Document:

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                                                                   EXHIBIT 10.23

                  SHARE-TRANSFER ACKNOWLEDGMENT AND AGREEMENT

                Catalytica Energy Systems, Inc. (the "Company")

                          and JSB Asset, LLC ("JSB")

                                   Recitals

     WHEREAS, Enron Ventures Corp., a Delaware corporation ("EVC") purchased
1,339,286 shares (the "Shares") of Series B Preferred Stock of the Company, as
set forth in a certain Series B Preferred Stock Purchase Agreement dated
December 9, 1997 (the "Original Purchase Agreement") and a Stockholders'
Agreement dated January 14, 1998 (the "Stockholders' Agreement").

     WHEREAS, EVC transferred the Shares to its affiliate, Ponderosa Assets,
L.P. ("Ponderosa") on December 18, 1998, and Ponderosa immediately thereafter
transferred the Shares to Sundance Assets, L.P. ("Sundance"), its affiliate and
an affiliate of EVC.

     WHEREAS, pursuant to that certain Omnibus Agreement dated August 29, 2000
(the "Omnibus Agreement") by and among Catalytica, Inc., the Company, Sundance
and Enron North America Corp. certain amendments were made to the Original
Purchase Agreement (the Original Purchase Agreement, as so amended, being
hereafter referred to as the "Purchase Agreement").

     WHEREAS, on December 6, 2000 Sundance transferred the Shares to Ponderosa
and Ponderosa immediately thereafter transferred the Shares to EVC.  On December
7, 2000 EVC transferred the Shares to JSB, its affiliate.
<PAGE>

     WHEREAS, pursuant to Section 2 of the Omnibus Agreement and the Amended and
Restated Certificate of Incorporation of the Company effective on or about
December 14, 2000, the Shares were converted into 1,342,889 (including 3,603
shares issued as a result of an adjustment to the conversion ratio) shares of
Company Common Stock on or about December 14, 2000, thereby resulting in the
termination of the Stockholders' Agreement pursuant to Section 3.1 thereof.

     WHEREAS, pursuant to Section 12 of the Omnibus Agreement, the Company's
right of first refusal under the Original Purchase Agreement was terminated.

     WHEREAS, pursuant to the terms and conditions of the Purchase Agreement,
the Company has certain rights of restrictions on transfer.

                                   Agreement

     In reliance on the information set forth in the above recitals regarding
the affiliation of Sundance, Ponderosa, EVC and JSB, the Company hereby
acknowledges and agrees that (1) the Stockholders' Agreement is terminated and
(2) the transfers of the Shares to Ponderosa as of December 6, 2000, to EVC as
of December 6, 2000 and to JSB as of December 7, 2000, were permitted by Section
10.3(a)(ii) of the Purchase Agreement.  JSB acknowledges and agrees that the
Shares transferred to it are subject to all of the provisions of the Purchase
Agreement.  The parties agree that the legend referred to in Section 4.7(c) of
the Stock Purchase Agreement is modified to delete references to the
Stockholders' Agreement and to a right of first refusal in the Company so that
the certificate issued to JSB shall contain the following legend:

                                       2
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     "THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFER SET FORTH IN THE
     STOCK PURCHASE AGREEMENT BETWEEN THE COMPANY AND ENRON VENTURES CORP., AS
     AMENDED, A COPY OF WHICH IS AVAILABLE FROM THE SECRETARY OF THE COMPANY."

Further, the Company hereby acknowledges and agrees that, pursuant to the filing
of the Company's Amended and Restated Certificate of Incorporation with the
Secretary of State of the State of Delaware on or about December 14, 2000, the
Shares have been converted into 1,342,889 shares of the Company's Common Stock
and that no further action on the part of JSB or EVC is required to affect such
conversion.

     IN WITNESS WHEREOF, the parties have executed this Share Transfer
Acknowledgment and Agreement as of this 15 day of December, 2000.

                              Catalytica Energy Systems, Inc.

