Exhibit 4.2


 


RIGHTS AGREEMENT


 


This Rights Agreement (this “Agreement”)
is made as of July 14, 2021, by and between CleanTech Acquisition Corp., a Delaware corporation (the “Company”), and Continental
Stock Transfer & Trust Company, a New York corporation (the “Rights Agent”).


 


WHEREAS, the Company is engaged in a public offering
(the “Public Offering”) of 15,000,000 units (the “Units”) of the Company (and up to 2,250,000 additional
Units if the underwriters’ over-allotment option is exercised in full), each Unit consisting of one share of common stock, par value
$0.0001 per share (the “Common Stock”), one right to receive one-twentieth of one share of Common Stock upon the happening
of the triggering event described herein (the “Right”), and one-half of a warrant to purchase one share of Common Stock
(the “Warrant”);


 


WHEREAS, the Company has filed with the Securities
and Exchange Commission (the “SEC”) a Registration Statement on Form S-1, File No. 333-256578 (the “Registration
Statement”), and related Prospectus (the “Prospectus”) for the registration, under the Securities Act of
1933, as amended (the “Act”), of, among other securities, the Rights and the shares of Common Stock issuable to the
holders of the Rights;


 


WHEREAS, the Company desires the Rights Agent
to act on behalf of the Company, and the Rights Agent is willing to so act, in connection with the issuance, registration, transfer and
exchange of the Rights;


 


WHEREAS, the Company desires to provide for the
form and provisions of the Rights, the terms upon which they shall be issued, and the respective rights, limitation of rights, and immunities
of the Company, the Rights Agent, and the holders of the Rights; and


 


WHEREAS, all acts and things have been done and
performed which are necessary to make the Rights, when executed on behalf of the Company and countersigned by or on behalf of the Rights
Agent, as provided herein, the valid, binding and legal obligations of the Company, and to authorize the execution and delivery of this
Agreement.


 


NOW, THEREFORE, in consideration of the mutual
agreements herein contained, the parties hereto agree as follows:


 


1.
Appointment of Rights Agent. The Company hereby appoints the Rights Agent to act as agent for the Company for the Rights,
and the Rights Agent hereby accepts such appointment and agrees to perform the same in accordance with the terms and conditions set forth
in this Agreement.


 


2.
Rights.


 


2.1 Form of Right. Each
Right shall be issued in registered form only, shall be in substantially the form of Exhibit A hereto, the provisions of which
are incorporated herein and shall be signed by, or bear the facsimile signature of, the Chairman of the Board, the Chief Executive Officer
or the Chief Financial Officer of the Company. In the event the person whose facsimile signature has been placed upon any Right shall
have ceased to serve in the capacity in which such person signed the Right before such Right is issued, it may be issued with the same
effect as if he or she had not ceased to be such at the date of issuance.


 






    


     


    

 


2.2 Effect of Countersignature.
Unless and until countersigned by the Rights Agent pursuant to this Agreement, a Right shall be invalid and of no effect and may not be
exchanged for shares of Common Stock.


 


2.3 Registration.


 


2.3.1 Right Register.
The Rights Agent shall maintain books (the “Right Register”) for the registration of original issuance and the registration
of transfer of the Rights. Upon the initial issuance of the Rights, the Rights Agent shall issue and register the Rights in the names
of the respective holders thereof in such denominations and otherwise in accordance with instructions delivered to the Rights Agent by
the Company.


 


2.3.2 Registered Holder.
Prior to due presentment for registration of transfer of any Right, the Company and the Rights Agent may deem and treat the person in
whose name such Right shall be registered upon the Right Register (the “registered holder”) as the absolute owner of
such Right and of each Right represented thereby (notwithstanding any notation of ownership or other writing on the Right Certificate
made by anyone other than the Company or the Rights Agent), for the purpose of the exchange thereof, and for all other purposes, and neither
the Company nor the Rights Agent shall be affected by any notice to the contrary.


