<PAGE>
                                                                   EXHIBIT 10.13

                   FIRST AMENDMENT TO ASSIGNMENT AND AGREEMENT

This FIRST AMENDMENT TO ASSIGNMENT AND AGREEMENT (this "First Amendment") is
made and entered into EFFECTIVE as of March 30, 2002, by and between THOMAS H.
HEBERT ("Assignor"), an individual residing in Lutz, Florida; GLOBAL ENERGY &
ENVIRONMENTAL RESEARCH, INC. ("GEER"), a Florida corporation; and GLOBAL ENERGY
GROUP, INC. ("Assignee"), a Delaware corporation.


                              W I T N E S S E T H:

For and in consideration of the mutual promises and covenants herein contained
and the mutual advantages accruing to Assignor and Assignee, and for other good
and valuable consideration the receipt and sufficiency of which are hereby
acknowledged, Assignor and Assignee hereby agree as follows:

1.       BACKGROUND. Assignor and GEER entered into that certain Assignment &
Agreement identified on Exhibit A to this First Amendment (the "Original
Agreement"). For the purposes of this First Amendment, each capitalized term
appearing in this First Amendment shall have the definition applicable to such
term in the First Amendment, unless the context in which such term is used in
this First Amendment clearly indicates otherwise. Assignee has assumed the
operations of GEER, and accordingly the parties have agreed that Assignee should
be substituted for GEER under the Original Agreement. In addition, the parties
have agreed that certain terms of the Original Agreement shall be modified.

2.       ASSIGNMENT, ASSUMPTION AND SUBSTITUTION. GEER does hereby assign to
Assignee all its right, title and interest in, to and under the Original
Agreement, and Assignor does hereby consent and agree to such assignment.
Assignor, Geer and Assignee further agree that (i) Assignee is hereby
substituted for GEER under the Original Agreement, as if Assignor and Assignee
were the original parties to the Original Agreement, (ii) Assignee does hereby
accept, assume and agree to pay and perform, as and when due, and as if Assignee
had been an original party to the Original Agreement, all obligations of GEER
and all obligations of the party designated "Assignee" under the Original
Agreement, (iii) GEER is hereby released from, is no longer a party to, and
shall have no further liability or obligation under or with respect to the
Original Agreement. Geer does hereby grant, bargain, assign and transfer to
Assignee all its right, title and interest in, to and under all Assigned
Products and all Assignor Patent Rights.

3.       ELIMINATION OF INITIAL ROYALTY PAYMENTS. Until April 1, 2004, the
royalty rate under the Original Agreement shall be 0%, and the minimum annual
royalty shall be $0, and no royalty or other payment shall be due or payable
under the Original Agreement until on or after April 1, 2004. All royalty
percentages and minimum annual royalty amounts for periods beginning on or after
April 1 2004 shall be as set forth in the Original Agreement. Notwithstanding
anything to the contrary, however, (i) this Section 3 shall not apply as to any
Assigned Product during any period during which any person or entity not
affiliated with Assignee has the right, by way of a


<PAGE>

license by Assignee to such person or entity, to manufacture, market and sell
such Assigned Product, and (ii) if Assignee sells all or substantially all of
its right, title and interest in, to and under an Assigned Product and the
related Assignor Patent Rights to any person or entity not affiliated with
Assignee, then this Section 3 shall not thereafter apply as to such Assigned
Product.

4.       ADJUSTMENT IN ROYALTY RATES. Every reference in the Original Agreement
to "five percent" or "5%" is amended to read "three percent" or "3%,"
respectively.

5.       DEFINITION OF "GROSS SALES PRICE." The definition in the Original
Agreement of "Gross Sales Price" in Paragraph1.6 of the Original Agreement is
amended by the addition of the following at the end of such definition:

