Document:

Exhibit 10.2

 

STOCKHOLDERS RIGHTS AGREEMENT

 

This STOCKHOLDERS
RIGHTS AGREEMENT (this “Agreement”), dated as of June 18, 2020, is entered into by and among Tortoise
Acquisition Corp., a Delaware corporation (the “Company”), and each of the stockholders of the Company
or Hyliion Inc., a Delaware corporation (“Hyliion”), whose name appears on the signature pages hereto
(each a “Stockholder,” and collectively, the “Stockholders”).

 

WHEREAS, the
Company, SHLL Merger Sub Inc., a Delaware corporation and wholly owned subsidiary of the Company (“Merger Sub”),
and Hyliion propose to enter into, simultaneously herewith, a business combination agreement and plan of reorganization (the “BCA”),
which provides, among other things, that, upon the terms and subject to the conditions thereof, Merger Sub will be merged with
and into Hyliion (the “Merger”), with Hyliion surviving the Merger as a wholly owned subsidiary of the
Company;

 

WHEREAS, prior
to the closing of the Merger, the Company will hold a meeting of the Company’s stockholders to consider, among other things,
approval and adoption of the BCA and the Merger and approval and adoption of the Second Amended and Restated Certificate of Incorporation
of the Company (the “Charter Proposals”), which provides for, among other things, a reclassification
of the Board of Directors of the Company (the “Board”); and

 

WHEREAS, in
connection with the BCA, the Stockholders and the Company have entered into this Agreement to set forth certain understandings
among such parties, including with respect to certain governance and voting matters.

 

NOW, THEREFORE,
in consideration of the mutual covenants contained herein and for good and valuable consideration, the receipt and sufficiency
of which are hereby acknowledged, the parties hereto hereby agree as follows:

 

Article I

GOVERNANCE AND VOTING MATTERS

 

Section 1.1
Board and Committees.

 

(a) The Company will
take all necessary action (to the extent permitted by applicable law and to the extent such action is consistent with the fiduciary
duties of the Board under Delaware law) to cause the following to occur immediately after the effective time of the Merger:

 

(i) The Board to consist
of seven directors, including Edward Olkkola, as Chair, Andrew Card, Vincent T. Cubbage, Thomas Healy, Howard Jenkins, Stephen
Pang and an individual mutually agreed to prior to the effective time of the Merger by Messrs. Cubbage and Healy that satisfies
the requirements set forth in Section 1.1(b) hereof (the “Additional Director”);

 

(ii) The audit committee
of the Board to consist of three directors, including the Additional Director, as Chair, Andrew Card and Stephen Pang;

  

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(iii) The compensation
committee of the Board to consist of three directors, including Howard Jenkins, as Chair, Andrew Card and Vincent T. Cubbage; and

 

(iv) The nominating and
governance committee of the Board to consist of three directors, including Vincent T. Cubbage, as Chair, Howard Jenkins and Edward
Olkkola.

 

(b) The Additional
Director shall be mutually agreed to prior to the effective time of the Merger by Messrs. Cubbage and Healy and shall qualify as
independent within the meaning of Rule 303A.02 of the New York Stock Exchange’s Listed Company Manual and Rule 10A-3(b)(1)
of the Securities Exchange Act of 1934, as amended, and otherwise satisfy the requirements for service on the audit committee of
the Board as a financial expert.

 

(c) Upon the effectiveness
of the Charter Proposals, the Company will take all necessary action (to the extent permitted by applicable law and to the extent
such action is consistent with the fiduciary duties of the Board under Delaware law) to cause the Board to be divided into three
classes serving staggered three-year terms immediately after the effective time of the Merger. The Class I, Class II and Class
III directors will serve until the Company’s annual meetings of stockholders in 2021, 2022 and 2023, respectively. Vincent
T. Cubbage and Thomas Healy will be assigned to Class I, Andrew Card, Howard Jenkins and Stephen Pang will be assigned to Class
II, and Edward Olkkola and the Additional Director will be assigned to Class III.

 

(d) After the closing
of the Merger, the Company will take all necessary action (to the extent permitted by applicable law and to the extent such action
is consistent with the fiduciary duties of the Board under Delaware law) to cause the Board to nominate and recommend for election
to the Board at the Company’s annual meeting of stockholders in 2021 (the “First Annual Meeting”)
each of Vincent T. Cubbage and Thomas Healy, each to serve until the Company’s annual meeting of stockholders in 2024, or
until their successors are elected and qualified, and to solicit proxies or consents in favor thereof.

 

Section 1.2
Voting. The Stockholders shall vote, or provide a written consent or proxy with respect to, their shares of the Company’s
Class A Common Stock, par value $0.0001 per share (the “Class A Common Stock”), in favor of Vincent T. Cubbage
and Thomas Healy for election to the Board at the First Annual Meeting.

 

Section 1.3
Restrictions on Other Agreements. The Stockholders shall not, directly or indirectly, grant any proxy or enter into
or agree to be bound by any voting trust, agreement or arrangement of any kind with respect to their shares of Class A Common
Stock if and to the extent the terms thereof conflict with the provisions of this Agreement (whether or not such proxy, voting
trust, agreement or agreements are with other holders of shares of Class A Common Stock that are not parties to this Agreement
or otherwise).

 

Article II

TERMINATION

 

Section 2.1
Termination. This Agreement shall terminate after the First Annual Meeting.

 

Article III

MISCELLANEOUS

 

Section 3.1
Notices. All notices, requests, demands and other communications under this Agreement shall be in writing and shall
be personally delivered, sent by nationally recognized overnight courier, mailed by registered or certified mail or be sent by
facsimile or electronic mail to such party at the address set forth below (or such other address as shall be specified by like
notice). Notices will be deemed to have been duly given hereunder if (i) personally delivered, when received, (ii) sent
by nationally recognized overnight courier, one business day after deposit with the nationally recognized overnight courier, (iii) mailed
by registered or certified mail, five business days after the date on which it is so mailed, and (iv) sent by facsimile or
electronic mail, on the date sent so long as such communication is transmitted before 5:00 p.m. in the time zone of the receiving
party on a business day, otherwise, on the next business day.

 

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(a) If to the Company
prior to the closing of the Merger, to:

 

Tortoise Acquisition Corp.

452 Fifth Avenue

14th Floor

New York, NY 10018

Attention: Vincent T. Cubbage; Steven C. Schnitzer

Email: vcubbage@tortoiseadvisors.com; sschnitzer@tortoiseadvisors.com

 

(b) If to the Company
after the closing of the Merger, to:

 

Hyliion Holdings Corp.

1202 BMC Drive

Cedar Park, TX 78613

Attention: Thomas Healy

Email: thomas@hyliion.com

 

(c) If to the Stockholders,
to the addresses set forth on the signature pages hereto.

 

Section 3.2
Severability. The provisions of this Agreement shall be deemed severable,
and the invalidity or unenforceability of any provision shall not affect the validity or enforceability of the other provisions
hereof. If any provision of this Agreement, or the application thereof to any person or any circumstance, is found to be invalid
or unenforceable in any jurisdiction, (a) a suitable and equitable provision shall be substituted therefor in order to carry
out, so far as may be valid and enforceable, the intent and purpose of such invalid or unenforceable provision and (b) the
remainder of this Agreement and the application of such provision to other persons or circumstances shall not be affected by such
invalidity or unenforceability, nor shall such invalidity or unenforceability affect the validity or enforceability of such provision,
or the application thereof, in any other jurisdiction.

 

Section 3.3
Counterparts. This Agreement may be executed in one or more counterparts,
each of which shall be deemed an original and all of which, taken together, shall be considered one and the same agreement.

 

Section 3.4
Entire Agreement; No Third Party Beneficiaries. This Agreement (a) constitutes
the entire agreement and supersedes all other prior agreements, both written and oral, among the parties hereto with respect to
the subject matter hereof and (b) is not intended to confer upon any person, other than the parties hereto, any rights or
remedies hereunder.

 

Section 3.5
Further Assurances. Each party hereto shall execute, deliver, acknowledge
and file such other documents and take such further actions as may be reasonably requested from time to time by the other parties
hereto to give effect to and carry out the transactions contemplated herein.

 

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Section 3.6
Governing Law; Equitable Remedies. THIS AGREEMENT SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS
OF THE STATE OF DELAWARE (WITHOUT GIVING EFFECT TO CONFLICT OF LAWS PRINCIPLES THEREOF). The parties hereto agree that irreparable
damage would occur in the event that any of the provisions of this Agreement were not performed in accordance with its specific
terms or was otherwise breached. It is accordingly agreed that the parties hereto shall be entitled to an injunction or injunctions
and other equitable remedies to prevent breaches of this Agreement and to enforce specifically the terms and provisions hereof
in any of the Selected Courts (as defined below), this being in addition to any other remedy to which they are entitled at law
or in equity. Any requirements for the securing or posting of any bond with respect to such remedy are hereby waived by each of
the parties hereto. Each party hereto further agrees that, in the event of any action for an injunction or other equitable remedy
in respect of such breach or enforcement of specific performance, it will not assert the defense that a remedy at law would be
adequate.