 


2.4 Detachability of Rights.
Each of the securities comprising the Units will begin to trade separately on (i) the 90th day after the effectiveness of the Registration
Statement, or (ii) such earlier date as Chardan Capital Markets, LLC, as representative of the underwriters, shall determine is acceptable
(such date, the “Detachment Date”). In no event will separate trading of the securities comprising the Units commence
until the Company (i) files a Current Report on Form 8-K with the SEC including audited balance sheet reflecting the Company’s receipt
of the gross proceeds of the Public Offering and (ii) issues a press release announcing when such separate trading will begin. Upon the
Detachment Date, the Units will no longer trade, and each holder of Units will become, without any action by such holder, the holder of
that number of shares of Common Stock, Warrants and Rights comprising the Units held by such holder.


 


3.
Terms and Exchange of Rights


 


3.1 Rights. Each Right
shall entitle the holder thereof to receive one-twentieth of one share of Common Stock upon the happening of an Exchange Event (defined
below). No additional consideration shall be paid by a holder of Rights in order to receive his, her or its shares of Common Stock upon
an Exchange Event as the purchase price for such shares of Common Stock has been included in the purchase price for the Units. In no event
will the Company be required to net cash settle the Rights or issue fractional shares of Common Stock.


 


3.2 Exchange Event. An
“Exchange Event” shall occur upon the Company’s consummation of an initial Business Combination (as defined in
the Company’s Amended and Restated Certificate of Incorporation).


 






    2


     


    

 


3.3 Exchange of Rights.


 


3.3.1 Issuance of Shares
of Common Stock. As soon as practicable upon the occurrence of an Exchange Event, the Company shall direct holders of the Rights to
return their Rights Certificates to the Rights Agent. Upon receipt of a valid Rights Certificate, the Company shall issue to the registered
holder of such Right(s) the number of full shares of Common Stock to which he, she or it is entitled, registered in such name or names
as may be directed by him, her or it and issue to such registered holder(s) a certificate or book-entry position for the such shares.
Notwithstanding the foregoing, or any provision contained in this Agreement to the contrary, in no event will the Company be required
to net cash settle the Rights. The Company shall not issue fractional shares upon exchange of Rights. In the event that any holder would
otherwise be entitled to any fractional share upon exchange of Rights, at the time of an Exchange Event, the Company will instruct the
Right Agent how any such entitlement will be addressed. To the fullest extent permitted by the Company’s Amended and Restated Certificate
of Incorporation the Company reserves the right to deal with any such fractional entitlement at the relevant time in any manner permitted
by the Act and the Amended and Restated Certificate of Incorporation, which would include the rounding down of any entitlement to receive
shares of Common Stock to the nearest whole share (and in effect extinguishing any fractional entitlement), or the holder being entitled
to hold any remaining fractional entitlement (without any share being issued) and to aggregate the same with any future fractional entitlement
to receive shares in the Company until the holder is entitled to receive a whole number. Any rounding down and extinguishment may be done
with or without any in lieu cash payment or other compensation being made to the holder of the relevant Rights, such that value received
on exchange of the Rights may be considered less than the value that the holder would otherwise expect to receive.


 


3.3.2 Valid Issuance.
All shares of Common Stock issued upon an Exchange Event in conformity with this Agreement shall be validly issued, fully paid and nonassessable.


 


3.3.3 Date of Issuance.
Each person in whose name any such certificate or book-entry position for shares of Common Stock is issued shall for all purposes be deemed
to have become the holder of record of such shares on the date of the Exchange Event, irrespective of the date of delivery of such certificate
or entry of position.


 


3.3.4 Company Not Surviving
Following Exchange Event. Upon an Exchange Event in which the Company does not continue as the publicly held reporting entity, the
definitive agreement will provide for the holders of Rights to receive the same per share consideration the holders of the shares of Common
Stock will receive in such transaction, for the number of shares such holder is entitled to pursuant to Section 3.3.1 above. If the
Company does not continue as the publicly held reporting entity upon an Exchange Event, each holder of a Right will be required to affirmatively
convert his/her or its rights in order to receive the one-twentieth of one share underlying each right (without paying any additional
consideration) upon consummation of the Exchange Event. In such a case, each holder of a Right will be required to indicate his, her or
its election to convert the Rights into underlying shares of Common Stock as well as to return the original certificates evidencing the
Rights to the Company.


