Document:

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                                                                   EXHIBIT 10.18

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                                                                      EXECUTION
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                             STOCKHOLDERS AGREEMENT

                                      AMONG

                               POWERSPRING, INC.,

                           METRETEK TECHNOLOGIES, INC.

                                       AND

                                 JOHN A. HARPOLE

                           DATED AS OF MARCH __, 2000

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<TABLE>
                                TABLE OF CONTENTS
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<CAPTION>
                                                                               PAGE
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<S>                                                                            <C>
SECTION 1.   DEFINITIONS.........................................................1
          1.1.       Certain Defined Terms.......................................1
          1.2.       Certain Other Defined Terms.................................3
          1.3.       Other Definitional Provisions...............................3

SECTION 2.   RESTRICTIONS ON TRANSFERS OF HARPOLE SHARES.........................3
          2.1.       General Restrictions on Transfer............................3
          2.2.       Effect of Prohibited Transfer...............................3

SECTION 3.   RIGHTS OF REFUSAL...................................................4
          3.1.       Right of First Refusal......................................4
          3.2.       Right of Second Refusal.....................................4
          3.3.       Purchase Price..............................................4
          3.4.       Closing of Rights of Refusal................................5
          3.5.       Sale to Prospective Purchaser...............................5
          3.6.       Permitted Transfers.........................................5
          3.7.       Securities Act Matters......................................6

SECTION 4.   CO-SALE RIGHTS......................................................6
          4.1.       Co-Sale Rights..............................................6
          4.2.       Co-Sale Notice..............................................6
          4.3.       Exercise of Co-Sale Right...................................7
          4.4.       Exceptions..................................................7

SECTION 5.   DRAG-ALONG RIGHT....................................................7
          5.1.       Drag-Along Right............................................7
          5.2.       Drag-Along Notice...........................................7
          5.3.       Agreement...................................................7

SECTION 6.   REGISTRATION RIGHTS.................................................8
          6.1.       Piggy-Back Registration.....................................8
          6.2.       Demand Right................................................8
          6.3.       Information.................................................9
          6.4.       Market Stand-Off............................................9
          6.5.       Expenses....................................................9
          6.6.       Indemnification by Initial Stockholder.....................10
          6.7.       Indemnification by The Company.............................10

SECTION 7.   PUT RIGHT..........................................................10
          7.1.       Put Right..................................................10
          7.2.       Put Exercise Period........................................11
          7.3.       Put Price..................................................11
          7.4.       Mechanics of Exercise......................................11
          7.5.       Closing of Put Right.......................................11
          7.6.       Payment of Purchase Price..................................11
          7.7.       Inability of Company.......................................12
</TABLE>

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<TABLE>
<CAPTION>
<S>                                                                            <C>
SECTION 8.   DILUTION MATTERS...................................................12
         8.1.        Preemptive Rights..........................................12
         8.2.        Metretek Funding of Purchaser..............................12

SECTION 9.   HARPOLE'S RIGHT AS A DIRECTOR......................................13

SECTION 10.  EFFECTUATION PROVISIONS............................................13
         10.1.       Enabling Action............................................13
         10.2.       Legend.....................................................13
         10.3.       Acknowledgement of Necessity of Restrictions...............14
         10.4.       Record of Transfers........................................14
         10.5.       Voting of Shares ..........................................14
         10.6.       No Contrary Action.........................................14
         10.7.       Company Determinations.....................................15

SECTION 11.  TERMINATION OF AGREEMENT...........................................15
         11.1.       Termination................................................15
         11.2.       Effect of Termination......................................15

SECTION 12.  ARBITRATION........................................................15

SECTION 13.  GENERAL PROVISIONS.................................................16
         13.1.       Governing Law..............................................16
         13.2.       Amendment..................................................16
         13.3.       Assignment.................................................16
         13.4.       Successors and Assigns.....................................16
         13.5.       Entire Agreement...........................................16
         13.6.       Notices....................................................16
         13.7.       Waiver.....................................................17
         13.8.       Severability...............................................18
         13.9.       Counterparts...............................................18
         13.10.      Headings...................................................18
         13.11.      No Third Party Beneficiaries...............................18
         13.12.      Further Assurances.........................................18
         13.13.      Best Efforts...............................................18
         13.14.      Expenses...................................................18
         13.15.      Construction...............................................18
         13.16.      Specific Performance.......................................18
         13.17.      No Agency or Partnership...................................19
</TABLE>

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                             STOCKHOLDERS AGREEMENT

         THIS STOCKHOLDERS AGREEMENT (this "Agreement") is made and entered into
as of the 17th day of March, 2000, by and between PowerSpring, Inc., a Delaware
corporation (the "Company"), and Metretek Technologies, Inc., a Delaware
corporation ("Metretek"), and John A. Harpole ("Harpole" and, collectively with
Metretek, the "Initial Stockholders").

                                    RECITALS
                                    --------

         WHEREAS, the Initial Stockholders are the holders of all (100%) of the
issued and outstanding shares of capital stock of the Company; and

         WHEREAS, the Company and Harpole are parties to an Agreement and Plan
of Merger, of even date herewith ("Merger Agreement"), pursuant to which the
Company is issuing shares of its Common Stock, par value $.01 per share
("Shares"), to Harpole in exchange in part for all the outstanding shares of
capital stock of Mercator Energy Incorporation, a Colorado corporation; and

         WHEREAS, it is a condition to the closing of the Merger Agreement that
Harpole and the Company enter into this Agreement on the terms and conditions
set forth herein; and

         WHEREAS, the Company and the Initial Stockholders believe it is in the
best interests of the Company and its stockholders to provide for the stability
of the ownership of the Company and to provide for the orderly issuance,
ownership and transfer of the Company's securities;

                                    AGREEMENT
                                    ---------

         NOW, THEREFORE, in consideration of the premises and the mutual
covenants and agreements set forth herein, and other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereto, intending to be legally bound, hereby agree as follows:

SECTION 1. DEFINITIONS.
           -----------

         1.1 Certain Defined Terms. As used herein, the following terms shall
have the following respective meanings:

         "Affiliate" means, with respect to any Person, any (i) officer,
director, general partner, trustee, manager, or record or beneficial holder of
more than 10% of the outstanding voting interests of, such Person, (ii) any
other Person which directly or indirectly controls, is controlled by, or is
under common control with such Person, or (iii) any Relation of any of the
foregoing Persons. For purposes of this definition, a Person shall be deemed to
"control" another Person if such Person possesses, directly or indirectly, the
power to direct or cause the direction of the management and policies of the
"controlled" Person, whether through ownership of voting securities, by
contract, or otherwise. For purposes of this Agreement, Persons are
"unaffiliated" with each other if neither is an Affiliate of the other.

<PAGE>   5
         "Agreement" means this Stockholders Agreement, as from time to time
amended, supplemented or restated in accordance with the terms of this
Agreement.

         "Board" means the Board of Directors of the Company.

         "By-Laws" means the By-Laws of the Company, as from time-to-time
amended, supplemented or restated in accordance with the terms of the Articles,
the By-Laws and the DGCL.

         "Certificate" means the Certificate of Incorporation of the Company, as
from time to time amended, supplemented or restated in accordance with the terms
of the Certificate and the DGCL.

         "Closing" means a closing of the purchase and sale of Shares made
pursuant to this Agreement.

         "DGCL" means the General Corporation Law of the State of Delaware, as
from time to time amended, and any successor statutes.

         "Harpole Shares" means any Shares owned from time to time by Harpole or
any Affiliate of Harpole.

         "IPO" means an underwritten initial public offering of Shares pursuant
to a registration statement which has become effective under the Securities Act.

         "Person" means an individual, corporation, partnership, limited
liability company, joint venture, trust, association, unincorporated
organization, regulatory or governmental body or authority or any other form of
business, entity or organization.

         "Purchase Price" means the purchase price to be paid for Shares
purchased and sold under this Agreement.