 

Section 3.7
Consent To Jurisdiction. With respect to any suit, action or proceeding (“Proceeding”)
arising out of or relating to this Agreement, each of the parties hereto hereby irrevocably (a) submits to the exclusive
jurisdiction of the Court of Chancery of the State of Delaware and the United States District Court for the District of Delaware
and the appellate courts therefrom (the “Selected Courts”) and waives any objection to venue being laid
in the Selected Courts whether based on the grounds of forum non conveniens or otherwise and hereby agrees not to commence any
such Proceeding other than before one of the Selected Courts; provided, however, that a party may commence any Proceeding
in a court other than a Selected Court solely for the purpose of enforcing an order or judgment issued by one of the Selected
Courts; (b) consents to service of process in any Proceeding by the mailing of copies thereof by registered or certified
mail, postage prepaid, or by recognized international express carrier or delivery service, to their respective addresses referred
to in Section 3.1 hereof; provided, however, that nothing herein shall affect the right of any party
hereto to serve process in any other manner permitted by law; and (c) TO THE EXTENT NOT PROHIBITED BY APPLICABLE LAW THAT
CANNOT BE WAIVED, WAIVES, AND COVENANTS THAT IT WILL NOT ASSERT (WHETHER AS PLAINTIFF, DEFENDANT OR OTHERWISE) ANY RIGHT TO TRIAL
BY JURY IN ANY ACTION ARISING IN WHOLE OR IN PART UNDER OR IN CONNECTION WITH THIS AGREEMENT, WHETHER NOW EXISTING OR HEREAFTER
ARISING, AND WHETHER SOUNDING IN CONTRACT, TORT OR OTHERWISE, AND AGREES THAT ANY OF THEM MAY FILE A COPY OF THIS PARAGRAPH WITH
ANY COURT AS WRITTEN EVIDENCE OF THE KNOWING, VOLUNTARY AND BARGAINED-FOR AGREEMENT AMONG THE PARTIES IRREVOCABLY TO WAIVE THE
RIGHT TO TRIAL BY JURY IN ANY PROCEEDING WHATSOEVER BETWEEN THEM RELATING TO THIS AGREEMENT AND TO HAVE ALL MATTERS RELATING TO
THIS AGREEMENT BE TRIED IN A COURT OF COMPETENT JURISDICTION BY A JUDGE SITTING WITHOUT A JURY.

 

Section 3.8
Amendments; Waivers.

 

(a) No provision of
this Agreement may be amended or waived unless such amendment or waiver is in writing and signed (i) in the case of an amendment,
by each of the parties hereto, and (ii) in the case of a waiver, by each of the parties against whom the waiver is to be effective.

 

(b) No failure or delay
by any party in exercising any right, power or privilege hereunder shall operate as waiver thereof nor shall any single or partial
exercise thereof preclude any other or further exercise thereof or the exercise of any other right, power or privilege. The rights
and remedies herein provided shall be cumulative and not exclusive of any rights or remedies provided by law.

 

Section 3.9
Assignment. Neither this Agreement nor any of the rights or obligations
hereunder shall be assigned or delegated by any of the parties hereto without the prior written consent of the other parties.
Subject to the preceding sentence, this Agreement will be binding upon, inure to the benefit of and be enforceable by the parties
and their respective successors and permitted assigns.

 

Section 3.10
No Recourse. This Agreement may only be enforced against, and any claims or cause of action
that may be based upon, arise out of or relate to this Agreement, or the negotiation, execution or performance of this Agreement
may only be made against the entities that are expressly identified as parties hereto, and no past, present or future affiliate,
director, officer, employee, incorporator, member, manager, partner, stockholder, agent, attorney or representative of any party
hereto shall have any liability for any obligations or liabilities of the parties to this Agreement or for any claim based on,
in respect of, or by reason of, the transactions contemplated hereby.

 

[Signature
page follows.]

 

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IN WITNESS WHEREOF,
the parties hereto have executed this Agreement as of the date first written above.

 

	 	COMPANY:
	 	 
	 	TORTOISE ACQUISITION CORP. 
	 	 
	 	By:	/s/ Vincent T. Cubbage
	 	 	Name: Vincent T. Cubbage
	 	 	Title:   Chief Executive Officer and President

 

[Signature Page to Stockholders Rights
Agreement]

 

     

     

    

 

	 	STOCKHOLDERS:
	 	 
	 	VINCENT T. CUBBAGE
	 	 
	 	/s/ Vincent T. Cubbage
	 	Vincent T. Cubbage
	 	 	 
	 	Address:  	      
	 	 	 
	 	 	 
	 	Email:	vcubbage@tortoiseadvisors.com

 

[Signature Page to Stockholders Rights
Agreement]

 

     

     

    

 

	 	STOCKHOLDERS:
	 	 
	 	STEPHEN PANG
	 	 
	 	/s/ Stephen
    Pang
	 	Stephen Pang
	 	 	 
	 	Address:  	452 Fifth Avenue
	 	 	14th Floor New York,
	 	 	NY 10018
	 	Email:	spang@tortoiseadvisors.com

 

[Signature Page to Stockholders Rights
Agreement]

 

     

     

    

 

	 	STOCKHOLDERS:
	 	 
	 	THOMAS HEALY
	 	 
	 	/s/ Thomas Healy
	 	Thomas Healy
	 	 	 
	 	Address:  	3201 Esperanza Crossing APT 510 
	 	 	Austin, 
	 	 	TX 78758

 

[Signature Page to Stockholders Rights
Agreement]

 

     

     

    

 

	 	STOCKHOLDERS:
	 	 
	 	EDWARD OLKKOLA
	 	 
	 	/s/ Edward Olkkola
	 	Edward Olkkola
	 	 
	 	Address:  	608 Innwood Dr
	 	 	Georgetown 
	 	 	TX 78628

 

[Signature Page to Stockholders Rights
Agreement]

 

     

     

    

 

	 	STOCKHOLDERS:
	 	 
	 	HOWARD JENKINS
	 	 
	 	/s/ Howard Jenkins
	 	Howard Jenkins
	 	 	 
	 	Address:  	601 South Boulevard
	 	 	Tampa, 
	 	 	FL 33606

 

[Signature Page to Stockholders Rights
Agreement]

 

     

     

    

 

	 	STOCKHOLDERS:
	 	 	 
	 	AXIOMA VENTURES, LLC
	 	 	 
	 	By:	Axioma Holdings, LLC
	 	Its:	Sole Member
	 	By:	Axioma Management, LLC
	 	Its:	Manager
	 	 	 
	 	By:	/s/ Howard Jenkins
	 	 	Name: Howard Jenkins
	 	 	Title: Manager

 

	 	Address:   	601 South Boulevard
	 	 	Tampa, 
	 	 	FL 33606

 

[Signature Page to Stockholders Rights
Agreement]Exhibit 10.3

 

Execution Version

SUBSCRIPTION AGREEMENT

 

This SUBSCRIPTION AGREEMENT
(this “Subscription Agreement”) is entered into this 18th day of June, 2020, by and among Tortoise
Acquisition Corp., a Delaware corporation (the “Issuer”), and [●] (“Subscriber”).

 

WHEREAS, concurrently
with the execution and delivery of this Subscription Agreement, the Issuer is entering into that certain Business Combination Agreement
and Plan of Reorganization, dated as of the date of this Subscription Agreement (as may be amended or supplemented from time to
time, the “Combination Agreement”), among the Issuer, Hyliion Inc., a Delaware corporation (“Hyliion”),
and SHLL Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of the Issuer, pursuant to which the Issuer will
acquire Hyliion, on the terms and subject to the conditions set forth therein (the “Transaction”);

 

WHEREAS, in connection
with the Transaction, on the terms and subject to the conditions set forth in this Subscription Agreement, Subscriber desires to
subscribe for and purchase from the Issuer the number of shares of the Issuer’s Class A common stock, par value $0.0001 per
share (the “Class A Shares”), set forth on the signature page hereto (the “Acquired Shares”)
for a purchase price of $10.00 per share (the “Share Purchase Price”), or the aggregate purchase price set forth
on the signature page hereto (the “Purchase Price”), and the Issuer desires to issue and sell to Subscriber
the Acquired Shares in consideration of the payment of the Purchase Price by or on behalf of Subscriber to the Issuer at or prior
to the Closing Date; and

 

WHEREAS, in connection
with the Transaction, certain other institutional “accredited investors” (as such term is defined in Rule 501 under
the Securities Act of 1933, as amended (the “Securities Act”, and each such institutional “accredited
investor”, an “Other Subscriber”)), have entered into subscription agreements with the Issuer substantially
similar to this Subscription Agreement, pursuant to which such Other Subscribers have agreed to subscribe for and purchase, and
the Issuer has agreed to issue and sell to such Other Subscribers, on the Closing Date, a total of at least [●] Class A Shares
at the Share Purchase Price (the “Other Subscription Agreements”).

 

NOW, THEREFORE, in
consideration of the foregoing and the mutual representations, warranties and covenants, and subject to the conditions, herein
contained, and intending to be legally bound hereby, the parties hereto hereby agree as follows:

 

1. Subscription.
Subject to the terms and conditions hereof, Subscriber hereby agrees to subscribe for and purchase, and the Issuer hereby agrees
to issue and sell to Subscriber, upon the payment of the Purchase Price, the Acquired Shares (such subscription and issuance, the
“Subscription”).

 

     

     

    

 

2. Closing.

 

a. Subject
to the satisfaction or waiver of the conditions set forth in Section 2(c), the closing of the Subscription contemplated
hereby (the “Closing”) shall occur on the date of, and at a time immediately prior to, the closing of the Transaction
(such date, the “Closing Date”). Not less than five (5) business days prior to the scheduled Closing Date (the
“Scheduled Closing Date”), the Issuer shall provide written notice to Subscriber (the “Closing Notice”)
of the Scheduled Closing Date.

 

b. On
the Closing Date, subject to the satisfaction or waiver of the conditions set forth in Section 2(c) (other than those conditions
that by their nature are to be satisfied at Closing, but without affecting the requirement that such conditions be satisfied or
waived at Closing):

 

(i) Subscriber
shall deliver to the Issuer on the Closing Date the Purchase Price for the Acquired Shares by wire transfer of U.S. dollars in
immediately available funds to the account specified by the Issuer in the Closing Notice; and

 

(ii) The
Issuer shall deliver to Subscriber the Acquired Shares in book-entry form, free and clear of any liens or other restrictions whatsoever
(other than those arising under state or federal securities laws), in the name of Subscriber (or its nominee in accordance with
its delivery instructions) or to a custodian designated by Subscriber, as applicable. Each book entry for the Acquired Shares shall
contain a notation, and each certificate (if any) evidencing the Acquired Shares shall be stamped or otherwise imprinted with a
legend, in substantially the following form:

 

THE SECURITIES
REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE UNITED STATES SECURITIES ACT OF 1933, AS AMENDED, OR THE SECURITIES LAWS
OF ANY STATE OR OTHER JURISDICTION, AND MAY NOT BE SOLD OR TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AN EXEMPTION THEREFROM.

