Document:

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                                                                    Exhibit 10.4

                                                     March 3, 2004

Tremisis Energy Acquisition Corporation
1775 Broadway
Suite 604
New York, New York 10019

EarlyBirdCapital, Inc.
600 Third Avenue
33rd Floor
New York, New York 10016

                  Re:      Initial Public Offering

Gentlemen:

                  The undersigned stockholder, officer and director of Tremisis
Energy Acquisition Corporation ("Company"), in consideration of
EarlyBirdCapital, Inc. ("EBC") entering into a letter of intent ("Letter of
Intent") to underwrite an initial public offering of the securities of the
Company ("IPO") and embarking on the IPO process, hereby agrees as follows
(certain capitalized terms used herein are defined in paragraph 12 hereof):

                  1. If the Company solicits approval of its stockholders of a
Business Combination, the undersigned will vote all Insider Shares owned by him
in accordance with the majority of the votes cast by the holders of the IPO
Shares.

                  2. In the event that the Company fails to consummate a
Business Combination within 18 months from the effective date ("Effective Date")
of the registration statement relating to the IPO (or 24 months under the
circumstances described in the prospectus relating to the IPO), the undersigned
will take all reasonable actions within his power to cause the Company to
liquidate as soon as reasonably practicable. The undersigned waives any and all
rights he may have to receive any distribution of cash, property or other assets
as a result of such liquidation with respect to his Insider Shares.

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Tremisis Energy Acquisition Corporation
EarlyBirdCapital, Inc.
May 3, 2004
Page 2

                  3. In order to minimize potential conflicts of interest which
may arise from multiple affiliations, the undersigned agrees to present to the
Company for its consideration, prior to presentation to any other person or
entity, any suitable opportunity to acquire an operating business, until the
earlier of the consummation by the Company of a Business Combination, the
liquidation of the Company or until such time as the undersigned ceases to be an
officer or director of the Company, subject to any pre-existing fiduciary
obligations the undersigned might have.

                  4. The undersigned acknowledges and agrees that the Company
will not consummate any Business Combination which involves a company which is
affiliated with any of the Insiders unless the Company obtains an opinion from
an independent investment banking firm reasonably acceptable to EBC that the
business combination is fair to the Company's stockholders from a financial
perspective.

                  5. Neither the undersigned, any member of the family of the
undersigned, nor any Affiliate of the undersigned will be entitled to receive
and will not accept any compensation for services rendered to the Company prior
to the consummation of the Business Combination; provided that the undersigned
shall be entitled to reimbursement from the Company for his out-of-pocket
expenses incurred in connection with seeking and consummating a Business
Combination.

                  6. Neither the undersigned, any member of the family of the
undersigned, or any Affiliate of the undersigned will be entitled to receive or
accept a finder's fee or any other compensation in the event the undersigned,
any member of the family of the undersigned or any Affiliate of the undersigned
originates a Business Combination.

                  7. The undersigned will escrow his Insider Shares for the
three year period commencing on the Effective Date subject to the terms of a
Stock Escrow Agreement which the Company will enter into with the undersigned
and American Stock Transfer & Trust Company as escrow agent.

                  8. The undersigned agrees that, during the three year period
terminating on January 27, 2007, he will not become involved (whether as owner,
manager, operator, creditor, partner, shareholder, joint venturer, member,
employee, officer, director, consultant or otherwise) with any Acquisition Fund
(as defined in Section 12(v) below) within the United States, unless such
Acquisition Fund engages EBC to be the managing underwriter of the initial
public offering of the Acquisition Fund's securities.

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Tremisis Energy Acquisition Corporation
EarlyBirdCapital, Inc.
May 3, 2004
Page 3

                           The undersigned hereby agrees and acknowledges that
(i) EBC would be irreparably injured in the event of a breach by the
undersigned of any of his obligations under this paragraph 8, (ii) monetary
damages would not be an adequate remedy for any such breach, and (iii) EBC shall
be entitled to injunctive relief, in addition to any other remedy it may have,
in the event of such breach.

