Exhibit
10.2


 


July
14, 2021


 


CleanTech
Acquisition Corp.


207
West 25th Street, 9th Floor


New York, NY 10001


 


Chardan
Capital Markets, LLC 17 State Street,


21st Floor New York, NY 10004


 


Re:
Initial Public Offering


 


Gentlemen:


 


This
letter is being delivered to you in accordance with the Underwriting Agreement (the “Underwriting Agreement”)
entered into by and between CleanTech Acquisition Corp., a Delaware corporation (the “Company”) and Chardan Capital
Markets, LLC, as representative (the “Representative”) of the Underwriters named in Schedule A thereto (the
“Underwriters”), relating to an underwritten initial public offering (the “IPO”) of the Company’s
units (the “Units”), each comprised of one share of Common Stock of the Company, par value $0.0001 per share (the
“Common Stock”), one right to receive one-twentieth of one share of Common Stock, and one-half of a warrant, with each
warrant being exercisable to purchase one share of Common Stock at a price of $11.50 per full share (“Warrant”). Certain
capitalized terms used herein are defined in paragraph 14 hereof.


 


In
order to induce the Company and the Underwriters to enter into the Underwriting Agreement and to proceed with the IPO, and in recognition
of the benefit that such IPO will confer upon the undersigned as a stockholder of the Company, and for other good and valuable consideration,
the receipt and sufficiency of which are hereby acknowledged, the undersigned hereby agrees with the Company as follows:


 


1. If
the Company solicits approval of its shareholders of a Business Combination, the undersigned will vote all shares of Common Stock beneficially
owned by him, her or it, whether acquired before, in or after the IPO, in favor of such Business Combination.


 


2. (a)
In the event that the Company fails to consummate a Business Combination within 12 months (or in the event the Company extended the time
to complete a Business Combination up to 18 months) from the closing of the Company’s IPO, the undersigned shall take all reasonable
steps to (i) cause the Trust Fund to be liquidated and distributed to the holders of IPO Shares and (ii) cause the Company to liquidate
as promptly as reasonably possible but not more than five business days after the date we are required to consummate a Business Combination.


 










     


     


    

 


(b) The undersigned hereby
waives any and all right, title, interest or claim of any kind in or to any distribution of the Trust Fund and any remaining net
assets of the Company as a result of such liquidation with respect to any shares he, she or it owns, including his, her or its
Insider Shares, IPO Shares and Private Warrants purchased during or after the offering, if any, (“Claim”)
and hereby waives any Claim the undersigned may have in the future as a result of, or arising out of, any contracts or agreements
with the Company and will not seek recourse against the Trust Fund for any reason whatsoever. The undersigned acknowledges and
agrees that there will be no distribution from the Trust Fund with respect to any Common Stock underlying the Private Warrants, all
rights of which will terminate on the Company’s liquidation.


 


(c) In
the event of the liquidation of the Trust Fund, the undersigned agrees to indemnify and hold harmless the Company against any and all
loss, liability, claims, damage and expense whatsoever (including, but not limited to, any and all legal or other expenses reasonably
incurred in investigating, preparing or defending against any litigation, whether pending or threatened, or any claim whatsoever) which
the Company may become subject as a result of any claim by any vendor or other person who is owed money by the Company for services rendered
or products sold or contracted for, but only to the extent necessary to ensure that such loss, liability, claim, damage or expense does
not reduce the amount of funds in the Trust Fund; provided, that such indemnity shall not apply if such vendor or other person
has executed an agreement waiving any claims against the Trust Fund.


 


(d) In
the event that the Company does not consummate a Business Combination and must liquidate and its remaining net assets are insufficient
to complete such liquidation, the undersigned agrees to advance such funds necessary to complete such liquidation and agrees not to seek
repayment for such expenses.


 


3. The
undersigned will place into escrow all of his, her or its Insider Shares pursuant to the terms of a Stock Escrow Agreement which the
Company will enter into with the undersigned and an escrow agent acceptable to the Company.


 


4. The
undersigned agrees that until the Company consummates a Business Combination, the undersigned’s Private Warrants will be subject
to the transfer restrictions described in the Subscription Agreement relating to the undersigned’s Private Warrants.


 


5. In
order to minimize potential conflicts of interest which may arise from multiple affiliations, the undersigned agrees to present to the
Company for its consideration, prior to presentation to any other person or entity, any suitable opportunity to acquire a target business,
until the earlier of the consummation by the Company of a Business Combination or the liquidation of the Company, subject to any pre-existing
fiduciary and contractual obligations the undersigned might have.


