Sec Form 3 Filing - Hennessy Thomas D @ TortoiseEcofin Acquisition Corp. III - 2023-07-19

FORM 3 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Hennessy Thomas D 2. Issuer Name and Ticker or Trading Symbol TortoiseEcofin Acquisition Corp. III [ TRTL] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 195 US HWY 50, SUITE 208 3. Date of Earliest Transaction (MM/DD/YY) 07/19/2023 (Street) ZEPHYR COVE, NV89448 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Class B Ordinary Shares ( 1 ) ( 1 ) ( 1 ) Class A Ordinary Shares 6,855,000 I See footnote ( 2 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Hennessy Thomas D 195 US HWY 50 SUITE 208 ZEPHYR COVE, NV89448 X X Hennessy Capital Growth Partners Fund I, LP 195 US HWY 50 SUITE 208 ZEPHYR COVE, NV89448 X Hennessy Capital Growth Partners Fund I SPV V, LLC 195 US HWY 50 SUITE 208 ZEPHYR COVE, NV89448 X Signatures /s/ Thomas D. Hennessy 07/31/2023 Signature of Reporting Person Date /s/ Thomas D. Hennessy, as the General Partner of Hennessy Capital Growth Partners Fund I, LP 07/31/2023 Signature of Reporting Person Date /s/ Thomas D. Hennessy, as the General Partner of Hennessy Capital Growth Partners Fund I, LP, as Managing Member of Hennessy Capital Growth Partners Fund I SPV V, LLC 07/31/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The Class B Ordinary Shares are convertible into the Issuer's Class A Ordinary Shares on a one-for-one basis, subject to adjustment pursuant to certain anti-dilution rights, and have no expiration date. ( 2 )Thomas D. Hennessy is the general partner of Hennessy Capital Growth Partners Fund I, LP (the "Fund"), which is the managing member of Hennessy Capital Growth Partners Fund I SPV V, LLC ("SPV"). On July 19, 2023, SPV acquired a limited liability company interest in TortoiseEcofin Sponsor III LLC, the sponsor of the Issuer (the "Sponsor"), and became the managing member of the Sponsor. By virtue of this relationship, each of Mr. Hennessy, the Fund and SPV may be deemed to have or share beneficial ownership of the securities held of record by the Sponsor. Each of Mr. Hennessy, the Fund and SPV disclaims any beneficial ownership of the reported Class B ordinary shares other than to the extent of any pecuniary interest he or it may have therein.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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