**COALOGIX
      INC.**




**COMMON
      STOCK PURCHASE AGREEMENT**







**TABLE
      OF CONTENTS**





**Page**1.
            PURCHASE
                AND SALE OF COMMON STOCK
            11.1.
            Sale
                and Issuance of Common Stock
            11.2.
            Closing;
                Delivery
            11.3.
            Defined
                Terms Used in this Agreement
            12.
            REPRESENTATIONS
              AND WARRANTIES OF THE COMPANY
            22.1.
            Organization,
                Good Standing, Corporate Power and Qualification
            32.2.
            Capitalization
            32.3.
            Subsidiaries
                and Affiliates
            42.4.
            Authorization
            42.5.
            Valid
                Issuance of Shares
            42.6.
            Governmental
                Consents and Filings
            42.7.
            Litigation
            42.8.
            Compliance
                with Other Instruments
            52.9.
            Rights
                of Registration and Voting Rights
            52.10.
            No
                Company Operations or Material Liabilities
            52.11.
            Changes
            52.12.
            Corporate
                Documents
            62.13.
            Offering
            62.14.
            Preemptive
                Rights
            62.15.
            Consents
            62.16.
            Employment
                and Non-Competition Agreements
            63.
            REPRESENTATIONS
              AND WARRANTIES OF THE PURCHASER
            73.1.
            Authorization
            73.2.
            Compliance
                with Other Instruments
            73.3.
            Purchase
                Entirely for Own Account
            73.4.
            Disclosure
                of Information
            73.5.
            Restricted
                Securities
            83.6.
            No
                Public Market
            83.7.
            Suitability
                of Investment
            83.8.
            Legends
            8




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**TABLE
        OF CONTENTS**
 (continued)


**Page**3.9.
            Accredited
                Investor
            93.10.
            Foreign
                Investors
            93.11.
            Residence
            94.
            CONDITIONS
              TO THE PURCHASER’S OBLIGATIONS AT CLOSING
            94.1.
            Qualifications
            94.2.
            Representations
                and Warranties of Company
            94.3.
            Opinion
                of Company Counsel
            94.4.
            Covenants
                of the Company
            94.5.
            Stockholders’
                Agreement
            94.6.
            Secretary’s
                Certificate
            94.7.
            Management
                Rights
            104.8.
            Board
                of Directors
            105.
            CONDITIONS
              TO THE COMPANY’S OBLIGATIONS AT CLOSING
            105.1.
            Qualifications
            105.2.
            Representations
                and Warranties of the Purchaser
            106.
            COVENANTS
              OF THE COMPANY
            106.1.
            Proceedings
                and Documents
            106.2.
            Securities
                Laws Compliance
            106.3.
            Use
                of Proceeds
            106.4.
            Pre-Closing
                Access and Information
            106.5.
            Conduct
                of the Company's Business.
            116.6.
            Notices
                to Purchaser
            116.7.
            Exclusivity
            117.
            SURVIVAL
              PERIOD; INDEMNIFICATION
            117.1.
            Survival
                of Representations, Warranties and Covenants
            117.2.
            Indemnification
            127.3.
            Limitations
                on Indemnification
            128.
            MISCELLANEOUS
            128.1.
            Transfer;
                Successors and Assigns
            128.2.
            Governing
                Law
            12




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**TABLE
        OF CONTENTS**
 (continued)


**Page**8.3.
            Counterparts
            128.4.
            Titles
                and Subtitles
            138.5.
            Notices
            138.6.
            No
                Finder’s Fees
            148.7.
            Fees
                and Expenses
            148.8.
            Amendments
                and Waivers
            148.9.
            Severability
            148.10.
            Delays
                or Omissions
            148.11.
            Entire
                Agreement
            148.12.
            Publicity
            158.13.
            Right
                to Conduct Activities
            158.14.
            Termination
            16





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**TABLE
      OF CONTENTS**


**Page**Exhibit
                A
            Schedule
                of PurchaserExhibit
                B
            Disclosure
                ScheduleExhibit
                C
            Form
                of Stockholders’ AgreementExhibit
                D
            Form
                of Management Rights LetterExhibit
                E
            Form
                of Legal Opinion of Company Counsel





-i-


**COMMON
      STOCK PURCHASE AGREEMENT**




This
      Common Stock Purchase Agreement (the “ **Agreement** ”)
      is
      made as of February 29, 2008 by and among CoaLogix Inc., a Delaware corporation
      (the “ **Company** ”),
      Acorn
      Energy, Inc., a Delaware corporation (the **“Parent** ”),
      and
      the investor listed on Exhibit
      A attached
      to this Agreement (the “ **Purchaser** ”).




The
      parties hereby agree as follows:




1.  Purchase
      and Sale of Common Stock .




1.1.  Sale
      and Issuance of Common Stock .
      Subject
      to the terms and conditions of this Agreement, the Purchaser agrees to purchase
      at the Closing and the Company agrees to sell and issue to the Purchaser at
      the
      Closing that number of shares of the Company’s Common Stock, $0.001
      par value per share (the
“ **Common
      Stock** ”)
      set
      forth opposite the Purchaser's name on Exhibit
      A ,
      at a
      purchase price of $126.1566 per share, payable as set forth on Exhibit
      A .
      The
      shares of Common Stock issued to the Purchaser pursuant to this Agreement shall
      be referred to in this Agreement as the “ **Shares** .”




1.2.  Closing;
      Delivery .




(a)  The **** purchase
      and sale of the Shares shall take place at 10:00 a.m., on the date on the
      business day on which the last of the conditions set forth in Sections
      4 and 5 of this
      Agreement that are capable of being satisfied before the Closing are fulfilled
      or waived in accordance with this Agreement, at the offices of Dechert LLP,
      counsel to EnerTech Capital Partners III L.P., 2929 Arch Street, Philadelphia,
      PA 19104-2808 or at such other time and place as the Company and the Purchaser
      mutually agree upon, orally or in writing (which time and place are designated
      as the “ **Closing** ”).