 






    3


     


    

 


3.4 Duration of Rights.
If an Exchange Event does not occur within the time period set forth in the Company’s Amended and Restated Certificate of Incorporation,
as the same may be amended from time to time, the Rights shall expire and shall be worthless.


 


4.
Transfer and Exchange of Rights.


 


4.1 Registration of Transfer.
The Rights Agent shall register the transfer, from time to time, of any outstanding Right upon the Right Register, upon surrender of such
Right for transfer, properly endorsed with signatures properly guaranteed and accompanied by appropriate instructions for transfer. Upon
any such transfer, a new Right representing an equal aggregate number of Rights shall be issued and the old Right shall be cancelled by
the Rights Agent. The Rights so cancelled shall be delivered by the Rights Agent to the Company from time to time upon request.


 


4.2 Procedure for Surrender
of Rights. Rights may be surrendered to the Rights Agent, together with a written request for exchange or transfer, and thereupon
the Rights Agent shall issue in exchange therefor one or more new Rights as requested by the registered holder of the Rights so surrendered,
representing an equal aggregate number of Rights; provided, however, that in the event that a Right surrendered for transfer bears a restrictive
legend and the new Rights to be issued will not bear a restrictive legend, the Rights Agent shall not cancel such Right and issue new
Rights in exchange therefor until the Rights Agent has received an opinion of counsel for the Company stating that such transfer may be
made and indicating no restrictive legend is required.


 


4.3 Fractional Rights.
The Rights Agent shall not be required to effect any registration of transfer or exchange which will result in the issuance of a Right
Certificate for a fraction of a Right.


 


4.4 Service Charges.
No service charge shall be made for any exchange or registration of transfer of Rights.


 


4.5 Adjustments to Conversion
Ratios. The number of shares of Common Stock that the holders of Rights are entitled to receive as a result of the occurrence of an
Exchange Event shall be equitably adjusted to reflect appropriately the effect of any share split, reverse share split, share dividend,
reorganization, recapitalization, reclassification, combination, exchange of shares or other like change with respect to the shares of
Common Stock occurring on or after the date hereof and prior to the Exchange Event.


 


4.6 Right Execution and Countersignature.
The Rights Agent is hereby authorized to countersign and to deliver, in accordance with the terms of this Agreement, the Rights required
to be issued pursuant to the provisions of this Section 4, and the Company, whenever required by the Rights Agent, will supply the
Rights Agent with Rights duly executed on behalf of the Company for such purpose.


 


5.
Other Provisions Relating to Rights of Holders of Rights.


 


5.1 No Rights as Stockholder.
Until the exchange of a Right for shares of Common Stock as provided for herein, a Right does not entitle the registered holder thereof
to any of the rights of a stockholder of the Company, including, without limitation, the right to receive dividends, or other distributions,
exercise any preemptive rights to vote or to consent or to receive notice as stockholders in respect of the meetings of stockholders or
the election of directors of the Company or any other matter.


 






    4


     


    

 


5.2 Lost, Stolen, Mutilated,
or Destroyed Rights. If any Right is lost, stolen, mutilated, or destroyed, the Company and the Rights Agent may on such terms as
to indemnity or otherwise as they may in their discretion impose (which shall, in the case of a mutilated Right, include the surrender
thereof), issue a new Right of like denomination, tenor, and date as the Right so lost, stolen, mutilated, or destroyed. Any such new
Right shall constitute a substitute contractual obligation of the Company, whether or not the allegedly lost, stolen, mutilated, or destroyed
Right shall be at any time enforceable by anyone.


 


5.3 Reservation of Shares
of Common Stock. The Company shall at all times reserve and keep available a number of its authorized but unissued shares of Common
Stock that will be sufficient to permit the exchange of all outstanding Rights issued pursuant to this Agreement.


