**Exhibit 10.75****CATALYTICA ENERGY SYSTEMS, INC.****AMENDED AND RESTATED EMPLOYMENT AGREEMENT**     This Amended and Restated Employment Agreement (the “Agreement”) by and between Robert Zack(the “Employee”) and Catalytica Energy Systems, Inc. (the “Company”), is amended and restatedeffective as of the latest date set forth by the signatures of the parties hereto below (the“Effective Date”).     1. Duties and Scope of Employment.          (a) Positions and Duties. As of the Effective Date, Employee will continue to serveas President and Chief Executive Officer and Chief Financial Officer of the Company. Employee willrender such business and professional services in the performance of his duties, consistent withEmployee’s position within the Company, as shall reasonably be assigned to him, by the Board ofDirectors of the Company (the “Board”); provided, however that at the Board’s discretion it mayappoint another President and Chief Executive Officer in which case Employee will continue to serveas Chief Financial Officer. The period of Employee’s employment under this Agreement is referredto herein as the “Employment Term.”          (b) Obligations. During the Employment Term, Employee will perform his dutiesfaithfully and to the best of his ability and will devote his full business efforts and time to theCompany. For the duration of the Employment Term, Employee agrees not to actively engage in anyother employment, occupation or consulting activity for any direct or indirect remuneration withoutthe prior approval of the Board.     2. At-Will Employment. The Company and the Employee acknowledge that the Employee’semployment is and shall continue to be at-will, as defined under applicable law. If the Employee’semployment terminates for any reason, including (without limitation) any termination after anannouncement of Change of Control and prior to twenty-four (24) months following a Change ofControl or the announcement of a Change of Control, whichever comes later, the Employee shall notbe entitled to any payments, benefits, damages, awards or compensation other than as provided bythis Agreement.     3. Compensation.          (a) Base Salary. During 2007, and retroactive to January 1, 2007, the Company willpay Employee as compensation for his services a base salary at the annualized rate of $300,000(“Base Salary”). In 2008 and subsequent years, the Base Salary may be increased by the Board orits Compensation Committee, in its sole discretion and may only be decreased with the consent ofEmployee. The Base Salary will be paid periodically in accordance with the Company’s normalpayroll practices and be subject to the usual, required withholding.
 

 
          (b) Annual Bonus. Employee shall be eligible to receive a annual bonus on account ofthe Company’s 2007 fiscal year with a target payment equal to 125% of Base Salary based uponcriteria developed by the Board or its Compensation Committee (the “Target Bonus”). In 2008 andsubsequent years, the Target Bonus may be increased by the Board or its Compensation Committee, inits sole discretion and may only be decreased with the consent of Employee. The Target Bonus maybe paid to Employee in a mixture of cash and equity compensation, as determined by the CompensationCommittee in its sole discretion; provided, however, that the cash component shall be no less than50% of the Target Bonus; provided, further, that for the 2007 fiscal year, the mixture shall be 50%cash and 75% equity compensation. In the event that the equity compensation component is paid instock options, the number of options shall be determined by dividing the dollar amount by theBlack-Scholes value of Company options (or by such other reasonable method of valuing Companyoptions as the Compensation Committee shall determine), and such options shall be subject to afour-year vesting schedule, with 1/8th of the covered shares vesting six monthsfollowing the grant date and 1/48th of the covered shares vesting each month thereafter,so as to be 100% vested on the four year anniversary of the grant date, subject to Employeeremaining a Service Provider, as such term is defined in the Company’s 1995 Stock Plan (“ServiceProvider”) on each vesting date.     4. Employee Benefits. During the Employment Term, Employee will be entitled toparticipate in the employee benefit plans currently and hereafter maintained by the Company ofgeneral applicability to other senior executives of the Company. The Company reserves the right tocancel or change the benefit plans and programs it offers to its employees at any time.     5. Severance Benefits.          (a) Termination Not in Connection with a Change of Control. If the Employee’semployment terminates as a result of Involuntary Termination (as defined below) other than forCause at any time prior to an announcement of a Change of Control or on or after the date that istwenty-four (24) months following a Change of Control or the announcement of a Change of Control,whichever comes later (a “Non-Change of Control Severance Termination”), then, subject to Employee(i) executing and not revoking a standard release of claims in favor of the Company; provided,however, that such release shall preserve all indemnification rights of Employee and all otherrights of Employee under the currently existing indemnification agreement or similar agreement withthe Company (a “Release”), and (ii) not breaching the provisions of Section 7 hereof, then Employeeshall be entitled to receive the following severance and non-competition benefits:               (i) Severance Payment. Following the Employment Termination Date the Company shallpay Employee an aggregate cash amount equal to two hundred percent (200%) of his AnnualCompensation, plus a pro rata cash payment of the current year Target Bonus, less applicable taxes,paid ratably over the remaining payroll periods in the same calendar year in which Employeeterminated.               (ii) Subsidized COBRA. Subject to Employee timely electing continuation coverageunder Title X of the Consolidated Budget Reconciliation Act of 1985 (“COBRA”), the Company shallsubsidize Employee and his eligible dependent’s COBRA
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premiums so that Employee pays the same premium as an active employee of the Company for aperiod equal to the lesser of (i) eighteen months following the Employee’s termination date, or(ii) the date upon which Employee becomes covered under the group health plans of another employerwith comparable group health benefits and levels of coverage.          (b) Termination in Connection with a Change of Control. If the Employee’s employmentterminates as a result of Involuntary Termination (as defined below) other than for Cause at anytime after an announcement of a Change of Control and prior to twenty-four (24) months following aChange of Control or the announcement of a Change of Control, whichever comes later (the “Change ofControl Period”) (a “Change of Control Severance Termination”), then, subject to Employee (i)executing and not revoking a Release, (ii) not breaching the provisions of Section 7 hereof, and(iii) the provisions of Section 9 hereof, the Employee shall be entitled to receive the followingseverance benefits:               (i) Severance and Non-Competition Payment. A cash payment in an amount equal to twohundred percent (200%) of the Employee’s Annual Compensation plus a pro rata cash payment of thecurrent year Target Bonus, less any Change of Control Retention Payments (as defined in Section 6hereof) already paid to Employee. Of this amount, one hundred percent (100%) of Employee’s AnnualCompensation is paid specifically in exchange for Employee entering into and not breaching thenon-competition provisions of Section 7 hereof.               (ii) Continued Employee Benefits. One hundred percent (100%) Company-paid health,dental and life insurance coverage at the same level of coverage as was provided to such employeeimmediately prior to the Change of Control Severance Termination (the “Company-Paid Coverage”). Ifsuch coverage included the Employee’s dependents immediately prior to the Change of ControlSeverance Termination, such dependents shall also be covered at Company expense. Company-PaidCoverage shall continue until the earlier of (i) two years from the date of the InvoluntaryTermination or (ii) the date that the Employee and his dependents become covered under anotheremployer’s group health, dental or life insurance plans that provide Employee and his dependentswith comparable benefits and levels of coverage. For purposes of COBRA, the date of the“qualifying event” for Employee and his dependents shall be the date upon which the Company-PaidCoverage terminates.               (iii) Option and Restricted Stock Accelerated Vesting. One Hundred percent (100%) ofthe unvested portion of any stock option or restricted stock (including restricted stock units)held by the Employee shall automatically be accelerated in full so as to become completely vested.Of this amount, fifty percent (50%) of such acceleration is made specifically in exchange forEmployee entering into and not breaching the non-competition provisions of Section 7 hereof.               (iv) Timing of Severance & Non-Competition Payments. Any Change of Control Severanceand non-competition payments to which Employee is entitled under Section 5(b)(1) shall be paid bythe Company to the Employee (or to the Employee’s successor in interest, pursuant to Section 11(b))in cash and in full, not later than thirty (30) calendar days following the Termination Date,subject to Section 13(f).