         "Purchaser" means any Person purchasing Shares under this Agreement.

         "Relation" means, with respect to any Person, such Person's
grandparents, parents, siblings, spouse, children, stepchildren or
grandchildren, whether by blood, marriage or adoption.

         "Representative" means, with respect to a Shareholder, the Person who
is in legal control of the Shares owned by such Shareholder, including, but not
limited to, an executor, representative, guardian or trustee of the Shareholder
or the Shareholder's estate, as applicable.

         "Securities Act" means the Securities Act of 1933, as amended.

         "Seller" means any Person selling Shares under this Agreement.

         "Shares" means the shares of Common Stock, par value $.01 per share, of
the Company, and other securities into which the shares of Common Stock are
converted, reclassified, reorganized or exchanged.

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<PAGE>   6
         "Stockholder" means each of Harpole and Metretek, and any other Person
whom after the date hereof becomes bound by the terms of, and a party to, this
Agreement, as the result of or in connection with a Transfer of Shares to such
Person or otherwise.

         "Subsidiary" means, with respect to any Person, another Person of which
at least a majority of the voting securities or voting interests of such Person
are owned, directly or indirectly, by such Person.

         "Transfer" means any sale, issuance, grant, assignment, transfer,
conveyance, distribution, pledge, hypothecation, encumbrance, disposition,
transfer, gift of, or attempt to create or grant a security interest in the
shares, whether voluntary or involuntary, by operation of law or otherwise
(including, without limitation, by will or intestate distribution, or pursuant
to a merger, consolidation, sale of assets or other form of reorganization).

         1.2 Certain Other Defined Terms. Capitalized terms used in this
Agreement that are not defined in Section 2.1 shall be used as defined in this
Agreement.

         1.3 Other Definitional Provisions. Except as otherwise expressly
provided herein, as used in this Agreement:

                  (a) Any reference to any federal, state, local or foreign
         statute or law shall be deemed also to refer to all rules and
         regulations promulgated thereunder.

                  (b) The term "including" means "including, without
         limitation".

                  (c) The number and gender of each name and pronoun and the
         term "Person" or "Persons" or the like shall be construed to mean such
         number and gender as the context, circumstances or its antecedent may
         require.

                  (d) The terms "hereof", "herein", "hereunder", and the like
         refer to this Agreement as a whole, and not to any Section, subsection,
         or clause of this Agreement.

                  (e) Each reference to a Section means such Section of this
         Agreement.

SECTION 2. RESTRICTIONS ON TRANSFERS OF HARPOLE SHARES.
           -------------------------------------------

         2.1. General Restrictions on Transfer. Harpole shall not directly or
indirectly Transfer or agree to Transfer any Shares now owned or hereafter
acquired by Harpole, unless (i) such Transfer is made in compliance in all
respects with the provisions of this Agreement, and the transferee (if other
than the Company or Metretek) has agreed in writing to become a party to, and be
bound by the terms of, this Agreement as a holder of Harpole Shares and subject
to the same terms and conditions as Harpole, or (ii) the Transfer is a
"Permitted Transfer" (as defined in Section 3.6).

         2.2. Effect of Prohibited Transfer. Any Transfer, or attempted or
purported Transfer, of Shares by Harpole which is not made in compliance in all
respects with, or which violates any of, the provisions of this Agreement shall
be null and void and be given no effect, and neither the Company nor any Person
acting as share transfer agent for the Company shall recognize the Transfer or
recognize the transferee as the holder of any Shares for any purpose.

                                       3
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SECTION 3. RIGHTS OF REFUSAL.
           -----------------

         3.1 Right of First Refusal.

                  (a) Notice of Offer. If Harpole desires to Transfer any or all
         of the Harpole Shares (the "Offer") at or above a particular purchase
         price (the "Offer Price") (the Shares subject to the Offer hereinafter
         referred to as the "Offered Shares"), then Harpole shall first offer
         such Shares at the Offer Price (the "Offer") and give notice of the
         Offer (the "Notice of Offer"), to the Company and to Metretek. The
         Notice of Offer shall include the number of Offered Shares, the Offer
         Price and, if any specific Transfer is then contemplated by Harpole,
         the terms of the proposed Transfer in reasonable detail, including the
         name and address of the prospective purchaser, and the other material
         terms of the Offer. The Notice of Offer shall also contain an
         irrevocable Offer to sell the Offered Shares to the Company and
         Metretek upon the terms and conditions of the Rights of Refusal set
         forth in this Agreement.

                  (b) Company's Right of First Refusal. The Company shall have
         the irrevocable first right and option (the "Right of First Refusal")
         to purchase any or all of the Offered Shares upon the terms and
         conditions set forth in this Section 3.1(b); provided that the Company
         may not purchase any of the Offered Shares unless the Company and
         Metretek have, collectively, agreed to purchase all of the Offered
         Shares. The Company may exercise its Right of First Refusal by giving
         written notice of such exercise (the "Notice of Exercise") to Harpole
         on or before the thirtieth (30th) day after the Company shall have
         received the Notice of Offer from Harpole. The Notice of Exercise shall
         specify the number of Offered Shares the Company desires to purchase.

                  (c) Notice of Re-Offer. If the Company declines to exercise
         its Right of First Refusal with respect to all of the Offered Shares,
         then the Company shall give notice of that effect (the "Re-Offer
         Notice") to Metretek promptly after making such decision, but in no
         event later than the thirtieth (30th) day after the Company shall have
         received the Notice of Offer. The Re-Offer Notice shall specify the
         number of Offered Shares which the Company shall have declined to
         purchase (the "Remaining Available Shares") and shall be accompanied by
         a copy of the Notice of Exercise, if any.

         3.2 Right of Second Refusal.

                  (a) Metretek's Right of Second Refusal.Upon receipt of the
         Re-Offer Notice, Metretek shall have the irrevocable right and option
         (the "Right of Second Refusal") to purchase all, but not less than all,
         of the Remaining Offered Shares which the Company shall have declined
         to purchase.

                  (b) Exercise of Right of Second Refusal. Metretek may exercise
         its Right of Second Refusal for all of the Remaining Offered Shares by
         giving written notice of such exercise to Harpole on or before the
         fifteenth (15th) day after Metretek shall have received the Re-Offer
         Notice from the Company.

                  3.3 Purchase Price. The Purchase Price to be paid for each
         Offered Share purchased by the Company or Metretek in accordance with
         this Section 3 shall be the Offer Price for such Offered Share as set
         forth in the Notice of Offer, and shall be paid on the same terms set
         forth in the Offer or, at the option of the Purchaser, by check or wire
         transfer of immediately

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         available funds, at the Closing, or by any other means mutually
         acceptable to the Purchaser and Harpole.

         3.4 Closing of Rights of Refusal. The Closing of the purchase and sale
of the Offered Shares pursuant to this Section 3 shall take place at the
principal place of business of the Company on a date forty-five (45) business
days after the date the Company receives the Notice of Offer, unless the
Purchaser and Harpole mutually agree on a different place or time. At the
Closing, Harpole shall deliver to the Purchaser all certificates representing
the Offered Shares duly endorsed in blank, or with duly endorsed blank stock
powers attached, and otherwise in proper form for Transfer, against payment by
each Purchaser by bank cashiers or certified check, or by wire transfer of
immediately available funds to an account designated by Harpole, of the Purchase
Price for the Offered Shares such Purchaser is purchasing, pursuant to the terms
and conditions of the Offer, as modified as permitted by this Agreement or by
Harpole, in his sole discretion. Upon Transfer, Harpole shall conclusively be
deemed, unless the Purchaser, in his sole discretion, permitting otherwise in
writing, to have given the following representations and warranties to the
Purchasers, which shall survive the Closing: (A) Harpole is the legal,
beneficial and record owner of the Offered Shares being purchased and sold, has
good and marketable title thereto and the absolute right to Transfer the same to
the Purchaser, and such Offered Shares, upon Transfer to the Purchaser, will be
free and clear of all security interests, pledges, claims, liens, option, rights
of first refusal, limitations or voting rights and restrictions of any kind
whatsoever (other than restrictions imposed by this Agreement and by federal and
state securities laws); and (B) the Transfer of Offered Shares by Harpole as
contemplated by this Agreement does not require any consent or approval of any
governmental authority, court or other Person that has not already been
obtained.