(b)  At
      the
      Closing, the Company shall deliver to the Purchaser a certificate representing
      the Shares being purchased by the Purchaser at such Closing against payment
      of
      the purchase price therefor by wire transfer to a bank account designated by
      the
      Company.




1.3.  Defined
      Terms Used in this Agreement .
      In
      addition to the terms defined above, the following terms used in this Agreement
      shall be construed to have the meanings set forth or referenced
      below.




“ **Affiliate** ”
means
      with respect to any person or entity (a “ **Person** ”)
      any
      Person which, directly or indirectly, controls, is controlled by, or is under
      common control with such Person, including, without limitation, any partner,
      officer, director, or member of such Person and any venture capital fund now
      or
      hereafter existing which is controlled by or under common control with one
      or
      more general partners or shares the same management company with such
      Person.




“ **Code** ”
means
      the Internal Revenue Code of 1986, as amended.









“ **Company
      Intellectual Property** ”
means
      all trademarks, service marks, tradenames, copyrights, trade secrets, licenses,
      information and proprietary rights and processes and all patents and patent
      rights owned or possessed by the Company.




“ **Exchange
      Act** ”
means
      the Securities Exchange Act of 1934, as amended, and the rules and regulations
      promulgated thereunder.




“ **Key
      Employee** ”
means
      any executive-level employee (including Vice President level positions) as
      well
      as any employee who either alone or in concert with others develops, invents,
      programs or designs any Company Intellectual Property.




“ **Management
      Rights Letter** ”
means
      the agreement between the Company and EnerTech Capital Partners III L.P., in
      the
      form of Exhibit
      D attached
      to this Agreement.




“ **Material
      Adverse Effect** ”
means
      a
      material adverse effect on the business, assets (including intangible assets),
      liabilities, financial condition, property, prospects  or
      results of operations of the Company or any of the SCR-Tech
      Entities.




“ **Purchaser** ”
means
      the Purchaser who is a party to this Agreement.




**“SCR-Tech
      Entities”** means
      CESI-TECH Technologies, CESI-SCR, Inc. and SCR Tech LLC.




“ **Securities
      Act** ”
means
      the Securities Act of 1933, as amended.




“ **Shares** ”
means
      the shares of Common Stock of the Company issued at the Closing.




“ **Stockholders’
      Agreement** ”
means
      the agreement between the Company, Parent and the Purchaser, dated as of the
      date hereof, in the form of Exhibit
      C attached
      to this Agreement.




“ **Transaction
      Agreements** ”
means
      this Agreement, the Stockholders’ Agreement, the Management Rights Letter, and
      any other agreements, instruments or documents entered into in connection with
      this Agreement.




2.  Representations
      and Warranties of the Company **.** The
      Company hereby represents and warrants to the Purchaser that, except as set
      forth on the **Disclosure
      Schedule** attached
      to this Agreement which exceptions shall be deemed to be part of the
      representations and warranties made hereunder, the following representations
      are
      true and complete as of the date hereof and will be true and correct as of
      the
      Closing, except as otherwise indicated. The **Disclosure
      Schedule** shall be
      arranged in sections corresponding to the numbered and lettered sections and
      subsections contained in this Section
      2 ,
      and the
      disclosures in any section or subsection of the **Disclosure
      Schedule** shall
      qualify other sections and subsections in this Section
      2 only to
      the extent it is readily apparent from a reading of the disclosure that such
      disclosure is applicable to such other sections and subsections.




2




For
      purposes of these representations and warranties, the phrase “to the Company’s
      knowledge” shall mean the knowledge after reasonable investigation of the Key
      Employees of the Company.




2.1.  Organization,
      Good Standing, Corporate Power and Qualification .
      The
      Company is a corporation duly organized, validly existing and in good standing
      under the laws of the State of Delaware and has all requisite corporate power
      and authority to carry on its business as presently conducted and as proposed
      to
      be conducted. The Company is duly qualified to transact business and is in
      good
      standing in each jurisdiction in which the failure to so qualify would have
      a
      Material Adverse Effect.




2.2.  Capitalization .
      The
      authorized capital of the Company consists, immediately prior to the Closing
      (unless otherwise noted), of:




(a)  150,000 **** shares
      of
      Common Stock, 87,500 shares of which are issued and outstanding immediately
      prior to the Closing. All of the outstanding shares of Common Stock have been
      duly authorized, are fully paid and nonassessable and were issued in compliance
      with all applicable federal and state securities laws. The Company holds no
      treasury stock.




(b)  **Section
      2.2(c) of the Disclosure Schedule** sets
      forth the options that the Company is committed to granting following the
      Closing.




(c)  **Section
      2.2(c)** **of the Disclosure Schedule** sets
      forth the capitalization of the Company immediately following the Closing
      including the number of shares of the following: (i) issued and outstanding
      Common Stock; (ii) the name of each holder of options for Common Stock,
      together with the number of shares for which such options are exercisable with
      respect to each holder, the applicable vesting schedule, if any, and the
      applicable exercise price; (iii) stock options not yet issued but reserved
      for issuance; and (iv) warrants or stock purchase rights, if any. Except
      for (A) the rights provided in Sections
      4 and 5 of the
      Stockholders’ Agreement, and (B) the securities and rights described in Section
      2.2(b) of this
      Agreement and **Section
      2.2(c)** **of the Disclosure Schedule** ,
      there
      are no outstanding options, warrants, rights (including conversion or preemptive
      rights and rights of first refusal or similar rights) or agreements, orally
      or
      in writing, to purchase or acquire from the Company, or sell to the Company,
      any
      shares of Common Stock, or contracts, commitments, understandings, or
      arrangements by which the Company is or may become bound to issue Common Stock
      or any securities convertible into or exchangeable for shares of Common Stock.
      Except as set forth on **Section
      2.2(c)** **of the Disclosure Schedule** ,
      no
      current or former shareholder of the Company's capital stock has, or with the
      giving of notice or any other actions may have, any appraisal rights or the
      right to obtain payment of the fair value of that shareholder's shares of Common
      Stock. Except for as provided in the Stockholders’ Agreement, no shareholder of
      the Company or other person has any right to designate members to serve on
      the
      Company's board of directors or any committee thereof.