                              By:     /s/ Craig N. Kitchen
                                 ------------------------------------------

                              Name:   Craig N. Kitchen
                                   ----------------------------------------

                              Title:  President and Chief Executive Officer
                                    ---------------------------------------

                                       3
<PAGE>

                              JSB Asset, LLC

                              By: ENRON VENTURES CORP., ITS CLASS A
                                  MEMBER

                              By:   /s/Ben F. Glisan, Jr.
                                 ------------------------------------------

                              Name: Ben F. Glisan, Jr.
                                   ----------------------------------------

                              Title:  Vice President, Finance and Treasurer
                                    ---------------------------------------

                                       4<PAGE>

                                                                   EXHIBIT 10.24

                            STOCK PURCHASE WARRANT
             To Purchase Shares of Common Stock, $.001 par value of
                        CATALYTICA ENERGY SYSTEMS, INC.

THE SALE, ASSIGNMENT OR TRANSFER OF THIS WARRANT IS PROHIBITED, OTHER THAN
SALES, ASSIGNMENTS OR TRANSFERS THAT ARE IN COMPLIANCE WITH THE TERMS AND
CONDITIONS OF A WARRANT PURCHASE AGREEMENT, DATED JUNE 25, 1997 BETWEEN
CATALYTICA, INC., CATALYTICA PHARMACEUTICALS, INC. AND GLAXOWELLCOME, INC. (THE
"WARRANT PURCHASE AGREEMENT"). THE RIGHTS TO ACQUIRE SHARES REPRESENTED BY THIS
WARRANT HAVE BEEN ACQUIRED FOR INVESTMENT AND NOT WITH A VIEW TO, OR IN
CONNECTION WITH, THE SALE OR DISTRIBUTION THEREOF.

WARRANT NO. 001
ISSUE DATE: December 15, 2000

     THIS CERTIFIES that, for value received, GlaxoWellcome Inc. is entitled,
upon the terms and subject to the conditions hereinafter set forth, at any time
on or after the date hereof and during the term of this Warrant, to subscribe
for and purchase from Catalytica Energy Systems, Inc., a Delaware corporation
(the "Company"), up to the number of fully paid and non-assessable shares equal
to the product of (a) the Distribution Ratio (as defined below), times (b)
2,000,000 ("Shares") of the Company's Common Stock, $.001 par value ("Common
Stock") at an exercise price per share as set forth below ("Exercise Price").
The Exercise Price and the number of shares for which the Warrant is exercisable
shall be subject to adjustment as provided herein. The Distribution Date is the
date upon which, immediately prior to and in connection with the merger (the
"Merger") of Synotex Acquisition Corporation with and into Catalytica, Inc.
("Catalytica"), Catalytica distributes to the holders of its common stock, all
of the shares of the Company's common stock owned by Catalytica (the
"Distribution").

     The Exercise Price will be calculated using the following formula:

                                 X = $12.00-Y
                                     --------
                                        Z

                where

                X = the Exercise Price;

                Y = the Merger Consideration, as defined in the Agreement and
                    Plan of Merger by and among Synotex Company, Inc., Synotex
                    Acquisition Corporation and
<PAGE>

                Catalytica, Inc., dated August 2, 2000;

            Z = the number of shares of common stock of the Company distributed
                by Catalytica in the Distribution with respect to each share of
                common stock of Catalytica (the "Distribution Ratio").

     This Warrant is being issued in order to effect the conversion of Stock
Purchase Warrant No. GW-1 for 2,000,000 shares of common stock of Catalytica
issued to GlaxoWellcome Inc. on July 31, 1997 (the "Catalytica Warrant"),
pursuant to section 4(c) of the Catalytica Warrant in accordance with Delaware
law, taking into account the Merger and the Distribution.  This Warrant
represents the conversion of the Catalytica Warrant, and all of the obligations
of Catalytica under the Catalytica Warrant are superseded by this Warrant, and
upon issuance of this Warrant, the Catalytica Warrant shall be null and void.

1.   Transferability of Warrant.  Prior to its expiration hereof, this Warrant
     --------------------------
     may be held only by GlaxoWellcome and may not be transferred, assigned or
     sold to any other individual or entity other than by transfers, assignments
     or sales that are in compliance with the terms and conditions of the
     Warrant Purchase Agreement.

