Exhibit 10.4


 


Execution Version


 


FIRST AMENDMENT

to

AMENDED AND RESTATED FORWARD PURCHASE AGREEMENT


 


This First Amendment
to Amended and Restated Forward Purchase Agreement (“Amendment”), is entered into effective as of June 18, 2020,
by and among Tortoise Acquisition Corp., a Delaware corporation (the “Company”), Tortoise Sponsor LLC, a Delaware
limited liability company (the “Sponsor”) and Atlas Point Energy Infrastructure Fund, LLC, a Delaware limited
liability company (the “Purchaser” and collectively with the Company and the Sponsor, the “Parties”
and each a “Party”).


 


WHEREAS, the Parties
are parties to that certain Amended and Restated Forward Purchase Agreement entered into as of February 6, 2019 (the “Forward
Purchase Agreement” or “FPA”);


 


WHEREAS, on February
27, 2019, the Company, the Sponsor, the Purchaser, Tortoise Borrower and certain other security holders named therein entered into
that certain Registration Rights Agreement (the “Existing Registration Rights Agreement”), pursuant to which
the Company granted the Sponsor, the Purchaser, Tortoise Borrower and such other holders named therein certain registration rights
with respect to certain securities of the Company;


 


WHEREAS, capitalized
terms not otherwise defined herein shall have the meanings set forth for such terms in the Amended and Restated Forward Purchase
Agreement;


 


WHEREAS, concurrently
herewith, the Company, SHLL Merger Sub Inc., a Delaware corporation and wholly owned subsidiary of the Company (“Merger
Sub”), and Hyliion Inc., a Delaware corporation (“Hyliion”), are entering into that certain Business
Combination Agreement and Plan of Reorganization, pursuant to which Merger Sub will, subject to the terms and conditions thereof,
merge with and into Hyliion, with Hyliion surviving the merger as a wholly owned subsidiary of the Company (the “Business
Combination”);


 


NOW THEREFORE, for
good and valuable consideration, the Parties hereby agree as follows:


 


		1.	The Purchaser hereby gives its irrevocable written consent (in its capacity as a party to the FPA
and not as a stockholder) confirming its commitment to purchase the Forward Purchase Securities and the amount of the Purchase
Price, each as specified herein, as contemplated by Section 4(c)(iv) of the FPA.



 


		2.	Section 1 of the FPA is hereby deleted in its entirety and replaced with the following:



 


“(a) Subject to the terms
and conditions hereof, the Purchaser hereby commits to purchase $17,500,000 (the “Purchase Price”), and the Company
agrees to issue and sell to the Purchaser such amount of forward purchase units at a price per unit equal to the IPO Unit Price,
consisting of Class A Shares (the “Forward Purchase Shares”) and Warrants (the “Forward Purchase Warrants”),
each having the same terms as, respectively, the Public Shares and the Public Warrants offered to the public in the IPO (such Forward
Purchase Shares and Forward Purchase Warrants, collectively, the “Forward Purchase Units”) or (ii) Forward Purchase
Shares at a price of $9.67 per Forward Purchase Share (such Forward Purchase Shares valued at $9.67 per share, or the Forward Purchase
Units, as the case may be, the “Forward Purchase Securities”). For the avoidance of doubt, the Forward Purchase
Units will have the same terms as the Public Units offered to the public other than as described in Section 5 and Section 6 of
this Agreement.


 



     


     


    

 


(b) For all purposes of this
Agreement including Section 1(a) hereof, the Parties agree that the Forward Purchase Securities to be purchased by the Purchaser
at the Closing shall consist of Forward Purchase Units.”


 


		3.	Section 2(b) of the FPA is hereby deleted in its entirety and replaced with the following:



 


“If the Purchaser does
not fund the Purchase Price for the Forward Purchase Securities as provided for herein, the Purchaser shall transfer back to the
Sponsor 900,000 Founder Shares such that the Purchaser shall retain 365,625 Founder Shares. At the closing of the Business Combination
Agreement, the Purchaser shall transfer back to the Sponsor 894,375 Founder Shares.”


 


		4.	If the Business Combination Agreement shall be terminated, this Amendment shall cease to have further
force and effect and the terms of the FPA shall continue to apply without amendment.



 


		5.	The Parties agree that the Purchaser will not have any further rights or obligations under the
Existing Registration Rights Agreement and instead shall have the rights and obligations specified on Annex A hereto.



 


		6.	This Amendment may be executed in any number of counterparts with the same effect as if all signatory
parties had signed the same document and shall be construed together and shall constitute one and the same instrument. Delivery
of an executed signature page of this Agreement by facsimile transmission or in portable document format (.pdf) or similar electronic
format shall be effective as delivery of a manually executed counterpart hereof.



 


		7.	If any provision of this Amendment shall be held invalid or unenforceable by a Governmental Authority
of competent jurisdiction, the remainder of this Amendment shall remain in full force and effect.