3




(d)  Except
      as
      set forth on **Section
      2.2(d)** **of the Disclosure Schedule** ,
      all
      outstanding shares of the Company’s Common Stock and all shares of the Company’s
      Common Stock underlying outstanding options are subject to a right of first
      refusal in favor of the Company upon any proposed transfer (other than transfers
      for estate planning purposes). Except as set forth on **Section
      2.2(d)** **of the Disclosure Schedule** ,
      none of
      the Company’s stock purchase agreements or stock option documents contains a
      provision for acceleration of vesting (or lapse of a repurchase right) upon
      the
      occurrence of any event or combination of events. Except as set forth on **Section
      2.2(d)** **of the Disclosure Schedule** ,
      the
      Company has never adjusted or amended the exercise price of any stock options
      previously awarded, whether through amendment, cancellation, replacement grant,
      repricing, or any other means.




2.3.  Subsidiaries
      and Affiliates .
      Except
      as set forth on **Section
      2.3 of the Disclosure Schedule** ,
      the
      Company does not own, directly or indirectly, any capital stock or other equity
      securities of any corporation or have any direct or indirect equity ownership
      in
      any business.




2.4.  Authorization .
      All
      corporate action required to be taken by the Company’s Board of Directors and
      stockholders in order to authorize the Company to enter into the Transaction
      Agreements, and to issue the Shares at the Closing, has been taken or, in the
      case of the stockholders, will be taken prior to the Closing. All action on
      the
      part of the officers of the Company necessary for the execution and delivery
      of
      the Transaction Agreements, the performance of all obligations of the Company
      under the Transaction Agreements to be performed as of the Closing, and the
      issuance and delivery of the Shares has been taken or will be taken prior to
      the
      Closing. The Transaction Agreements, when executed and delivered by the Company,
      shall constitute valid and legally binding obligations of the Company,
      enforceable against the Company in accordance with their respective terms except
      (i) as limited by applicable bankruptcy, insolvency, reorganization,
      moratorium, fraudulent conveyance, or other laws of general application relating
      to or affecting the enforcement of creditors’ rights generally, (ii) as limited
      by laws relating to the availability of specific performance, injunctive relief,
      or other equitable remedies, or (iii) to the extent the indemnification
      provisions contained in the Stockholders’ Agreement may be limited by applicable
      federal or state securities laws.




2.5.  Valid
      Issuance of Shares .
      The
      Shares, when issued, sold and delivered in accordance with the terms and for
      the
      consideration set forth in this Agreement, will be validly issued, fully paid
      and nonassessable and free of restrictions on transfer other than restrictions
      on transfer under this Agreement, the Stockholders’ Agreement, applicable state
      and federal securities laws and liens or encumbrances created by or imposed
      by
      the Purchaser. Assuming the accuracy of the representations of the Purchaser
      in Section
      3 of this
      Agreement, the Shares will be issued in compliance with all applicable federal
      and state securities laws.




2.6.  Governmental
      Consents and Filings .
      Assuming the accuracy of the representations made by the Purchaser in Section
      4 of this
      Agreement, no consent, approval, order or authorization of, or registration,
      qualification, designation, declaration or filing with, any federal, state
      or
      local governmental authority is required on the part of the Company in
      connection with the consummation of the transactions contemplated by this
      Agreement, except for filings, if any, pursuant to Regulation D of the
      Securities Act, and applicable state securities laws, which have been made
      or
      will be made in a timely manner.




2.7.  Litigation .
      There
      is no claim, action, suit, proceeding, arbitration, complaint, charge or
      investigation pending or, to the Company’s knowledge, currently threatened that
      questions the validity of the Transaction Agreements or the right of the Company
      to enter into them, or to consummate the transactions contemplated by the
      Transaction Agreements.




4




2.8.  Compliance
      with Other Instruments .
      The
      execution, delivery and performance of the Transaction Agreements and the
      consummation of the transactions contemplated by the Transaction Agreements
      will
      not result in any violation or be in conflict with or constitute, with or
      without the passage of time and giving of notice, either (i) a default under
      any
      instrument, judgment, order, writ, decree, contract or agreement to which the
      Company is a party or by which it is bound or (ii) an event which results in
      the
      creation of any lien, charge or encumbrance upon any property or assets of
      the
      Company or the suspension, revocation, forfeiture, or nonrenewal of any permit
      or license applicable to the Company.




2.9.  Rights
      of Registration and Voting Rights .
      Except
      as provided in the Stockholders’ Agreement, the Company is not under any
      obligation to register under the Securities Act any of its currently outstanding
      securities or any securities issuable upon exercise or conversion of its
      currently outstanding securities. Except as contemplated in the Stockholders’
Agreement, no stockholder of the Company has entered into any agreements with
      respect to the voting of capital shares of the Company.




2.10.  No
      Company Operations or Material Liabilities .
      The
      Company is a holding company without operations other than the ownership of
      stock of its subsidiaries. The Company, excluding its subsidiaries, has no
      material liabilities or obligations, contingent or otherwise, other than
      liabilities (i) under that certain Stock Purchase Agreement, dated November
      7,
      2007, by and among the Company, Parent, Catalytica Energy Systems, Inc. and
      with
      respect to Article 11 thereof only, Renegy Holdings, Inc., (ii) under this
      Agreement, or (iii) as set
      forth on **Section
      2.10** **of the Disclosure Schedule** .