 

c. The
Closing shall be subject to the satisfaction on the Closing Date, or the waiver by each of the parties hereto, of each of the following
conditions:

 

(i) no
suspension of the qualification of the Acquired Shares for offering or sale or trading in any jurisdiction, or initiation or threatening
of any proceedings for any of such purposes, shall have occurred;

 

(ii) all
representations and warranties of the Issuer and Subscriber contained in this Subscription Agreement shall be true and correct
in all material respects (other than representations and warranties that are qualified as to materiality or Material Adverse Effect
(as defined herein), which representations and warranties shall be true in all respects) at and as of the Closing Date, and consummation
of the Closing shall constitute a reaffirmation by each of the Issuer and Subscriber of each of the representations, warranties
and agreements of each such party contained in this Subscription Agreement as of the Closing Date (other than those representations
and warranties expressly made as of an earlier date, which shall be true and correct in all material respects as of such earlier
date);

 

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(iii) the
Issuer and Subscriber shall have performed, satisfied and complied in all material respects with all covenants, agreements and
conditions required by this Subscription Agreement to be performed, satisfied or complied with by it at or prior to the Closing,
except where the failure of such performance or compliance would not or would not reasonably be expected to prevent, materially
delay, or materially impair the ability of the Issuer to consummate the Closing;

 

(iv) no
governmental authority shall have enacted, issued, promulgated, enforced or entered any judgment, order, law, rule or regulation
(whether temporary, preliminary or permanent) which is then in effect and has the effect of making consummation of the transactions
contemplated hereby illegal or otherwise preventing or prohibiting consummation of the transactions contemplated hereby, and no
governmental authority shall have instituted or threatened in writing a proceeding seeking to impose any such prevention or prohibition;

 

(v) no
amendment or modification of the Combination Agreement shall have occurred that would reasonably be expected to materially and
adversely affect the economic benefits that Subscriber would reasonably expect to receive under this Subscription Agreement, including,
without limitation, any material amendment or waiver of any representation or covenant of the Issuer or Hyliion relating to the
financial position or outstanding indebtedness of the Issuer or Hyliion;

 

(vi) No
Company Material Adverse Effect or TortoiseCorp Material Adverse Effect (each as defined in the Combination Agreement) shall have
occurred between the date of the Combination Agreement and the Closing Date; and

 

(vii) all
conditions precedent to the closing of the Transaction, including all necessary approvals of the Issuer’s stockholders and
regulatory approvals, if any, shall have been satisfied or waived (other than those conditions that may only be satisfied at the
closing of the Transaction, but subject to satisfaction of such conditions as of the closing of the Transaction).

 

d. At
the Closing, the parties hereto shall execute and deliver such additional documents and take such additional actions as the parties
reasonably may deem to be practical and necessary in order to consummate the Subscription as contemplated by this Subscription
Agreement.

 

e. In
the event the Transaction does not occur within one (1) business day of the Closing, the Issuer shall promptly (but not later than
two (2) business days thereafter) return the Purchase Price to Subscriber, and any book entries or share certificates shall be
deemed cancelled and any share certificates shall be promptly (but not later than two (2) business days thereafter) returned to
the Issuer.

 

3. Issuer
Representations and Warranties. The Issuer represents and warrants that:

 

a. The
Issuer has been duly incorporated and is validly existing as a corporation in good standing under the laws of the State of Delaware,
with corporate power and authority to own, lease and operate its properties and conduct its business as presently conducted and
to enter into, deliver and perform its obligations under this Subscription Agreement.

 

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b. The
Acquired Shares have been duly authorized and, when issued and delivered to Subscriber against full payment for the Acquired Shares
in accordance with the terms of this Subscription Agreement and registered with the Issuer’s transfer agent, the Acquired
Shares will be validly issued, fully paid and non-assessable and will not have been issued in violation of or subject to any preemptive
or similar rights created under the Issuer’s certificate of incorporation and bylaws or under the laws of the State of Delaware.

 

c. This
Subscription Agreement, the Other Subscription Agreements and the Combination Agreement (collectively, the “Transaction
Documents”) have been duly authorized, executed and delivered by the Issuer and are enforceable against the Issuer in
accordance with their respective terms, except as may be limited or otherwise affected by (i) bankruptcy, insolvency, fraudulent
conveyance, reorganization, moratorium or other laws relating to or affecting the rights of creditors generally, and (ii) principles
of equity, whether considered at law or equity.

 

d. The
execution and delivery by the Issuer of the Transaction Documents, and the performance by the Issuer of its obligations under the
Transaction Documents, including the issuance and sale of the Acquired Shares and the consummation of the other transactions contemplated
herein, do not and will not conflict with or result in a breach or violation of any of the terms or provisions of, or constitute
a default under, or result in the creation or imposition of any lien, charge or encumbrance upon any of the property or assets
of the Issuer pursuant to the terms of (i) any indenture, mortgage, deed of trust, loan agreement, lease, license or other agreement
or instrument to which the Issuer is a party or by which the Issuer is bound or to which any of the property or assets of the Issuer
is subject, which would reasonably be expected to have, individually or in the aggregate, a material adverse effect on the business,
properties, financial condition, stockholders’ equity or results of operations of the Issuer (a “Material Adverse
Effect”) or materially affect the validity of the Acquired Shares or the legal authority of the Issuer to comply in all
material respects with the terms of this Subscription Agreement; (ii) the organizational documents of the Issuer; or (iii) any
statute or any judgment, order, rule or regulation of any court or governmental agency or body, domestic or foreign, having jurisdiction
over the Issuer or any of its properties that would reasonably be expected to have, individually or in the aggregate, a Material
Adverse Effect or materially affect the validity of the Acquired Shares or the legal authority of the Issuer to comply in all material
respects with this Subscription Agreement.

 

e. There
are no securities or instruments issued by or to which the Issuer is a party containing anti-dilution or similar provisions that
will be triggered by the issuance of (i) the Acquired Shares, (ii) the Class A Shares to be issued pursuant to any Other Subscription
Agreement or (iii) any securities to be issued pursuant to the Amended and Restated Forward Purchase Agreement, dated February
6, 2019 (the “Forward Purchase Agreement”), among the Issuer, Tortoise Sponsor LLC and Atlas Point Energy Infrastructure
Fund, LLC, in each case, that have not been or will not be validly waived on or prior to the Closing Date.

 

f. The
Issuer is not in default or violation (and no event has occurred which, with notice or the lapse of time or both, would constitute
a default or violation) of any term, condition or provision of (i) the organizational documents of the Issuer, (ii) any loan or
credit agreement, note, bond, mortgage, indenture, lease or other agreement, permit, franchise or license to which the Issuer is
now a party or by which the Issuer’s properties or assets are bound or (iii) any statute or any judgment, order, rule or
regulation of any court or governmental agency or body, domestic or foreign, having jurisdiction over the Issuer or any of its
properties, except, in the case of clauses (ii) and (iii), for defaults or violations that have not had and would not be reasonably
expected to have, individually or in the aggregate, a Material Adverse Effect.

 

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g. The
Issuer is not required to obtain any consent, waiver, authorization or order of, give any notice to, or make any filing or registration
with, any court or other federal, state, local or other governmental authority, self-regulatory organization or other person in
connection with the execution, delivery and performance by the Issuer of this Subscription Agreement (including, without limitation,
the issuance of the Acquired Shares), other than (i) the filing with the Securities and Exchange Commission (the “Commission”)
of the Registration Statement (as defined below), (ii) filings required by applicable state or federal securities laws, (iii) the
filings required in accordance with Section 9(n), (iv) those required by the New York Stock Exchange (the “NYSE”),
including with respect to obtaining stockholder approval, and (v) the failure of which to obtain would not be reasonably expected
to have, individually or in the aggregate, a Material Adverse Effect.

 

h. The
authorized capital stock of the Issuer consists of (i) 1,000,000 shares of preferred stock, par value $0.0001 per share (“Preferred
Stock”), (ii) 200,000,000 Class A Shares and (iii) 20,000,000 shares of Class B common stock, par value $0.0001 per share
(“Class B Shares”). As of the date hereof and as of immediately prior to the Closing: (i) no shares of Preferred
Stock are issued and outstanding, (ii) 23,300,917 Class A Shares are issued and outstanding, (iii) 5,825,230 Class B Shares
are issued and outstanding, and (iv) 18,310,641 warrants, each entitling the holder thereof to purchase one Class A Share at an
exercise price of $11.50 per Class A Share, are outstanding. As of March 31, 2020 and as of the Closing, the Issuer had and will
have no outstanding long-term indebtedness (other than deferred underwriting fees and expenses deferred from its initial public
offering).

 

i. The
Issuer has not received any written communication since December 31, 2019, from a governmental entity that alleges that the Issuer
is not in compliance with or is in default or violation of any applicable law, except where such non-compliance, default or violation
would not, individually or in the aggregate, be reasonably expected to have a Material Adverse Effect.

 

j. The
issued and outstanding Class A Shares are registered pursuant to Section 12(b) of the Securities Exchange Act of 1934, as
amended (the “Exchange Act”), and are listed for trading on the NYSE. There is no suit, action, proceeding or
investigation pending or, to the knowledge of the Issuer, threatened against the Issuer by the NYSE or the Commission with respect
to any intention by such entity to deregister the Class A Shares or prohibit or terminate the listing of the Class A Shares on
the NYSE. The Issuer has taken no action that is designed to terminate the registration of the Class A Shares under the Exchange
Act.

 

k. Assuming
the accuracy of Subscriber’s representations and warranties set forth in Section 4, no registration under the Securities
Act is required for the offer and sale of the Acquired Shares by the Issuer to Subscriber in the manner contemplated by this Subscription
Agreement.

 

    5

     

    

 

l. Neither
the Issuer nor any person acting on its behalf has engaged or will engage in any form of general solicitation or general advertising
(within the meaning of Regulation D of the Securities Act) in connection with any offer or sale of the Acquired Shares.