 


6.
Concerning the Rights Agent and Other Matters.


 


6.1 Payment of Taxes.
The Company will from time to time promptly pay all taxes and charges that may be imposed upon the Company or the Rights Agent in respect
of the issuance or delivery of shares of Common Stock upon the exchange of Rights, but the Company shall not be obligated to pay any transfer
taxes in respect of the Rights or such shares of Common Stock.


 


6.2 Resignation, Consolidation,
or Merger of Rights Agent.


 


6.2.1 Appointment of Successor
Rights Agent. The Rights Agent, or any successor to it hereafter appointed, may resign its duties and be discharged from all further
duties and liabilities hereunder after giving sixty (60) days’ notice in writing to the Company. If the office of the Rights
Agent becomes vacant by resignation or incapacity to act or otherwise, the Company shall appoint in writing a successor Rights Agent in
place of the Rights Agent. If the Company shall fail to make such appointment within a period of 30 days after it has been notified in
writing of such resignation or incapacity by the Rights Agent or by the holder of the Right (who shall, with such notice, submit his,
her or its Right for inspection by the Company), then the holder of any Right may apply to the Supreme Court of the State of New York
for the County of New York for the appointment of a successor Rights Agent at the Company’s cost. Any successor Rights Agent, whether
appointed by the Company or by such court, shall be a corporation organized and existing under the laws of the State of New York, in good
standing and having its principal office in the Borough of Manhattan, City and State of New York, and authorized under such laws to exercise
corporate trust powers and subject to supervision or examination by federal or state authority. After appointment, any successor Rights
Agent shall be vested with all the authority, powers, rights, immunities, duties, and obligations of its predecessor Rights Agent with
like effect as if originally named as Rights Agent hereunder, without any further act or deed; but if for any reason it becomes necessary
or appropriate, the predecessor Rights Agent shall execute and deliver, at the expense of the Company, an instrument transferring to such
successor Rights Agent all the authority, powers, and rights of such predecessor Rights Agent hereunder; and upon request of any successor
Rights Agent the Company shall make, execute, acknowledge, and deliver any and all instruments in writing for more fully and effectually
vesting in and confirming to such successor Rights Agent all such authority, powers, rights, immunities, duties, and obligations.


 






    5


     


    

 


6.2.2 Notice of Successor
Rights Agent. In the event a successor Rights Agent shall be appointed, the Company shall give notice thereof to the predecessor Rights
Agent and the transfer agent for the shares of Common Stock not later than the effective date of any such appointment.


 


6.2.3 Merger or Consolidation
of Rights Agent. Any corporation into which the Rights Agent may be merged or with which it may be consolidated or any corporation
resulting from any merger or consolidation to which the Rights Agent shall be a party shall be the successor Rights Agent under this Agreement
without any further act.


 


6.3 Fees and Expenses of
Rights Agent.


 


6.3.1 Remuneration. The
Company agrees to pay the Rights Agent reasonable remuneration for its services as such Rights Agent hereunder and will reimburse the
Rights Agent upon demand for all expenditures that the Rights Agent may reasonably incur in the execution of its duties hereunder.


 


6.3.2 Further Assurances.
The Company agrees to perform, execute, acknowledge, and deliver or cause to be performed, executed, acknowledged, and delivered all such
further and other acts, instruments, and assurances as may reasonably be required by the Rights Agent for the carrying out or performing
of the provisions of this Agreement.


 


6.4 Liability of Rights Agent.


 


6.4.1 Reliance on Company
Statement. Whenever in the performance of its duties under this Agreement, the Rights Agent shall deem it necessary or desirable that
any fact or matter be proved or established by the Company prior to taking or suffering any action hereunder, such fact or matter (unless
other evidence in respect thereof be herein specifically prescribed) may be deemed to be conclusively proved and established by a statement
signed by the Chief Executive Officer or Chief Financial Officer and delivered to the Rights Agent. The Rights Agent may rely upon such
statement for any action taken or suffered in good faith by it pursuant to the provisions of this Agreement.