2.11.  Changes .
      To the
      Company’s knowledge, since November 7, 2007, there has not been:




(a)  any
      change in the assets, liabilities, financial condition or operating results
      of
      the SCR-Tech Entities, except changes in the ordinary course of business that
      have not caused, in the aggregate, a Material Adverse Effect on the SCR-Tech
      Entities;




(b)  any
      damage, destruction or loss, whether or not covered by insurance, that would
      have a Material Adverse Effect on the SCR-Tech Entities;




(c)  any
      waiver or compromise by the Company of a valuable right or of a material debt
      owed to any of the SCR-Tech Entities;




(d)  any
      satisfaction or discharge of any lien, claim, or encumbrance or payment of
      any
      obligation by the Company, except in the ordinary course of business and the
      satisfaction or discharge of which would not have a Material Adverse Effect
      on
      the SCR-Tech Entities;




(e)  any
      material change to a material contract or agreement by which the SCR-Tech
      Entities or any of their assets is bound or subject;




5




(f)  any
      mortgage, pledge, transfer of a security interest in, or lien, created by the
      Company, with respect to any of the material properties or assets of the
      SCR-Tech Entities, except liens for taxes not yet due or payable and liens
      that
      arise in the ordinary course of business and do not materially impair the
      Company’s or the SCR-Tech Entities’ ownership or use of such property or
      assets;




(g)  any
      sale,
      assignment or transfer of any Company Intellectual Property **** that
      could reasonably be expected to result in a Material Adverse Effect to the
      SCR-Tech Entities;




(h)  receipt
      of notice that there has been a loss of, or material order cancellation by,
      any
      major customer of any of the SCR-Tech Entities; or




(i)  any
      other
      event or condition of any character, other than events affecting the economy
      or
      the Company’s industry generally, that could reasonably be expected to result in
      a Material Adverse Effect to the SCR-Tech Entities.




To
      the
      Company’s knowledge, since November 7, 2007 (x) the SCR-Tech Entities have
      carried on and operated their business in the ordinary course of business and
      (y) the SCR-Tech Entities have not suffered a Material Adverse
      Effect.




2.12.  Corporate
      Documents .
      The
      Certificate of Incorporation and Bylaws of the Company are in the form provided
      to the Purchaser. The copy of the minute books of the Company provided to the
      Purchaser contains minutes of all meetings of directors and stockholders and
      all
      actions by written consent without a meeting by the directors and stockholders
      since November 7, 2007 and accurately reflects in all material respects all
      actions by the directors (and any committee of directors) and stockholders
      with
      respect to all transactions referred to in such minutes.




2.13.  Offering .
      Subject
      in part to the truth and accuracy of the Purchaser’s representations set forth
      in Article III of this Agreement, the offer, sale and issuance of the Shares
      as
      contemplated by this Agreement are exempt from the registration requirements
      of
      the Securities Act of 1933, as amended, and neither the Company nor any
      authorized agent acting on its behalf will take any action hereafter that would
      cause the loss of such exemption.




2.14.  Preemptive
      Rights .
      The
      Company has fully satisfied (including with respect to rights of timely
      notification) or obtained enforceable waivers in respect of any preemptive
      or
      similar rights directly or indirectly affecting any of its
      securities.




2.15.  Consents .
      All
      consents, approvals, releases, filings, terminations and waivers by third
      parties necessary to complete the transactions contemplated hereby that are
      set
      forth in **Section
      2.15** **of the Disclosure Schedule** have
      been obtained and delivered to the Purchaser and such consents, approvals,
      releases, filings, terminations and waivers have not expired or been
      withdrawn.




2.16.  Employment
      and Non-Competition Agreements .
      William
      McMahon, Michael Mattes, Frank Wenz and Michael Cooper are bound by and have
      executed employment agreements with the Company and the SCR-Tech Entities.
      All
      other employees of the SCR-Tech Entities have entered into non-competition
      agreements with the SCR-Tech Entities.




6




3.  Representations
      and Warranties of the Purchaser .
      The
      Purchaser hereby represents and warrants to the Company that:




3.1.  Authorization .
      The
      Purchaser has full power and authority to enter into the Transaction Agreements.
      The Transaction Agreements to which the Purchaser is a party, when executed
      and
      delivered by the Purchaser, will constitute valid and legally binding
      obligations of the Purchaser, enforceable in accordance with their terms, except
      (a) as limited by applicable bankruptcy, insolvency, reorganization,
      moratorium, fraudulent conveyance, and any other laws of general application
      affecting enforcement of creditors’ rights generally, and as limited by laws
      relating to the availability of a specific performance, injunctive relief,
      or
      other equitable remedies, or (b) to the extent the indemnification
      provisions contained in the Stockholders’ Agreement may be limited by applicable
      federal or state securities laws.




3.2.  Compliance
      with Other Instruments .
      The
      execution and delivery of this Agreement by the Purchaser, and the performance
      by the Purchaser of its obligations hereunder, will not conflict, or result
      in
      any violation of, or default under, any provision of any charter, bylaws, trust
      agreement, partnership agreement or other governing instrument applicable to
      the
      Purchaser, or any agreement or other instrument to which the Purchaser is a
      party or by which the Purchaser or any of its properties are bound, or any
      permit, franchise, judgment, decree, order, rule or regulation applicable to
      the
      Purchaser or the Purchaser’s business or properties.




3.3.  Purchase
      Entirely for Own Account .
      This
      Agreement is made with the Purchaser in reliance upon the Purchaser’s
      representation to the Company, which by the Purchaser’s execution of this
      Agreement, the Purchaser hereby confirms, that the Shares to be acquired by
      the
      Purchaser will be acquired for investment for the Purchaser’s own account, not
      as a nominee or agent, and not with a view to the resale or distribution of
      any
      part thereof, and that the Purchaser has no present intention of selling,
      granting any participation in, or otherwise distributing the same. By executing
      this Agreement, the Purchaser further represents that the Purchaser does not
      presently have any contract, undertaking, agreement or arrangement with any
      person to sell, transfer or grant participations to such person or to any third
      person, with respect to any of the Shares. The Purchaser has not been formed
      for
      the specific purpose of acquiring the Shares.




3.4.  Disclosure
      of Information .
      The
      Purchaser has had an opportunity to discuss the Company’s business, management,
      financial affairs and the terms and conditions of the offering of the Shares
      with the Company’s management. Except as set forth in the Transaction
      Agreements, no representations or warranties, whether written or oral, have
      been
      made to the Purchaser by the Company or any officer, employee, affiliate or
      agent of the Company. The foregoing, however, does not limit or modify the
      representations and warranties of the Company in Section
      2 of this
      Agreement or the right of the Purchaser to rely thereon.