 

m. The
Issuer has not entered into any side letter or similar agreement with any Other Subscriber in connection with such Other Subscriber’s
direct or indirect investment in the Issuer and no Other Subscription Agreement includes terms and conditions that are materially
more advantageous to any such Other Subscriber than Subscriber hereunder. The Other Subscription Agreements have not been amended
in any material respect following the date of this Subscription Agreement and reflect the same Share Purchase Price and terms that
are no more favorable to any such Other Subscriber thereunder than the terms of this Subscription Agreement. Other than pursuant
to the Forward Purchase Agreement, pursuant to which the Issuer may issue units comprised of Class A Shares and warrants, the Issuer
has not agreed and will not agree to issue any warrants to any person in connection with the Transaction.

 

n. The
Issuer has made available to Subscriber (including via the Commission’s EDGAR system) a copy of each form, report, statement,
schedule, prospectus, proxy, registration statement and other document, if any, filed by the Issuer with the Commission since its
initial registration of the Class A Shares (the “SEC Documents”), which SEC Documents, as of their respective
filing dates, complied in all material respects with the requirements of the Exchange Act applicable to the SEC Documents and the
rules and regulations of the Commission promulgated thereunder applicable to the SEC Documents. None of the SEC Documents filed
under the Exchange Act (except to the extent that information contained in any SEC Document has been superseded by a later timely
filed SEC Document) contained, when filed any untrue statement of a material fact or omitted to state a material fact required
to be stated therein or necessary to make the statements therein, in light of the circumstances under which they were made, not
misleading; provided, that, with respect to the proxy statement to be filed by the Issuer with respect to the Transaction
or any of its affiliates included in any SEC Document or filed as an exhibit thereto, the representation and warranty in this sentence
is made to the Issuer’s knowledge. The Issuer has timely filed each report, statement, schedule, prospectus, and registration
statement that the Issuer was required to file with the Commission since its inception. There are no material outstanding or unresolved
comments in comment letters from the Staff of the Commission with respect to any of the SEC Documents.

 

o. Except
for such matters as have not had and would not be reasonably expected to have, individually or in the aggregate, a Material Adverse
Effect, there is no (i) proceeding pending, or, to the knowledge of the Issuer, threatened against the Issuer or (ii) judgment,
decree, injunction, ruling or order of any governmental entity or arbitrator outstanding against the Issuer.

 

p. Except
for placement fees payable to Barclays Capital Inc. and Goldman Sachs & Co. LLC, in their capacity as placement agents for
the offer and sale of the Acquired Shares (in such capacity, the “Placement Agents”), the Issuer has not paid,
and is not obligated to pay, any brokerage, finder’s or other commission or similar fee in connection with its issuance and
sale of the Acquired Shares, including, for the avoidance of doubt, any fee or commission payable to any stockholder or affiliate
of the Issuer.

 

    6

     

    

 

4. Subscriber
Representations and Warranties. Subscriber represents and warrants that as of the Closing Date:

 

a. Subscriber
has been duly formed or incorporated and is validly existing in good standing under the laws of its jurisdiction of incorporation
or formation, with the requisite entity power and authority to enter into, deliver and perform its obligations under this Subscription
Agreement.

 

b. This
Subscription Agreement has been duly authorized, executed and delivered by Subscriber. This Subscription Agreement is enforceable
against Subscriber in accordance with its terms, except as may be limited or otherwise affected by (i) bankruptcy, insolvency,
fraudulent conveyance, reorganization, moratorium or other laws relating to or affecting the rights of creditors generally, and
(ii) principles of equity, whether considered at law or equity.

 

c. The
execution and delivery by Subscriber of this Subscription Agreement, and the performance by Subscriber of its obligations under
this Subscription Agreement, including the purchase of the Acquired Shares and the consummation of the other transactions contemplated
herein, will not conflict with or result in a breach or violation of any of the terms or provisions of, or constitute a default
under, or result in the creation or imposition of any lien, charge or encumbrance upon any of the property or assets of Subscriber
pursuant to the terms of (i) any indenture, mortgage, deed of trust, loan agreement, lease, license or other agreement or instrument
to which Subscriber is a party or by which Subscriber is bound or to which any of the property or assets of Subscriber is subject,
which would reasonably be expected to have a material adverse effect on the business, properties, financial condition, stockholders’
equity or results of operations of Subscriber, taken as a whole (a “Subscriber Material Adverse Effect”), or
materially affect the legal authority of Subscriber to comply in all material respects with the terms of this Subscription Agreement;
(ii) the organizational documents of Subscriber; or (iii) any statute or any judgment, order, rule or regulation of any court or
governmental agency or body, domestic or foreign, having jurisdiction over Subscriber or any of Subscriber’s properties that
would reasonably be expected to have a Subscriber Material Adverse Effect or materially affect the legal authority of Subscriber
to comply in all material respects with this Subscription Agreement.

 

d. Subscriber
(i) is a “qualified institutional buyer” (as defined in Rule 144A under the Securities Act) or an institutional “accredited
investor” (within the meaning of Rule 501(a) under the Securities Act), in each case, satisfying the applicable requirements
set forth on Schedule A, (ii) is acquiring the Acquired Shares only for its own account and not for the account of
others, or if Subscriber is subscribing for the Acquired Shares as a fiduciary or agent for one or more investor accounts, each
owner of such account is a “qualified institutional buyer” (as defined above) and Subscriber has full investment discretion
with respect to each such account, and the full power and authority to make the acknowledgements, representations and agreements
herein on behalf of each owner of each such account and (iii) is not acquiring the Acquired Shares with a view to, or for offer
or sale in connection with, any distribution thereof in violation of the Securities Act. Subscriber has completed Schedule A
following the signature page hereto and the information contained therein is accurate and complete. Subscriber is not an entity
formed for the specific purpose of acquiring the Acquired Shares.

 

    7

     

    

 

e. Subscriber
understands that the Acquired Shares are being offered in a transaction not involving any public offering within the meaning of
the Securities Act and that the Acquired Shares have not been registered under the Securities Act. Subscriber understands that
the Acquired Shares may not be resold, transferred, pledged or otherwise disposed of by Subscriber absent an effective registration
statement under the Securities Act, except (i) to the Issuer or a subsidiary thereof, (ii) to non-U.S. persons pursuant to offers
and sales that occur outside the United States within the meaning of Regulation S under the Securities Act, (iii) pursuant to Rule
144 under the Securities Act, provided that all of the applicable conditions thereof have been met or (iv) pursuant to another
applicable exemption from the registration requirements of the Securities Act, and that any certificates or book-entry records
representing the Acquired Shares shall contain a legend to such effect. Subscriber acknowledges that the Acquired Shares will not
be eligible for resale pursuant to Rule 144A promulgated under the Securities Act. Subscriber understands and agrees that the Acquired
Shares will be subject to transfer restrictions and, as a result of these transfer restrictions, Subscriber may not be able to
readily resell the Acquired Shares and may be required to bear the financial risk of an investment in the Acquired Shares for an
indefinite period of time. Subscriber understands that it has been advised to consult legal counsel prior to making any offer,
resale, pledge or transfer of any of the Acquired Shares.

 

f. Subscriber
understands and agrees that Subscriber is purchasing the Acquired Shares directly from the Issuer. Subscriber further acknowledges
that there have been no representations, warranties, covenants and agreements made to Subscriber by the Issuer or any of its officers
or directors, expressly or by implication, other than those representations, warranties, covenants and agreements included in this
Subscription Agreement.

 

g. Subscriber’s
acquisition and holding of the Acquired Shares will not constitute or result in a non-exempt prohibited transaction under section
406 of the Employee Retirement Income Security Act of 1974, as amended, section 4975 of the Internal Revenue Code of 1986, as amended
(the “Code”), or any applicable similar law.

 

h. In
making its decision to subscribe for and purchase the Acquired Shares, Subscriber represents that it has relied solely upon its
own independent investigation. Without limiting the generality of the foregoing, Subscriber has not relied on any statements or
other information provided by the Placement Agents concerning the Issuer or the Acquired Shares or the offer and sale of the Acquired
Shares. Subscriber acknowledges and agrees that Subscriber has received such information as Subscriber deems necessary in order
to make an investment decision with respect to the Acquired Shares, including with respect to the Issuer and the Transaction. Subscriber
represents and agrees that Subscriber and Subscriber’s professional advisor(s), if any, have had the full opportunity to
ask such questions, receive such answers and obtain such information as Subscriber and such Subscriber’s professional advisor(s),
if any, have deemed necessary to make an investment decision with respect to the Acquired Shares.

 

i. Subscriber
became aware of this offering of the Acquired Shares solely by means of direct contact between Subscriber and the Issuer or the
Placement Agents, and the Acquired Shares were offered to Subscriber solely by direct contact between Subscriber and the Issuer
or the Placement Agents. Subscriber did not become aware of this offering of the Acquired Shares, nor were the Acquired Shares
offered to Subscriber, by any other means. Subscriber acknowledges that the Issuer represents and warrants that the Acquired Shares
(i) were not offered by any form of general solicitation or general advertising and (ii) are not being offered in a manner involving
a public offering under, or in a distribution in violation of, the Securities Act, or any state securities laws.

 

    8

     

    

 

j. Subscriber
acknowledges that it is aware that there are substantial risks incident to the purchase and ownership of the Acquired Shares. Subscriber
has such knowledge and experience in financial and business matters as to be capable of evaluating the merits and risks of an investment
in the Acquired Shares, and Subscriber has sought such accounting, legal and tax advice as Subscriber has considered necessary
to make an informed investment decision.

 

k. Subscriber
acknowledges and agrees that neither the Placement Agents nor any Affiliate of the Placement Agents has provided Subscriber with
any information or advice with respect to the Subscribed Shares nor is such information or advice necessary or desired. Subscriber
acknowledges that the Placement Agents and their representatives (i) have not made any representation as to the Issuer or the quality
of the Acquired Shares, (ii) may have acquired non-public information with respect to the Issuer which Subscriber agrees need not
be provided to it, (iii) have made no independent investigation with respect to the Issuer or the Acquired Shares or the accuracy,
completeness or adequacy of any information supplied to Subscriber by the Issuer, (iv) have not acted as Subscriber’s
financial advisor or fiduciary in connection with the issue and purchase of the Acquired Shares and (v) have not prepared a disclosure
or offering document in connection with the offer and sale of the Acquired Shares.