         3.5 Sale to Prospective Purchaser. If the Right of First Refusal and
the Right of Second Refusal (collectively, the "Rights of Refusal") shall not in
the aggregate have been timely exercised for the purchase of all (100%) of the
Offered Shares, then Harpole shall have the right, for a period ending 180 days
after the earlier of (i) the day the Second Right of Refusal expires, or (ii)
the day Harpole receives notice that the Company and Metretek will not exercise
their Rights of Refusal to purchase 100% of the Offered Shares, to Transfer all,
but not less than all, of the Offered Shares free of the Rights of Refusal to
any other Person (the "Offered Shares Purchaser") at the same price and
otherwise upon the same terms (or at a price that is greater than and/or upon
terms more favorable to Harpole than) described in the Offer. If Harpole does
not Transfer the Offered Shares to the Prospective Purchaser within such 180-day
period, then the Transfer by Harpole of the Offered Shares will be again subject
to the Rights of Refusal. It shall be a condition of the effectiveness of the
Transfer of the Offered Shares to an Offered Shares Purchaser that (i) at least
ten (10) business days prior to the Closing of the sale of the Offered Shares to
the Offered Shares Purchaser, Harpole shall give written notice to the Company
of the name, address, and reasonable background and identity of the Offered
Shares Purchaser and the date of the scheduled Closing, and the Company shall
not, within 10 business days after such notice, have given written notice to
Harpole that it is exercising its right, in its reasonable discretion, to reject
to the Offered Shares Purchaser for valid business reasons, in its reasonable
discretion, and (ii) the Offered Shares Purchaser shall have agreed in writing
with the Company and Metretek to become a party to this Agreement as a
Shareholder, and to be bound by and to comply with all the terms of this
Agreement applicable to Harpole, and that the Offered Shares so purchased shall
be subject to all of the restrictions applicable to the Harpole Shares set forth
in this Agreement.

                                       5
<PAGE>   9

         3.6 Permitted Transfers. Notwithstanding any other provision of this
Section 3 to the contrary, the following Transfers (collectively, the "Permitted
Transfers") of Shares by Harpole shall not be subject to the Rights of Refusal:

                  (a) any Transfer of Shares made by Harpole in connection with
         an IPO;

                  (b) any Transfer of Shares made by Harpole to the Company;

                  (c) any Transfer of Shares made by Harpole to any Relation of
         Harpole or an Entity owned or controlled by Harpole or any Relation of
         Harpole, for no considerations (provided the transferee complies with
         the provisions in clause (ii) of the last sentence of Section 3.5 as if
         the transferee were an Offered Shares Purchaser);

                  (d) any Transfer of Shares by Harpole to Metretek;

                  (e) any Transfer of Shares made by Harpole pursuant to
         Harpole's Co-Sale Right under Section 5; and

                  (f) any Transfer of Shares made by Harpole that has been
         approved in writing by Metretek.

         3.7 Securities Act Matters. Notwithstanding any other provision of this
Agreement to the contrary, but subject to express written waiver by the Company
in the exercise of its good faith and reasonable judgment, Harpole shall not
make any Transfer of Shares without the registration of the Transfer of such
Shares under the Securities Act and applicable state securities laws or until
the Company shall have received such legal opinions or other assurances that
such Transfer is exempt from the registration requirements under the Securities
Act and applicable state securities laws as the Company in its good faith and
reasonable discretion deems appropriate in light of the fact and circumstances
relating to such proposed Transfer, together with such representations,
warranties and indemnifications from the transferor and the transferee as the
Company in its good faith and reasonable discretion deems appropriate to confirm
the accuracy of the facts and circumstances that are the basis for any such
opinion or other assurances and to protect the Company and the other
Stockholders from any liability resulting from any such Transfer.

SECTION 4. CO-SALE RIGHTS.
           --------------

         4.1 Co-Sale Rights. In the event Metretek desires to Transfer all or
part of its Shares for value to an unaffiliated third party ("Co-Sale
Purchaser"), then Harpole shall have the right ("Co-Sale Right"), subject to
applicable law and compliance with any other restrictions applicable to such
Transfer, to participate in such Transfer in accordance with this Section 4.

         4.2 Co-Sale Notice. Metretek may Transfer any Shares pursuant to
Section 4 only if (i) the Co-Sale Purchaser agrees to provide Harpole with the
right to participate in the Transfer of the Shares to such Co-Sale Purchaser
upon the same terms and conditions as Metretek, and (ii) Metretek first notifies
Harpole, in writing, of such intended Transfer at least fifteen days prior to
the proposed date of Transfer (the "Co-Sale Notice"). The Co-Sale Notice shall
set forth in reasonable detail the terms of the Transfer, the date on or about
which such Transfer is to be consummated, the number of Shares to the
Transferred, and the name and address of the Co-Sale Purchaser.

                                       6
<PAGE>   10
         4.3 Exercise of Co-Sale Right.If Harpole desires to exercise his
Co-Sale Right under this Section 5, then Harpole shall notify Metretek in
writing within ten (10) days after receipt of the Co-Sale Notice that he will
sell to either the Prospective Purchaser or to Metretek, at Metretek's option, a
number of Shares on the same terms and conditions as the Selling Stockholder set
forth in the Co-Sale Notice. If the Co-Sale Purchaser will not purchase all of
the Shares which Harpole wishes to sell pursuant to this Section 4, then the
number of Shares which Harpole may Transfer pursuant to this Section 4 shall be
equal to the product obtained by multiplying (x) the total number of Shares
being purchased by the Co-Sale Purchaser, by (y) a fraction, (i) the numerator
of which is the total number of Shares owned by Harpole, and (ii) the
denominator of which is the total number of shares owned by Harpole and
Metretek.

         4.4 Exceptions. Notwithstanding any other provision of this Section 4
to the contrary, the Co-Sale Right of Harpole set forth in this Section 4 shall
not apply to the following Transfers:

                  (i) any Transfer of Shares made by Metretek in connection with
         an IPO;

                  (ii) any Transfer of Shares by Metretek to Harpole;

                  (iii) any Transfer of Shares by Metretek to the Company;

                  (iv) any Trust of Shares by Metretek to an Affiliate of
         Metretek or the Company; or

                  (v) any other Transfer of Shares that has been approved in
         writing by Harpole

SECTION 5. DRAG-ALONG RIGHT.
           ----------------

         5.1 Drag-Along Right. If Metretek desires to Transfer all of its Shares
in any transaction with an unaffiliated third party ("Drag-Along Purchaser"),
then Metretek shall have the right (the "Drag-Along Right"), subject to
applicable law and compliance with any other restrictions applicable to such
Transfer, to require Harpole to Transfer, and Harpole hereby agrees to Transfer,
all of the Shares then owned by Harpole to the Drag-Along Purchaser, upon the
same terms and conditions as applicable to Metretek.

         5.2 Drag-Along Notice. In order to exercise its Drag-Along Right,
Metretek shall give written notice to Harpole at least 15 days prior to the
proposed date of Transfer (the "Drag-Along Notice"). The Drag-Along Notice shall
set forth in reasonable detail the terms and conditions of the Transfer, the
date on which such Transfer is to be consummated, and the name and address of
the Drag-Along Purchaser.