          "When an Assigned Product is included as part of an Assignee Product
         containing, incorporating or including products and materials other
         than Assigned Products, any royalty or other amount payable under this
         Assignment and Agreement shall be payable only with respect to the
         portion of the Gross Sales Price for such Assignee Product allocable to
         the included Assigned Product(s). The Gross Sales Price allocable to
         such included Assigned Product(s) shall be the cost of such Assigned
         Product(s) increased by the markup on the entire Assignee Product.
         Example: ASSIGNEE sells a 10-ton package rooftop unit containing an
         Assigned Product for $5,000. The cost of the entire package is $3,846,
         meaning that the package is sold with a 30% markup. The aggregate cost
         of the Assigned Product(s) included in the system is $540. Accordingly
         the "Gross Sales Price" of such Assigned Product(s) in this example
         would be $702. For the purposes of this paragraph, (i) "Assignee
         Product" means and includes any item, product, system and/or package,
         and/or any collection or aggregation of items, products, systems and/or
         packages, marketed and either licensed or sold by ASSIGNEE, (ii) any
         reference to the "cost" of an Assignee Product or any element,
         component, part or portion of an Assignee Product means the cost
         thereof to ASSIGNEE (or other person selling such Assignee Product) as
         reflected on the books and records of the seller, and (iii) any
         reference to the "markup" on, of or with respect to any Assignee
         Product means the excess, if any, of the gross selling price of such
         Assignee Product over the cost thereof, divided by such cost, expressed
         as a percentage." With respect to any Assigned Product or Assignee
         Product sold by any Licensee, royalties and other amounts are payable
         under this Assignment and Agreement only with respect to the amounts
         actually received by ASSIGNEE and not with respect to the amounts
         received by the Licensee.

Every reference in the Original Agreement to the capitalized term "Gross Selling
Price" is amended to read "Gross Sales Price."

6.       DOCUMENTATION. Each party, at its own expense and without further
consideration, will execute and deliver such other documents, and take such
other action, as may be necessary or appropriate in order to consummate more
effectively the transactions contemplated hereby,


<PAGE>

including in particular as necessary or appropriate to effectuate the transfer
of all Assigned Products and all Assignor Patent Rights to Assignee.

7.       EFFECT OF AMENDMENT; NO OTHER MODIFICATION. This First Amendment
together with the Original Agreement constitute the entire agreement between
Assignor and Assignee as to the subject matter of the Original Agreement and
this First Amendment, and there are no other agreements, understandings,
restrictions, warranties or representations between the parties relating to such
subject matter. To the extent that the Original Agreement is inconsistent with
the terms of this First Amendment, it is superseded and controlled by this First
Amendment. Any provision of the Original Agreement inconsistent with this First
Amendment is hereby amended to be consistent with this First Amendment. Other
than as amended by this First Amendment, the Original Agreement remains in full
force and effect, and, except as modified by this First Amendment, the terms and
provisions of the Original Agreement are hereby ratified and affirmed.

8.       COUNTERPARTS AND FACSIMILE. This First Amendment may be executed in two
counterparts, each of which shall be considered an original, but both of which
together shall constitute one and the same instrument, and shall become
effective when each of the parties has executed at least one of the counterparts
even if both parties have not executed the same counterpart. The parties
expressly acknowledge and agree that the printed product of a facsimile
transmittal shall be deemed to be "written" and a "writing" for all purposes of
the Original Agreement and this First Amendment.


<PAGE>

IN WITNESS WHEREOF, the parties hereto have set their hands and seals to
indicate that each of them does fully understand and agree with and to the
foregoing.



                                     /s/ Thomas H. Hebert
                            ----------------------------------------------
                            THOMAS H. HEBERT
                            ("Assignor")



                            GLOBAL ENERGY GROUP, INC.
                            ("Assignee")



                            By:      /s/ Joseph H. Richardson
                                ------------------------------------------
                            Name:             Joseph H. Richardson
                                  ----------------------------------------
                            Title:            President
                                   ---------------------------------------



                            GLOBAL ENERGY & ENVIRONMENTAL
                            RESEARCH, INC.
                            ("GEER")



                            By:      /s/ Joseph H. Richardson
                                ------------------------------------------
                            Name:             Joseph H. Richardson
                                  ----------------------------------------
                            Title:            President
                                   ---------------------------------------


<PAGE>

                                    EXHIBIT A
                      IDENTIFICATION OF ORIGINAL AGREEMENT


DATE OF ORIGINAL AGREEMENT:

         August 10, 1999


"ASSIGNED PRODUCT" UNDER ORIGINAL AGREEMENT:

         Direct Refrigerant Geothermal Heat Exchange or Multiple Source
         Subcool/Postheat/Precool System and Method Therefor as disclosed and
         claimed in the United States Patent Application dated October 6, 1998
         and any improvements thereon that are dominated by U. S. Patent
         Application Number 097/167,429


RELATED PATENT OR PATENT APPLICATION NOS. (IF ANY):

         U. S. Patent #6,167,715
         U. S. Patent Application #097/167,429


<PAGE>

         This is an Assignment and Agreement, dated this 10th day of August,
1999, by and between Thomas H. Hebert of 1340 Eastwood Drive, Lutz, Florida
33549 (hereinafter "ASSIGNOR") and Global Energy Environmental Research, Inc., a
State of Florida corporation, having its mailing address at 15445 N. Nebraska
Ave., Lutz, Florida 33549 (hereinafter "ASSIGNEE").

                             ARTICLE I - DEFINITIONS

1.1      "Assigned Product" shall mean the Direct Refrigerant Geothermal Heat
         Exchange or Multiple Source Subcool/Postheat/Precool System and Method
         Therefor as disclosed and claimed in the United States Patent
         Application dated Oct. 6, 1998 and any improvements thereon that are
         dominated by U.S. Patent Application Number 097/167,429.

1.2      "Assignor Patent Rights" shall mean U.S. Patent Application Number
         097/167,429 or any additional patent applications filed on any
         improvements of the Assigned Product, all U.S. patents issuing thereon,
         and any corresponding foreign patents and patent applications
         throughout the world, where and if GEER has elected to provide the
         necessary funding to secure international patents, which lay claim
         convention priority upon, or is dominated by, such United States patent
         or patent application.

1.3      "Licensee" shall mean any entity, whether a partnership, firm, company,
         corporation or otherwise to which ASSIGNEE grants a license under
         Assignor's Patent Rights.

1.4      "Valid Claim" shall mean any claim in any patent application that is
         allowed, resulting in an issuance of a United States Letters of Patent
         or any patent not yet expired included in the Assignor Patent Rights in
         the respective countries which has not been denied, nor invalidated by
         a decree of a Tribunal of competent jurisdiction, from which no further
         appeal is available.

1.5      "Commercially Exploited" shall mean the use, sale, lease or other
         activity serving to generate income on the Assigned Product.

1.6      "Gross Sales Price" shall mean the gross selling price received by
         Assignee and its Licensees of the Assigned Product, F.O.B. factory,
         without any deductions for cash discounts, including retail, wholesale
         and direct sales by mail order.

                        ARTICLE II - ASSIGNMENT OF RIGHTS

2.1      ASSIGNOR hereby assigns to ASSIGNEE all of the Assignor Patent Rights
         throughout the world.

2.2      The assignment granted under Paragraph 2.1 of this Article II includes
         the right to grant licenses to import, make, have made, use and sell
         the Assigned Product


<PAGE>

         throughout the world. ASSIGNEE shall give written notice to ASSIGNOR
         with respect to each license granted by the ASSIGNEE.

2.3      The assignment of rights hereunder is limited to those rights included
         in Assignor Patent Rights.

                              ARTICLE III - ROYALTY

3.1      In consideration of the Assignment of Paragraph 2.1 of Article II,
         Assignee shall pay Assignor, royalties as set forth in Paragraph 3.2 of
         this Article III.

3.2      ASSIGNEE agrees to pay ASSIGNOR an accrued royalty in the amount of
         five percent (5%) of the Gross Selling Price for each product
         manufactured, distributed, sold, etc. that is covered by/under, or
         becomes covered by a Letters of Patent, derived or accomplished by the
         Patent Application set forth in Paragraph 1.1 of Article I. To the
         extent ASSIGNEE grants a license to a third party under Assignor Patent
         Rights and receives royalties or other remuneration therefor, then
         ASSIGNEE agrees to pay ASSIGNOR five percent (5%) of such royalties
         and/or license fees.

3.3      No royalty shall be paid twice on the same Assigned Product and any
         customer or ASSIGNEE or its Licensees is entitled to resale or export
         the Assigned Product anywhere in the world without the payment of
         additional royalties.

