EX-10.8





 Exhibit 10.8 

THIS PROMISSORY NOTE (THIS “NOTE”) HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES
ACT”). THIS NOTE HAS BEEN ACQUIRED FOR INVESTMENT ONLY AND MAY NOT BE SOLD, TRANSFERRED OR ASSIGNED IN THE ABSENCE OF REGISTRATION OF THE RESALE THEREOF UNDER THE SECURITIES ACT OR AN OPINION OF COUNSEL REASONABLY SATISFACTORY IN FORM,
SCOPE AND SUBSTANCE TO THE MAKER THAT SUCH REGISTRATION IS NOT REQUIRED. 
 PROMISSORY NOTE 

 

			
	Principal Amount: Up to $250,000	  	Dated as of March 25, 2021

 WHEREAS AltEnergy Acquisition Corp., a Delaware corporation (the “Maker”), promises to pay to
the order of AltEnergy Acquisition Sponsor, LLC, a Delaware limited liability company, or its registered assigns or successors in interest (the “Payee”), or order, the principal sum of Two Hundred Fifty Thousand Dollars
($250,000), or such lesser amount as shall have been advanced by Payee to Maker and shall remain unpaid under this Note, in lawful money of the United States of America, on the terms and conditions described below. All payments on this Note
shall be made by check or wire transfer of immediately available funds or as otherwise determined by the Maker to such account as the Payee may from time to time designate by written notice in accordance with the provisions of this Note. 

1. Principal. The principal balance of this Note shall be payable on the earlier of: (i) December 31, 2021 and
(ii) the date on which Maker consummates an initial public offering of its securities (the “IPO”). The principal balance may be prepaid at any time. 

2. Interest. No interest shall accrue on the unpaid principal balance of this Note. 

3. Drawdown Requests. The principal of this Note may be drawn down from time to time prior to the earlier of:
(i) December 31, 2021 and (ii) the date on which Maker consummates the IPO, upon request from Maker to Payee (each, a “Drawdown Request”). Payee shall fund each Drawdown Request within five (5) business days
after receipt of a Drawdown Request; provided, however, that the maximum amount of drawdowns collectively under this Note is Two Hundred Fifty Thousand Dollars ($250,000). Once an amount is drawn down under this Note, it shall not be
available for future Drawdown Requests even if prepaid. No fees, payments or other amounts shall be due to Payee in connection with, or as a result of, any Drawdown Request by Maker. 

4. Application of Payments. All payments shall be applied first to payment in full of any costs incurred in the collection of
any sum due under this Note, including (without limitation) reasonable attorney’s fees, then to the payment in full of any late charges and finally to the reduction of the unpaid principal balance of this Note. 

5. Events of Default. The following shall constitute an event of default (“Event of Default”): 

(a) Failure to Make Required Payments. Failure by Maker to pay the principal amount due pursuant to this Note within five
(5) business days of the date specified in Section 1 above. 
 (b) Voluntary Bankruptcy, Etc. The commencement by Maker
of a voluntary case under any applicable bankruptcy, insolvency, reorganization, rehabilitation or other similar law, or the consent by it to the appointment of or taking possession by a receiver, liquidator, assignee, trustee, custodian,
sequestrator (or other similar official) of Maker or for any substantial part of its property, or the making by it of any assignment for the benefit of creditors, or the failure of Maker generally to pay its debts as such debts become due, or the
taking of corporate action by Maker in furtherance of any of the foregoing. 
 (c) Involuntary Bankruptcy, Etc. The entry of a
decree or order for relief by a court having jurisdiction in the premises in respect of Maker in an involuntary case under any applicable bankruptcy, insolvency or other similar law, or appointing a receiver, liquidator, assignee, custodian,
trustee, sequestrator (or similar official) of Maker or for any substantial part of its property, or ordering the winding-up or liquidation of its affairs, and the continuance of any such decree or order
unstayed and in effect for a period of 60 consecutive days. 












 6. Remedies. 

(a) Upon the occurrence of an Event of Default specified in Section 5(a) hereof, Payee may, by written notice to Maker, declare this
Note to be due immediately and payable, whereupon the unpaid principal amount of this Note, and all other amounts payable hereunder, shall become immediately due and payable without presentment, demand, protest or other notice of any kind, all of
which are hereby expressly waived, anything contained herein or in the documents evidencing the same to the contrary notwithstanding. 