                  9. I agree to be a director of the Company until the earlier
of the consummation by the Company of a Business Combination or the liquidation
of the Company. The undersigned's biographical information furnished to the
Company and EBC and attached hereto as Exhibit A is true and accurate in all
respects, does not omit any material information with respect to the
undersigned's background and contains all of the information required to be
disclosed pursuant to Section 401 of Regulation S-K, promulgated under the
Securities Act of 1933. The undersigned's Questionnaire furnished to the Company
and EBC and annexed as Exhibit B hereto is true and accurate in all respects.
The undersigned represents and warrants that:

         (a) he is not subject to or a respondent in any legal action for, any
injunction, cease-and-desist order or order or stipulation to desist or refrain
from any act or practice relating to the offering of securities in any
jurisdiction;

         (b) he has never been convicted of or pleaded guilty to any crime (i)
involving any fraud or (ii) relating to any financial transaction or handling of
funds of another person, or (iii) pertaining to any dealings in any securities
and he is not currently a defendant in any such criminal proceeding; and

         (c) he has never been suspended or expelled from membership in any
securities or commodities exchange or association or had a securities or
commodities license or registration denied, suspended or revoked.

                  10. I have full right and power, without violating any
agreement by which I am bound, to enter into this letter agreement and to serve
as a member of the Board of Directors of the Company.

                  11. I authorize any employer, financial institution, or
consumer credit reporting agency to release to EBC and its legal representatives
or agents (including any investigative search firm retained by EBC) any
information they may have about my background and finances ("Information").
Neither EBC nor its agents shall be violating my right of privacy in any manner
in requesting and obtaining the Information and I hereby release them from
liability for any damage whatsoever in that connection.

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Tremisis Energy Acquisition Corporation
EarlyBirdCapital, Inc.
May 3, 2004
Page 4

                  12. As used herein, (i) a "Business Combination" shall mean an
acquisition by merger, capital stock exchange, asset or stock acquisition,
reorganization or otherwise, of an operating business selected by the Company;
(ii) "Insiders" shall mean all officers, directors and stockholders of the
Company immediately prior to the IPO; (iii) "Insider Shares" shall mean all of
the shares of Common Stock of the Company owned by an Insider prior to the IPO;
(iv) "IPO Shares" shall mean the shares of Common Stock issued in the Company's
IPO; and (v) "Acquisition Fund" shall mean any company formed with the intent to
offer securities to the public and use the proceeds to consummate one or more
Business Combinations which are unspecified at the time of the securities
offering.

                                                     Jon Schotz
                                                     ----------
                                                     Print Name of Insider

                                                     /s/ Jon Schotz
                                                     --------------
                                                     Signature

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                                    EXHIBIT A

     JON SCHOTZ has been a director of ours since our inception. Mr. Schotz has
been a partner of Saybrook Capital, LLC, a private investment bank engaged in
capital management and financial advisory services, since he co-founded it in
February 1990 and has managed the Saybrook Tax-Exempt Opportunity Funds since
May 1999. Mr. Schotz also helps manage the investments of Saybrook's proprietary
capital as well as the investments of the Saybrook Fund. Prior to co-founding
Saybrook, Mr. Schotz was involved in opening the Los Angeles office of Ehrlich
Bober & Co., Inc., a public finance investment bank, in 1983. Mr. Schotz is also
a director of Saybrook Capital Corp. Mr. Schotz received a B.A. and a Master of
Public and Private Management degree from Yale University.<PAGE>

                      INVESTMENT MANAGEMENT TRUST AGREEMENT

                  This Agreement is made as of __________ ____, 2004 by and
between Tremisis Energy Acquisition Corporation (the "Company") and American
Stock Transfer & Trust Company ("Trustee").