2.   Exercise of Warrant.
     -------------------

     a.   The terms of this Warrant shall commence on July 31, 1997, and will
          expire at the close of business California time on July 31, 2003. The
          Warrant may be exercised for all or part of the Shares, in whole or in
          part, at any time during the term of this Warrant by the surrender of
          this Warrant and a duly executed Notice of Warrant Exercise in the
          form of Exhibit 1 at the office of the Company at 430 Ferguson Drive,
          Mountain View, California 94043 (or such other office or agency of the
          Company as it may designate by notice in writing to the holder of this
          Warrant), and upon payment of the Exercise Price of the Shares thereby
          purchased (by wire transfer or by certified check or by bank draft
          payable to the order of the Company in an amount equal to the Exercise
          Price of the Shares thereby purchased); whereupon the holder of this
          Warrant shall be entitled to receive a certificate for the number of
          Shares so purchased. The Shares so purchased shall be deemed issued to
          such holder as the record owner of such Shares as of the close of
          business California time on the date on which this Warrant shall have
          been exercised.

     b.   In the event of any exercise of the purchase right represented by this
          Warrant, certificates for the Shares so purchased shall be delivered
          to the holder hereof within fifteen (15) days of the effective date
          of such purchase and, unless this Warrant has been fully exercised or
          expired, a new Warrant representing the portion of the Shares, if any,
          with respect to which this Warrant shall not then have been exercised
          shall also be issued to the holder hereof within such fifteen (15) day
          period. Upon the effective date of such purchase, the holder shall be
          deemed to be the holder of record of the
<PAGE>

             Shares, notwithstanding that Certificates representing the Shares
             shall not then be actually delivered to such holder or that such
             Shares are not then set forth on the stock transfer books of the
             Company.

         c.  The Company covenants that all Shares that may be issued upon the
             exercise of rights represented by this Warrant will, upon exercise
             in accordance with the terms of this Warrant, be fully paid and
             nonassessable and free from all taxes, liens and charges in respect
             of the issue (other than taxes in respect of any transfer occurring
             contemporaneously with such issue).

     3.  No Fractional Shares or Scrip. No fractional shares or scrip
         ----------------------------
         representing fractional shares shall be issued upon the exercise of
         this Warrant.

     4.  Adjustments. The purchase rights set forth herein are subject to
         -----------
         adjustment as provided below.

         a.  Stock Splits, Stock Combinations and Stock Dividends. If the
             ----------------------------------------------------
             Company shall at any time subdivide the outstanding shares of
             Common Stock, then the number of shares of Common Stock for which
             this Warrant is exercisable immediately prior to that subdivision
             (the "Number of Warrant Shares") shall be proportionately increased
             and the exercise price therefor proportionately decreased, and if
             the Company shall at any time combine the outstanding shares of
             Common Stock, then the Number of Warrant Shares shall be
             proportionately decreased and the exercise price therefore
             proportionately increased. If the Company shall at any time
             declare or pay a dividend in shares of Common Stock to holders of
             its outstanding Common Stock, the Number of Warrant Shares
             purchasable upon exercise of this Warrant immediately prior thereto
             shall be adjusted so that the holder of this Warrant shall be
             entitled to receive the kind and number of Shares or other
             securities of the Company which the holder would have owned or have
             been entitled to receive had such Warrant been exercised in advance
             thereof. Any adjustment under this Section 4.1 shall become
             effective at the close of business on the date the subdivision or
             combination becomes effective.

         b.  Reclassification, Exchange and Substitution. If the Common Stock
             -------------------------------------------
             issuable on exercise of this Warrant shall be changed into the same
             or a different number of shares of any other class or classes of
             stock, whether by capital reorganization, reclassification, or
             otherwise (other than a subdivision or combination of shares
             provided for above), then the holder of this Warrant shall, upon
             its exercise, be entitled to receive, in lieu of the Common Stock
             that the holder would have become entitled to receive but for such
             change, that number of shares of such other class or classes of
             stock that is equivalent to the number of shares of Common Stock
             that would have been subject to receipt by the holder on exercise
             of this Warrant immediately prior to that change.