 

l. Alone,
or together with any professional advisor(s), Subscriber represents and acknowledges that Subscriber has adequately analyzed and
fully considered the risks of an investment in the Acquired Shares and determined that the Acquired Shares are a suitable investment
for Subscriber and that Subscriber is able at this time and in the foreseeable future to bear the economic risk of a total loss
of Subscriber’s investment in the Issuer. Subscriber acknowledges specifically that a possibility of total loss exists.

 

m. Subscriber
understands and agrees that no federal or state agency has passed upon or endorsed the merits of the offering of the Acquired Shares
or made any findings or determination as to the fairness of an investment in the Acquired Shares.

 

n. Subscriber
is not (i) a person or entity named on the List of Specially Designated Nationals and Blocked Persons, the Executive Order 13599
List, the Foreign Sanctions Evaders List, or the Sectoral Sanctions Identification List, each of which is administered by the U.S.
Treasury Department’s Office of Foreign Assets Control (“OFAC”) (collectively “OFAC Lists”),
(ii) owned or controlled by, or acting on behalf of, a person, that is named on an OFAC List, (iii) organized, incorporated,
established, located, resident or born in, or a citizen, national, or the government, including any political subdivision, agency,
or instrumentality thereof, of, Cuba, Iran, North Korea, Syria, the Crimea region of Ukraine, or any other country or territory
embargoed or subject to substantial trade restrictions by the United States, (iv) a Designated National as defined in the Cuban
Assets Control Regulations, 31 C.F.R. Part 515 or (v) a non-U.S. shell bank or providing banking services indirectly to a non-U.S.
shell bank (collectively, a “Prohibited Investor”). Subscriber represents that if it is a financial institution
subject to the Bank Secrecy Act (31 U.S.C. section 5311 et seq.) (the “BSA”), as amended by the USA PATRIOT
Act of 2001 (the “PATRIOT Act”), and its implementing regulations (collectively, the “BSA/PATRIOT Act”),
that Subscriber maintains policies and procedures reasonably designed to comply with applicable obligations under the BSA/PATRIOT
Act. Subscriber also represents that, to the extent required, it maintains policies and procedures reasonably designed to ensure
compliance with OFAC-administered sanctions programs, including for the screening of its investors against the OFAC Lists. Subscriber
further represents and warrants that, to the extent required, it maintains policies and procedures reasonably designed to ensure
that the funds held by Subscriber and used to purchase the Acquired Shares were legally derived.

 

    9

     

    

 

o. If
Subscriber is an employee benefit plan that is subject to Title I of the Employee Retirement Income Security Act of 1974, as amended
(“ERISA”), a plan, an individual retirement account or other arrangement that is subject to section 4975 of
the Code or an employee benefit plan that is a governmental plan (as defined in section 3(32) of ERISA), a church plan (as defined
in section 3(33) of ERISA), a non-U.S. plan (as described in section 4(b)(4) of ERISA) or other plan that is not subject to the
foregoing but may be subject to provisions under any other federal, state, local, non-U.S. or other laws or regulations that are
similar to such provisions of ERISA or the Code (collectively, “Similar Laws”), or an entity whose underlying
assets are considered to include “plan assets” of any such plan, account or arrangement (each, a “Plan”)
subject to the fiduciary or prohibited transaction provisions of ERISA or section 4975 of the Code, then Subscriber represents
and warrants that (i) neither the Issuer, nor any of its respective affiliates (the ”Transaction Parties”)
has acted as the Plan’s fiduciary, or has been relied on for advice, with respect to its decision to acquire and hold the
Acquired Shares, and none of the Transaction Parties shall at any time be relied upon as the Plan’s fiduciary with respect
to any decision to acquire, continue to hold or transfer the Acquired Shares; (ii) the decision to invest in the Acquired Shares
has been made at the recommendation or direction of an “independent fiduciary” (“Independent Fiduciary”)
within the meaning of US Code of Federal Regulations 29 C.F.R. section 2510.3 21(c), as amended from time to time (the “Fiduciary
Rule”) who is (A) independent of the Transaction Parties; (B) is capable of evaluating investment risks independently,
both in general and with respect to particular transactions and investment strategies (within the meaning of the Fiduciary Rule);
(C) is a fiduciary (under ERISA and/or section 4975 of the Code) with respect to Subscriber’s investment in the Acquired
Shares and is responsible for exercising independent judgment in evaluating the investment in the Acquired Shares; and (D) is aware
of and acknowledges that (I) none of the Transaction Parties is undertaking to provide impartial investment advice, or to give
advice in a fiduciary capacity, in connection with the purchaser’s or transferee’s investment in the Acquired Shares,
and (II) the Transaction Parties have a financial interest in the purchaser’s investment in the Acquired Shares on account
of the fees and other remuneration they expect to receive in connection with transactions contemplated hereunder.

 

p. Subscriber
has, and at the Closing will have, sufficient funds to pay the Purchase Price pursuant to Section 2(b)(i).

 

5. Additional
Subscriber Agreement. Subscriber hereby agrees that, from the date of this Agreement, none of Subscriber or any person or entity
acting on behalf of Subscriber or pursuant to any understanding with Subscriber will engage in any Short Sales with respect to
securities of the Issuer prior to the Closing. For purposes of this Section 5, “Short Sales” shall include,
without limitation, all “short sales” as defined in Rule 200 promulgated under Regulation SHO under the Exchange Act,
and all types of direct and indirect stock pledges (other than pledges in the ordinary course of business as part of prime brokerage
arrangements), forward sale contracts, options, puts, calls, swaps and similar arrangements (including on a total return basis),
and sales and other transactions through non-U.S. broker dealers or foreign regulated brokers. Notwithstanding the foregoing, nothing
herein shall prohibit other entities under common management with the Subscriber that have no knowledge of this Subscription Agreement
or of Subscriber’s participation in the Transaction (including the Subscriber’s controlled affiliates and/or affiliates)
from entering into any Short Sales.

 

    10

     

    

 

6. Registration
Rights.

 

a. The
Issuer agrees that, within thirty (30) calendar days after the consummation of the Transaction (the “Filing Date”),
the Issuer will file with the Commission (at the Issuer’s sole cost and expense) a registration statement registering the
resale of the Acquired Shares (the “Registration Statement”), and the Issuer 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 60th calendar day (or 90th calendar day if the Commission notifies the Issuer that it will “review”
the Registration Statement) following the Closing and (ii) the 10th business day after the date the Issuer is notified (orally
or in writing, whichever is earlier) by the Commission 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 Issuer’s obligations to include the Acquired Shares in the Registration Statement are contingent upon Subscriber
furnishing in writing to the Issuer such information regarding Subscriber, the securities of the Issuer held by Subscriber and
the intended method of disposition of the Acquired Shares as shall be reasonably requested by the Issuer to effect the registration
of the Acquired Shares, and Subscriber shall execute such documents in connection with such registration as the Issuer may reasonably
request that are customary of a selling stockholder in similar situations, including providing that the Issuer 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 Issuer to file the Registration Statement by the Filing
Date or to effect such Registration Statement by the Effectiveness Date shall not otherwise relieve the Issuer of its obligations
to file or effect the Registration Statement as set forth above in this Section 6. The Issuer will provide a draft of the
Registration Statement to the undersigned for review at least two (2) business days in advance of filing the Registration Statement.
In no event shall the undersigned be identified as a statutory underwriter in the Registration Statement unless requested by the
SEC; provided, that if the SEC requests that the undersigned be identified as a statutory underwriter in the Registration
Statement, the undersigned will have an opportunity to withdraw from the Subscription. Notwithstanding the foregoing, if the SEC
prevents the Issuer from including any or all of the shares proposed to be registered under the Registration Statement due to limitations
on the use of Rule 415 of the Securities Act for the resale of the Acquired Shares by the applicable shareholders or otherwise,
such Registration Statement shall register for resale such number of Acquired Shares which is equal to the maximum number of Acquired
Shares as is permitted by the SEC. In such event, the number of Acquired Shares to be registered for each selling shareholder named
in the Registration Statement shall be reduced pro rata among all such selling shareholders.

 

    11

     

    

 