                  WHEREAS, the Company's Registration Statement on Form S-1, No.
333-______ ("Registration Statement"), for its initial public offering of
securities ("IPO") has been declared effective as of the date hereof by the
Securities and Exchange Commission ("Effective Date"); and

                  WHEREAS, EarlyBirdCapital, Inc. ("EBC") is acting as the
representative of the underwriters in the IPO; and

                  WHEREAS, as described in the Company's Registration Statement,
and in accordance with the Company's Certificate of Incorporation, $17,850,000
of the gross proceeds of the IPO ($20,606,250 if the underwriters over-allotment
option is exercised in full) will be delivered to the Trustee to be deposited
and held in a trust account for the benefit of the Company and the holders of
the Company's common stock, par value $.0001 per share, issued in the IPO (the
amount to be delivered to the Trustee will be referred to herein as the
"Property"; the stockholders for whose benefit the Trustee shall hold the
Property will be referred to as the "Public Stockholders," and the Public
Stockholders and the Company will be referred to together as the
"Beneficiaries"); and

                  WHEREAS, the Company and the Trustee desire to enter into this
Agreement to set forth the terms and conditions pursuant to which the Trustee
shall hold the Property;

                  IT IS AGREED:

1.  Agreements and Covenants of Trustee. The Trustee hereby agrees and covenants
to:

                  (a) Hold the Property in trust for the Beneficiaries in
accordance with the terms of this Agreement in a segregated trust account
("Trust Account") established by the Trustee at a branch of JPMorgan Chase NY
Bank selected by the Trustee;

                  (b) Manage, supervise and administer the Trust Account subject
to the terms and conditions set forth herein;

                  (c) In a timely manner, upon the instruction of the Company,
to invest and reinvest the Property in any "Government Security." As used
herein, Government Security means any Treasury Bill issued by the United States,
having a maturity of one hundred and eighty days or less;

                  (d) Collect and receive, when due, all principal and income
arising from the Property, which shall become part of the "Property," as such
term is used herein;

                  (e) Notify the Company of all communications received by it
with respect to
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any Property requiring action by the Company;

                  (f) Supply any necessary information or documents as may be
requested by the Company in connection with the Company's preparation of the tax
returns for the Trust Account;

                  (g) Participate in any plan or proceeding for protecting or
enforcing any right or interest arising from the Property if, as and when
instructed by the Company to do so;

                  (h) Render to the Company and to EBC, and to such other person
as the Company may instruct, monthly written statements of the activities of and
amounts in the Trust Account reflecting all receipts and disbursements of the
Trust Account; and

                  (i) Commence liquidation of the Trust Account only after
receipt of and only in accordance with the terms of a letter ("Termination
Letter"), in a form substantially similar to that attached hereto as either
Exhibit A or Exhibit B, signed on behalf of the Company by its President or
Chairman of the Board and Secretary, and complete the liquidation of the Trust
Account and distribute the Property in the Trust Account only as directed in the
Termination Letter and the other documents referred to therein.

2. Agreements and Covenants of the Company. The Company hereby agrees and
covenants to:

                  (a) Give all instructions to the Trustee hereunder in writing,
signed by the Company's President or Chairman of the Board. In addition, except
with respect to its duties under paragraph 1(i) above, the Trustee shall be
entitled to rely on, and shall be protected in relying on, any verbal or
telephonic advice or instruction which it in good faith believes to be given by
any one of the persons authorized above to give written instructions, provided
that the Company shall promptly confirm such instructions in writing;

                  (b) Hold the Trustee harmless and indemnify the Trustee from
and against, any and all expenses, including reasonable counsel fees and
disbursements, or loss suffered by the Trustee in connection with any action,
suit or other proceeding brought against the Trustee involving any claim, or in
connection with any claim or demand which in any way arises out of or relates to
this Agreement, the services of the Trustee hereunder, or the Property or any
income earned from investment of the Property, except for expenses and losses
resulting from the Trustee's gross negligence or willful misconduct. Promptly
after the receipt by the Trustee of notice of demand or claim or the
commencement of any action, suit or proceeding, pursuant to which the Trustee
intends to seek indemnification under this paragraph, it shall notify the
Company in writing of such claim (hereinafter referred to as the "Indemnified
Claim"). The Trustee shall have the right to conduct and manage the defense
against such Indemnified Claim, provided, that the Trustee shall obtain the
consent of the Company with respect to the selection of counsel, which consent
shall not be unreasonably withheld. The Company may participate in such action
with its own counsel; and

                  (c) Pay the Trustee an initial acceptance fee of $1,000 and an
annual fee of

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$3,000 (it being expressly understood that the Property shall not be used to pay
such fee). The Company shall pay the Trustee the initial acceptance fee and
first year's fee at the consummation of the IPO and thereafter on the
anniversary of the Effective Date. The Trustee shall refund to the Company the
fee (on a pro rata basis) with respect to any period after the liquidation of
the Trust Fund. The Company shall not be responsible for any other fees or
charges of the Trustee except as may be provided in paragraph 2(b) hereof (it
being expressly understood that the Property shall not be used to make any
payments to the Trustee under such paragraph).