         5.3 Agreement. If Metretek exercises its Drag-Along Right, then Harpole
shall agree to enter into a purchase agreement in form and substance approved by
Metretek to the extent such Agreement shall contain customary representations
from Harpole as to the ownership of the Shares to be purchased in the absence of
liens thereon and customary indemnification provisions solely with respect to
such representations from Harpole. Harpole shall not be required to participate
in a proposed Transfer pursuant to the exercise of the Drag-Along Right unless
his liability for breaches of representations and warranties made in connection
with the Transfer is limited to no more than the total sales price received by
Harpole in such sale.

                                       7
<PAGE>   11
SECTION 6. REGISTRATION RIGHTS.
           -------------------

         6.1 Piggy-Back Registration.

                  (a) Right to Piggy-Back. If, at any time during the period
         commencing on the date after an IPO and ending three years thereafter
         (the "Registration Period"), the Company proposes to register with the
         Securities and Exchange Commission (the "SEC") the sale for cash of any
         of its Shares of common stock by filing a registration statement under
         the Securities Act, for its own account or for the account of any of
         its stockholders (except pursuant to registration statements filed on
         Form S-4 or Form S-8 or any successor or similar forms or other
         unsuitable forms), the Company shall promptly give written notice of
         such proposed filing to each Initial Stockholder and offer each Initial
         Stockholders the opportunity to register such number of Shares owned by
         the Initial Stockholders (the "Registerable Shares") as it may request
         in writing. Upon the written request of an Initial Stockholder received
         by the Company within fifteen (15) days after the giving of the notice
         by the Company, the Company shall use its best efforts to cause the
         number of Registerable Shares that the Initial Stockholder requests to
         be so registered to be included in such registration.

                  (b) Underwriting Procedures. If any registration pursuant to
         this Section 12(a) shall be, in whole or in part, in connection with an
         underwritten public offering of Common Stock of the Company, then the
         Company shall not be required to include any Registerable Shares in the
         registration unless such Initial Stockholder accepts the terms and
         conditions of the underwriting as agreed upon between the Company and
         the underwriters. If the managing underwriter determines and advises
         the Company in writing (which shall promptly notify such Initial
         Stockholder) that the inclusion in the underwriting of all or any of
         the Registerable Shares proposed to be included by the Initial
         Stockholder would be reasonably likely to jeopardize the successful
         marketing of the securities proposed to be registered for the
         underwriting by the Company or materially adversely affect the price,
         time or distribution of the public offering, then the Company shall
         only be required to include the number of the Registerable Shares of an
         Initial Stockholder that the managing underwriter determines, in its
         sole discretion, will not materially adversely affect the public
         offering, and, if any such reduction is so determined by the managing
         underwriter to be appropriate in accordance with the standards set
         forth above, then the number of Registerable Shares requested to be
         included in the underwriting by the Initial Stockholders shall be
         reduced, pro rata among such Initial Stockholders to the number
         determined to be appropriate by the managing underwriter (which may
         include a reduction to zero).

                  (c) No Company Obligation. Neither the giving of a notice by
         the Company nor any request by an Initial Stockholder under this
         Section 6(a) shall, in any way, obligate the Company to file any
         registration statement at any time or within any specific time period
         after receipt of an Initial Stockholder's written request and,
         notwithstanding the filing of any registration statement, the Company
         may, at any time before the effective date thereof, elect to delay or
         terminate the entire registration process for any reason or no reason
         and without the consent of an Initial Stockholder, without any further
         obligation to an Initial Stockholder in respect of such registration
         statement.

         6.2 Demand Right. If, at any time during the Registration Period, the
Company shall receive a written request ("Demand Request") from an Initial
Stockholder for the registration of any or all of the Registerable Shares of the
Initial Stockholder, then the Company, upon the terms and subject to the
conditions set forth in this Section 6.2, shall use its best efforts to cause
all such Registerable Shares to be registered in an appropriate registration
statement of the SEC

                                       8
<PAGE>   12
as shall be selected by the Company, provided that if the Company is eligible to
use Form S-3 (or any successor form thereto) for such registration, then such
registration statement shall be used unless such form is inappropriate or the
Company desires to use a different form. If an Initial Stockholder intends for
the public offering covered by its Demand Request to occur by means of an
underwriting, it shall so advise the Company as a part of its Demand Request,
and the managing underwriter of such underwritten public offering shall be
selected by such Initial Stockholder and shall be reasonably acceptable to the
Company. The Company shall be obligated to register the Registerable Shares of
any Initial Stockholder under this Section 6.2 after receipt of a Demand Request
on one occasion per Initial Stockholder only. The Company shall be entitled to
include in any registration statement filed pursuant to this Section 6.2
additional shares of capital stock for its own account and for the account of
its other security holders. If the managing underwriter advises the Company in
writing that the inclusion of any or all such additional shares of capital stock
would materially adversely affect the marketing of the public offering of the
Registerable Shares of any Initial Stockholder, then the Company shall not be
entitled to include such additional shares of capital stock in any such
registration statement to the extent the managing underwriter advises.
Notwithstanding the provisions of this Section 6.2, the Company shall have the
right to delay or suspend the filing of a registration statement for up to
ninety (90) days from the time the filing thereof would otherwise be required
under this Section 6.2 if, in the good faith determination of the Company's
board of directors, such registration would be seriously detrimental to the
Company and its stockholders or would materially adversely affect the business,
affairs, properties, financial condition, results of operations or prospects of
the Company or any pending or proposed acquisition, merger, reorganization,
recapitalization or other transaction or public offering of the Company's
securities, or would require premature disclosure thereof not in the best
interests of the Company; provided, however, that the Company shall not be
entitled to exercise this right more than once.

         6.3 Information. It shall be condition precedent to the obligation of
the Company hereunder to register the Registerable Shares under this Section 6
that an Initial Stockholder furnish to the Company and the managing underwriters
such information regarding itself, the intended method of disposition of such
securities and such other information as the Company or the managing underwriter
shall from time to time reasonably request and that shall be reasonably required
to effect the registration of the Registerable Shares.

         6.4 Market Stand-Off. Each Initial Stockholder agrees in connection
with any underwritten public offering of the Company's securities that, upon the
request of the managing underwriter, it shall commit itself in writing not to
sell or offer to sell any shares other than such shares included in the
underwritten public offering, during 30 days prior to, and for a period not to
exceed 180 days after, the date of the final prospectus used in such offering.

         6.5 Expenses. Each Initial Stockholder shall pay all underwriting and
brokerage fees, discounts and commissions and other selling expenses related to
the sale of its Registerable Shares in a public offering registered pursuant to
the provisions of this Section 6, together with the fees and expenses of any
separate counsel, accountants and other advisors retained by an Initial
Stockholder in connection with the offering. All other fees, costs and expenses
incurred in connection with any registration of public offering including, but
not limited to, all federal and state registration, qualification, filing fees,
printed and document distribution costs and expenses, fees and disbursements of
its counsel, accountants and other experts, Nasdaq additional listing fees,
transfer fees, exchange fees, fees of transfer agents and registrants shall be
borne as follows: (i) if pursuant to a Demand Request under Section 6.2, the
Company shall bear all reasonable costs, fees and expenses incurred by the
Company (provided the offering being registered is not pursuant to an

                                       9
<PAGE>   13
underwriting), except if the public offering is underwritten at the request of
an Initial Stockholder, then the Company and such Initial Stockholder shall
share equally all such fees, and (ii) if pursuant to a piggy-back registration
under Section 6.1, by the Company.