b. The
Issuer further agrees that, in the event that (i) the Registration Statement has not
been declared effective by the Commission by the Effectiveness Date, (ii) after such Registration Statement is declared effective
by the Commission, (A) such Registration Statement ceases for any reason (including by reason of a stop order, or the Issuer’s
failure to update the Registration Statement), to remain continuously effective as to all Acquired Shares for which it is required
to be effective or (B) Subscriber is not permitted to utilize the Registration Statement to resell the Acquired Shares (in
each case of (A) and (B), (x) other than within the time period(s) permitted by this Subscription Agreement and (y) excluding
by reason of a post-effective amendment required in connection with the Issuer’s filing of an amendment thereto (a “Special
Grace Period”) (which Special Grace Period shall not be treated as a Registration Default (as defined below)), or (iii) after
the date six months following the Closing Date, and only in the event the Registration Statement is not effective or available
to sell all Acquired Shares, the Issuer fails to file with the Commission any required reports under Section 13 or 15(d) of
the Exchange Act such that it is not in compliance with Rule 144(c)(1) or Rule 144(i)(2), as applicable, as a result of which Subscribers
who are not affiliates of the Issuer are unable to sell the Acquired Shares without restriction under Rule 144 (or any successor
thereto) (each such event referred to in clauses (i) through (iii), a “Registration Default” and, for purposes
of such clauses, the date on which such Registration Default occurs, a “Default Date”), then in addition to
any other rights Subscriber may have hereunder or under applicable law, on each such Default Date and on each monthly anniversary
of each such Default Date (if the applicable Registration Default shall not have been cured by such date) until the applicable
Registration Default is cured, the Issuer shall pay to each Subscriber an amount in cash, as partial liquidated damages and not
as a penalty (“Liquidated Damages”), equal to 0.5% of the aggregate Purchase Price paid by Subscriber pursuant
to this Subscription Agreement for any Acquired Shares held by Subscriber on the Default Date; provided, however, that
if Subscriber fails to provide the Issuer with any information requested by the Issuer that is required to be provided in such
Registration Statement with respect to Subscriber as set forth herein, then, for purposes of this Section 6, the
Filing Date or Effectiveness Date, as applicable, for a Registration Statement with respect to Subscriber shall be extended until
two (2) business days following the date of receipt by the Issuer of such required information from Subscriber; and in no
event shall the Issuer be required hereunder to pay to Subscriber pursuant to this Subscription Agreement an aggregate amount that
exceeds 5.0% of the aggregate Purchase Price paid by Subscriber for its Acquired Shares. The Liquidated Damages pursuant to the
terms hereof shall apply on a daily pro-rata basis for any portion of a month prior to the cure of a Registration Default,
except in the case of the first Default Date. The Issuer shall deliver the cash payment to Subscriber with respect to any Liquidated
Damages by the fifth business day after the date payable. If the Issuer fails to pay said cash payment to Subscriber in full by
the fifth business day after the date payable, the Issuer will pay interest thereon at a rate of 5.0% per annum (or such lesser
maximum amount that is permitted to be paid by applicable law, and calculated on the basis of a year consisting of 360 days) to
such Subscriber, accruing daily from the date such Liquidated Damages are due until such amounts, plus all such interest thereon,
are paid in full. Notwithstanding the foregoing, nothing shall preclude any Subscriber from pursuing or obtaining any available
remedies at law, specific performance or other equitable relief with respect to this Section 6 in accordance
with applicable law. The parties agree that notwithstanding anything to the contrary herein, no Liquidated Damages shall be payable
to Subscriber with respect to any period during which all of such Subscriber’s Acquired Shares may be sold by Subscriber
without volume or manner of sale restrictions under Rule 144 and the Issuer is in compliance with the current public information
requirements under Rule 144(c)(1) or Rule 144(i)(2), as applicable.

 

    12

     

    

 

c. In
the case of the registration, qualification, exemption or compliance effected by the Issuer pursuant to this Subscription Agreement,
the Issuer shall, upon reasonable request, inform Subscriber as to the status of such registration, qualification, exemption and
compliance. At its expense the Issuer shall:

 

(i) except
for such times as the Issuer 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 Issuer determines to obtain, continuously effective with respect to Subscriber, 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) Subscriber ceases to hold any Acquired Shares or (ii) the date all Acquired Shares held by Subscriber 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 Issuer 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 Issuer is required hereunder to keep a Registration Statement effective
is referred to herein as the “Registration Period.”

 

(ii) advise
Subscriber within two (2) business days:

 

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

 

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

 

(3) of
the issuance by the Commission 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 Issuer of any notification with respect to the suspension of the qualification of the Acquired Shares 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 Subscription Agreement, 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 Issuer shall not, when so advising Subscriber of such events, provide Subscriber with any
material, nonpublic information regarding the Issuer other than to the extent that providing notice to Subscriber of the occurrence
of the events listed in (1) through (5) above constitutes material, nonpublic information regarding the Issuer;

 

    13

     

    

 

(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 Issuer is permitted hereunder to suspend, and has
suspended, the use of a prospectus forming part of a Registration Statement, the Issuer 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 Acquired Shares 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 Acquired Shares to be listed on each securities exchange or market, if any, on
which the Class A Shares issued by the Issuer have been listed; and

 

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

 

d. Notwithstanding
anything to the contrary in this Subscription Agreement, the Issuer shall be entitled to delay or postpone the effectiveness of
the Registration Statement, and from time to time to require Subscriber not to sell under the Registration Statement or to suspend
the effectiveness thereof, if the negotiation or consummation of a transaction by the Issuer or its subsidiaries is pending or
an event has occurred, which negotiation, consummation or event the Issuer’s board of directors reasonably believes, upon
the advice of legal counsel, would require additional disclosure by the Issuer in the Registration Statement of material information
that the Issuer 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 Issuer’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 Issuer 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 Issuer 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, Subscriber agrees that (i) it will immediately discontinue offers and sales of the Acquired Shares
under the Registration Statement (excluding, for the avoidance of doubt, sales conducted pursuant to Rule 144) until Subscriber
receives copies of a supplemental or amended prospectus (which the Issuer 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 Issuer 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 Issuer unless otherwise required by law or subpoena. If so directed by the Issuer,
Subscriber will deliver to the Issuer or, in Subscriber’s sole discretion destroy, all copies of the prospectus covering
the Acquired Shares in Subscriber’s possession; provided, however, that this obligation to deliver or destroy
all copies of the prospectus covering the Acquired Shares shall not apply (i) to the extent Subscriber 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.

 

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e. Subscriber
may deliver written notice (an “Opt-Out Notice”) to the Issuer requesting that Subscriber not receive notices
from the Issuer otherwise required by this Section 6; provided, however, that Subscriber may later revoke
any such Opt-Out Notice in writing. Following receipt of an Opt-Out Notice from Subscriber (unless subsequently revoked), (i) the
Issuer shall not deliver any such notices to Subscriber and Subscriber shall no longer be entitled to the rights associated with
any such notice and (ii) each time prior to Subscriber’s intended use of an effective Registration Statement, Subscriber
will notify the Issuer 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 Section 6(e)) and the related
suspension period remains in effect, the Issuer will so notify Subscriber, within one (1) business day of Subscriber’s notification
to the Issuer, by delivering to Subscriber a copy of such previous notice of Suspension Event, and thereafter will provide Subscriber
with the related notice of the conclusion of such Suspension Event immediately upon its availability.

 

f. The
Issuer shall, notwithstanding any termination of this Subscription Agreement, indemnify, defend and hold harmless Subscriber (to
the extent a seller under the Registration Statement), the officers, directors and agents of Subscriber, and each person who controls
Subscriber (within the meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act) to the fullest
extent permitted by applicable law, from and against any and all losses, claims, damages, liabilities, costs (including, without
limitation, reasonable attorneys’ fees) and expenses (collectively, “Losses”), as incurred, that arise
out of or are based upon (i) any untrue or alleged untrue statement of a material fact contained in the Registration Statement,
any prospectus included in the Registration Statement or any form of prospectus or in any amendment or supplement thereto or in
any preliminary prospectus, or arising out of or relating to any omission or alleged omission to state a material fact required
to be stated therein or necessary to make the statements therein (in the case of any prospectus or form of prospectus or supplement
thereto, in light of the circumstances under which they were made) not misleading, or (ii) any violation or alleged violation
by the Issuer of the Securities Act, Exchange Act or any state securities law or any rule or regulation thereunder, in connection
with the performance of its obligations under this Section 6, except to the extent, but only to the extent, that such
untrue statements, alleged untrue statements, omissions or alleged omissions are based upon information regarding Subscriber furnished
in writing to the Issuer by Subscriber expressly for use therein or Subscriber has omitted a material fact from such information
or otherwise violated the Securities Act, Exchange Act or any state securities law or any rule or regulation thereunder; provided,
however, that the indemnification contained in this Section 6 shall not apply to amounts paid in settlement of any Losses
if such settlement is effected without the consent of the Issuer (which consent shall not be unreasonably withheld, conditioned
or delayed), nor shall the Issuer be liable for any Losses to the extent they arise out of or are based upon a violation which
occurs (A) in reliance upon and in conformity with written information furnished by Subscriber, (B) in connection with any failure
of such person to deliver or cause to be delivered a prospectus made available by the Issuer in a timely manner or (C) in connection
with any offers or sales effected by or on behalf of Subscriber in violation of Section 6(d) hereof. The Issuer shall notify
Subscriber promptly of the institution, threat or assertion of any proceeding arising from or in connection with the transactions
contemplated by this Section 6 of which the Issuer is aware. Such indemnity shall remain in full force and effect regardless
of any investigation made by or on behalf of an indemnified party and shall survive the transfer of the Shares by Subscriber.

 

    15

     

    

 

g. Subscriber
shall, severally and not jointly, indemnify and hold harmless the Issuer, its directors, officers, agents and employees, and each
person who controls the Issuer (within the meaning of Section 15 of the Securities Act and Section 20 of the Exchange
Act), to the fullest extent permitted by applicable law, from and against all Losses, as incurred, (i) arising out of or based
upon any untrue or alleged untrue statement of a material fact contained in any Registration Statement, any prospectus included
in the Registration Statement, or any form of prospectus, or in any amendment or supplement thereto or in any preliminary prospectus,
or (ii) arising out of or relating to any omission or alleged omission of a material fact required to be stated therein or necessary
to make the statements therein (in the case of any prospectus, or any form of prospectus or supplement thereto, in light of the
circumstances under which they were made) not misleading, with respect to (i) and/or (ii), to the extent, but only to the extent,
that such untrue or alleged untrue statements or omissions or alleged omissions are based upon information regarding Subscriber
furnished in writing to the Issuer by Subscriber expressly for use therein; provided, however, that the indemnification
contained in this Section 6(g) shall not apply to amounts paid in settlement of any Losses if such settlement is effected
without the consent of Subscriber (which consent shall not be unreasonably withheld, conditioned or delayed). In no event shall
the liability of Subscriber be greater in amount than the dollar amount of the net proceeds received by Subscriber upon the sale
of the Shares giving rise to such indemnification obligation. Subscriber shall notify the Issuer promptly of the institution, threat
or assertion of any proceeding arising from or in connection with the transactions contemplated by this Section 6(g)
of which Subscriber is aware. Such indemnity shall remain in full force and effect regardless of any investigation made by or on
behalf of an indemnified party and shall survive the transfer of the Shares by Subscriber.