3. Limitations of Liability. The Trustee shall have no responsibility or
liability to:

                  (a) Take any action with respect to the Property, other than
as directed in paragraph 1 hereof and the Trustee shall have no liability to any
party except for liability arising out of its own gross negligence or willful
misconduct;

                  (b) Institute any proceeding for the collection of any
principal and income arising from, or institute, appear in or defend any
proceeding of any kind with respect to, any of the Property unless and until it
shall have received instructions from the Company given as provided herein to do
so and the Company shall have advanced or guaranteed to it funds sufficient to
pay any expenses incident thereto;

                  (c) Change the investment of any Property, other than in
compliance with paragraph 1(c);

                  (d) Refund any depreciation in principal of any Property;

                  (e) Assume that the authority of any person designated by the
Company to give instructions hereunder shall not be continuing unless provided
otherwise in such designation, or unless the Company shall have delivered a
written revocation of such authority to the Trustee;

                  (f) The other parties hereto or to anyone else for any action
taken or omitted by it, or any action suffered by it to be taken or omitted, in
good faith and in the exercise of its own best judgment, except for its gross
negligence or willful misconduct. The Trustee may rely conclusively and shall be
protected in acting upon any order, notice, demand, certificate, opinion or
advice of counsel (including counsel chosen by the Trustee), statement,
instrument, report or other paper or document (not only as to its due execution
and the validity and effectiveness of its provisions, but also as to the truth
and acceptability of any information therein contained) which is believed by the
Trustee, in good faith, to be genuine and to be signed or presented by the
proper person or persons. The Trustee shall not be bound by any notice or
demand, or any waiver, modification, termination or rescission of this agreement
or any of the terms hereof, unless evidenced by a written instrument delivered
to the Trustee signed by the proper party or parties and, if the duties or
rights of the Trustee are affected, unless it shall give its prior written
consent thereto;

                  (g) Verify the correctness of the information set forth in the
Registration Statement or to confirm or assure that any acquisition made by the
Company or any other action taken by it is as contemplated by the Registration
Statement; and

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<PAGE>

                  (h) Pay any taxes on behalf of the Trust Account (it being
expressly understood that the Property shall not be used to pay any such taxes
and that such taxes, if any, shall be paid by the Company from funds not held in
the Trust Account).

4. Termination. This Agreement shall terminate as follows:

                  (a) If the Trustee gives written notice to the Company that it
desires to resign under this Agreement, the Company shall use its reasonable
efforts to locate a successor trustee. At such time that the Company notifies
the Trustee that a successor trustee has been appointed by the Company and has
agreed to become subject to the terms of this Agreement, the Trustee shall
transfer the management of the Trust Account to the successor trustee, including
but not limited to the transfer of copies of the reports and statements relating
to the Trust Account, whereupon this Agreement shall terminate; provided,
however, that, in the event that the Company does not locate a successor trustee
within ninety days of receipt of the resignation notice from the Trustee, the
Trustee may submit an application to have the Property deposited with the United
States District Court for the Southern District of New York and upon such
deposit, the Trustee shall be immune from any liability whatsoever;

                  (b) At such time that the Trustee has completed the
liquidation of the Trust Account in accordance with the provisions of paragraph
1(i) hereof, and distributed the Property in accordance with the provisions of
the Termination Letter, this Agreement shall terminate except with respect to
Paragraph 2(b); or

                  (c) On such date after ________ __, 2006 when the Trustee
deposits the Property with the United States District Court for the Southern
District of New York in the event that, prior to such date, the Trustee has not
received a Termination Letter from the Company pursuant to paragraph 1(i).