3.4      Royalties will accrue on each product manufactured, distributed, or
         sold that is covered by/under a Patent Pending Application. Royalties
         will not be paid or disbursed until such time as the actual Patent has
         issued. In the event that a Patent Application is; a) abandoned, b)
         allowed no claims, c) rejected, or d) determined to be without the
         ability to file arguments that would result in Valid Claims, then no
         royalty would be paid, and all royalties accrued would revert to
         ASSIGNEE. In the event a Patent Application results in an issuance of a
         United States Letter of Patents, then all accrued royalties will be
         dispersed in accordance with Paragraphs 6.1 and 6.2 of Article VI.

3.5      Minimum Annual Royalties are as follows:

         Upon and from the date of Patent Issuance -

         Year One -                 0
         Year Two -                 0
         Year Three -               $ 10,000.00
         Year Four -                $ 25,000.00
         Year Five -                $ 40,000.00
         Year Six -                 $ 60,000.00
         Year Seven -               $ 75,000.00

         Every Year Thereafter Until the Expiration of the Letters of Patent -
         $100,000.00


<PAGE>

           ARTICLE IV - COMMERCIAL EXPLOITATION AND PATENT PROSECUTION

4.1      ASSIGNEE shall use reasonable efforts to COMMERCIALLY EXPLOIT the
         Assigned Product.

4.2      ASSIGNEE shall have control of the preparation and prosecution of all
         pending patent applications, in respect to the aforementioned patents
         as covered in the Assigned Product and any pending patent applications,
         in respect to the aforementioned patent application as covered in the
         Assigned Product, included within Assignor Patent Rights.

4.3      ASSIGNEE shall pay for the expenses and costs relating to such
         preparation and prosecution of those applications contemplated by
         Paragraph 4.2 of the Article IV.

4.4      ASSIGNEE shall pay for any taxes, annuities, maintenance fees, renewal
         and extension charges, and other out-of-pocket expenses, and related
         legal fees, in connection with any patent or patent applications
         included within the Assignor's Patent Rights.

4.5      Should ASSIGNEE decided, in its sole and absolute discretion, to
         abandon any pending patent application or to stop paying for the
         expenses and costs contemplated by Paragraphs 4.3 and 4.4, ASSIGNEE
         shall so notify ASSIGNOR to allow ASSIGNOR the opportunity to assume
         prosecution of the pending patent application and to begin paying for
         all of the expenses and costs.

                               ARTICLE V - RECORDS

5.1      ASSIGNEE shall submit or cause to be submitted to ASSIGNOR within one
         month following each semi-annual period (six months) a report setting
         forth (1) the number and (2) the Gross Sales Price of the Assigned
         Product, which ASSIGNEE has Commercially Exploited and (3) the amount
         of licensing royalties and remuneration received during that
         semi-annual period and which have not been previously reported.

5.2      ASSIGNEE agrees to keep books and records of account pertaining to
         Paragraph 5.1 of this Article V in such a manner as to permit the
         correctness and accuracy of any of the reports rendered in compliance
         with Paragraph 5.1 of this Article V to be ascertained. ASSIGNEE shall
         permit so much of the books and records thereof as pertain to the
         subject matter of this Assignment and Agreement to be confidentially
         inspected by a certified public accountant or ASSIGNOR'S designate,
         during ordinary business hours, but not more than once each semi-annual
         period, to confirm the correctness and accuracy of the reports rendered
         under Paragraph 5.1 of this Article V.


<PAGE>

                              ARTICLE VI - PAYMENTS

6.1      ASSIGNEE agrees to pay the amounts contemplated by Paragraph 3.2 of
         Article III, semi-annually on a calendar basis and, within one month
         following each semi-annual calendar period and shall tender such
         payments to ASSIGNOR concurrently with the reports contemplated by
         Paragraph 5.1 of Article V.

6.2      ASSIGNEE agrees to pay the amounts contemplated by Article III at
         ASSIGNOR address listed hereinabove, or at such other places as
         ASSIGNOR may specify from time to time, in United States dollars and
         through a United States bank designed by ASSIGNOR.