(b) Upon the occurrence of an Event of Default specified in Sections 5(b) or 5(c), the unpaid principal balance of this Note, and all
other sums payable with regard to this Note, shall automatically and immediately become due and payable, in all cases without any action on the part of Payee. 

7. Waivers. Maker and all endorsers and guarantors of, and sureties for, this Note waive presentment for payment, demand,
notice of dishonor, protest, and notice of protest with regard to the Note, all errors, defects and imperfections in any proceedings instituted by Payee under the terms of this Note, and all benefits that might accrue to Maker by virtue of any
present or future laws exempting any property, real or personal, or any part of the proceeds arising from any sale of any such property, from attachment, levy or sale under execution, or providing for any stay of execution, exemption from civil
process, or extension of time for payment; and Maker agrees that any real estate that may be levied upon pursuant to a judgment obtained by virtue hereof, or any writ of execution issued hereon, may be sold upon any such writ in whole or in part in
any order desired by Payee. 
 8. Unconditional Liability. Maker hereby waives all notices in connection with the delivery,
acceptance, performance, default, or enforcement of the payment of this Note, and agrees that its liability shall be unconditional, without regard to the liability of any other party, and shall not be affected in any manner by any indulgence,
extension of time, renewal, waiver or modification granted or consented to by Payee, and consents to any and all extensions of time, renewals, waivers, or modifications that may be granted by Payee with respect to the payment or other provisions of
this Note, and agrees that additional makers, endorsers, guarantors, or sureties may become parties hereto without notice to Maker or affecting Maker’s liability hereunder. 

9. Notices. All notices, statements or other documents which are required or contemplated by this Note shall be in writing and
delivered to a party: (i) personally or sent by first class registered or certified mail, overnight courier service to the address designated in writing by such party, (ii) by facsimile to the number most recently designated in writing by
such party or (iii) by electronic mail to the electronic mail address most recently designated in writing by such party. Any notice or other communication so transmitted shall be deemed to have been given on the day of delivery, if
delivered personally, on the business day following receipt of written confirmation, if sent by facsimile or electronic mail, one (1) business day after delivery to an overnight courier service or five (5) days after mailing if sent by
mail. 
 10. Construction. THIS NOTE SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH THE LAWS OF NEW YORK, WITHOUT REGARD
TO CONFLICT OF LAW PROVISIONS THEREOF. 
 11. Severability. Any provision contained in this Note which is prohibited or
unenforceable in any jurisdiction shall, as to such jurisdiction, be ineffective to the extent of such prohibition or unenforceability without invalidating the remaining provisions hereof, and any such prohibition or unenforceability in any
jurisdiction shall not invalidate or render unenforceable such provision in any other jurisdiction. 
 12. Trust
Waiver. Notwithstanding anything herein to the contrary, the Payee hereby waives any and all right, title, interest or claim of any kind (“Claim”) in or to any distribution of or from the trust account to be established in
which the proceeds of the IPO and the proceeds of the sale of the warrants issued in private placements to occur prior to the consummation of the IPO are to be deposited, as described in greater detail in the registration statement and prospectus to
be filed with the Securities and Exchange Commission in connection with the IPO, and hereby agrees not to seek recourse, reimbursement, payment or satisfaction for any Claim against the trust account for any reason whatsoever. 

  
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 13. Amendment; Waiver. Any amendment hereto or waiver of any provision hereof
may be made with, and only with, the written consent of the Maker and the Payee. 
 14. Assignment. No assignment or transfer
of this Note or any rights or obligations hereunder may be made by any party hereto (by operation of law or otherwise) without the prior written consent of the other party hereto and any attempted assignment without the required consent shall be
void. 
 [SIGNATURE PAGE FOLLOWS] 

  
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 IN WITNESS WHEREOF, Maker and Payee, intending to be legally bound hereby, have
caused this Note to be duly executed by the undersigned as of the day and year first above written. 
  

			
	ALTENERGY ACQUISITION CORP.
		
	By:	 	 /s/ Russell Stidolph

	Name:	 	Russell Stidolph
	Title:	 	Chief Executive Officer


  

			
	Acknowledged and Agreed:
	
	ALTENERGY ACQUISITION SPONSOR, LLC
		
	By:	 	 /s/ Russell Stidolph

	Name:	 	Russell Stidolph
	Title:	 	Manager


  
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