         6.6 Indemnification by Initial Stockholder. If any of the Registration
Shares of an Initial Stockholder are included in a registration, to the extent
permitted by law, Initial Stockholder shall indemnify and hold harmless the
Company, each of its directors, each of its officers who have signed the
registration statement, each person, if any, who controls the Company within the
meaning of Section 15 of Securities Act or Section 20 of the Securities Exchange
Act of 1934, as amended (the "Exchange Act"), any underwriter, and any
controlling person of any such underwriter, from and against any and all losses,
claims, liabilities, damages and expenses (including any investigative, legal,
accounting and other expenses reasonably incurred in connection with, and any
amount paid in settlement of, any action, suit or proceeding or any claim (the
"Damages") asserted to which any of the foregoing persons may become subject
under the Securities Act, the Exchange Act, or other federal or state law,
common law or otherwise, insofar as such Damages arise out of or are based upon
any untrue statement or alleged untrue statement of a material fact contained in
such registration statement, any preliminary prospectus or final prospectus, or
any amendments or supplements thereto, 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, or any violation or alleged violation by the
Company of the Securities Act, the Exchange Act, any state securities law or any
rule or regulation promulgated under the Securities Act, the Exchange Act or any
state securities law (collectively, a "Violation"), to the extent that such
Violation occurs in reliance upon and in conformity with written information
furnished to the Company by the Initial Stockholder expressly for use in
connection with such registration; and Initial Stockholder shall pay, as
incurred, any legal or other expenses reasonably incurred by any person intended
to be indemnified pursuant to this Section 6.6 in connection with the
investigation or defense of any such Damages.

         6.7 Indemnification by the Company. If any of the Registerable Shares
of an Initial Stockholder are included in a registration, to the extent
permitted by law, the Company shall indemnify and hold harmless such Initial
Stockholder, each of its directors and officers from and against any and all
Damages asserted to which any of the foregoing persons may become subject under
the Securities Act, the Exchange Act, or other federal or state law, common law
or otherwise, insofar as such Damages arise out of or are based upon any untrue
statement or alleged untrue statement of a material fact contained in such
registration statement, any preliminary prospectus or final prospectus, or any
amendments or supplements thereto, 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, or any Violation or alleged Violation by such
Initial Stockholder, to the extent that such Violation occurs in reliance upon
and in conformity with written information furnished to such Initial Stockholder
by the Company expressly for use in connection with such registration; and the
Company shall pay, as incurred, any legal or other expenses reasonably incurred
by any person intended to be indemnified pursuant to this Section 6.7 in
connection with the investigation or defense of any such Damages.

SECTION 7. PUT RIGHT.
           ---------

         7.1 Put Right. Harpole shall have the right (the "Put Right") to
require the Company to repurchase all of the Shares he then owns (the "Put
Shares") on the terms and conditions set forth in this Section 8.

                                       10
<PAGE>   14

         7.2 Put Exercise Period. The Put Right shall be exercisable, on one
occasion only, at any time during the one-year period (the "Put Exercise
Period") commencing on the second anniversary of the date of this Agreement, if,
and only if, (i) prior to such exercise the Company shall not have consummated
any of the following: (A) an IPO; (B) a sale of all or substantially all of its
assets or business; (C) a merger, consolidation, reorganization or similar
transaction pursuant to which all or substantially all of its assets, business,
capital stock or voting power shall have been Transferred to one or more Persons
unaffiliated with the Company, Metretek or Harpole, or (D) the sale of all of
substantially all of its capital stock to an unaffiliated third party; and (ii)
Harpole shall not, at the time of exercise, be in material breach of any term or
condition of this Agreement.

         7.3 Put Price. The Purchase Price to be paid for the Put Share
purchased in accordance with this Section 7 (the "Put Price") shall be equal to
the value of such Put Shares as determined in the written opinion of an
appraiser (the "Put Appraiser"). The Put Appraiser shall be The Wallach Company,
Inc., ("Wallach") or, if either the Company or Harpole reject, in its reasonable
discretion, Wallach within twenty (20) business days after Harpole gives the Put
Notice (as defined below) to the Company, then Harpole shall designate another
qualified appraiser that is unaffiliated with Harpole and that is an investment
banking firm or otherwise in the business of conducting, and is qualified to
conduct, an appraisal of businesses such as the business of the Company. The
designation of a Put Appraiser by Harpole shall be subject to the approval of
Metretek, which approval shall not be unreasonably withheld and will be deemed
to have given absent the Company delivering to Harpole written notice of
objection to such designation within ten (10) business days after receipt of
written notice of the name, address and other reasonable identification of the
Put Appraiser from Harpole. Harpole shall pay all costs and expenses of the Put
Appraiser. Harpole shall cause a signed copy of the appraisal conducted by the
Put Appraiser (the "Put Appraisal") to be delivered to the Company.

         7.4 Mechanics of Exercise. Harpole shall exercise his Put Right at any
time during the Put Exercise Period by giving written notice thereof to the
Company (the "Put Notice").

         7.5 Closing of Put Right. The Closing of the purchase and sale of the
Put Shares pursuant to this Section 8 shall take place at the principal place of
business of the Company no later than fifteen (15) business days after the date
the Company receives a copy of the Put Appraisal, unless the Company and Harpole
mutually agree on a different place or time. At the Closing, Harpole shall
deliver to the Company all certificates representing the Put Shares duly
endorsed in blank, or with duly endorsed blank stock powers attached, and
otherwise in proper form for Transfer, against payment by the Company of the Put
Price in the manner set forth in Section 8.6. At the Closing, Harpole shall
conclusively be deemed, unless the Company, in its sole discretion, permits
otherwise in writing, to have given the following representations and warranties
to the Company, which shall survive the Closing: (A) Harpole is the legal,
beneficial and record owner of the Put Shares, as good and marketable title
thereto and the absolute right to Transfer the same to the Company, and the Put
Shares, upon Transfer to the Company, will be free and clear of all security
interests, pledges, claims, liens, options, right to first refusal, limitations
on voting rights and restrictions of any kind whatsoever (other than
restrictions imposed by this Agreement and by federal and state securities
laws); and (B) the Transfer of the Put Shares by Harpole as contemplated by this
Agreement does not require any consent or approval of any governmental
authority, court or other Person that has not already been obtained.

         7.6 Payment of Purchase Price.In the event that the Company shall
purchase the Put Shares at the Closing, then at the Closing the Company shall
pay to Harpole, out of funds

                                       11
<PAGE>   15
legally available for repurchase of the Put Shares under Delaware law,
one-fourth of the Purchase Price by check or by wire transfer of immediately
available funds to an account designated by Harpole; and shall deliver to
Harpole a Promissory Note evidencing the Company's obligation to pay Harpole the
balance of the Put Price in three equal annual installments of principal, each
installment being due and payable on the anniversary date of the Closing (each,
a "Payment Date"), along with accrued and unpaid interest from the date of
Closing on the unpaid principal balance at a rate of interest equal to 8% per
annum. The Company shall have the right to prepay all or any part of the
indebtedness evidenced by the Promissory Note at any time or from time to time,
without premium, penalty or other charge, and the amount of any such prepayment
shall be applied first to interest accrued on the unpaid principal balance of
such indebtedness, and second to the unpaid balance of such indebtedness. Upon
default on the payment of any installment due on the Promissory Note, which
default is not cured within thirty (30) days after notice of such default is
given to the Company by Harpole, then the rate of interest on the unpaid
principal balance owed to Harpole under the Promissory Note shall be increased
to a rate equal to 12% per annum.

         7.7 Inability of Company. If the Company is legally or otherwise unable
to pay the Put Price on the terms set forth in Section 7.5, then the Company
shall take all reasonable action to remove the impediments to the payment of the
Put Price, and the Company shall pay the Put Price at the earliest possible
time. Notwithstanding the foregoing, Metretek shall not be obligated to
contribute any additional capital to the Company.

SECTION 8. DILUTION MATTERS.
           ----------------

         8.1 Preemptive Rights. Except as set forth in Section 8.2 below or as
otherwise mutually agreed in writing, neither Metretek nor Harpole shall have
any right, preemptive or otherwise, to subscribe for, purchase or otherwise
acquire any shares of capital stock or other equity securities of the Company,
or any securities convertible into or exercisable or exchangeable for any shares
of capital stock or other equity securities of the Company, or any options,
warrants or other rights to acquire any of the foregoing ("New Purchaser
Securities"), in connection with the offer, issuance, sale or exchange by the
Company of any New Purchaser Securities, regardless of whether such offer,
issuance, sale or exchange is made in connection with any investment by outside
investors, issuance in exchange for services, founders' stock issuances, stock
option plans and programs, warrant issuances or otherwise.