 

7. Termination.
This Subscription Agreement shall terminate and be void and of no further force and effect, and all rights and obligations of the
parties hereunder shall terminate without any further liability on the part of any party in respect thereof, upon the earlier to
occur of (a) such date and time as the Combination Agreement is terminated in accordance with the terms therein, (b) upon the mutual
written agreement of each of the parties hereto to terminate this Subscription Agreement, (c) if any of the conditions to Closing
set forth in Section 2(c) are not satisfied on or prior to the Closing Date and, as a result thereof, the transactions contemplated
by this Subscription Agreement are not consummated at the Closing or (d) at the election of Subscriber, on or after the date 180
days following the date of this Subscription Agreement, if the closing of the Transaction has not occurred on or before such date;
provided, that nothing herein will relieve any party from liability for any willful breach hereof prior to the time of termination,
and each party will be entitled to any remedies at law or in equity to recover out-of-pocket losses, liabilities or damages arising
from such breach. The Issuer shall promptly notify Subscriber of the termination of the Combination Agreement promptly after the
termination of such agreement.

 

    16

     

    

 

8. Trust
Account Waiver. Subscriber acknowledges that the Issuer is a blank check company with the powers and privileges to effect a
merger, asset acquisition, reorganization or similar business combination involving the Issuer and one or more businesses or assets.
Subscriber further acknowledges that, as described in the Issuer’s prospectus relating to its initial public offering dated
February 27, 2019 (the “Prospectus”), available at www.sec.gov, substantially all of the Issuer’s assets
consist of the cash proceeds of the Issuer’s initial public offering and private placements of its securities, and substantially
all of those proceeds have been deposited in a trust account (the “Trust Account”) for the benefit of the Issuer,
its public stockholders and the underwriters of the Issuer’s initial public offering. Except with respect to interest earned
on the funds held in the Trust Account that may be released to the Issuer to pay its tax obligations, if any, the cash in the Trust
Account may be disbursed only for the purposes set forth in the Prospectus. For and in consideration of the Issuer entering into
this Subscription Agreement, the receipt and sufficiency of which are hereby acknowledged, Subscriber, on behalf of itself and
its representatives, hereby irrevocable waives any and all right, title and interest, or any claim of any kind they have or may
have in the future arising out of this Subscription Agreement, in or to any monies held in the Trust Account, and agrees not to
seek recourse against the Trust Account as a result of, or arising out of, this Subscription Agreement; provided, however,
that nothing in this Section 8 shall be deemed to limit any Subscriber’s right, title, interest or claim to the Trust
Account by virtue of such Subscriber’s record or beneficial ownership of securities of the Issuer acquired by any means other
than pursuant to this Subscription Agreement, including but not limited to any redemption right with respect to any such securities
of the Issuer.

 

9. Miscellaneous.

 

a. Subscriber
acknowledges that the Issuer, the Placement Agents and others will rely on the acknowledgments, understandings, agreements, representations
and warranties contained in this Subscription Agreement. Prior to the Closing, Subscriber agrees to promptly notify the Issuer
if any of the acknowledgments, understandings, agreements, representations and warranties made by Subscriber as set forth herein
are no longer accurate in all material respects. Subscriber further acknowledges and agrees that the Placement Agents are third-party
beneficiaries of the representations and warranties of Subscriber contained in Section 4.

 

b. Each
of the Issuer and Subscriber is entitled to rely upon this Subscription Agreement and is irrevocably authorized to produce this
Subscription Agreement or a copy hereof to any interested party in any administrative or legal proceeding or official inquiry with
respect to the matters covered hereby to the extent required by law or by regulatory bodies.

 

c. Notwithstanding
anything to the contrary in this Subscription Agreement, prior to the Closing, Subscriber may transfer or assign all or a portion
of its rights under this Subscription Agreement; provided, that, such transferee or assignee agrees in writing to be bound
by and subject to the terms and conditions of this Subscription Agreement, makes the representations and warranties in Section
4 and completes Schedule A hereto. In the event of such a transfer or assignment, Subscriber shall update Schedule
B to provide the information required therein.

 

d. All
the agreements, representations and warranties made by each party hereto in this Subscription Agreement shall survive the Closing.

 

    17

     

    

 

e. The
Issuer may request from Subscriber such additional information as the Issuer may reasonably deem necessary to evaluate the eligibility
of Subscriber to acquire the Acquired Shares, and Subscriber shall provide such information as may be reasonably requested, to
the extent readily available and to the extent consistent with its internal policies and procedures; provided, that the
Issuer agrees to keep any such information provided by Subscriber confidential.

 

f. This
Subscription Agreement may not be modified, waived or terminated except by an instrument in writing, signed by the party against
whom enforcement of such modification, waiver, or termination is sought.

 

g. This
Subscription Agreement constitutes the entire agreement, and supersedes all other prior agreements, understandings, representations
and warranties, both written and oral, among the parties, with respect to the subject matter hereof.

 

h. Except
as otherwise provided herein, this Subscription Agreement shall be binding upon, and inure to the benefit of the parties hereto
and their heirs, executors, administrators, successors, legal representatives, and permitted assigns, and the agreements, representations,
warranties, covenants and acknowledgments contained herein shall be deemed to be made by, and be binding upon, such heirs, executors,
administrators, successors, legal representatives and permitted assigns.

 

i. If
any provision of this Subscription Agreement shall be invalid, illegal or unenforceable, the validity, legality or enforceability
of the remaining provisions of this Subscription Agreement shall not in any way be affected or impaired thereby and shall continue
in full force and effect.

 

j. This
Subscription Agreement may be executed in two (2) or more counterparts (including by electronic means), all of which shall be considered
one and the same agreement and shall become effective when signed by each of the parties and delivered to the other parties, it
being understood that all parties need not sign the same counterpart.

 

k. Each
party shall pay all of its own expenses in connection with this Subscription Agreement and the transactions contemplated herein.

 

l. Notices.
Any notice or communication required or permitted hereunder shall be in writing and either delivered personally, emailed or telecopied,
sent by overnight mail via a reputable overnight carrier, or sent by certified or registered mail, postage prepaid, and shall be
deemed to be given and received (a) when so delivered personally, (b) upon receipt of an appropriate electronic answerback or confirmation
when so delivered by telecopy (to such number specified below or another number or numbers as such person may subsequently designate
by notice given hereunder), (c) when sent, with no mail undeliverable or other rejection notice, if sent by email, or (d) five
(5) business days after the date of mailing to the address below or to such other address or addresses as such person may hereafter
designate by notice given hereunder:

 

(i) if
to Subscriber, to such address or addresses set forth on the signature page hereto;

 

    18

     

    

 

(ii) if to the
Issuer, to:

 

Tortoise Acquisition Corp.

452 Fifth Avenue

14th Floor

New York, NY 10018

Attn: Vincent T. Cubbage; Steven C. Schnitzer, Stephen
Pang

Email: VCubbage@tortoiseadvisors.com; SSchnitzer@tortoiseadvisors.com; SPang@tortoiseadvisors.com

 

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

 

Vinson & Elkins L.L.P.

1114 Avenue of the Americas

32nd Floor

New York, NY 10036

Attention: Brenda Lenahan; Ramey Layne; John Kupiec

Email: blenahan@velaw.com; rlayne@velaw.com; jkupiec@velaw.com;
and

 

(iii) if to the
Placement Agents, to:

 

Barclays Capital, Inc.

745 Seventh Avenue

5th Floor

New York, NY 10019

Attn: Amit Chandra

Email: amit.chandra@barclays.com

 

Goldman Sachs & Co. LLC

200 West Street

New York, NY 10282

Attn: Olympia McNerney

Email: Olympia.McNerney@gs.com

 

m. This
Subscription Agreement, and any claim or cause of action hereunder based upon, arising out of or related to this Subscription Agreement
(whether based on law, in equity, in contract, in tort or any other theory) or the negotiation, execution, performance or enforcement
of this Subscription Agreement, shall be governed by and construed in accordance with the Laws of the State of New York, without
giving effect to the principles of conflicts of law thereof.

 

    19

     

    

 

THE PARTIES HERETO
IRREVOCABLY SUBMIT TO THE EXCLUSIVE JURISDICTION OF THE UNITED STATES DISTRICT COURT FOR THE SOUTHERN DISTRICT OF NEW YORK, THE
SUPREME COURT OF THE STATE OF NEW YORK AND THE FEDERAL COURTS OF THE UNITED STATES OF AMERICA LOCATED IN THE STATE OF NEW YORK
SOLELY IN RESPECT OF THE INTERPRETATION AND ENFORCEMENT OF THE PROVISIONS OF THIS SUBSCRIPTION AGREEMENT AND THE DOCUMENTS REFERRED
TO IN THIS SUBSCRIPTION AGREEMENT AND IN RESPECT OF THE TRANSACTIONS CONTEMPLATED HEREBY, AND HEREBY WAIVE, AND AGREE NOT TO ASSERT,
AS A DEFENSE IN ANY ACTION, SUIT OR PROCEEDING FOR INTERPRETATION OR ENFORCEMENT HEREOF OR ANY SUCH DOCUMENT THAT IS NOT SUBJECT
THERETO OR THAT SUCH ACTION, SUIT OR PROCEEDING MAY NOT BE BROUGHT OR IS NOT MAINTAINABLE IN SAID COURTS OR THAT VENUE THEREOF
MAY NOT BE APPROPRIATE OR THAT THIS SUBSCRIPTION AGREEMENT OR ANY SUCH DOCUMENT MAY NOT BE ENFORCED IN OR BY SUCH COURTS, AND THE
PARTIES HERETO IRREVOCABLY AGREE THAT ALL CLAIMS WITH RESPECT TO SUCH ACTION, SUIT OR PROCEEDING SHALL BE HEARD AND DETERMINED
BY SUCH A NEW YORK STATE OR FEDERAL COURT. THE PARTIES HEREBY CONSENT TO AND GRANT ANY SUCH COURT JURISDICTION OVER THE PERSON
OF SUCH PARTIES AND OVER THE SUBJECT MATTER OF SUCH DISPUTE AND AGREE THAT MAILING OF PROCESS OR OTHER PAPERS IN CONNECTION WITH
SUCH ACTION, SUIT OR PROCEEDING IN THE MANNER PROVIDED IN SECTION 9(l) OR IN SUCH OTHER MANNER AS MAY BE PERMITTED BY LAW
SHALL BE VALID AND SUFFICIENT SERVICE THEREOF.