 


6. The
undersigned acknowledges and agrees that prior to entering into a Business Combination with a target business that is affiliated with
any Insiders of the Company or their affiliates, including any company that is a portfolio company of, or otherwise affiliated with,
or has received financial investment from, an entity with which any Insider or their affiliates is affiliated, such transaction must
be approved by a majority of the Company’s disinterested independent directors and the Company must obtain an opinion from an independent
investment banking firm that such Business Combination is fair to the Company’s unaffiliated stockholders from a financial point
of view.


 







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7. Neither
the undersigned, any member of the family of the undersigned, nor any affiliate of the undersigned will be entitled to receive or accept
a finder’s fee or any other compensation in the event the undersigned, any member of the family of the undersigned or any affiliate
of the undersigned originates a Business Combination.


 


8. The
undersigned’s FINRA Questionnaire and Director and Officer Questionnaire previously furnished to the Company and the Representative
is true and accurate in all material respects. The undersigned represents and warrants that, except as disclosed in the undersigned’s
Director and Officer Questionnaire:


 


		(a)	he/she/it
                                            has never had a petition under the federal bankruptcy laws or any state insolvency law been
                                            filed by or against (i) him/her/it or any partnership in which he/she/it was a general partner
                                            at or within two years before the time of filing; or (ii)
any corporation or business association of which he/she/it was an executive officer at or within two years before the time of such filing;






 


		(b)	he/she/it
                                            has never had a receiver, fiscal agent or similar officer been appointed by a court for his/her/its
                                            business or property, or any such partnership;



 


		(c)	he/she/it
                                            has never been convicted of fraud in a civil or criminal proceeding;



 


		(d)	he/she/it/
                                            has never been convicted in a criminal proceeding or named the subject of a pending criminal
                                            proceeding (excluding traffic violations and minor offenses);



 


		(e)	he/she/it
                                            has never been the subject of any order, judgment or decree, not subsequently reversed, suspended
                                            or vacated, of any court of competent jurisdiction, permanently or temporarily enjoining
                                            or otherwise limiting him/her/it from (i) acting as a futures commission merchant, introducing
                                            broker, commodity trading advisor, commodity pool operator, floor broker, leverage transaction
                                            merchant, any other person regulated by the Commodity Futures Trading Commission (“CFTC”)
                                            or an associated person of any of the foregoing, or as an investment adviser, underwriter,
                                            broker or dealer in securities, or as an affiliated person, director or employee of any investment
                                            company, bank, savings and loan association or insurance company, or from engaging in or
                                            continuing any conduct or practice in connection with any such activity; or (ii) engaging
                                            in any type of business practice; or (iii) engaging in any activity in connection with the
                                            purchase or sale of any security or commodity or in connection with any violation of federal
                                            or state securities or federal commodities laws;



 


		(f)	he/she/it
                                            has never been the subject of any order, judgment or decree, not subsequently reversed, suspended
                                            or vacated, of any federal or state authority barring, suspending or otherwise limiting for
                                            more than 60 days his/her/its right to engage in any activity described in 9(e)(i) above,
                                            or to be associated with persons engaged in any such activity;



 


		(g)	he/she/it
                                            has never been found by a court of competent jurisdiction in a civil action or by the SEC
                                            to have violated any federal or state securities law, where the judgment
in such civil action or finding by the SEC has not been subsequently reversed, suspended or vacated;



 


			





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		(h)	he/she/it
                                            has never been found by a court of competent jurisdiction in a civil action or by the CFTC
                                            to have violated any federal commodities law, where the judgment in such civil action or
                                            finding by the CFTC has not been subsequently reversed, suspended or vacated;



 


		(i)	he/she/it
                                            has never been the subject of, or a party to, any Federal or State judicial or administrative
                                            order, judgment, decree or finding, not subsequently reversed, suspended or vacated, relating
                                            to an alleged violation of (i) any Federal or State securities or commodities law or regulation,
                                            (ii) any law or regulation respecting financial institutions or insurance companies including,
                                            but not limited to, a temporary or permanent injunction, order of disgorgement or restitution,
                                            civil money penalty or temporary or permanent cease-and desist order, or removal or prohibition
                                            order or (iii) any law or regulation prohibiting mail or wire fraud or fraud in connection
                                            with any business entity;



 


		(j)	he/she/it
                                            has never been the subject of, or party to, any sanction or order, not subsequently reversed,
                                            suspended or vacated, or any self-regulatory organization, any registered entity, or any
                                            equivalent exchange, association, entity or organization that has disciplinary authority
                                            over its members or persons associated with a member;



 