7




3.5.  Restricted
      Securities .
      The
      Purchaser understands that the Shares have not been, and will not be, registered
      under the Securities Act, by reason of a specific exemption from the
      registration provisions of the Securities Act which depends upon, among other
      things, the bona fide nature of the investment intent and the accuracy of the
      Purchaser’s representations as expressed herein. The Purchaser understands that
      the Shares are “restricted securities” under applicable U.S. federal and state
      securities laws and that, pursuant to these laws, the Purchaser must hold
      the **** Shares
      indefinitely unless they are registered with the Securities and Exchange
      Commission and qualified by state authorities, or an exemption from such
      registration and qualification requirements is available. The Purchaser
      acknowledges that the Company has no obligation to register or qualify the
      Shares for resale except as set forth in the Stockholders’ Agreement. The
      Purchaser further acknowledges that if an exemption from registration or
      qualification is available, it may be conditioned on various requirements
      including, but not limited to, the time and manner of sale, the holding period
      for the Shares, and on requirements relating to the Company which are outside
      of
      the Purchaser’s control, and which the Company is under no
      obligation ** and
      may
      not be able to satisfy.




3.6.  No
      Public Market .
      The
      Purchaser understands that no public market now exists for the Shares, and
      that
      the Company has made no assurances that a public market will ever exist for
      the
      Shares.




3.7.  Suitability
      of Investment .
      The
      Purchaser has such knowledge and experience in financial, business and tax
      matters that the Purchaser is capable of evaluating the merits and risks
      relating to the Purchaser’s investment in the Shares and making an investment
      decision with respect to the Company. The Purchaser acknowledges that it has
      had
      the opportunity to review this Agreement and the transactions contemplated
      by
      this Agreement with its own legal counsel. The Purchaser is not relying on
      any
      statements or representations of the Company or any of its agents for legal
      advice with respect to this investment or the transactions contemplated by
      this
      Agreement other than as set forth in the Transaction Agreements.




3.8.  Legends .
      The
      Purchaser understands that the Shares and any securities issued in respect
      of or
      exchange for the Shares, may bear one or all of the following
      legends:




(a)  “THE
      SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE
      SECURITIES ACT OF 1933 (THE “ACT”), AND HAVE BEEN ACQUIRED FOR INVESTMENT AND
      NOT WITH A VIEW TO, OR IN CONNECTION WITH, THE SALE OR DISTRIBUTION THEREOF.
      NO
      SUCH TRANSFER MAY BE EFFECTED WITHOUT AN EFFECTIVE REGISTRATION STATEMENT
      RELATED THERETO OR AN OPINION OF COUNSEL IN A FORM SATISFACTORY TO THE COMPANY
      THAT SUCH REGISTRATION IS NOT REQUIRED UNDER THE ACT, UNLESS SUCH TRANSFER
      SHALL
      (I) CONSTITUTE A ROUTINE SALE UNDER RULE 144 OF THE ACT OR (II) BE OF SHARES
      THAT ARE ELIGIBLE FOR RESALE UNDER RULE 144(B)(1) OF THE ACT.”




(b)  Any
      legend set forth in, or required by, the other Transaction
      Agreements.




(c)  Any
      legend required by the securities laws of any state to the extent such laws
      are
      applicable to the Shares represented by the certificate so
      legended.




8




3.9.  Accredited
      Investor .
      The
      Purchaser is an accredited investor as defined in Rule 501(a) of Regulation
      D
      promulgated under the Securities Act.




3.10.  Foreign
      Investors .
      If the
      Purchaser is not a United States person (as defined by Section 7701(a)(30)
      of the Code), such Purchaser hereby represents that it has satisfied itself
      as
      to the full observance of the laws of its jurisdiction in connection with any
      invitation to subscribe for the Shares or any use of this Agreement, including
      (i) the legal requirements within its jurisdiction for the purchase of the
      Shares, (ii) any foreign exchange restrictions applicable to such purchase,
      (iii) any governmental or other consents that may need to be obtained, and
      (iv) the income tax and other tax consequences, if any, that may be
      relevant to the purchase, holding, redemption, sale, or transfer of the Shares.
      Such Purchaser’s subscription and payment for and continued beneficial ownership
      of the Shares, will not violate any applicable securities or other laws of
      the
      Purchaser’s jurisdiction.




3.11.  Residence .
      The
      office or offices of the Purchaser in which its principal place of business
      is
      located at the address or addresses of the Purchaser set forth on Exhibit
      A .




4.  Conditions
      to the Purchaser’s Obligations at Closing .
      The
      obligations of the Purchaser to purchase Shares at the Closing are subject
      to
      the fulfillment, on or before Closing, of each of the following conditions,
      unless otherwise waived:




4.1.  Qualifications .
      All
      authorizations, approvals or permits, if any, of any governmental authority
      or
      regulatory body of the United States or of any state that are required in
      connection with the lawful issuance and sale of the Shares pursuant to this
      Agreement shall be obtained and effective as of such Closing.




4.2.  Representations
      and Warranties of Company .
      The
      representations and warranties of the Company contained in Section 2 shall
      be
      true and correct in all material respects as of Closing, except that any such
      representation and warranties shall be true and correct in all respects where
      such representation and warranty is qualified with respect to materiality in
      Section 2, and the Company shall have performed and complied with all covenants,
      agreements, obligations and conditions contained in this Agreement that are
      required to be performed or complied with by it on or before
      Closing.




4.3.  Opinion
      of Company Counsel .
      The
      Purchaser shall have received from Eilenberg Krause & Paul LLP, counsel for
      the Company, an opinion, dated as of the Closing, in substantially the form
      of
      Exhibit E (but without assumptions related to issuance of the
      Shares).




4.4.  Covenants
      of the Company .
      The
      Company shall have in all material respects performed the obligations and
      complied with the covenants required by this Agreement to be performed or
      complied with by it at or prior to the Closing.