 


6.4.2 Indemnity. The
Rights Agent shall be liable hereunder only for its own gross negligence, willful misconduct or bad faith. Subject to Section 6.6
below, the Company agrees to indemnify the Rights Agent and save it harmless against any and all liabilities, including judgments, costs
and reasonable counsel fees, for anything done or omitted by the Rights Agent in the execution of this Agreement except as a result of
the Rights Agent’s gross negligence, willful misconduct, or bad faith.


 


6.4.3 Exclusions. The
Rights Agent shall have no responsibility with respect to the validity of this Agreement or with respect to the validity or execution
of any Right (except its countersignature thereof); nor shall it be responsible for any breach by the Company of any covenant or condition
contained in this Agreement or in any Right; nor shall it by any act hereunder be deemed to make any representation or warranty as to
the authorization or reservation of any shares of Common Stock to be issued pursuant to this Agreement or any Right or as to whether any
shares of Common Stock will when issued be valid and fully paid and nonassessable.


 






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6.5 Acceptance of Agency.
The Rights Agent hereby accepts the agency established by this Agreement and agrees to perform the same upon the terms and conditions
herein set forth.


 


6.6 Waiver. The Rights
Agent hereby waives any right of set-off or any other right, title, interest or claim of any kind (“Claim”) in, or
to any distribution of, the Trust Account (as defined in that certain Investment Management Trust Agreement, dated as of the date hereof,
by and between the Company and the Rights Agent as trustee thereunder) and hereby agrees not to seek recourse, reimbursement, payment
or satisfaction for any Claim against the Trust Account for any reason whatsoever.


 


7.
Miscellaneous Provisions.


 


7.1 Successors. All the
covenants and provisions of this Agreement by or for the benefit of the Company or the Rights Agent shall bind and inure to the benefit
of their respective successors and assigns.


 


7.2 Notices. Any notice,
statement or demand authorized by this Agreement to be given or made by the Rights Agent or by the holder of any Right to or on the Company
shall be sufficiently given when so delivered if by hand or overnight delivery or if sent by certified mail or private courier service
within five days after deposit of such notice, postage prepaid, addressed (until another address is filed in writing by the Company with
the Rights Agent), as follows:


 


CleanTech Acquisition Corp.

207 West 25th Street, 9th Floor

New York, NY 10001


 


with a copy (which shall not constitute notice)
to:


 


Loeb & Loeb LLP

345 Park Avenue

New York, New York 10154

Attn: Giovanni Caruso


 


Any notice, statement or demand authorized by
this Agreement to be given or made by the holder of any Right or by the Company to or on the Rights Agent shall be sufficiently given
when so delivered if by hand or overnight delivery or if sent by certified mail or private courier service within five days after deposit
of such notice, postage prepaid, addressed (until another address is filed in writing by the Rights Agent with the Company), as follows:


 


Continental Stock Transfer & Trust Company

One State Street, 30th Floor

New York, New York 10004

Attn: Compliance Department


 






    7


     


    

 


7.3 Applicable Law and Exclusive
Forum. The validity, interpretation, and performance of this Agreement and of the Rights shall be governed in all respects by the
laws of the State of New York, without giving effect to conflict of laws. Subject to applicable law, the Company and the Rights Agent
hereby agree that any action, proceeding or claim against either of them arising out of or relating in any way to this Agreement shall
be brought and enforced in the courts of the State of New York or the United States District Court for the Southern District of New York,
and irrevocably submits to such jurisdiction, which jurisdiction shall be exclusive forum for any such action, proceeding or claim. The
Company and the Rights Agent hereby waive any objection to such exclusive jurisdiction and that such courts represent an inconvenient
forum. Notwithstanding the foregoing, the provisions of this paragraph will not apply to suits brought to enforce any liability or duty
created by the Securities Exchange Act of 1934, as amended, or any other claim for which the federal district courts of the United States
of America are the sole and exclusive forum.