 

EACH PARTY ACKNOWLEDGES
AND AGREES THAT ANY CONTROVERSY WHICH MAY ARISE UNDER THIS SUBSCRIPTION AGREEMENT OR THE TRANSACTIONS CONTEMPLATED HEREBY IS LIKELY
TO INVOLVE COMPLICATED AND DIFFICULT ISSUES, AND THEREFORE EACH SUCH PARTY HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVES ANY RIGHT
SUCH PARTY MAY HAVE TO A TRIAL BY JURY IN RESPECT OF ANY LITIGATION DIRECTLY OR INDIRECTLY ARISING OUT OF OR RELATING TO THIS SUBSCRIPTION
AGREEMENT OR THE TRANSACTIONS CONTEMPLATED BY THIS SUBSCRIPTION AGREEMENT. EACH PARTY CERTIFIES AND ACKNOWLEDGES THAT (I) NO REPRESENTATIVE,
AGENT OR ATTORNEY OF ANY OTHER PARTY HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT SUCH OTHER PARTY WOULD NOT, IN THE EVENT OF
LITIGATION, SEEK TO ENFORCE THE FOREGOING WAIVER; (II) SUCH PARTY UNDERSTANDS AND HAS CONSIDERED THE IMPLICATIONS OF THE FOREGOING
WAIVER; (III) SUCH PARTY MAKES THE FOREGOING WAIVER VOLUNTARILY AND (IV) SUCH PARTY HAS BEEN INDUCED TO ENTER INTO THIS SUBSCRIPTION
AGREEMENT BY, AMONG OTHER THINGS, THE MUTUAL WAIVER AND CERTIFICATIONS IN THIS SECTION 9(m).

 

n. The
Issuer shall, by 9:00 a.m., New York City time, on the first (1st) business day immediately following the date of this Subscription
Agreement, issue one or more press releases or file with the Commission a Current Report on Form 8-K (collectively, the “Disclosure
Document”) disclosing all material terms of the transactions contemplated hereby, the Transaction, and any other material,
nonpublic information that the Issuer has provided to Subscriber at any time prior to the filing of the Disclosure Document. From
and after the issuance of the Disclosure Document, to the Issuer’s knowledge, Subscriber shall not be in possession of any
material, nonpublic information received from the Issuer or any of its officers, directors or employees. Notwithstanding anything
in this Subscription Agreement to the contrary, the Issuer shall not publicly disclose the name of Subscriber or any of its affiliates,
or include the name of Subscriber or any of its affiliates in any press release or in any filing with the Commission or any regulatory
agency or trading market, without the prior written consent of Subscriber, except (i) as required by the federal securities law
in connection with the Registration Statement, (ii) in a press release or marketing materials of the Issuer in connection with
the Transaction if agreeable by Subscriber and in a manner acceptable to Subscriber and (iii) to the extent such disclosure is
required by law, at the request of the Staff of the Commission or regulatory agency or under the regulations of the NYSE, in which
case the Issuer shall provide Subscriber with prior written notice of such disclosure permitted under this subclause (iii).

 

[Signature pages follow.]

 

    20

     

    

 

IN WITNESS WHEREOF, each of the Issuer
and Subscriber has executed or caused this Subscription Agreement to be executed by its duly authorized representative as of the
date set forth below.

 

	 	TORTOISE ACQUISITION CORP.
	 	 	 
	 	By:	 
	 	 	Name:
	 	 	Title:

 

Date: _____________________, 2020

 

Signature Page to 

Subscription Agreement

 

     

     

    

 

 

	SUBSCRIBER:	 
	 	 
	Signature of Subscriber:	 
	 	 
	[SUBSCRIBER]	 
	 	                                                	 
	By:	 	 
	Name: 	 	 
	Title:	 	 
	 	 
	 	 
	Date: _______________________, 2020	 
	 	 
	Name of Subscriber:	 
	 	 
	 	 
	(Please print.  Please indicate name and

capacity of person signing above)	 
	 	 
	 	 
	 	 
	Name in which securities are to be registered	 
	(if different):	 
	 	 
	Email Address:	 
	 	 
	Subscriber’s EIN: _______________	 
	 	 
	Address:	 
	 	 
	 	 
	 	 
	 	 
	 	 
	Attn: _________________________________	 
	 	 
	Telephone No.: __________________________	 
	 	 
	Facsimile No.: ___________________________	 
	 	 
	Aggregate Number of Acquired Shares subscribed for:	 
	 	 
	[●]	 

 

Signature Page to 

Subscription Agreement

 

     

     

    

 

Aggregate Purchase Price: $[●]

 

You must pay the Purchase Price by wire transfer of United States
dollars in immediately available funds to the account specified by the Issuer in the Closing Notice.

 

Number of Acquired Shares subscribed for and Aggregate Purchase
Price as of ___________, 2020, accepted and agreed to as of this _____ day of ____________, 2020, by:

 

	TORTOISE ACQUISITION CORP.	 
	 	 	 
	By:	 	 
	 	Name:	 
	 	Title:	 
	 	 
	Signature of Subscriber:	 
	 	 
	[SUBSCRIBER]	 
	 	 	 
	By:	 	 
	 	Name:	 
	 	Title:	 

 

Signature Page to 

Subscription Agreement

 

     

     

    

 

SCHEDULE A

ELIGIBILITY REPRESENTATIONS OF SUBSCRIBER

 

This Schedule must be completed by
Subscriber and forms a part of the Subscription Agreement to which it is attached. Capitalized terms used and not otherwise defined
in this Schedule have the meanings given to them in the Subscription Agreement. Subscriber must check the applicable box in either
Part A or Part B below and the applicable box in Part C below.

 

	A.	QUALIFIED INSTITUTIONAL BUYER STATUS

(Please check the applicable subparagraphs):

 

	☐	Subscriber is a “qualified institutional buyer” (as defined in Rule 144A under the Securities Act (a “QIB”)).

 

	☐	Subscriber is subscribing for the Acquired Shares as a fiduciary or agent for one or more investor accounts, and each owner
of such accounts is a QIB.

 

*** OR ***

 

		B.	INSTITUTIONAL ACCREDITED INVESTOR STATUS

(Please check the applicable subparagraphs):

 

Subscriber is an institutional “accredited investor”
(within the meaning of Rule 501(a) under the Securities Act) and has checked below the box(es) for the applicable provision under
which Subscriber qualifies as such:

 

		☐	Subscriber is an organization described in Section 501(c)(3) of the Internal Revenue Code of 1986, as amended, a corporation,
Massachusetts or similar business trust, or partnership that was not formed for the specific purpose of acquiring the securities
of the Issuer being offered in this offering, with total assets in excess of $5,000,000.

 

		☐	Subscriber is a “private business development company” as defined in Section 202(a)(22) of the Investment Advisers
Act of 1940.

 

		☐	Subscriber is a “bank” as defined in Section 3(a)(2) of the Securities Act.

 

		☐	Subscriber is a “savings and loan association” or other institution as defined in Section 3(a)(5)(A) of the Securities
Act, whether acting in its individual or fiduciary capacity.

 

		☐	Subscriber is a broker or dealer registered pursuant to Section 15 of the Exchange Act.

 

		☐	Subscriber is an “insurance company” as defined in Section 2(a)(13) of the Securities Act.

 

		☐	Subscriber is an investment company registered under the Investment Company Act of 1940.

 

    Schedule A-1

     

    

 

		☐	Subscriber is a “business development company” as defined in Section 2(a)(48) of the Investment Company Act of
1940.

 

		☐	Subscriber is a “Small Business Investment Company” licensed by the U.S. Small Business Administration under either
Section 301(c) or (d) of the Small Business Investment Act of 1958.

 

		☐	Subscriber is a plan established and maintained by a state, its political subdivisions, or any agency or instrumentality of
a state or its political subdivisions, for the benefit of its employees, and such plan has total assets in excess of $5,000,000.

 

		☐	Subscriber is an employee benefit plan within the meaning of the Employee Retirement Income Security Act of 1974 if the investment
decision is made by a plan fiduciary, as defined in Section 3(21) of such act, which is one of the following.

 

		☐	A bank;

 

		☐	A savings and loan association;

 

		☐	A insurance company; or

 

		☐	A registered investment adviser.

 

		☐	Subscriber is an employee benefit plan within the meaning of the Employee Retirement Income Security Act of 1974 with total
assets in excess of $5,000,000.

 

		☐	Subscriber is an employee benefit plan within the meaning of the Employee Retirement Income Security Act of 1974 that is a
self-directed plan with investment decisions made solely by persons that are accredited investors.

 

		☐	Subscriber is a trust with total assets in excess of $5,000,000, not formed for the specific purpose of acquiring the securities
offered by the Issuer in this offering, whose purchase is directed by a sophisticated person as described in Rule 506(b)(2)(ii)
under the Securities Act.

 

*** AND ***

 

		C.	AFFILIATE STATUS

(Please check the applicable
box)

 

SUBSCRIBER:

 

		☐	is:

 

		☐	is not:

 

an “affiliate” (as
defined in Rule 144 under the Securities Act) of the Issuer or acting on behalf of an affiliate of the Issuer.

 

    Schedule A-2

     

    

 

SCHEDULE B

SCHEDULE OF TRANSFERS

 

Subscriber’s Subscription was in the
amount of [●] shares of Class A Shares. The following transfers of a portion of the Subscription have been made:

 

	Date of Transfer or Reduction	 	Transferee	 	Number of Transferee Acquired Shares Transferred or Reduced	 	Subscriber Revised Subscription Amount
	 	 	 	 	 	 	 
	 	 	 	 	 	 	 
	 	 	 	 	 	 	 
	 	 	 	 	 	 	 
	 	 	 	 	 	 	 
	 	 	 	 	 	 	 

 

Schedule B as of ______________, 20__, accepted and agreed to
as of this ____ day of ____________, 20__ by:

 

	TORTOISE ACQUISITION CORP.	 
	 	 	 
	By:	 	 
	 	Name:	 
	 	Title:	 

 

	Signature of Subscriber:	 
	 	 
	[SUBSCRIBER]	 
	 	 	 
	By:	 	 
	 	Name:	 
	 	Title:	 

 

 

Schedule B-1

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