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          (c) Voluntary Resignation; Termination For Cause. If the Employee’s employmentterminates by reason of the Employee’s voluntary resignation (and is not an InvoluntaryTermination), or if the Employee is terminated for Cause, then the Employee shall not be entitledto receive severance or other benefits except for those (if any) as may then be established underthe Company’s then existing option, severance and benefits plans and practices.          (d) Disability; Death. If the Company terminates the Employee’s employment as aresult of the Employee’s Disability, or such Employee’s employment is terminated due to the deathof the Employee, then the Employee shall not be entitled to receive severance or other benefitsexcept for those (if any) as may then be established under the Company’s then existing severanceand benefits plans and practices or pursuant to other agreements with the Company.     6. Retention Payments. In the event of a Change of Control (other than a liquidationor dissolution of the Company) wherein Employee is employed by the acquiring entity in the positionof Chief Financial Officer or a greater position, then Employee shall receive cash retentionpayments (the “Change of Control Retention Payments”) as to 1/3 of Annual Compensation on the dateof the Change of Control, another 1/3 of Annual Compensation on the date that is six monthsfollowing the Change of Control, and a final 1/3 of Annual Compensation on the one year anniversaryof the Change of Control, subject to his remaining employed by the acquiring entity through suchdates.     7. Conditional Nature of Section 5 and 6 Payments.          (a) Noncompete. Employee acknowledges that the nature of the Company’s business issuch that if Employee were to become employed by, or substantially involved in, the business of acompetitor of the Company during the 12 months following the termination of Employee’s employmentwith the Company, it would be very difficult for Employee not to rely on or use the Company’s tradesecrets and confidential information. Thus, to avoid the inevitable disclosure of the Company’strade secrets and confidential information, Employee agrees and acknowledges that Employee’s rightto receive the payments set forth in Section 5 or 6 (to the extent Employee is otherwise entitledto such payments) shall be conditioned upon Employee not directly or indirectly engaging in(whether as an employee, consultant, agent, proprietor, principal, partner, stockholder, corporateofficer, director or otherwise), nor having any ownership interested in or participating in thefinancing, operation, management or control of, any person, firm, corporation or business thatcompetes with the Company or is a customer or client of the Company during the one year periodfollowing the Employment Termination Date (“Competition”); provided, however, that nothing in thisSection 7 shall prevent Employee from performing services for the acquirer of the Company’s Dieselbusiness following a Sale of the Diesel Business; provided, further, that following his terminationof employment with the Company, Employee shall be permitted to work for an entity in Competitionwith the Company whose primary business is not providing products or services competitive with theproducts or services of the Company, so long Employee does not engage in a business that makes suchentity in Competition with the Company. Notwithstanding the foregoing, Employee may, withoutviolating this Section 7, own, as a passive investment, shares of capital stock of a publicly-heldcorporation that engages in Competition where the number of shares of such corporation’s capitalstock that are owned by Employee represent less than three percent of the total number of shares ofsuch corporation’s capital stock outstanding.
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          (b) Non-Solicitation. Until the date 12 months after the termination of Employee’semployment with the Company for any reason, Employee agrees and acknowledges that Employee’s rightto receive the severance and retention payments set forth in Section 5 and 6 (to the extentEmployee is otherwise entitled to such payments) shall be conditioned upon Employee not eitherdirectly or indirectly soliciting, inducing, recruiting or encouraging an employee to leave his orher employment either for Employee or for any other entity or person with which or whom Employeehas a business relationship.          (c) Understanding of Covenants. Employee represents that he (i) is familiar with theforegoing covenants not to compete and not to solicit, and (ii) is fully aware of his obligationshereunder, including, without limitation, the reasonableness of the length of time, scope andgeographic coverage of these covenants.          (d) Remedy for Breach. Upon any breach of this section by Employee, all severance andretention payments pursuant to Section 5 or 6 shall immediately cease, and that shall be the soleremedy available to the Company for such breach.     8. Attorney Fees, Costs and Expenses. With respect to any Change of Control SeveranceTermination only, the Company shall reimburse Employee for the reasonable attorney fees, costs andexpenses incurred by the Employee in connection with any action brought by Employee to enforce hisrights hereunder, provided such action is not decided in favor of the Company.     