4.5.  Stockholders’
      Agreement .
      The
      Company and the Purchaser and the other stockholders of the Company named as
      parties thereto have executed and delivered the Stockholders’
Agreement.




4.6.  Secretary’s
      Certificate .
      The
      Secretary of the Company has delivered to the Purchaser at the Closing a
      certificate certifying (i) the Certificate of Incorporation and Bylaws of the
      Company and (ii) resolutions of the Board of Directors of the Company approving
      the Transaction Agreements and the transactions contemplated under the
      Transaction Agreements.




9




4.7.  Management
      Rights .
      A
      Management Rights Letter has been executed by the Company and delivered to
      EnerTech Capital Partners III L.P.




4.8.  Board
      of Directors .
      The
      Company’s Board of Directors shall be comprised of John A. Moore, Scott Ungerer
      and William McMahon.




5.  Conditions
      to the Company’s Obligations at Closing .
      The
      obligations of the Company to sell Shares to the Purchaser at the Closing are
      subject to the fulfillment, on or before the Closing, of each of the following
      conditions, unless otherwise waived:




5.1.  Qualifications .
      All
      authorizations, approvals or permits, if any, of any governmental authority
      or
      regulatory body of the United States or of any state that are required in
      connection with the lawful issuance and sale of the Stock pursuant to this
      Agreement shall be obtained and effective as of the Closing.




5.2.  Representations
      and Warranties of the Purchaser .
      The
      representations and warranties of the Purchaser contained in Section
      3 shall be
      true and correct in all material respects as of Closing, except that any such
      representation and warranties shall be true and correct in all respects where
      such representation and warranty is qualified with respect to materiality in Section
      3 ,
      and the
      Company shall have performed and complied with all covenants, agreements,
      obligations and conditions contained in this Agreement that are required to
      be
      performed or complied with by it on or before Closing.




6.  Covenants
      of the Company .




6.1.  Proceedings
      and Documents .
      The
      Purchaser shall receive all such counterpart original and certified or other
      copies of such documents as reasonably requested. Such documents may include
      good standing certificates.




6.2.  Securities
      Laws Compliance .
      The
      Company shall make in a timely manner any filings required by applicable federal
      or state securities or Blue Sky laws, or those of any other applicable
      jurisdiction.




6.3.  Use
      of
      Proceeds .
      As set
      forth on **Section
      6.3** **of the Disclosure Schedule** ,
      the
      Company agrees that the purchase price paid by the Purchaser shall be used
      by it
      for working capital expenses only, and shall not be used to reduce any
      outstanding indebtedness of the Company or to make payments to any stockholder
      or affiliate of the Company.




6.4.  Pre-Closing
      Access and Information .
      From
      the date hereof to the Closing, the Company will give the Purchaser and their
      authorized representatives (including accountants, legal counsel and
      environmental consultants) full access at all reasonable times, upon reasonable
      notice, to all of the offices and other facilities of the Company, to all
      contracts, agreements, commitments, books and records of the Company, to the
      personnel (including auditors) of the Company and to the customers and suppliers
      of the Company.




10




6.5.  Conduct
      of the Company's Business .




(a)  Except
      as
      contemplated by this Agreement, during the period from the date of this
      Agreement to the Closing Date, the Company shall conduct the operations of
      the
      Company according to its ordinary course of business and consistent with past
      practice, and shall use commercially reasonable efforts to preserve intact
      its
      business organization, keep available the services of its officers and
      employees, and maintain satisfactory relationships with suppliers, contractors,
      distributors, customers and others having business relationships with the
      Company. During the period from the date of this Agreement to the Closing Date,
      the Company agrees that it will not take any action reasonably within its
      control, or omit to take any action reasonably within its control, which would
      cause any of the representations and warranties of the Company in this Agreement
      to become untrue.




(b)  Without
      limiting the foregoing, during the period from the date of this Agreement to
      the
      Closing Date, the Company shall not take any of the actions specified in Section
      2.11 without
      the prior written consent the Purchaser.




6.6.  Notices
      to Purchaser .
      Prior
      to the Closing, the Company shall give prompt written notice to the Purchaser
      of: (a) any breach or default by the Company of the representations, warranties,
      covenants or agreements hereunder or under any document or instrument
      contemplated hereby; (b) any notice or other communication from any third party
      alleging that the consent of such third party is or may be required in
      connection with the transactions contemplated by this Agreement; (c) any notice
      or other communication from any governmental authority in connection with the
      transactions contemplated by this Agreement; (d) any Material Adverse Effect;
      and (e) any claim, action, or proceeding against the Company which could
      reasonably be expected to have a Material Adverse Effect.




6.7.  Exclusivity .
      From
      the date hereof to the Closing, the Company shall not, nor shall it authorize
      or
      permit any officer, director or employee of or any investment banker, broker,
      attorney, accountant, or other representative retained by the Company to,
      solicit, initiate or encourage (including by way of furnishing information)
      submission of any proposal or offer from any person which constitutes, or may
      reasonably be expected to lead to, a Financing Proposal. As used herein, a
      “ **Financing
      Proposal** ”
shall
      mean any proposal for a merger or other business combination involving the
      Company, or any proposal or offer to acquire in any manner an equity interest
      in
      or a material portion of the assets of the Company (other than sales in the
      ordinary course of business consistent with past practice) or to extend
      indebtedness to the Company. If the Company receives a Financing Proposal prior
      to the Closing, the Company shall notify the Purchaser immediately and shall
      provide to the Purchaser a copy of any written documentation of such Financing
      Proposal.




7.  Survival
      Period; Indemnification .




7.1.  Survival
      of Representations, Warranties and Covenants .
      Unless
      otherwise set forth in this Agreement, the representations and warranties of
      the
      Company and the Purchaser contained in or made pursuant to this Agreement (x)
      shall survive the execution and delivery of this Agreement and the Closing
      until
      the date that is one year after the Closing Date, except that the
      representations and warranties in Sections
      2.1, 2.2, 2.3, 2.4 and 2.5 shall
      survive the Closing indefinitely, and (y) shall in no way be affected by any
      investigation of the subject matter thereof made by or on behalf of the
      Purchaser or the Company and shall bind the parties’ successors and assigns
      (including, without limitation, any successor to the Company by way of
      acquisition, merger or otherwise), whether so expressed or not. This Section
      7
      shall survive the Closing and the covenants contained in this Agreement shall
      survive the Closing for the periods contemplated by their terms.




