**EXHIBIT10.21**

**REGISTRATION RIGHTS AGREEMENT**

THIS REGISTRATION RIGHTSAGREEMENT (“Agreement”) is made and entered into as of the 4th day of May, 2006,by and between **EARTHBIOFUELS, INC.**, a Delawarecorporation having its principal place of business at 3001 Knox Street — Suite403, Dallas, Texas 75205-7305 (the “Company”), and **GREENWICHPOWER, L.L.C.**, a Delaware limited liability company having itsprincipal place of business at 537 Steamboat Road, Greenwich, Connecticut06830-7153 (the “Holder”).

RECITALS:

A. Contemporaneously withthe execution hereof, the Holder is purchasing from the Company (i) $1,000,000principal amount of the Company’s 7% secured promissory notes, which notes areconvertible into the Company’s common stock, $0.001 par value (the “CommonStock”) as therein provided, and (ii) a warrant to purchase 920,810 (subject toadjustment) shares of Common Stock (the shares of Common Stock issuable uponconversion of the said notes and upon exercise of the said warrant arehereinafter referred to as the “Shares”).

B. The Holder has requested,and the Company has agreed, as a condition to the Holder’s obligation to acquirethe said notes and warrant, to register the Shares under the Securities Act,upon the terms, and subject to the conditions, hereinafter set forth.

NOW, THEREFORE, inconsideration of the premises and the mutual covenants and agreements containedherein and other good, valuable and sufficient consideration, the receipt andadequacy of which are hereby acknowledged, the parties hereto, intending to belegally bound, hereby agree as follows:

*1.*Demand Registration.The Company agrees that the Company will, not later than sixty (60) days followingthe date on which it receives a request therefor by the Holder (but no earlierthan August 31, 2006), file a registration statement (the “Registration Statement”)with the Securities and Exchange Commission (“Commission”) relating to theShares. The Company shall use its best efforts to cause such RegistrationStatement promptly to become effective under the Securities Act and to qualifythe same under the blue sky laws of such states as may be requested. Providedthat such registration enables the Holder to dispose of substantially all ofthe Shares, the Company shall be obligated to effect registration and qualificationpursuant to a request of the Holder no more than once.

*2.*IncidentalRegistration. If at any time the Company proposes to register any equitysecurities under the Securities Act for its own account or for the account ofany of its stockholders, in connection with an underwritten public offering ofsuch securities, on a form that would also permit registration of the Shares,the Company shall, each such time, give the Purchaser not less than twenty (20)days’ written notice of such proposed registration. Upon the written request ofthe Holder, given within twenty (20) days after receipt of any such notice fromthe Company, the Company shall cause to be included in such registration all of

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theShares the Holder requests be registered in such registration. There shall beno restriction with respect to the number of times the Holder may request such incidentalregistration.

*3.*Expenses.All of its costs and expenses of the registration and qualifications pursuantto this Agreement shall be borne by the Company. Such costs and expenses shallinclude, without limitation, the fees and expenses of counsel for the Companyand of its accountants, all other costs, fees and expenses of the Companyincident to the preparation, printing and filing under the Securities Act ofthe registration statement and all amendments and supplements thereto, the costof furnishing copies of each preliminary prospectus, each final prospectus andeach amendment or supplement thereto to underwriters, dealers and otherpurchasers of the Shares and the costs and expenses (including fees anddisbursements of counsel) incurred in connection with the qualification of theShares under the blue sky laws of various jurisdictions. The Company shall not,however, pay any underwriting discount or commissions to the extent related tothe sale of Shares sold in any registration and qualification.

*4.*Procedures.

(a) The Company will keepthe Holder advised in writing as to the initiation of proceedings for suchregistration and qualification and as to the completion thereof, and willadvise the Holder, upon request, of the progress of such proceedings.

(b) The Company will keepthe registration and qualifications under this Agreement effective (and incompliance with the Securities Act) by such action as may be necessary orappropriate until such time, if any as the Shares shall have been sold. TheCompany’s obligations under this Section 4(b) shall include, withoutlimitation, the filing of post-effective amendments and supplements to anyregistration statement or prospectus necessary to keep the RegistrationStatement current and the further qualification under any applicable blue skyor other state securities laws to permit such sale or distribution, all asrequested by the Holder. The Company will immediately notify the Holder at anytime when a prospectus relating thereto is required to be delivered under theSecurities Act, of the happening of any event as a result of which theprospectus included in such Registration Statement, as then in effect, includesan untrue statement of a material fact or omits to state any material fact requiredto be stated therein or necessary to make the statements therein not misleadingin light of the circumstances then existing.