		(k)	he/she/it
                                            has never been convicted of any felony or misdemeanor: (i) in connection with the purchase
                                            or sale of any security; (ii) involving the making of any false filing with the SEC; or (iii)
                                            arising out of the conduct of the business of an underwriter, broker, dealer, municipal securities
                                            dealer, investment advisor or paid solicitor of purchasers of securities;



 


		(l)	he/she/it
                                            was never subject to a final order of a state securities commission (or an agency of officer
                                            of a state performing like functions); a state authority that supervises or examines banks,
                                            savings associations, or credit unions; a state insurance commission (or an agency or officer
                                            of a state performing like functions); an appropriate federal banking agency; the CFTC; or
                                            the National Credit Union Administration that is based on a violation of any law or regulation
                                            that prohibits fraudulent, manipulative, or deceptive conduct;



 


		(m)	he/she/it
                                            has never been subject to any order, judgment or decree of any court of competent jurisdiction,
                                            that, at the time of such sale, restrained or enjoined him/her/it from engaging or continuing
                                            to engage in any conduct or practice: (i) in connection with the purchase or sale of any
                                            security; (ii) involving the making of any false filing with the SEC; or (iii) arising out
                                            of the conduct of the business of an underwriter, broker, dealer, municipal securities dealer,
                                            investment adviser or paid solicitor of purchasers of securities;



 


		(n)	he/she/it
                                            has never been subject to any order of the SEC that orders him/her/it to cease and desist
                                            from committing or causing a future violation of: (i) any scienter-based
anti-fraud provision of the federal securities laws, including, but not limited to, Section 17(a)(1) of the Securities Act, Section 10(b)
of the Exchange Act and Rule 10b-5 thereunder, and Section 206(1) of the Advisers Act or any other rule or regulation thereunder; or
(ii) Section 5 of the Securities Act;



 





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		(o)	he/she/it
                                            has never been named as an underwriter in any registration statement or Regulation A offering
                                            statement filed with the SEC that was the subject of a refusal order, stop order, or order
                                            suspending the Regulation A exemption, or is, currently, the subject of an investigation
                                            or proceeding to determine whether a stop order or suspension order should be issued;



 


		(p)	he/she/it
                                            has never been subject to a United States Postal Service false representation order, or is
                                            currently subject to a temporary restraining order or preliminary injunction with respect
                                            to conduct alleged by the United States Postal Service to constitute a scheme or device for
                                            obtaining money or property through the mail by means of false representations;



 


		(q)	he/she/it
                                            is not subject to a final order of a state securities commission (or an agency of officer
                                            of a state performing like functions); a state authority that supervises or examines banks,
                                            savings associations, or credit unions; a state insurance commission (or an agency or officer
                                            of a state performing like functions); an appropriate federal banking agency; the CFTC; or
                                            the National Credit Union Administration that bars the undersigned from: (i) association
                                            with an entity regulated by such commission, authority, agency or officer; (ii) engaging
                                            in the business of securities, insurance or banking; or (iii) engaging in savings association
                                            or credit union activities;



 


		(r)	he/she/it
                                            is not subject to an order of the SEC entered pursuant to section 15(b) or 15B(c) of the
                                            Securities Exchange Act of 1934 (the “Exchange Act”) or section 203(e) or 203(f)
                                            of the Investment Advisers Act of 1940 (the “Advisers Act”) that: (i) suspends
or revokes the undersigned’s registration as a broker, dealer, municipal securities dealer or investment adviser; (ii) places limitations
on the activities, functions or operations of, or imposes civil money penalties on, such person; or (iii) bars the undersigned from being
associated with any entity or from participating in the offering of any penny stock; and










 


		(s)	he/she/it
                                            has never been suspended or expelled from membership in, or suspended or barred from association
                                            with a member of, a securities self-regulatory organization (e.g., a registered national
                                            securities exchange or a registered national or affiliated securities association) for any
                                            act or omission to act constituting conduct inconsistent with just and equitable principles
                                            of trade.



 


9. The
undersigned has full right and power, without violating any agreement by which he, she or it is bound, to enter into this letter agreement
and to serve as a director or officer of the Company, as applicable.


 







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10. The
undersigned hereby waives his, her or its right to exercise conversion rights with respect to any shares of Common Stock owned or to
be owned by the undersigned, directly or indirectly, whether purchased by the undersigned prior to the IPO, in the IPO or in the aftermarket,
and agrees that he, she or it will not seek conversion with respect to or otherwise sell, such shares in connection with any vote to
approve a Business Combination with respect thereto, a vote to amend the provisions of the Company’s Amended and Restated Certificate
of Incorporation, or a tender offer by the Company prior to a Business Combination.