<PAGE>

          c.  Reorganizations, Mergers or Consolidations. If at any time there
              ------------------------------------------
              shall be a capital reorganization of the Common Stock (other than
              a subdivision, combination, reclassification or exchange of shares
              provided for elsewhere in this Warrant) or merger or consolidation
              of the Company with or into another corporation, then as a part of
              such reorganization, merger or consolidation of the Company with
              or into another corporation, then as a part of such
              reorganization, merger or consolidation, lawful provision shall be
              made so that the holder of this Warrant shall thereafter be
              entitled to receive upon exercise of this Warrant, during the
              period specified in this Warrant, the number of shares of stock or
              other securities or property of the Company, or of the successor
              corporation resulting from such merger or consolidation, to which
              a holder of the Common Stock deliverable upon exercise of this
              Warrant would have been entitled on such capital reorganization,
              merger or consolidation if this Warrant had been exercised
              immediately prior to that reorganization, merger or consolidation.
              In any such case, appropriate adjustment shall be made in the
              application of the provisions of this Warrant with respect to the
              rights of the holder after the reorganization, merger or
              consolidation to the end that the provisions of this Warrant
              (including adjustment of the Number of Warrant Shares then in
              effect) shall be applicable after that event in a manner as nearly
              equivalent as may be practicable.

          d.  Notice of Adjustments. The Company shall promptly give written
              ---------------------
              notice of each adjustment or readjustment of the number of shares
              of Common Stock or other securities issuable upon exercise of this
              Warrant at the holder's address as shown on the Company's books.
              This notice shall state that adjustment or readjustment and show
              in reasonable detail the facts on which that adjustment or
              readjustment is based.

          e.  No Change Necessary. The form of this Warrant need not be changed
              -------------------
              because of any adjustment in the number of shares of Common Stock
              issuable upon its exercise. A Warrant issued after any adjustment
              on exercise or upon replacement may continue to express the same
              number of shares of Common Stock as are stated on this Warrant as
              initially issued, and such number of shares shall be considered to
              have been so changed as of the close of business on the date of
              adjustment.

          f.  Reservation of Stock. The Company covenants that it will at all
              --------------------
              times reserve and keep available, solely for issuance upon
              exercise of this Warrant, all shares of its Common Stock from time
              to time issuable upon exercise of this Warrant, and if at any time
              the number of authorized but unissued shares of Common Stock shall
              not be sufficient to effect the exercise of this Warrant, the
              Company will take such corporate action as may, in the opinion of
              its counsel, be necessary to increase its authorized but unissued
              shares of Common Stock to such number of shares as shall be
              sufficient for each purpose.

      5.  Notice of Record Date. In the event of any taking by the Company of a
          ---------------------
          record of the holders of any class of securities for the purpose of
          determining the holders thereof who are entitled to receive any
          dividend or other distribution in cash or securities or property other
          than shares.
<PAGE>

     of Common Stock, the Company shall mail to the holder of this Warrant at
     least fifteen days prior to the date specified therein, a notice specifying
     the date on which any such record is to be taken for the purpose of such
     dividend or distribution.

6.   Charges, Taxes and Expenses. Issuance of certificates for shares of
     ---------------------------
     Common Stock upon the exercise of this Warrant shall be made without
     charge to the holder hereof for any issue or transfer tax or other
     incidental expense in respect of the issuance of such certificate, all
     of which taxes and expenses shall be paid by the Company. Such
     certificates shall be issued in the name of the holder of this Warrant.

7.   No Rights as Stockholder. This Warrant does not entitle the holder to
     ------------------------
     any voting rights or other rights as a stockholder of the Company prior
     to the exercise of this Warrant.

8.   Investment Representations. The holder of this Warrant by receiving this
     --------------------------
     Warrant makes the representations to the Company contained in paragraph
     2.1 of the Warrant Purchase Agreement.

     a.   Legends. Each certificate representing Shares shall be endorsed
          -------
          with the following legend (in addition to any legend required by
          applicable state securities laws):

          THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED
          FOR INVESTMENT AND NOT WITH A VIEW TO, OR IN CONNECTION WITH,
          THE SALE OR DISTRIBUTION THEREOF. NO SUCH SALE OR DISPOSITION
          MAY BE EFFECTED WITHOUT AN EFFECTIVE REGISTRATION STATEMENT
          RELATED THERETO OR AN OPINION OF COUNSEL REASONABLY SATISFACTORY
          TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED UNDER THE
          SECURITIES ACT OF 1933.