(c) Without limiting anyother provision hereof, in connection with any registration of Shares underthis Agreement, the Company will use its best efforts to comply with the SecuritiesAct, the Securities Exchange Act of 1934, as amended (the “Exchange Act”), andall applicable rules and regulations of the Commission.

(d) In connection with anyregistration of Shares under this Agreement, the Company will provide, ifappropriate, a transfer agent and registrar for the Shares not later than theeffective date of such Registration Statement.

(e) In connection with anyregistration of Shares under this Agreement, the Company will, if requested bythe underwriters for any Shares included in such registration, enter into 

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anunderwriting agreement with such underwriters for such offering, such agreementto contain such representations and warranties by the Company and such otherterms and provisions as are customarily contained in underwriting agreementswith respect to secondary distributions, including, without limitation, provisionsrelating to indemnification and contribution.

*5.*Indemnification.The Company will indemnify and hold harmless the Holder and each person, ifany, who controls the Holder within the meaning of the Securities Act againstany losses, claims, damages or liabilities, joint or several, and expenses(including reasonable attorneys’ fees and expenses and reasonable costs ofinvestigation) to which the Holder or such controlling person may be subject,under the Securities Act or otherwise, insofar as any thereof arise out of orare based upon (i) any untrue statement or alleged untrue statement of amaterial fact contained in (A) the Registration Statement under which theHolder’s Shares were registered under the Securities Act pursuant to thisAgreement, any prospectus or preliminary prospectus contained therein, or anyamendment or supplement thereto or (B) any other document incident to theregistration of the Shares under the Securities Act or the qualification of theShares under any state securities laws applicable to the Company, (ii) theomission or alleged omission to state in any item referred to in the precedingclause (i) a material fact required to be stated therein or necessary to makethe statements therein not misleading, or (iii) any violation or allegedviolation by the Company of the Securities Act, the Exchange Act or any otherfederal or state securities law, rule or regulation applicable to the Companyand relating to action or inaction by the Company in connection with any suchregistration or qualification, except insofar as such losses, claims, damages,liabilities or expenses arise out of or are based upon any untrue statement oralleged untrue statement or omission or alleged omission based upon informationfurnished to the Company in writing by the Holder expressly for use therein(with respect to which information the Holder shall so indemnify and holdharmless the Company, any underwriter for the Company and each person, if any,who controls the Company or such underwriter within the meaning of theSecurities Act).

*6.*Notices.Any notice or demand required or permitted to be made or given hereunder shallbe deemed sufficiently made and given if given by personal service or by themailing of such notice or demand by certified or registered mail, returnreceipt requested, or by overnight courier service providing for proof ofdelivery, addressed, if to the Company, at the Company’s address first abovewritten, with a copy to Roger A. Crabb, Esq., Scheef & Stone, L.L.P., 5956Sherry Lane — Suite 1400, Dallas, Texas 75225-8031; or if to the Holder, at theHolder’s address first above written, with a copy in like manner to Hilary B.Miller, Esq., 112 Parsonage Road, Greenwich, Connecticut 06830-3942. Eitherparty may change its address by like notice to the other party.

*7.*GoverningLaw; Forum. This Agreement shall be construed and enforced in accordancewith the substantive laws of the State of Delaware without regard to conflictof law principles. Each party hereby consents and submits to the exclusivepersonal and subject matter jurisdiction of the state and federal courtslocated in New York County, New York for 

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purposesof any action or proceeding related to this Agreement. Trial by jury in anyaction arising, proceeding or counterclaim arising hereunder is hereby waived.

*8.*BindingEffect; Assignment; Third Party Beneficiaries. This Agreement shall bebinding upon the parties and their respective successors and assigns and shallinure to the benefit of the parties and their respective successors andassigns. No person (including, without limitation, any employee of a party)shall be, or be deemed to be, a third party beneficiary of this Agreement.