         8.2 Metretek Funding of Purchaser. Prior to the date of this Agreement,
Metretek has provided substantial assets and funds to, and paid expenses for the
benefit of, the Company ("Capital Contributions") for the purpose of funding the
initial stages of its development and organization, including financing a
significant portion of the agreement between Metretek and Scient Corporation for
the benefit of the Company. Within 15 business days of the date of this
Agreement, Metretek agrees to make additional Capital Contributions to the
Company in an amount equal to (i) $6,000,000, less (ii) the cumulative amount of
Capital Contributions made by Metretek to or for the benefit of the Company
(including TotalPlan, Inc.) from inception through the date of this Agreement
(the "Required Capital Contributions"). In exchange for such $6,000,000 of
Required Capital Contributions, Metretek shall be entitled to receive a total of
17,500,000 Shares, such total number of Shares to include the number of Shares
issued to Metretek prior to the date hereof, the number of Shares received by
Metretek upon the merger of TotalPlan, Inc. and the Company, and the number of
Shares to be issued in consideration of the additional capital contributions
made after the date hereof (up to the amount of the Required Contributions).
Although the Company and Harpole acknowledge and agree that Metretek is

                                       12
<PAGE>   16
under no obligation to provide any additional funds to or make any further
capital investments in the Company beyond the Required Capital Contributions,
the Company and Harpole acknowledge and agree that after Metretek has met the
Required Capital Contributions, then with respect to any and all additional
Capital Contributions, it makes in or provides to or for the benefit of the
Company, Metretek shall have the right to elect, in its sole discretion, either
(i) to receive additional Shares, at the rate of $0.30 per Share, or (ii) to
treat the excess funds as loans, repayble by the Company on terms reflecting
then current market prices rates.

SECTION 9. HARPOLE'S RIGHTS AS A DIRECTOR.
           ------------------------------

         So long a Harpole shall continue to own at least 7% of the outstanding
Shares of the Company, (i) Harpole shall have the right to be a member of the
Board of Directors of the Company and (ii) Metretek agrees to vote all its
Shares, at any meeting of the stockholders for the purpose of electing
directors, or to execute a consent in writing in lieu thereof, in order to elect
Harpole as a director of the Company. This right of Harpole to be a director of
the Company (i) shall expire on the second anniversary of the date of this
Agreement, and (ii) shall be personal to Harpole and shall not be assignable or
transferable to any Person, whether or not an Affiliate or Relative of Harpole,
and whether or not Harpole Transfers any Harpole Shares to such Person.

SECTION 10. EFFECTUATION PROVISIONS
            -----------------------

         10.1 Enabling Action.

                  (a) If any amendment to the Certificate and/or of the By-Laws
         of the Company, or any other action requiring the vote, consent or
         approval of the Stockholders, is required in order to make permissible
         or lawful any of the purchases of its own Shares which the Company may
         be obligated or entitled to make in accordance with the terms of this
         Agreement, then such Initial Stockholder shall vote all Shares of the
         Company at the time held by him in favor of, or shall consent in
         writing to, such amendment or action, whether such amendment or action
         is voted upon or consented to at, prior to or after the time of such
         purchase or purchases by the Company.

                  (b) Any agreement by such Initial Stockholder herein to vote
         its Shares in a certain manner shall be deemed, in each instance, to
         include an agreement by such Initial Stockholder to use its best
         efforts to take all actions necessary to call, or cause the Company and
         the appropriate officers and directors of the Company to call, as
         promptly as practicable, a special meeting of Stockholders or to act by
         written consent.

                  (c) When any action is required to be taken by such Initial
         Stockholder pursuant to this Agreement, such Initial Stockholder shall
         take all steps necessary to implement such action, including calling a
         special meeting of Stockholders or executing or causing to be executed,
         one or more consents in writing in lieu of a meeting of the
         Stockholders pursuant to Section 228 of the DGCL, in each case as
         promptly as practical.

         10.2 Legend. The Company shall cause each certificate representing
Harpole Shares to bear, in bold, all-caps typeface, the following legends (or
legends to a similar effect):

                                       13
<PAGE>   17
         THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
         UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR THE SECURITIES LAWS OF
         ANY STATE AND, ACCORDINGLY, NEITHER THESE SHARES NOR ANY INTEREST
         THEREIN MAY BE OFFERED, SOLD, ASSIGNED, TRANSFERRED, PLEDGED OR
         OTHERWISE DISPOSED OF UNLESS THE SAME IS REGISTERED UNDER THE
         SECURITIES ACT OF 1933, AS AMENDED, AND ANY APPLICABLE STATE SECURITIES
         LAWS OR UNLESS IN THE OPINION OF COUNSEL FOR THE COMPANY AN EXEMPTION
         FROM SUCH REGISTRATION IS AVAILABLE AND THE COMPANY RECEIVES EVIDENCE
         OF SUCH EXEMPTION REASONABLY SATISFACTORY TO IT (WHICH EVIDENCE MAY
         INCLUDE AN OPINION OF COUNSEL).

         THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO RESTRICTIONS
         ON TRANSFER CONTAINED IN THAT CERTAIN STOCKHOLDERS AGREEMENT DATED AS
         OF MARCH 17, 2000 BETWEEN THE CORPORATION AND ITS STOCKHOLDERS. THE
         COMPANY WILL MAIL A COPY OF SUCH AGREEMENT TO THE HOLDER OF THIS
         CERTIFICATE WITHOUT CHARGE WITHIN FIVE (5) DAYS AFTER RECEIPT OF A
         WRITTEN REQUEST THEREFOR.

         10.3 Acknowledgement of Necessity of Restrictions. Such Initial
Stockholder and the Company agree and acknowledge that the restrictions on the
issuance, transfer and encumbrance of Shares of the Company imposed by this
Agreement are imposed to accomplish legitimate purposes of the Company, and that
such restrictions are not more restrictive than necessary to accomplish those
purposes.

         10.4 Record of Transfers. The Company shall not make or record any
Transfer of its Shares which are subject to the provisions of this Agreement on
its books and records unless and until there shall have been full compliance
with the provisions of this Agreement and there shall have been furnished to the
Company such affidavits, certificate or other documents evidencing such
compliance as the Company may reasonably request.

         10.5 Voting of Shares. Such Initial Stockholder shall vote any and all
Shares or other voting securities of the Company which he owns or has the right
or power to vote to cause the Company to provide the Stockholders with the
rights and benefits contemplated by this Agreement, and to comply with and
perform fully each of the obligations, commitments, covenants, and agreements of
the Company to and with the Stockholders contained in this Agreement and shall
take any and all action as a Shareholder of the Company as may be necessary to
cause the Company to provide such rights and benefits and to comply with such
obligations, commitments, covenants, and agreements.

         10.6 No Contrary Action. No Shareholder shall take any action as an
officer, director or shareholder of the Company which would prevent such Initial
Stockholder or the Company from providing the Stockholders with the rights and
benefits contemplated by this Agreement, or which would otherwise cause such
Initial Stockholder or the Company to breach any of its

                                       14
<PAGE>   18
obligations, commitments, covenants and agreement to and with the Stockholders
set forth in this Agreement.

         10.7 Company Determinations. All determinations hereunder by the
Company to exercise any of its rights and obligations shall be made by the
Board, exclusive of the Shareholder who owns, controls or holds the Shares at
issue and his Affiliates.