9. Golden Parachute Excise Tax – Capped Gross-Up. In the event that the benefitsprovided for in this agreement or otherwise (a) constitute “parachute payments” within the meaningof Section 280G of the Internal Revenue Code of 1986, as amended (the “Code”), (b) would be subjectto the excise tax imposed by Section 4999 of the Code, and (c) the aggregate value of suchparachute payments, as determined in accordance with Section 280G of the Code and the TreasuryRegulations thereunder is less than the product obtained by multiplying 3.59 by Employee’s “baseamount” within the meaning of Code Section 280G(b)(3), then such benefits shall be reduced to theextent necessary (but only to that extent) so that no portion of such benefits will be subject toexcise tax under Section 4999 of the Code. Alternatively, in the event that the benefits providedfor in this agreement (a) constitute “parachute payments” within the meaning of Section 280G of theCode, (b) would be subject to the excise tax imposed by Section 4999 of the Code, and (c) theaggregate value of such parachute payments, as determined in accordance with Section 280G of theCode and the Treasury Regulations thereunder is equal to or greater than the product obtained bymultiplying 3.59 by Employee’s “base amount” within the meaning of Code Section 280G(b)(3), thenEmployee shall receive (i) a payment from the Company sufficient to pay such excise tax plus anyinterest or penalties incurred by Employee with respect to such excise tax, plus (ii) an additionalpayment from the Company sufficient to pay the excise tax and federal and state income andemployment taxes arising from the payments made by the Company to Employee pursuant to thissentence; provided, however, that the Company shall not be required to pay Employee more than$150,000 (less applicable withholding) in such gross-up payments under this Section 9. UnlessEmployee and the Company agree otherwise in writing, the determination of Employee’s excise taxliability and the amount required to be paid or reduced under this Section 9 shall be made inwriting by the Company’s outside tax advisors who are primarily used by the Company immediatelyprior to the
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Change of Control (the “Accountants”). For purposes of making the calculations required bythis Section 9, the Accountants may make reasonable assumptions and approximations concerningapplicable taxes and may rely on reasonable, good faith interpretations concerning the applicationof Sections 280G and 4999 of the Code. Employee and the Company shall furnish to the Accountantssuch information and documents as the Accountants may reasonably request in order to make adetermination under this section 9. The Company shall bear all costs the Accountants mayreasonably incur in connection with any calculations contemplated by this section 9.     10. Definition of Terms. The following terms referred to in this Agreement shall havethe following meanings:          (a) Annual Compensation. “Annual Compensation” means an amount equal to the greaterof (i) Employee’s Base Salary for the twelve (12) months preceding the Change of Control plus theemployee’s target bonus for the same period, or (ii) Employee’s Base Salary on an annualized basisand the employee’s target bonus as of the Termination Date.          (b) Cause. “Cause” shall mean (i) any act of personal dishonesty taken by theEmployee in connection with his responsibilities as an employee and intended to result insubstantial personal enrichment of the Employee, (ii) the conviction of or plea of nolocontendere to a felony, (iii) a willful act by the Employee that constitutes gross misconductand that is injurious to the Company, or (iv) for a period of not less than thirty (30) daysfollowing delivery to the Employee of a written demand for performance from the Company thatdescribes the basis for the Company’s belief that the Employee has not substantially performed hisduties, continued violations by the Employee of the Employee’s obligations to the Company that aredemonstrably willful and deliberate on the Employee’s part. Any dismissal for cause must beapproved by the Company’s Board of Directors prior to the dismissal date.          (c) Change of Control. “Change of Control” means the occurrence of any of thefollowing events:               (i) Any “person” (as such term is used in Sections 13(d) and 14(d) of the Securities ExchangeAct of 1934, as amended) becomes the “beneficial owner” (as defined in Rule 13d-3 under said Act),directly or indirectly, of securities of the Company representing fifty percent (50%) or more ofthe total voting power represented by the Company’s then outstanding voting securities;               (ii) A change in the composition of the Board occurring within a twelve-month period, as aresult of which fewer than a majority of the directors are Incumbent Directors. “IncumbentDirectors” shall mean directors who either (A) are directors of the Company as of the date hereof,or (B) are elected, or nominated for election, to the Board with the affirmative votes of at leasta majority of the Incumbent Directors at the time of such election or nomination (but shall notinclude an individual whose election or nomination is in connection with an actual or threatenedproxy contest relating to the election of directors to the Company);               (iii) The consummation of a merger or consolidation of the Company with any other corporation,other than a merger or consolidation that would result in the voting securities
