Holder set forth in the Subscription
      Agreement;

    


    or,
      in
      any case, at such other address or addresses as shall have been furnished in
      writing to the Company (in the case of the Holder) or to the Holder (in the
      case
      of the Company) in accordance with the provisions of this
      paragraph.

    


    (c) Notwithstanding
      the place where this Agreement may be executed by any of the parties hereto,
      all
      the terms and provisions hereof shall be construed in accordance with and
      governed by the laws of the Commonwealth of Massachusetts, without giving effect
      to its conflict of law principles. Any dispute which may arise out of or in
      connection with this Agreement shall be adjudicated before a court located
      in
      Boston, Massachusetts and the parties hereby submit to the exclusive
      jurisdiction of the courts of the Commonwealth of Massachusetts located in
      Boston, Massachusetts and of the federal courts in Boston, Massachusetts with
      respect to any action or legal proceeding commenced by any party, and
      irrevocably waive any objection they now or hereafter may have respecting the
      venue of any such action or proceeding brought in such a court or respecting
      the
      fact that such court is an inconvenient forum, relating to or arising out of
      this Agreement or any acts or omissions relating to the sale of the Shares,
      and
      each of the undersigned consents to the service of process in any such action
      or
      legal proceeding by means of registered or certified mail, return receipt
      requested, in care of the address set forth below or such other address as
      the
      undersigned shall furnish in writing to the Company. In the event any such
      action is brought, whether at law or in equity, then the prevailing party shall
      be paid its reasonable attorney's fees, expenses and disbursements arising
      out
      of such action. Each of the undersigned hereby waives trial by jury in any
      action or proceeding involving, directly or indirectly, any matter (whether
      sounding in tort, contract, fraud or otherwise) in any way arising out of or
      in
      connection with this Agreement or the Holder’s purchase of a
      Debenture.

    


    (d) This
      Agreement may not be amended or modified, and no provision hereof may be waived,
      without the written consent of the Company and the Holders of at least a
      majority of the outstanding Registrable Securities.


    
      
         

      

      
        -12-

        
          

        

      

      
         

      

    


    


    (e) This
      Agreement may be executed in two or more counterparts, each of which shall
      be
      deemed an original, but all of which together shall constitute one and the
      same
      instrument.

    


    (f) The
      obligations of the Company to register the Registrable Securities under this
      Agreement shall terminate on the tenth anniversary of the date of this
      Agreement.

    


    (g) If
      any
      provision of this Agreement shall be held to be illegal, invalid or
      unenforceable, such illegality, invalidity or unenforceability shall attach
      only
      to such provision and shall not in any manner affect or render illegal, invalid
      or unenforceable any other provision of this Agreement, and this Agreement
      shall
      be carried out as if any such illegal, invalid or unenforceable provision were
      not contained herein.

    


    Please
      indicate your acceptance of the foregoing by signing and returning the enclosed
      counterpart of this letter, whereupon this Agreement shall be a binding
      agreement between the Company and you.

    


    
      	 	
              Very
                truly yours,

            
	 	 	 
	 	
              AmericanDG
                Energy Inc.

            
	 	 	 
	 	
              By:

            	
               
                

            
	 	 	 
	 	
              Name:
                Anthony S. Loumidis

            
	 	
              Title:
                Chief Financial Officer

            


    

    


    


    AGREED
      TO
      AND ACCEPTED as of

    the
      date
      first above written.

    


    
      	
              By:

            	
               
                

            	 
	 	 	 
	
              Name:
                

            	
               
                

            	 
	 	 	 
	
              Title:

            	
               
                

            	 


    

    


    


    


    
      
         

      

      
        -13-