*9.*Miscellaneous.This Agreement constitutes the entire contract between the parties with respectto the subject matter hereof and cancels and supersedes all of the previous contracts,commitments, representations, warranties and understandings (whether oral orwritten) by, between or among the parties with respect to the subject matterhereof. No addition to, and no cancellation, renewal, extension, modificationor amendment of, this Agreement shall be binding upon a party unless suchaddition, cancellation, renewal, extension, modification or amendment is setforth in a written instrument which states that it adds to, amends, cancels,renews, extends or modifies this Agreement and has been approved by all of theparties hereto. No waiver of any provision of this Agreement shall be bindingupon a party unless such waiver is expressly set forth in a written instrumentwhich is executed and delivered by such party or on behalf of such party by anofficer of, or attorney-in-fact for, such party. Such waiver shall be effectiveonly to the extent specifically set forth in such written instrument. Neitherthe exercise (from time to time and at any time) by a party of, nor the delayor failure (at any time or for any period of time) to exercise, any right,power or remedy shall constitute a waiver of the right to exercise, or impair,limit or restrict the exercise of, such right, power or remedy or any otherright, power or remedy at any time and from time to time thereafter. No waiverof any right, power or remedy of a party shall be deemed to be a waiver of anyother right, power or remedy of such party or shall, except to the extent sowaived, impair, limit or restrict the exercise of such right, power or remedy.If any provision of this Agreement shall hereafter be held to be invalid,unenforceable or illegal, in whole or in part, in any jurisdiction under anycircumstances for any reason, (i) such provision shall be reformed to theminimum extent necessary to cause such provision to be valid, enforceable andlegal while preserving the intent of the parties as expressed in, and the benefitsto the parties provided by, this Agreement or (ii) if such provision cannot beso reformed, such provision shall be severed from this Agreement and anequitable adjustment shall be made to this Agreement (including, withoutlimitation, addition of necessary further provisions to this Agreement) so asto give effect to the intent as so expressed and the benefits so provided. Suchholding shall not affect or impair the validity, enforceability or legality ofsuch provision in any other jurisdiction or under any other circumstances.Neither such holding nor such reformation or severance shall affect or impairthe legality, validity or enforceability of any other provision of thisAgreement.

*10.*Remedies.The rights, powers and remedies of the parties set forth herein for a breach ofor default under this Agreement are cumulative and in addition to, and not inlieu of, any rights or remedies that any party may otherwise have under thisAgreement, at law or in equity. The parties acknowledge that the Shares areunique, and that any violation of this 

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Agreementcannot be compensated for by damages alone. Accordingly, in addition to all ofthe other remedies which may be available hereunder or under applicable law,any party shall have the right to any equitable relief which may be appropriateto remedy a breach or threatened breach by any other party hereunder,including, without limitation, the right to enforce specifically the terms ofthis Agreement by obtaining injunctive relief in respect of any violation ornon-performance hereof, and any party shall have the right to seek recovery ofand be awarded attorneys’ fees and expenses in any proceeding with respect tothis Agreement as reasonably determined by the court in which such proceedingis brought.

*11.*Headings;Counterparts. The headings set forth in this Agreement have been insertedfor convenience of reference only, shall not be considered a part of thisAgreement and shall not limit, modify or affect in any way the meaning orinterpretation of this Agreement. This Agreement may be signed in any number ofcounterparts, each of which (when executed and delivered) shall constitute anoriginal instrument, but all of which together shall constitute one and thesame instrument. It shall not be necessary when making proof of this Agreementto account for any counterparts other than a sufficient number of counterpartswhich, when taken together, contain signatures of all of the parties. Aphotocopy or electronic facsimile of this Agreement or any signature hereonshall be valid as an original.

IN WITNESS WHEREOF, theparties have duly executed and delivered this Agreement as of the date firstabove written.
| EARTH BIOFUELS, INC.               |   | GREENWICH POWER, L.L.C.            |
|------------------------------------|--------|------------------------------------|
|                               |   |                               |
|                               |   |                               |
| By: /s/ DENNIS  G. MCLAUGHLIN, III |   | By:  /s/ LANCE A. BAKROW |
| Dennis G. McLaughlin, III          |   | Lance A. Bakrow                    |
| Its President                      |   | Its Manager                        |

 

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