                     ARTICLE VII - VALIDITY AND INFRINGEMENT

7.1      In the event that a Valid Claim of the patent included in Assignor
         Patent Rights is finally held to be invalid or limited in scope by a
         court of competent jurisdiction from which appeal can no longer be
         taken, ASSIGNEE from the date of entry of the decision of such Court,
         shall be permanently relieved to the extent of such holding of
         invalidity or limitation of scope as to the obligation to pay accrued
         royalties on the Assigned Product in accordance with Paragraph 3.2 of
         Article III, provided that such Assigned Product is not covered by
         another Valid Claim on one or more patents coming with Assignor Patent
         Rights assigned hereunder which have not been held to be invalid or
         limited in scope as provided herein.

7.2      In the event ASSIGNOR and ASSIGNEE agree that a particular Assigned
         Product or the use thereof does not infringe a particular Valid Claim
         of any patent included in Assignor Patent Rights, ASSIGNEE shall
         thereafter be permanently relieved, with respect to any Assigned
         Product or use thereof which is the same as the Assigned Product or use
         thereof, agreed not to be infringed from the Assigned Product, the
         obligation of making further payments to ASSIGNOR which might otherwise
         be due under Paragraph 3.2 of Article III, such relief to be effective
         as of the date of entry, of such date, of such agreement; provided
         however, that the Assigned Product is not covered by another Valid
         Claim of one or more patents within Assignor Patent Rights which have
         not been held or agreed not to be infringed as provided, herein.

7.3      ASSIGNEE may, in its own name, bring or prosecute infringement suits
         against others who are infringing the patents within Assignor Patent
         Rights and shall be entitled to all recovery therefrom. ASSIGNEE shall
         have the full and sole right to control such or other proposed
         litigation and may discontinue any such suit or proposed litigation at
         any time upon giving thirty (30) days written notice of its intent to
         do so, to ASSIGNOR. ASSIGNOR may at their option, thereafter elect to
         continue such suit or other litigation at its own expense as evidenced
         by written notice to ASSIGNEE, and in such event, ASSIGNOR shall be
         entitled to all recovery therefrom, but shall keep ASSIGNEE fully
         advised of the progress of such continued suit or other litigation.


<PAGE>

7.4      It is mutually agreed between the parties nothing herein contained
         shall be construed to require either party to expend money in
         litigation or in the enforcing of Assignor Patent Rights unless it so
         elects and in the event a party proceeds with litigation in the name of
         the other party any cause in which such other party is not voluntarily
         a party, as evidenced by written notice, such party shall and agrees to
         hold harmless the other party from any and all liabilities arising
         thereunder, including, but not limited to, attorneys fees, court costs,
         and damages arising out of counterclaims, cross claims and the like.

7.5      ASSIGNOR represents that he is unaware of any rights of others which
         would be infringed by the Commercial Exploitation of the Assigned
         Product.

                               ARTICLE VIII - TERM

8.1      This Assignment and Agreement shall become effective upon mutual
         execution hereof and shall continue in effect until the expiration of
         the last to expire of the patent in Assignor Patent Rights coming
         hereunder.

8.2      If ASSIGNEE shall have failed in the performance of any of its
         covenants under this Assignment and Agreement, including the payment of
         royalties contemplated by Paragraph 3.2 of Article III, ASSIGNOR may
         terminate this Assignment and Agreement provided (a) ASSIGNOR provides
         ASSIGNEE written notice listing the specific failure of performance,
         (b) ASSIGNEE fails to cure such failure of performance within
         forty-five (45) days following its receipt of such notice, and (c) the
         default is in fact existing. Should a dispute arise over whether the
         default is in fact existing, ASSIGNEE may institute arbitration
         proceedings contemplated by Paragraph 11.3 of Article XI within the
         forty-five (45) day cure period whereupon termination shall be held in
         abeyance pending a decision of the arbitrator(s).

8.3      ASSIGNEE may terminate this Assignment and Agreement at any time,
         provided however, a forty-five (45) day written notice of ASSIGNEE'S
         intent to terminate this Assignment and Agreement is tendered to
         ASSIGNOR at the address contained herein.

8.4      Termination of this Assignment and Agreement shall not relieve either
         party of its obligations incurred up to the date of termination.

8.5      Upon termination, the rights listed in Assignor Patent Rights
         transferred hereunder shall revert to ASSIGNOR.