 


Any person or entity purchasing or otherwise acquiring
any interest in the Rights shall be deemed to have notice of and to have consented to the forum provisions in this Section 7.3. If
any action, the subject matter of which is within the scope the forum provisions above, is filed in a court other than a court located
within the State of New York or the United States District Court for the Southern District of New York (a “foreign action”)
in the name of any Rights holder, such Rights holder shall be deemed to have consented to: (x) the personal jurisdiction of the state
and federal courts located within the State of New York or the United States District Court for the Southern District of New York in connection
with any action brought in any such court to enforce the forum provisions (an “enforcement action”), and (y) having
service of process made upon such Rights holder in any such enforcement action by service upon such Rights holder’s counsel in the
foreign action as agent for such Rights holder.


 


7.4 Persons Having Rights
under this Agreement. Nothing in this Agreement expressed and nothing that may be implied from any of the provisions hereof is intended,
or shall be construed, to confer upon, or give to, any person or corporation other than the parties hereto and the registered holders
of the Rights and any right, remedy, or claim under or by reason of this Agreement or of any covenant, condition, stipulation, promise,
or agreement hereof. All covenants, conditions, stipulations, promises, and agreements contained in this Agreement shall be for the sole
and exclusive benefit of the parties hereto and their successors and assigns and of the registered holders of the Rights.


 


7.5 Examination of the Right
Agreement. A copy of this Agreement shall be available at all reasonable times at the office of the Rights Agent in the Borough of
Manhattan, City and State of New York, for inspection by the registered holder of any Right. The Rights Agent may require any such holder
to submit his, her or its Right for inspection by it.


 


7.6 Counterparts. This
Agreement may be executed in any number of original or facsimile counterparts and each of such counterparts shall for all purposes be
deemed to be an original, and all such counterparts shall together constitute but one and the same instrument.


 


7.7 Effect of Headings.
The Section headings herein are for convenience only and are not part of this Agreement and shall not affect the interpretation thereof.


 


7.8 Amendments. This
Agreement may be amended by the parties hereto without the consent of any registered holder for the purpose of curing any ambiguity, or
of curing, correcting or supplementing any defective provision contained herein or adding or changing any other provisions with respect
to matters or questions arising under this Agreement as the parties may deem necessary or desirable and that the parties deem shall not
adversely affect the interest of the registered holders. All other modifications or amendments shall require the written consent or vote
of the registered holders of a majority of the then outstanding Rights.


 


7.9 Severability. This
Agreement shall be deemed severable, and the invalidity or unenforceability of any term or provision hereof shall not affect the validity
or enforceability of this Agreement or of any other term or provision hereof. Furthermore, in lieu of any such invalid or unenforceable
term or provision, the parties hereto intend that there shall be added as a part of this Agreement a provision as similar in terms to
such invalid or unenforceable provision as may be possible and be valid and enforceable.


 


[Signature Page Follows]








 






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IN WITNESS WHEREOF, this Agreement has been duly
executed by the parties hereto as of the day and year first above written.


 





	 	CLEANTECH ACQUISITION CORP.
	 	 
	 	By: 	/s/ Eli Spiro             
	 	 	Name: 	Eli Spiro
	 	 	Title:	Chief Executive Officer


 


	 	CONTINENTAL STOCK TRANSFER & TRUST COMPANY
	 	 
	 	By: 	/s/ Erika Young
	 	 	Name:	Erika Young
	 	 	Title:	Vice President



 


[Signature Page to Rights Agreement]


 




    9


     


    

 


Exhibit A

Form of Right


 


	NUMBER	RIGHTS


 


 


CLEANTECH ACQUISITION CORP.


 


INCORPORATED UNDER THE LAWS OF DELAWARE


RIGHT


 


SEE REVERSE FOR

CERTAIN DEFINITIONS


 


CUSIP [__]


 


THIS CERTIFIES THAT, for value received,
______________________


 


is the registered holder of a right or rights
(each, a “Right”) to automatically receive one-twentieth of one share of common stock, $0.0001 par value (“Common Stock”),
of CleanTech Acquisition Corp. (the “Company”) for each Right evidenced by this Rights Certificate on the Company’s
completion of an initial Business Combination (as defined in the Company’s Amended and Restated Certificate of Incorporation) upon
surrender of this Right Certificate pursuant to the Rights Agreement between the Company and Continental Stock Transfer & Trust Company,
as Rights Agent. In no event will the Company be required to net cash settle any Right.