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of the Company outstanding immediately prior thereto continuing to represent (either byremaining outstanding or by being converted into voting securities of the surviving entity or suchsurviving entity’s parent) at least fifty percent (50%) of the total voting power represented bythe voting securities of the Company or such surviving entity or such surviving entity’s parentoutstanding immediately after such merger or consolidation;               (iv) The consummation of the sale or disposition by the Company of all or seventy-five percent(75%) or more of the Company’s assets.          (d) Disability. “Disability” shall mean that the Employee has been unable to performhis Company duties as the result of his incapacity due to physical or mental illness, and suchinability, at least twenty-six (26) weeks after its commencement, is determined to be total andpermanent by a physician selected by the Company or its insurers and acceptable to the Employee orthe Employee’s legal representative (such Agreement as to acceptability not to be unreasonablywithheld). Termination resulting from Disability may only be effected after at least thirty (30)days’ written notice by the Company of its intention to terminate the Employee’s employment. Inthe event that the Employee resumes the performance of substantially all of his duties hereunderbefore the termination of his employment becomes effective, the notice of intent to terminate shallautomatically be deemed to have been revoked.          (e) Involuntary Termination. “Involuntary Termination” shall mean (i) without theEmployee’s express written consent, the significant reduction of the Employee’s duties, authorityor responsibilities, relative to the Employee’s duties, authority or responsibilities as in effectimmediately prior to such reduction, or the assignment to Employee of such reduced duties,authority or responsibilities; provided, however, that so long as Employee’s title, duties,authority and responsibility are at the level of Chief Financial Officer or greater, whether at theCompany or at an acquirer following a Change of Control, then that will not constitute anInvoluntary Termination under this clause (i), (ii) without the Employee’s express written consent,a substantial reduction, without good business reasons, of the facilities and perquisites(including office space and location) available to the Employee immediately prior to suchreduction; (iii) a reduction by the Company in the base salary or target bonus of the Employee asin effect immediately prior to such reduction; (iv) a material reduction by the Company in the kindor level of employee benefits to which the Employee was entitled immediately prior to suchreduction with the result that the Employee’s overall benefits package is significantly reduced;(v) the relocation of the Employee to a facility or a location more than twenty-five (25) milesfrom the Employee’s then present location, without the Employee’s express written consent; (vi) anypurported termination of the Employee by the Company that is not effected for Disability or forCause, or, during the Change of Control Period only, any purported termination for which thegrounds relied upon are not valid; (vii) the failure of the Company to obtain the assumption ofthis Agreement by any successors contemplated in Section 11(a) below; (viii) requiring Executive towork outside of Arizona on more than **[50%]**of the business days in any **[90]**consecutive day periodor (viii) during the Change of Control Period only, any act or set of facts or circumstances thatwould, under California case law or statute constitute a constructive termination of the Employee.However, with respect to any Non-Change of Control Severance Termination, an InvoluntaryTermination shall not be deemed to have occurred unless Employee provides written notice to theCompany describing the nature of the event that he
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believes forms the basis for Involuntary Termination and the Company does not cure such eventwithin ten (10) days following receipt of such notice.          (f) Termination Date. “Termination Date” shall mean (i) if this Agreement isterminated by the Company for Disability, thirty (30) days after notice of termination is given tothe Employee (provided that the Employee shall not have returned to the performance of theEmployee’s duties on a full-time basis during such thirty (30)-day period), (ii) if the Employee’semployment is terminated by the Company for any other reason, the date on which a notice oftermination is given, provided that if within thirty (30) days after the Company gives the Employeenotice of termination, the Employee notifies the Company that a dispute exists concerning thetermination or the benefits due pursuant to this Agreement, then the Termination Date shall be thedate on which such dispute is finally determined, either by mutual written agreement of theparties, or a by final judgment, order or decree of a court of competent jurisdiction (the time forappeal therefrom having expired and no appeal having been perfected), or (iii) if the Agreement isterminated by the Employee, the date on which the Employee delivers the notice of termination tothe Company.     11. Successors.          (a) Company’s Successors. Any successor to the Company (whether direct or indirectand whether by purchase, merger, consolidation, liquidation or otherwise) to all or substantiallyall of the Company’s business and/or assets shall assume the obligations under this Agreement andagree expressly to perform the obligations under this Agreement in the same manner and to the sameextent as the Company would be required to perform such obligations in the absence of a succession.For all purposes under this Agreement, the term “Company” shall include any successor to theCompany’s business and/or assets which executes and delivers the assumption agreement described inthis Section 11(a) or which becomes bound by the terms of this Agreement by operation of law.          (b) Employee’s Successors. The terms of this Agreement and all rights of the Employeehereunder shall inure to the benefit of, and be enforceable by, the Employee’s personal or legalrepresentatives, executors, administrators, successors, heirs, distributees, devisees and legatees.     12. Notice.          (a) General. Notices and all other communications contemplated by this Agreementshall be in writing and shall be deemed to have been duly given when personally delivered or whenmailed by U.S. registered or certified mail, return receipt requested and postage prepaid. In thecase of the Employee, mailed notices shall be addressed to him at the home address which he mostrecently communicated to the Company in writing. In the case of the Company, mailed notices shallbe addressed to its corporate headquarters, and all notices shall be directed to the attention ofits Secretary.          (b) Notice of Termination. Any termination by the Company for Cause or by theEmployee as a result of a voluntary resignation or an Involuntary Termination shall be communicatedby a notice of termination to the other party hereto given in accordance with Section 12 (a) ofthis Agreement. Such notice shall indicate the specific termination provision in
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this Agreement relied upon, shall set forth in reasonable detail the facts and circumstancesclaimed to provide a basis for termination under the provision so indicated, and shall specify thetermination date (which shall be not more than thirty (30) days after the giving of such notice).The failure by the Employee to include in the notice any fact or circumstance which contributes toa showing of Involuntary Termination shall not waive any right of the Employee hereunder orpreclude the Employee from asserting such fact or circumstance in enforcing his rights hereunder.     13. Miscellaneous Provisions.          (a) No Duty to Mitigate. The Employee shall not be required to mitigate the amount ofany payment contemplated by this Agreement, nor shall any such payment be reduced by any earningsthat the Employee may receive from any other source.          (b) Waiver. No provision of this Agreement shall be modified, waived or dischargedunless the modification, waiver or discharge is agreed to in writing and signed by the Employee andby an authorized officer of the Company (other than the Employee). No waiver by either party ofany breach of, or of compliance with, any condition or provision of this Agreement by the otherparty shall be considered a waiver of any other condition or provision or of the same condition orprovision at another time.          (c) Whole Agreement. This Agreement and any outstanding stock option agreementsrepresent the entire understanding of the parties hereto with respect to the subject matter hereofand supersedes in their entirety all prior arrangements and understandings regarding same,including the Change of Control Severance Agreement previously entered into by and between Employeeand the Company and any offer letter, promotion letter, employment agreement or other agreementregarding Employee’s employment terms with the Company. Other than the agreements described in thepreceding sentence, no agreements, representations or understandings (whether oral or written andwhether express or implied) which are not expressly set forth in this Agreement have been made orentered into by either party with respect to the subject matter hereof.          (d) Choice of Law. The validity, interpretation, construction and performance of thisAgreement shall be construed and enforced in accordance with, and the rights of the parties shallbe governed by, the laws of the State of Arizona without regard to principles of conflicts of laws.          (e) Severability. The invalidity or unenforceability of any provision or provisionsof this Agreement shall not affect the validity or enforceability of any other provision hereof,which shall remain in full force and effect.          (f) Withholding. All payments made pursuant to this Agreement will be subject towithholding of applicable income and employment taxes.          (g) Counterparts. This Agreement may be executed in counterparts, each of which shallbe deemed an original, but all of which together will constitute one and the same instrument.
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     IN WITNESS WHEREOF, each of the parties has executed this Agreement, in the case of theCompany by its duly authorized officer, as of the day and year set forth below.       COMPANY CATALYTICA ENERGY SYSTEMS, INC.           By: /s/ Ricardo Levy           Date: February 27, 2007         EMPLOYEE /s/ Robert Zack                Date: March 23 , 2007  
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