SECTION 11. TERMINATION OF AGREEMENT
            ------------------------

         11.1 Termination. This Agreement, and the rights and obligations of the
parties hereunder, shall remain in effect until terminated on the earlier of:

                  (a) The date this Agreement is terminated by unanimous written
         consent of all Stockholders;

                  (b) The date on which only Metretek holds Shares;

                  (c) The date of the consummation of an IPO (except that in
         such event the provisions of Sections 7, 10, 13 and 14 shall survive an
         IPO);

                  (d) The date of the completion of the liquidation, dissolution
         or winding-up of the affairs of the Company; or

                  (e) The date of the sale of all of the Shares of the Company
         to a third party in compliance with this Agreement.

         11.2 Effect of Termination. Termination of this Agreement for any
reason shall not affect any rights or obligations of such Initial Stockholder or
of the Company accrued hereunder prior to such termination, or any right or
remedy with respect to a breach or default hereunder.

SECTION 12. ARBITRATION.
            -----------

         Any dispute, controversy or claim arises out of, under or in connection
with, or otherwise relating to, this Agreement (a "Dispute"), including but not
limited to the parties' rights and obligations hereunder, or any actual or
alleged breach hereof, shall be determined and settled by binding arbitration in
Denver, Colorado in accordance with the rules of the commercial rules and
procedures of the American Arbitration Association, as amended by this
Agreement. Promptly after a Dispute arises, the parties agree to make a good
faith effort to select one mutually agreeable arbitrator. If the parties are
unable to reach agreement on an arbitrator within thirty (30) days after the
Dispute is submitted to arbitration, one arbitrator shall be selected in
accordance with the commercial rules and procedures of the American Arbitration
Association. Any determination, resolution or award made by the arbitrators
shall specify the findings of fact of the arbitrators and the reasons for the
determination, resolution or award, and such determination, resolution or award
shall be final and binding. If the parties hereto mutually agree to a resolution
of any Dispute prior to the arbitrators' decision, the agreement of the parties
shall resolve the Dispute. The party prevailing in any arbitration, as
determined by the arbitrator, shall be entitled to an award of all of its
out-of-pocket costs and expenses incurred in connection with the Dispute,
including but not limited to reasonable attorneys' fees, court costs and expert
fees. An arbitration award or decision may be entered by any court of competent
jurisdiction, or application may be made to such a court for judicial acceptance
of the award or decision and any

                                       15
<PAGE>   19
appropriate order, including enforcement. The parties hereby consent to the
submission of any Dispute for settlement by binding arbitration in accordance
with this Section 12 and agrees to carry out without delay the provisions of any
arbitration award, decision or resolution.

SECTION 13. GENERAL PROVISIONS.
            ------------------

         13.1 Governing Law. This Agreement shall in all respects be governed
by, and construed in accordance with, the internal substantive laws of the State
of Delaware, without giving effect to any conflict or choice of law principles
or rules.

         13.2 Amendment. This Agreement may not be amended or modified in whole
or in part in any manner except in a writing which makes reference to this
Agreement executed by all parties hereto.

         13.3 Assignment. Harpole may not assign any or all of his rights or
delegate any or all of his duties under this Agreement without the prior written
consent of each of the other parties hereto.

         13.4 Successors and Assigns. This Agreement shall inure to the benefit
of and be binding upon the parties hereto and their respective heirs, legatees,
personal representatives, devisees, executors, successors and permitted assigns.

         13.5 Entire Agreement. This Agreement sets forth the entire agreement
and understanding of the parties hereto with respect to the subject matter
hereof and supersedes in their entirety all prior and contemporaneous written
and oral agreements, arrangements, understandings, negotiations, communications,
covenants, representations and warranties among the parties hereto relating to
the subject matter hereof.

         13.6 Notices. Any and all notices, demands, requests, elections and
other communications required or permitted to be given hereunder shall be in
writing and shall be deemed to have been duly given (i) upon personal delivery;
(ii) upon confirmation of receipt when sent by facsimile transmission; (iii) one
business day after deposit during normal business hours with a nationally
recognized overnight courier, specifying next day delivery, with written
verification of receipt; (iv) five business days after being sent by first class
(certified or registered) mail, postage prepaid, return receipt requested, in
each case to the following addresses:

                                    If to the Company, to:

                                    PowerSpring, Inc.
                                    1675 Broadway, Suite 2150
                                    Denver, Colorado  80202
                                    Attn:  Chief Executive Officer
                                    Telephone:  (303) 592-5555
                                    Facsimile:  (303) 592-5556

                                       16
<PAGE>   20
                                    With copies to:

                                    Metretek Technologies, Inc.
                                    1675 Broadway, Suite 2150
                                    Denver, Colorado  80202
                                    Attn:  W. Phillip Marcum, President
                                    Telephone:  (303) 592-5555
                                    Facsimile:  (303) 592-5556

                                    Paul R. Hess, Esq.
                                    Kegler, Brown, Hill & Ritter Co., L.P.A.
                                    65 E. State Street, Suite 1800
                                    Columbus, Ohio  43215
                                    Telephone:  (614) 462-5400
                                    Facsimile:  (614) 464-2634

                                    If to Harpole, to:

                                    John A. Harpole
                                    Mercator Energy Incorporated
                                    600 17th Street, Suite 600 South
                                    Denver, Colorado 80202
                                    Telephone:  (303) 825-1100
                                    Facsimile:  (303) 825-2300

                                    With a copy to:

                                    Ducker, Montgomery & Lewis, P.C.
                                    1560 Broadway, Suite 1500
                                    Denver, Colorado 80202
                                    Attn: Bruce Ducker
                                    Telephone:  (303) 861-2828
                                    Facsimile:  (303) 861-4017

         Any party hereto may send any notice, demand, request, election or
other communication to the intended recipient at its address set forth above
using any other means (such as expedited courier, messenger service, telecopy,
telex, ordinary mail or electronic mail), but no such notice, demand, request or
other communication shall be deemed to have been given until it is actually
received by the recipient. Any party hereto may change its designated address by
giving written notice to all other parties. Upon receipt of a request, the
Company shall provide such Initial Stockholder with a list of all such
addresses.

         13.7 Waiver. The obligations of any party hereunder may be waived only
with the written consent of the party or parties entitled to the benefits the
obligations so involved. Any waiver of a breach or violation of or default under
any provision of this Agreement shall not be construed or operate as, or
constitute, a waiver of any other or subsequent breach or violation of or
default under that provision or any other provision of this Agreement. The
failure of any party to insist upon strict compliance with any provision of this
Agreement on any one or more occasions shall not be construed or operate as, or
constitute, a continuing waiver of, or an

                                       17
<PAGE>   21
estoppel of that party's right to insist upon strict compliance with, that
provision or any other provision of this Agreement.

         13.8 Severability. If any provision of this Agreement is determined by
any court of law to be illegal, invalid or unenforceable in any situation, such
illegality, invalidity or unenforceability shall not affect or impair the
legality, validity or enforceability of that provision in any other situation or
of any other provision of this Agreement in any situation which shall remain in
full force and effect and this Agreement shall be construed as if such illegal,
invalid or unenforceable provision were omitted. The provisions of this
Agreement shall be deemed severable and the invalidity or unenforceability of
any provision shall not affect the validity or enforceability of the other
provisions hereof or thereof. If any provision of this Agreement, or the
application thereof to any Person or any circumstance, is invalid or
unenforceable: (a) a suitable and equitable provision shall be substituted
therefor in order to carry out, so far as may be valid and enforceable, the
intent and purpose of such invalid or unenforceable provision; and (b) the
remainder of this Agreement and the application of such provision to other
Persons or circumstances shall not be affected by such invalidity or
unenforceability, nor shall such invalidity or unenforceability affect the
validity or enforceabilty of such provision, or the application thereof, in any
other jurisdiction.

         13.9 Counterparts. This Agreement may be executed in any number of
counterparts (including counterparts executed by less than all parties hereto),
each of which shall be deemed to be an original, but all of which together shall
constitute one and the same instrument.

         13.10 Headings. The headings used herein are solely for convenience of
reference and shall not be given any effect in the construction or
interpretation of this Agreement.