 


11. The
undersigned hereby agrees to not propose, or vote in favor of, an amendment to the Company’s Amended and Restated Certificate of
Incorporation with respect to stockholder’s rights or the Company’s pre-Business Combination activities (including the substance
or timing within which we have to complete a business combination) of a Business Combination unless the Company offers holders of IPO
Shares the right to receive their pro rata portion of the funds then held in the Trust Fund upon approval of any amendment.


 


12. In
connection with Section 5-1401 of the General Obligations Law of the State of New York, this letter agreement shall be governed by, and
construed in accordance with, the laws of the State of New York without regard to principles of conflicts of law that would result in
the application of the substantive law of another jurisdiction. The parties hereto agree that any action, proceeding or claim arising
out of or relating in any way to this letter agreement shall be resolved through final and binding arbitration in accordance with the
International Arbitration Rules of the American Arbitration Association (“AAA”). The arbitration shall be brought
before the AAA International Center for Dispute Resolution’s offices in New York City, New York, will be conducted in English and
will be decided by a panel of three arbitrators selected from the AAA Commercial Disputes Panel and that the arbitrator panel’s
decision shall be final and enforceable by any court having jurisdiction over the party from whom enforcement is sought. The cost of
such arbitrators and arbitration services, together with the prevailing party’s legal fees and expenses, shall be borne by the
non-prevailing party or as otherwise directed by the arbitrators.


 


13. As
used herein, (i) a “Business Combination” shall mean a merger, share exchange, asset acquisition, stock
purchase, recapitalization, reorganization or other similar business combination with one or more businesses or entities; (ii)
“Insiders” shall mean all officers, directors and stockholders of the Company immediately prior to the
IPO; (iii) “Insider Shares” shall mean all of the shares of Common Stock of the Company acquired by
an Insider prior to the IPO and the purchase of the Private Warrants; (iv) “IPO Shares” shall mean the
shares of Common Stock issued in the Company’s IPO; (v) “Private Warrants” shall mean the 6,500,000
warrants (or up to 7,175,000 warrants if the over-allotment option granted to the Underwriters in connection with the IPO is
exercised in full) purchased in the private placement taking place simultaneously with the consummation of the Company’s IPO;
(vi) “Registration Statement” means the registration statement on Form S-1 filed by the Company with
respect to the IPO; and (vii) “Trust Fund” shall mean the trust fund into which a portion of the net
proceeds of the Company’s IPO will be deposited.


 


14. Any
notice, consent or request to be given in connection with any of the terms or provisions of this letter agreement shall be in writing
and shall be sent by express mail or similar private courier service, by certified mail (return receipt requested), by hand delivery
or facsimile transmission.


 







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If
to the Representative:


 


Chardan
Capital Markets, LLC


17 State Street, 21st Floor


New York, NY 10004


Attn:
Jonas Grossman


Facsimile: (646) 465-9002


 


Copy
(which copy shall not constitute notice) to:


Cooley
LLP


55
Hudson Yards


New
York, New York 10001


Attn:
Yvan-Claude Pierre; Peter Byrne


Email: ypierre@cooley.com


           pbyrne@cooley.com


 


Fax:


 


If
to the Company:


 


CleanTech
Acquisition Corp.


207 West 25th Street, 9th Floor


New York, NY 10001


Attn:
Eli Spiro


Facsimile:


 


Copy
(which copy shall not constitute notice) to:


 


Loeb
& Loeb LLP


345 Park Avenue


New York, NY 10154


Attn:
Mitchell S. Nussbaum, Esq. and Giovanni Caruso


Facsimile: (212) 504-3013


 


15. No
party hereto may assign either this letter agreement or any of its rights, interests, or obligations hereunder without the prior written
consent of the other party. Any purported assignment in violation of this paragraph shall be void and ineffectual and shall not operate
to transfer or assign any interest or title to the purported assignee. This letter agreement shall be binding on the parties hereto and
any successors and assigns thereof.


 


16. The
undersigned acknowledges and understands that the Underwriters and the Company will rely upon the agreements, representations and warranties
set forth herein in proceeding with the IPO. Nothing contained herein shall be deemed to render the Underwriters a representative of,
or a fiduciary with respect to, the Company, its stockholders or any creditor or vendor of the company with respect to the subject matter
hereof.


 


[Signature
page to follow]


 




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Sincerely,


 


	 	CLEANTECH INVESTMENTS, LLC
	 	 
	 	/s/ Jonas Grossman 
	 	Name:  	Jonas Grossman 
	 	Title: 	Managing Member
	 	 
	 	CLEANTECH SPONSOR I LLC
	 	 
	 	/s/ Eli Spiro
	 	Name: 	Eli Spiro
	 	Title: 	Managing Member




 


[Signature
Page to Insider Letter]