The Company need not register a transfer of Shares unless the conditions
specified in the foregoing legend are satisfied. The Company may also instruct
its transfer agent not to register the transfer of any of the Shares unless the
conditions specified in the foregoing legend are satisfied.

     b.   Removal of Legends and Transfer Restrictions. The legend relating
          --------------------------------------------
          to the Act endorsed on a stock certificate pursuant to Section 8.1 and
          the stop transfer instructions with respect to the Shares represented
          by such certificate shall be removed and the Company shall issue a
          certificate without such legend to the holder of such Shares if such
          holder provides to the Company an opinion of counsel for such holder
          of the Shares reasonably satisfactory to the Company or a no-action
          letter or interpretive opinion of the staff of the Securities and
          Exchange Commission to the effect that a public sale, transfer or
          assignment of such Shares may be made without registration and without
          compliance with any restriction such as Rule 144.
<PAGE>

9.   Loss, Theft, Destruction or Mutilation of Warrant. Upon receipt by the
     -------------------------------------------------
     Company of evidence reasonably satisfactory to it of the loss, theft,
     destruction or mutilation of this Warrant, and in case of loss, theft or
     destruction, of indemnity or security reasonably satisfactory to it, and
     upon reimbursement to the Company of all reasonable expenses incidental
     thereto, and upon surrender and cancellation of this Warrant, if mutilated,
     the Company will make and deliver a new Warrant of like tenor and dated, as
     of such cancellation, in lieu of this Warrant.

10.  Saturdays, Sundays, Holidays, etc. If the last or appointed day for the
     ---------------------------------
     taking of any action or the expiration of any right required or granted
     herein shall be a Saturday or a Sunday or shall be a legal holiday, then
     such action may be taken or such right may be exercised on the next
     succeeding day not a legal holiday.

11.  Miscellaneous.
     -------------

     i.   The provisions of this Warrant shall be construed and shall be given
          effect in all respects as if it had been issued and delivered by the
          Company on the date of this Warrant. This Warrant shall be binding
          upon any successors or assigns of the Company. This Warrant shall
          constitute a contract under the laws of the State of Delaware and for
          all purposes shall be construed in accordance with and governed by the
          laws of said state (irrespective of its choice of law principles).

     ii.  The holder acknowledges that the Common Stock acquired upon the
          exercise of this Warrant shall have restrictions upon its resale
          imposed by state and federal securities laws described in the
          Warrant Purchase Agreement.

<PAGE>

  IN WITNESS WHEREOF, Catalytica Energy Systems, Inc. has caused this Warrant to
be executed by its duly authorized officer.

Dated: December 15, 2000

                                       CATALYTICA ENERGY SYSTEMS, INC.

                                       /s/ Craig N. Kitchen
                                       -------------------------------
                                       Craig N. Kitchen
                                       President and Chief Executive Officer

<PAGE>

                                   Exhibit 1
                                   ---------

                          NOTICE OF WARRANT EXERCISE
                          --------------------------

To:     CATALYTICA ENERGY SYSTEMS, INC.

        (1)     The undersigned hereby elects to purchase ______________ shares
of Common Stock of Catalytica Energy Systems, Inc. pursuant to the terms of the
attached Warrant, and tenders herewith payment of the exercise price in full.

        (2)     Please issue a certificate or certificates representing said
shares of Common Stock in the name of the undersigned. The undersigned tax
identification number is ___________________________.

        (3)     The undersigned represents that the aforesaid shares of Common
Stock are being acquired for the account of the undersigned for investment and
not with a view to, or for resale in connection with, the distribution thereof.
The undersigned confirms and remakes as of the date of this notice the
representations to the Company which are contained in Section 2.1 of the Warrant
Purchase Agreement, dated June 25, 1997, between Catalytica, Inc., Catalytica
Pharmaceuticals, Inc. and GlaxoWellcome, Inc.

                                               ---------------------------------
(Date)                                         (Signature)

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