         13.11 No Third Party Beneficiaries. Nothing in this Agreement, express
or implied, in intended to create or confer and shall not be construed or
operate as creating or conferring, any rights or remedies under or by reason of
this Agreement, upon any Person other than the parties hereto and their
respective successors and permitted assigns.

         13.12 Further Assurances. The parties hereto agree to take or cause to
be taken all actions, including without limitation, the execution and delivery
of documents and the voting of their Shares, which are necessary, convenient or
desirable in order to effect the transactions contemplated by this Agreement.

         13.13 Best Efforts. Each of the parties hereto shall act in good faith
and use its best efforts to bring about the transactions contemplated by this
Agreement.

         13.14 Expenses. Each of the parties to this Agreement shall pay its own
costs and expenses incurred in connection with this Agreement and the
consummation of the transactions contemplated hereby.

         13.15 Construction. In the event an ambiguity or question or intent or
interpretation arises, this Agreement shall be construed as if drafted jointly
by the parties hereto and no presumption or burden of proof shall arise favoring
or disfavoring any party hereto by virtue of the authorship of any of the
provisions of this Agreement

         13.16 Specific Performance. Each of the parties hereto acknowledges and
agrees that the other parties hereto would suffer irreparable damage for which
an adequate remedy at law

                                       18
<PAGE>   22
would not be available in the event any of the provisions of this Agreement is
not performed in accordance with its specific terms or otherwise is breached.
Accordingly, each of the parties hereto agrees that the non-breaching parties
shall be entitled to an injunction, restraining order or other form of equitable
relief from any court of competent jurisdiction to prevent breaches of, and to
specifically enforce, the provisions of this Agreement.

         13.17 No Agency or Partnership. Nothing contained in this Agreement
shall make or constitute any party to the representative, agent, principal or
partner of any other party and it is understood that no party has the capacity
to make commitments of any kind whatsoever or incur obligations or liabilities
binding upon any other party.

                                   * * * * *

                                       19
<PAGE>   23
         IN WITNESS WHEREOF, the parties hereto have duly executed, or cause
their duly authorized representatives to duly execute, this Stockholders
Agreement to be effective as of the day first above written.

                                  THE COMPANY:

                                  POWERSPRING, INC.

                                  By:/s/ W. Phillip Marcum
                                     ------------------------------------
                                     W. Phillip Marcum, President

                                  INITIAL STOCKHOLDERS:

                                  /s/ John A. Harpole
                                  ---------------------------------------
                                  John A. Harpole

                                  METRETEK TECHNOLOGIES, INC.

                                  By:/s/ W. Phillip Marcum
                                     ------------------------------------
                                     W. Phillip Marcum, President

                                       20<PAGE>   1
                                                                   EXHIBIT 10.19
                         NON-NEGOTIABLE PROMISSORY NOTE
                         ------------------------------

                                                                Denver, Colorado
$741,666.00                                                       March 17, 2000

         FOR VALUE RECEIVED, the undersigned, PowerSpring, Inc., a Delaware
corporation (the "Maker"), hereby promises to pay to John A. Harpole (the
"Payee"), at 600 17th Street, Suite 600 South, Denver, Colorado 80202, or at
such other address as the Payee may from time to time designate in writing, in
lawful money of the United States of America, the principal sum of Seven Hundred
Forty-One Thousand, Six Hundred Sixty-Six Dollars and No Cents ($741,666.00),
together with interest on the unpaid principal balance of this Note at the rate
set forth below.

         1. Principal. The unpaid principal balance of this Note and shall be
due and payable in two annual installments, as follows: the first installment
shall be in the amount of $408,333.00 and due and payable on the first
anniversary of the date of the Note; and the second installment shall be in the
amount of $333,333.00 and due and payable on the second anniversary of the date
of this Note.

         2. Interest. The unpaid principal balance of this Note shall bear
interest from the date hereof at a rate per annum of 6.00%. Interest shall be
due and payable in arrears on the same dates as the principal is due as set
forth in Section 1, until the principal sum of this Note and all accrued and
unpaid interest thereon has been paid in full. Such interest shall be computed
on the basis of the actual number of days during which the unpaid principal
balance is outstanding, divided by a 365/366 day year, as applicable, including
the first day but excluding the last day.

         3. Prepayments. The Maker shall have the right, at its option, to
prepay in whole at any time or in part from time to time the unpaid principal
balance of this Note and the interest due thereon accrued to the date of the
prepayment, without penalty or premium.

         4. Application of Payments. All payments shall first be applied to
accrued and unpaid interest and the balance, if any, shall be applied to the
unpaid principal balance of this Note.

         5. Default. If the Maker shall fail to timely make any payment due
hereunder within thirty (30) days after receipt of written notice of default
from the Payee, then at the option of the Payee, exercised by giving written
notice to the Maker, the entire unpaid principal balance of this Note, plus all
accrued and unpaid interest thereon, shall become immediately due and payable.
After the unpaid principal balance of this Note shall have become due and
payable, whether due to maturity, by acceleration or otherwise, then the unpaid
principal balance of this Note, plus all accrued and unpaid interest thereon,
shall bear interest at the rate per annum of the lesser of 12% or the maximum
amount permitted by law.

         6. Waiver of Procedural Defenses. The Maker and all other persons now
or hereafter liable for the payment of all or any part of the principal or
interest due on this Note, including without limitation indorsers, sureties and
guarantors, whether bound by this or separate instrument or agreement, do hereby
expressly waive presentment for payment, demand, notice of non-payment, notice
of dishonor, protest and notice of protest, and any and all other notices and
demands whatsoever, and agree to remain bound hereunder until the principal and
interest on this Note are paid in full, notwithstanding any extensions of time
for payment which may be granted by the Payee, even though the period of
extension may be

<PAGE>   2
indefinite, and notwithstanding any inaction by or failure to assert any legal
right available to the Payee. No conduct of the Payee shall be deemed to be a
waiver or release of such liability, unless the Payee expressly releases such
person in writing.

         7. Severability. If any term or provision of this Note or the
application thereof to any person, property or circumstance shall to any extent
be determined to be invalid or unenforceable, then all other terms and
provisions of this Note, and the application of such invalid or unenforceable
term or provision to persons, properties and circumstances other than those as
to which this Note is invalid or unenforceable, shall not be affected thereby,
and to that end the terms and provisions of this Note shall be severable, and
each term and provision of this Note shall be valid and enforceable to the
fullest extent permitted by law.

         8. No Waiver. No delay or omission by the Payee in exercising any right
or power arising under this Note shall impair any such right or power or be
deemed to be a waiver of any such right or power, nor shall any single or
partial exercise of any right or power preclude other or further exercise
thereof, or the exercise of any other right or power hereunder or otherwise. No
waiver or modification of the terms of this Note shall be valid unless set forth
in writing executed by the Payee, and a waiver on one or more occasions will not
be construed as a consent to or a waiver of any of the Payee's rights or
remedies on any future occasions.

         9. Governing Law. This Note shall be governed by and construed in
accordance with the internal substantive laws of the State of Colorado, without
giving effect to choice or conflicts of law.

         10. Integration; Amendment. The terms and conditions of this Note
constitute the entire agreement among the Maker and the Payee with respect to
the subject matter hereof and supersede any prior representations, agreements or
understandings relating thereto by or between the Maker and the Payee, whether
written or oral. No amendment or modification of this Note or waiver of the
terms or conditions hereof shall be binding upon the Maker or the Payee, unless
approved in writing by such party.

         11. No Assignment. Neither this Note nor the rights or obligations of
the Maker or the Payee hereunder may be assigned, whether by assignment,
transfer, merger, consolidation, sale, operation of law or otherwise, by either
the Maker or the Payee without the prior written consent of the other.

                                   MAKER:

                                   POWERSPRING, INC.

                                   By:/s/ W. Phillip Marcum
                                      ----------------------------------------
                                      W. Phillip Marcum, President

                                        2

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