 


[Signature page follows.]


 



     


     


    

 


EXECUTED to be effective as of the date
first above written.


 


	TORTOISE ACQUISITION CORP.	 
	 	 	 
	By:	/s/
    Vincent T. Cubbage	 
	Name: 	Vincent T. Cubbage	 
	Title:	Chief Executive
    Officer and President	 
	 	 	 
	TORTOISE SPONSOR LLC	 
	 	 	 
	By:	/s/
    Ed Russell	 
	Name: 	Ed Russell	 
	Title:	Chief Executive Officer	 
	 	 	 
	ATLAS POINT ENERGY INFRASTRUCTURE
    FUND, LLC
	 	 	 
	By:	/s/ Adam
    Karpf	 
	Name:	Adam Karpf	 
	Title:	Managing Director and Portfolio Manager	 


 


Signature Page to FPA Amendment


 



     


     


    

 





Annex A


 


Registration Rights.


 


a.
The Company agrees that, within thirty (30) calendar days after the consummation of the Transaction (the “Filing
Date”), the Company will file with the SEC (at the Company’s sole cost
and expense) a registration statement registering the resale of the Forward Purchase Securities and the Founder Shares (the
“Registrable Securities”, and such registration statement, the “Registration
Statement”), and the Company shall use its commercially reasonable efforts to have the Registration Statement
declared effective as soon as practicable after the filing thereof, but no later than the earlier of (i) the 90th calendar
day (or 120th calendar day if the SEC notifies the Company that it will “review” the Registration Statement)
following the Closing and (ii) the 10th business day after the date the Company is notified (orally or in writing, whichever
is earlier) by the SEC that the Registration Statement will not be “reviewed” or will not be subject to further
review (such earlier date, the “Effectiveness Date”); provided, however, that the Company’s
obligations to include the Registrable Securities in the Registration Statement are contingent upon Purchaser furnishing in
writing to the Company such information regarding Purchaser, the securities of the Company held by Purchaser and the intended
method of disposition of the Registrable Securities as shall be reasonably requested by the Company to effect the
registration of the Registrable Securities, and Purchaser shall execute such documents in connection with such registration
as the Company may reasonably request that are customary of a selling stockholder in similar situations, including providing
that the Company shall be entitled to postpone and suspend the effectiveness or use of the Registration Statement during any
customary blackout or similar period or as permitted hereunder. For purposes of clarification, any failure by the Company to
file the Registration Statement by the Filing Date or to effect such Registration Statement by the Effectiveness Date shall
not otherwise relieve the Company of its obligations to file or effect the Registration Statement as set forth above in this
Annex A.


 


b. In the
case of the registration, qualification, exemption or compliance effected by the Company pursuant to this FPA, the Company shall,
upon reasonable request, inform Purchaser as to the status of such registration, qualification, exemption and compliance. At its
expense the Company shall:


 


(i) except for such times as the Company is permitted
hereunder to suspend the use of the prospectus forming part of a Registration Statement, use its commercially reasonable efforts
to keep such registration, and any qualification, exemption or compliance under state securities laws which the Company determines
to obtain, continuously effective with respect to Purchaser, and to keep the applicable Registration Statement or any subsequent
shelf registration statement free of any material misstatements or omissions, until the earlier of the following: (i) Purchaser
ceases to hold any Registrable Securities or (ii) the date all Registrable Securities held by Purchaser may be sold without restriction
under Rule 144, including without limitation, any volume and manner of sale restrictions which may be applicable to affiliates
under Rule 144 and without the requirement for the Company to be in compliance with the current public information required under
Rule 144(c)(1) or Rule 144(i)(2), as applicable, and (iii) two years from the Effective Date of the Registration Statement. The
period of time during which the Company is required hereunder to keep a Registration Statement effective is referred to herein
as the “Registration Period.”


 


(ii) advise Purchaser within five (5) business days:


 


(1) when a Registration Statement
or any amendment thereto has been filed with the SEC and when such Registration Statement or any post-effective amendment thereto
has become effective;


 



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(2) of any request by the SEC for amendments or supplements
to any Registration Statement or the prospectus included therein or for additional information;


 


(3) of the issuance by the SEC of any stop order suspending
the effectiveness of any Registration Statement or the initiation of any proceedings for such purpose;


 


(4) of the receipt by the Company of any notification
with respect to the suspension of the qualification of the Registrable Securities included therein for sale in any jurisdiction
or the initiation or threatening of any proceeding for such purpose; and


 


(5) subject to the provisions in this FPA, of the
occurrence of any event that requires the making of any changes in any Registration Statement or prospectus so that, as of such
date, the statements therein are not misleading and do not omit to state a material fact required to be stated therein or necessary
to make the statements therein (in the case of a prospectus, in the light of the circumstances under which they were made) not
misleading.