11




7.2.  Indemnification .
      The
      Company and the Purchaser shall, with respect to the representations, warranties
      and agreements made by them herein, indemnify, pay, defend and hold the Company
      or the Purchaser, as the case may be, and each of the Company or the Purchaser’s
      officers, directors, partners, employees and agents and their respective
      Affiliates, as the case may be, (the “ **Indemnitees** ”)
      harmless against any and all liabilities, obligations, losses, damages,
      penalties, actions, judgments, suits, claims, costs, expenses and disbursements
      of counsel for such Indemnitees in connection with any investigative,
      administrative or judicial proceeding (collectively, “ **Losses** ”),
      whether or not such Indemnitees shall be designated a party thereto, which
      may
      be (a) imposed on such Indemnitee, or (b) incurred by such Indemnitee, as a
      result of (i) the violation or breach of any representation, warranty or
      covenant of the Company or the Parent or the Purchaser, as the case may be,
      under this Agreement or the Stockholders’ Agreement; (ii) the Purchaser’s
      investment in or ownership of the Shares; or (iii) actions or omissions by
      any
      agent, representative or employee of the Company or the Parent or the Purchaser,
      as the case may be.




7.3.  Limitations
      on Indemnification .
      The
      Company or the Purchaser, as the case may be, shall not have liability under
      Section 7.2 until the aggregate amount of Losses of the Indemnitees exceeds
      $50,000, in which case the Indemnitees shall be entitled to Losses in an amount
      up to the purchase price of $1,947,983.55 in the aggregate.




8.  Miscellaneous .




8.1.  Transfer;
      Successors and Assigns .
      The
      terms and conditions of this Agreement shall inure to the benefit of and be
      binding upon the respective successors and assigns of the parties. The Company
      may not assign this Agreement or any rights or obligations hereunder without
      the
      prior written consent of a majority of the Shares. Nothing in this Agreement,
      express or implied, is intended to confer upon any party other than the parties
      hereto or their respective successors and assigns any rights, remedies,
      obligations, or liabilities under or by reason of this Agreement, except as
      expressly provided in this Agreement.




8.2.  Governing
      Law .
      This
      Agreement shall be governed by and construed in accordance with the internal
      laws of the State of Delaware, without regard to its principles of conflicts
      of
      laws .




8.3.  Counterparts .
      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. This Agreement may also be executed and delivered by facsimile
      signature and 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.




12




8.4.  Titles
      and Subtitles .
      The
      titles and subtitles used in this Agreement are used for convenience only and
      are not to be considered in construing or interpreting this
      Agreement.




8.5.  Notices .
      All
      notices and other communications given or made pursuant to this Agreement shall
      be in writing and shall be deemed effectively given: (a) upon personal delivery
      to the party to be notified, (b) when sent by confirmed electronic mail or
      facsimile if sent during normal business hours of the recipient, and if not
      so
      confirmed, then on the next business day, (c) five (5) days after having been
      sent by registered or certified mail, return receipt requested, postage prepaid,
      or (d) one (1) day after deposit with a nationally recognized overnight courier,
      specifying next day delivery, with written verification of receipt. All
      communications shall be sent to the respective parties at their address as
      set
      forth on the signature page or Exhibit A ,
      or to
      such e-mail address, facsimile number or address as subsequently modified by
      written notice given in accordance with this Section
      8.5 .




If
      notice
      is given to the Company or Parent, it shall be sent to:




CoaLogix


11701
      Mt.
      Holly Road


Charlotte,
      NC 28214





Acorn
      Energy, Inc.


4
      W.
      Rockland Road


P.O.
      Box
      9


Montchanin,
      Delaware 19710





A
      copy
      shall also be sent to:




Eilenberg
      Krause & Paul LLP


11
      East
      44th Street, 19th Floor


New
      York,
      New York 10017


Fax
      No.
      (212) 986-2399


Attention:
      Sheldon Krause, Esq.





Womble
      Carlyle Sandridge & Rice, PLLC


One
      Wachovia Center, Suite 3500


301
      South
      College Street


Charlotte,
      NC 28202-6037


Fax
      No.
      (704) 338-7819


Attention:
      Joe B. Cogdell





If
      notice
      is given to the Purchaser, it shall be sent to the address sent forth on Exhibit
      A. A copy shall also be sent to:




Dechert
      LLP


Cira
      Centre


2929
      Arch
      St.


Philadelphia,
      PA 19104-2808


Fax
      No.
      (215) 994-2222


Attention:
      Ian A. Hartman, Esq.




13




8.6.  No
      Finder’s Fees .
      Except
      as set forth in **Section
      8.6** **of the Disclosure Schedule** ,
      each
      party represents that it neither is nor will be obligated for any finder’s fee,
      commission or other compensation in connection with this transaction. The
      Purchaser agrees to indemnify and to hold harmless the Company from any
      liability for any commission or compensation in the nature of a finder’s fee
      arising out of this transaction (and the costs and expenses of defending
      against such liability or asserted liability) for which the Purchaser or any
      of
      its officers, employees, or representatives is responsible. The Company agrees
      to indemnify and hold harmless the Purchaser from any liability for any
      commission or compensation in the nature of a finder’s or broker’s fee
      arising out of this transaction (and the costs and expenses of defending against
      such liability or asserted liability) for which the Company or any of its
      officers, employees or representatives is responsible.




8.7.  Fees
      and Expenses .
      At
      Closing, the Company shall pay the reasonable fees and expenses of Dechert
      LLP,
      special counsel to EnerTech Capital Partners III L.P., as well as other costs
      and expenses incurred by EnerTech Capital Partners III L.P., in connection
      with
      the financing.