<PAGE>

                              ARTICLE IX - MARKING

9.1      ASSIGNEE agrees that each and every Assigned Patent commercially
         exploited by it hereunder covered by Assignor Patent Rights shall be
         marked with the statutory patent marking, or if it is not practical to
         mark the Assigned Product, to mark the container in which they are
         commercially exploited. ASSIGNEE further agrees to secure similar
         commitments from its Licensees.

                               ARTICLE X - NOTICE

10.1     Any notice or communication required or permitted hereunder shall be
         deemed to be duly given when sent by certified mail, return receipt
         requested, to the last known address of the other party.

10.2     Until otherwise notified in writing, the addresses of the parties
         hereto for purposes of such notice or communications are as set forth
         on page one of this Assignment and Agreement.

                           ARTICLE XI - MISCELLANEOUS

11.1     This Assignment and Agreement shall enure to the benefit of and be
         binding upon ASSIGNEE and may be transferred to or assigned by ASSIGNEE
         without the written consent of ASSIGNOR.

11.2     If at any time either party hereto shall elect not to assert its rights
         under any provision of this Agreement and Assignment in the event of
         breach of said provision by the other party, its action or lack of
         action in that respect shall not be construed as its continuing waiver
         of its rights under such provision or under any other provision of this
         Assignment and Agreement.

11.3     This Assignment and Agreement shall be construed under and in
         accordance with the laws of the State of Florida. Any controversy or
         claim arising out of this Assignment and Agreement or a breach or
         alleged breach thereof shall be settled by (a) arbitration in
         accordance with the rules of the American Arbitration Association
         ("AAA"), such arbitration to take place in Tampa, Florida, and any
         judgment upon the award rendered by the arbitrator may be entered in
         any court having jurisdiction thereof, or (b) a mutually agreed upon,
         licensed, State of Florida certified attorney, who will sit as the
         designated arbitrator and any judgment or award rendered by the
         arbitrator may be entered in any court having jurisdiction thereof.
         Each party agrees that any action or proceeding that may be brought in
         connection with this Assignment and Agreement must be brought against
         each party in the Federal Court of the Middle District of Florida in
         Tampa and each party hereto hereby consents and shall not oppose for
         any reason such jurisdiction and venue.


<PAGE>

11.4     In the event any Article or part thereof contained in this Assignment
         and Agreement is declared invalid or unenforceable by final judgment or
         decree of the arbitrators or by a court of competent jurisdiction from
         which no appeal is taken, all other Articles and parts thereof
         contained in this Agreement and Assignment shall remain in full force
         and effect and shall not be affected thereby.

11.5.    This Assignment and Agreement shall supercede all prior written and
         oral agreement between the parties. No changes, modifications, or
         amendments shall be effective unless in writing and executed by both
         parties hereof with the same formality as this Assignment and
         Agreement.



THOMAS H. HEBERT                 GLOBAL ENERGY & ENVIRONMENTAL RESEARCH, INC.



/s/ Thomas H. Hebert             /s/ Richard E. Wiles
---------------------            --------------------
     Thomas H. Hebert            By: Richard E. Wiles
                                     ----------------
                                 Its:  President
                                       --------------
Date:  8/10/99                   Date:  8/10/1999
       --------                         ---------

State of Florida
County of Hillsborough

On this the 10 day of August, 1999, before me personally came the above named
Thomas H. Hebert, ( ) personally known to me, or (X) who produced a Florida
Driver's Lic. as identification I.D.#H163-828-40-326-0 as acknowledged to me
that he executed the same of his own free will for the purposes set forth
herein.



/s/ Annie L. Middleton
----------------------
Notary Public, State of Florida at Large

My Commission Expires: November 11, 2001 (Stamp)
                       -------------------------
                                  Seal

State of Florida
County of Hillsborough

On this the 10 day of August, 1999, before me personally came the above named
Thomas H. Hebert, ( ) personally known to me, or (X) who produced a Florida
Driver's Lic. as identification I.D. # W420-745-43-436-0 as acknowledged to me
that he executed the same of his own free will for the purposes set forth
herein.

/s/ Annie L. Middleton
----------------------
Notary Public, State of Florida at Large

My Commission Expires: November 11, 2001 (Stamp)
                       -------------------------
                                 Seal