5. Miscellaneous.

                  (a) The Company and the Trustee each acknowledge that the
Trustee will follow the security procedures set forth below with respect to
funds transferred from the Trust Account. Upon receipt of written instructions,
the Trustee will confirm such instructions with an Authorized Individual at an
Authorized Telephone Number listed on the attached Exhibit C. The Company and
the Trustee will each restrict access to confidential information relating to
such security procedures to authorized persons. Each party must notify the other
party immediately if it has reason to believe unauthorized persons may have
obtained access to such information, or of any change in its authorized
personnel. In executing funds transfers, the Trustee will rely upon account
numbers or other identifying numbers of a beneficiary, beneficiary's bank or
intermediary bank, rather than names. The Trustee shall not be liable for any
loss, liability or expense resulting from any error in an account number or
other identifying number, provided it has accurately transmitted the numbers
provided.

                  (b) This Agreement shall be governed by and construed and
enforced in

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accordance with the laws of the State of New York, without giving effect to
conflict of laws. It may be executed in several counterparts, each one of which
shall constitute an original, and together shall constitute but one instrument.

                  (c) This Agreement contains the entire agreement and
understanding of the parties hereto with respect to the subject matter hereof.
This Agreement or any provision hereof may only be changed, amended or modified
by a writing signed by each of the parties hereto; provided, however, that no
such change, amendment or modification may be made without the prior written
consent of EBC. As to any claim, cross-claim or counterclaim in any way relating
to this Agreement, each party waives the right to trial by jury.

                  (d) The parties hereto consent to the jurisdiction and venue
of any state or federal court located in the City of New York for purposes of
resolving any disputes hereunder.

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

                  if to the Trustee, to:

                           American Stock Transfer
                             & Trust Company
                           59 Maiden Lane
                           New York, New York 10038
                           Attn:
                           Fax No.:

                  if to the Company, to:

                           Tremisis Energy Acquisition Corporation
                           1775 Broadway
                           Suite 604
                           New York, New York 10019
                           Attn:    Lawrence S. Coben, Chairman
                           Fax No.:

                  in either case with a copy to:

                           EarlyBirdCapital, Inc.
                           600 Third Avenue, 33rd Floor
                           New York, New York 10016
                           Attn:    David M. Nussbaum, Chairman
                           Fax No.:  (212) 269-3796

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<PAGE>

                  (f) This Agreement may not be assigned by the Trustee without
the prior consent of the Company.

                  (g) Each of the Trustee and the Company hereby represents that
it has the full right and power and has been duly authorized to enter into this
Agreement and to perform its respective obligations as contemplated hereunder.
The Trustee acknowledges and agrees that it shall not make any claims or proceed
against the Trust Account, including by way of set-off, and shall not be
entitled to any funds in the Trust Account under any circumstance.

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<PAGE>

                  IN WITNESS WHEREOF, the parties have duly executed this
Investment Management Trust Agreement as of the date first written above.

                             AMERICAN STOCK TRANSFER & TRUST
                             COMPANY, as Trustee

                             By: ____________________________
                                 Name:
                                 Title:

                             TREMISIS ENERGY ACQUISITION CORPORATION

                             By: _____________________________
                                 Name:       Lawrence S. Coben
                                 Title:      Chairman

                                       7
<PAGE>

                                                                       EXHIBIT A

                             [LETTERHEAD OF COMPANY]

                                       [INSERT DATE]

American Stock Transfer
  & Trust Company
59 Maiden Lane
New York, New York 10038
Attn:

                  Re:   Trust Account No. [             ] Termination Letter

Gentlemen:

                  Pursuant to paragraph 1(i) of the Investment Management Trust
Agreement between Tremisis Energy Acquisition Corporation ("Company") and
American Stock Transfer & Trust Company ("Trustee"), dated as of _____________,
2004 ("Trust Agreement"), this is to advise you that the Company has entered
into an agreement ("Business Agreement") with __________________ ("Target
Business") to consummate a business combination with Target Business ("Business
Combination") on or about [INSERT DATE]. The Company shall notify you at least
48 hours in advance of the actual date of the consummation of the Business
Combination ("Consummation Date").