 


Upon liquidation of the Company in the event an
initial business combination is not consummated during the required period as identified in the Company’s Amended and Restated Certificate
of Incorporation, the Right shall expire and be worthless. As more fully described in the prospectus relating to the Company’s initial
public offering (“Prospectus”), the holder of a Right shall have no right or interest of any kind in the Company’s trust
account established in connection with the Company’s initial public offering.


 


Upon due presentment for registration of transfer
of the Right Certificate at the office or agency of the Rights Agent, a new Right Certificate or Right Certificates of like tenor and
evidencing in the aggregate a like number of Rights shall be issued to the transferee in exchange for this Right Certificate, without
charge except for any applicable tax or other governmental charge. The Company shall not issue fractional shares upon exchange of Rights.
The Company reserves the right to deal with any fractional entitlement at the relevant time in any manner (as provided in the Rights Agreement).


 


The Company and the Rights Agent may deem and
treat the registered holder as the absolute owner of this Right Certificate (notwithstanding any notation of ownership or other writing
hereon made by anyone), for the purpose of any conversion hereof, of any distribution to the registered holder, and for all other purposes,
and neither the Company nor the Right Agent shall be affected by any notice to the contrary.


 






    A-1


     


    

 


This Right does not entitle the registered holder
to any of the rights of a shareholder of the Company.


 


Dated:


 


	 	 	 
	CHAIRMAN	 	SECRETARY


 


	 	 
	Continental Stock Transfer & Trust Company, as Rights Agent	 


 


The following abbreviations, when used in the
inscription on the face of this certificate, shall be construed as though they were written out in full according to applicable laws or
regulations:


 


	TEN COM – as tenants in common	UNIF GIFT MIN ACT - __________ Custodian __________
	TEN ENT – as tenants by the entireties	(Cust) (Minor)
	JT TEN – as joint tenants with right of survivorship	under Uniform Gifts to Minors
	and not as tenants in common	Act __________
	 	(State)



 


 


Additional Abbreviations may also be used though
not in the above list.


 




    A-2


     


    

 


CleanTech Acquisition Corp.


 


The Company will furnish without
charge to each shareholder who so requests the powers, designations, preferences and relative, participating, optional or other special
rights of each class of shares or series thereof of the Company and the qualifications, limitations, or restrictions of such preferences
and/or rights. This certificate and the rights represented thereby are issued and shall be held subject to all the provisions of the Amended
and Restated Certificate of Incorporation and all amendments thereto and resolutions of the Board of Directors providing for the issue
of shares of Common Stock (copies of which may be obtained from the secretary of the Company), to all of which the holder of this certificate
by acceptance hereof assents.


 


For value received, ___________________________
hereby sell, assign and transfer unto


 


PLEASE INSERT SOCIAL SECURITY OR OTHER
IDENTIFYING NUMBER OF ASSIGNEE


 


	 	 


 


(PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING
ZIP CODE, OF ASSIGNEE)


 


	 	 
	 	 
	 	 
	 	 
	 	 rights
	represented by the within Certificate, and do hereby irrevocably constitute and appoint	 
	 	 Attorney
	to transfer said rights on the books of the within named Company will full power of substitution in the premises.	 


 


 


Dated _____________________


 


	 	Notice:	The signature to this assignment must correspond with the name as written upon the face of the certificate in every particular, without alteration or enlargement or any change whatever.


Signature(s) Guaranteed:


 


	THE SIGNATURE(S) MUST BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM, PURSUANT TO S.E.C. RULE 17Ad-15).	 


 


As more fully described in the Prospectus, the
holder of this certificate shall have no right or interest of any kind in or to the funds held in the Company’s trust account established
in connection with the Company’s initial public offering.


 


 


A-3