8.8.  Amendments
      and Waivers .
      Any
      term of this Agreement may be amended, terminated or waived only with the
      written consent of the Company and the Purchaser. Any amendment or waiver
      effected in accordance with this Section 8.8 shall be
      binding upon the Company, the Purchaser, and each transferee of the Shares,
      each
      future holder of all such securities and the Company. In the event a nonmaterial
      provision of this Agreement is required to be amended by the Purchaser after
      the
      Closing, the Company will not unreasonably withhold its consent to such
      amendment.




8.9.  Severability .
      The
      invalidity of unenforceability of any provision hereof shall in no way affect
      the validity or enforceability of any other provision.




8.10.  Delays
      or Omissions .
      No
      delay or omission to exercise any right, power or remedy accruing to any party
      under this Agreement, upon any breach or default of any other party under this
      Agreement, shall impair any such right, power or remedy of such non-breaching
      or
      non-defaulting party nor shall it be construed to be a waiver of any such breach
      or default, or an acquiescence therein, or of or in any similar breach or
      default thereafter occurring; nor shall any waiver of any single breach or
      default be deemed a waiver of any other breach or default theretofore or
      thereafter occurring. Any waiver, permit, consent or approval of any kind or
      character on the part of any party of any breach or default under this
      Agreement, or any waiver on the part of any party of any provisions or
      conditions of this Agreement, must be in writing and shall be effective only
      to
      the extent specifically set forth in such writing. All remedies, either under
      this Agreement or by law or otherwise afforded to any party, shall be cumulative
      and not alternative.




8.11.  Entire
      Agreement .
      This
      Agreement (including the Exhibits hereto, if any), and the other Transaction
      Agreements constitute the full and entire understanding and agreement between
      the parties with respect to the subject matter hereof, and any other written
      or
      oral agreement relating to the subject matter hereof existing between the
      parties are expressly canceled.




14




8.12.  Publicity .
      The
      Company may disclose the existence of the financing, as well as the investment
      in the Company by the Purchaser, solely to the Company’s investors, investment
      bankers, lenders, accountants, legal counsel, bona fide prospective investors
      and employees, in each case only where such persons or entities were under
      appropriate nondisclosure obligations. In addition, the Company may disclose
      to
      third parties that the Purchaser is an investor in the Company without the
      requirement for nondisclosure agreements. The Company is permitted to issue
      a
      press release within 60 days of the Closing disclosing that the Purchaser has
      invested in the Company; provided that the release does not disclose the amount
      or other specific terms of the investment and the final form of the press
      release is approved in advance in writing by the Purchaser. The Company may
      not
      use the name of the Purchaser, or any of its Affiliates in any trade
      publication, in any marketing materials or otherwise to the general public
      without the prior written consent of the Purchaser, which consent may be
      withheld in the sole discretion of the Purchaser. Notwithstanding the foregoing,
      nothing in this Section
      8.12 shall
      prevent the Company from taking any action required to assist Parent in
      complying with its obligations under the Exchange Act or under the rules or
      regulations of any stock exchange or other market on which the Parent’s
      securities are listed for trading.




8.13.  Right
      to Conduct Activities .
      The
      Company acknowledges and agrees that (i) the Purchaser and its respective
      partners, affiliates and affiliates of its partners engage in a wide variety
      of
      activities and have investments in many other companies, some of which may
      be
      competitive with the business of the Company; (ii) subject to any fiduciary
      obligations of the Purchaser’s designees to the Company’s Board of Directors,
      except as waived by the Company pursuant to this Section, it is critical that
      the Purchaser be permitted to continue to develop its current and future
      business and investment activities without any restriction arising from an
      investment by the Purchaser in the Company, the right of the Purchaser to
      designate directors of the Company or any other relationship, contractual or
      otherwise, between the Purchaser, on the one hand, and the Company or any of
      its
      affiliates, on the other hand; and (iii) from time to time, in connection with
      the foregoing activities of the Purchaser (collectively, the “Activities”), the
      Purchaser may have information that may be useful to the Company or its other
      stockholders (which information may or may not be known by the member of the
      Company’s Board of Directors designated by the Purchaser), and neither the
      Purchaser nor any director so designated shall have any duty to disclose any
      information known to such person or entity to the Company or any of its other
      stockholders. In addition, the Purchaser shall not be liable for any claim
      arising out of, or based upon, (i) the investment by the Purchaser in any entity
      competitive to the Company, (ii) actions taken by any partner, officer or other
      representative of the Purchaser to assist any such competitive company, whether
      or not such action was taken as a board member of such competitive company,
      or
      otherwise, and whether or not such action has a detrimental effect on the
      Company, unless such claim arises directly from the Purchaser’s misuse of
      confidential information in material breach of Section
      3.4 of the
      Stockholders’ Agreement.




15




8.14.  Termination .
      Except
      with respect to provisions that expressly survive the termination of this
      Agreement, this Agreement may be terminated at any time prior to Closing: (a)
      by
      the Purchaser if a court of competent jurisdiction or governmental or regulatory
      body shall have issued an order, decree or ruling, or taken any other action,
      restraining, enjoining or otherwise prohibiting the Closing of the transactions
      contemplated hereby and such order, decree, ruling or other action shall have
      become final and non-appealable; or (b) by either the Purchaser or the Company
      if the Closing shall not have occurred by 8:00 p.m., New York City Time, on
      March 3, 2008 and the terminating parties are not in material breach of this
      Agreement.




[Remainder
      of Page Intentionally Left Blank]




16


The
      parties have executed this Common Stock Purchase Agreement as of the date first
      written above.




**COALOGIX
                INC.**By:
            /s/William
                J. McMahonName: William
                J. McMahonTitle:   President
                & CEO**ACORN
                ENERGY, INC.**By:
            /s/John
                A. MooreName: John
                A. MooreTitle:   CEO





**PURCHASER:****ENERTECH
                CAPITAL PARTNERS III L.P.**By:
            ECP
                III Management L.P.,Its
                general partnerBy:
            ECP
                III Management LLC,Its
                general partner





By:
            /s/
                Scott UngererName: Scott
                UngererTitle:   CEO