                  In accordance with the terms of the Trust Agreement, we hereby
authorize you to commence liquidation of the Trust Account to the effect that,
on the Consummation Date, all of funds held in the Trust Account will be
immediately available for transfer to the account or accounts that the Company
shall direct on the Consummation Date.

                  On the Consummation Date (i) counsel for the Company shall
deliver to you written notification that the Business Combination has been
consummated, and (ii) the Company shall deliver to you written instructions with
respect to the transfer of the funds held in the Trust Account ("Instruction
Letter"). You are hereby directed and authorized to transfer the funds held in
the Trust Account immediately upon your receipt of the counsel's letter and the
Instruction Letter, in accordance with the terms of the Instruction Letter. In
the event that certain deposits held in the Trust Account may not be liquidated
by the Consummation Date without penalty, you will notify the Company of the
same and the Company shall direct you as to whether such funds should remain in
the Trust Account and distributed after the Consummation Date to the Company.
Upon the distribution of all the funds in the Trust Account pursuant to the
terms hereof, the Trust Agreement shall be terminated.

                  In the event that the Business Combination is not consummated
on the Consummation Date described in the notice thereof and we have not
notified you on or before the original Consummation Date of a new Consummation
Date, then the funds held in the Trust Account shall be reinvested as provided
in the Trust Agreement on the business day immediately following the
Consummation Date as set forth in the notice.

                                      Very truly yours,

                                      TREMISIS ENERGY ACQUISITION CORPORATION

                                       8
<PAGE>

                                      By:________________________________
                                           Lawrence S. Coben, Chairman

                                      By:________________________________
                                           Isaac Kier, Secretary

                                       9
<PAGE>

                                                                       EXHIBIT B

                            [LETTERHEAD OF COMPANY]

                                      [INSERT DATE]

American Stock Transfer
  & Trust Company
59 Maiden Lane
New York, New York 10038
Attn:

                  Re:    Trust Account No. [           ] Termination Letter

Gentlemen:

                  Pursuant to paragraph 1(i) of the Investment Management Trust
Agreement between Tremisis Energy Acquisition Corporation ("Company") and
American Stock Transfer & Trust Company ("Trustee"), dated as of _____________,
2004 ("Trust Agreement"), this is to advise you that the Board of Directors of
the Company has voted to dissolve and liquidate the Company. Attached hereto is
a copy of the minutes of the meeting of the Board of Directors of the Company
relating thereto, certified by the Secretary of the Company as true and correct
and in full force and effect.

                  In accordance with the terms of the Trust Agreement, we hereby
authorize you, to commence liquidation of the Trust Account. You will notify the
Company and ___________ ("Designated Paying Agent") in writing as to when all of
the funds in the Trust Account will be available for immediate transfer
("Transfer Date"). The Designated Paying Agent shall thereafter notify you as to
the account or accounts of the Designated Paying Agent that the funds in the
Trust Account should be transferred to on the Transfer Date so that the
Designated Paying Agent may commence distribution of such funds in accordance
with the Company's instructions. You shall have no obligation to oversee the
Designated Paying Agent's distribution of the funds. Upon the payment to the
Designated Paying Agent of all the funds in the Trust Account, the Trust
Agreement shall be terminated.

                                 Very truly yours,

                                 TREMISIS ENERGY ACQUISITION CORPORATION

                                 By:________________________________
                                      Lawrence S. Coben, Chairman

                                 By:________________________________
                                     Isaac Kier, Secretary

                                       10
<PAGE>

                                    EXHIBIT C

AUTHORIZED INDIVIDUAL(S)                    AUTHORIZED
FOR TELEPHONE CALL BACK                     TELEPHONE NUMBER(S)

COMPANY:

Tremisis Energy Acquisition Corporation
1775 Broadway
Suite 604
New York, New York 10019
Attn:  Lawrence S. Coben, Chairman

TRUSTEE:

American Stock Transfer
  & Trust Company
59 Maiden Lane
New York, New York 10038
Attn:

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