 


Notwithstanding anything to the contrary set forth
herein, the Company shall not, when so advising Purchaser of such events, provide Purchaser with any material, nonpublic information
regarding the Company other than to the extent that providing notice to Purchaser of the occurrence of the events listed in (1)
through (5) above constitutes material, nonpublic information regarding the Company;


 


(iii) use its commercially reasonable
efforts to obtain the withdrawal of any order suspending the effectiveness of any Registration Statement as soon as reasonably
practicable;


 


(iv) upon the occurrence of any
event contemplated above, except for such times as the Company is permitted hereunder to suspend, and has suspended, the use of
a prospectus forming part of a Registration Statement, the Company shall use its commercially reasonable efforts to as soon as
reasonably practicable prepare a post-effective amendment to such Registration Statement or a supplement to the related prospectus,
or file any other required document so that, as thereafter delivered to purchasers of the Registrable Securities included therein,
such prospectus will not include any untrue statement of a material fact or omit to state any material fact necessary to make the
statements therein, in the light of the circumstances under which they were made, not misleading;


 


(v) use its commercially reasonable
efforts to cause all Registrable Securities to be listed on each securities exchange or market, if any, on which the Class A Shares
issued by the Company have been listed; and


 


(vi) use its commercially reasonable
efforts to take all other steps necessary to effect the registration of the Registrable Securities contemplated hereby and to enable
Purchaser to sell the Registrable Securities under Rule 144.


 



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c. Notwithstanding
anything to the contrary in this FPA, the Company shall be entitled to delay or postpone the effectiveness of the Registration
Statement, and from time to time to require Purchaser not to sell under the Registration Statement or to suspend the effectiveness
thereof, if the negotiation or consummation of a transaction by the Company or its subsidiaries is pending or an event has occurred,
which negotiation, consummation or event the Company’s board of directors reasonably believes, upon the advice of legal counsel,
would require additional disclosure by the Company in the Registration Statement of material information that the Company has a
bona fide business purpose for keeping confidential and the non-disclosure of which in the Registration Statement would be expected,
in the reasonable determination of the Company’s board of directors, upon the advice of legal counsel, to cause the Registration
Statement to fail to comply with applicable disclosure requirements (each such circumstance, a “Suspension Event”);
provided, however, that the Company may not delay or suspend the Registration Statement on more than two occasions or for more
than sixty (60) consecutive calendar days, or more than ninety (90) total calendar days, in each case during any twelve-month period.
Upon receipt of any written notice from the Company of the happening of any Suspension Event during the period that the Registration
Statement is effective or if as a result of a Suspension Event the Registration Statement or related prospectus contains any untrue
statement of a material fact or omits to state any material fact required to be stated therein or necessary to make the statements
therein, in light of the circumstances under which they were made (in the case of the prospectus) not misleading, Purchaser agrees
that (i) it will immediately discontinue offers and sales of the Registrable Securities under the Registration Statement (excluding,
for the avoidance of doubt, sales conducted pursuant to Rule 144) until Purchaser receives copies of a supplemental or amended
prospectus (which the Company agrees to promptly prepare) that corrects the misstatement(s) or omission(s) referred to above and
receives notice that any post-effective amendment has become effective or unless otherwise notified by the Company that it may
resume such offers and sales, and (ii) it will maintain the confidentiality of any information included in such written notice
delivered by the Company unless otherwise required by law or subpoena. If so directed by the Company, Purchaser will deliver to
the Company or, in Purchaser’s sole discretion destroy, all copies of the prospectus covering the Registrable Securities
in Purchaser’s possession; provided, however, that this obligation to deliver or destroy all copies of the prospectus covering
the Registrable Securities shall not apply (i) to the extent Purchaser is required to retain a copy of such prospectus (a) in order
to comply with applicable legal, regulatory, self-regulatory or professional requirements or (b) in accordance with a bona fide
pre-existing document retention policy or (ii) to copies stored electronically on archival servers as a result of automatic data
back-up.


 


d. Purchaser
may deliver written notice (an “Opt-Out Notice”) to the Company requesting that Purchaser not receive notices
from the Company otherwise required by this Annex A; provided, however, that Purchaser may later revoke any such Opt-Out Notice
in writing. Following receipt of an Opt-Out Notice from Purchaser (unless subsequently revoked), (i) the Company shall not deliver
any such notices to Purchaser and Purchaser shall no longer be entitled to the rights associated with any such notice and (ii)
each time prior to Purchaser’s intended use of an effective Registration Statement, Purchaser will notify the Company in
writing at least two (2) business days in advance of such intended use, and if a notice of a Suspension Event was previously delivered
(or would have been delivered but for the provisions of this provision (d)) and the related suspension period remains in effect,
the Company will so notify Purchaser, within one (1) business day of Purchaser’s notification to the Company, by delivering
to Purchaser a copy of such previous notice of Suspension Event, and thereafter will provide Purchaser with the related notice
of the conclusion of such Suspension Event immediately upon its availability.


 


 


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