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                                                                    Exhibit 10.2

                                                     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.
March 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 commencing on the
Effective Date, Coqui Capital Partners, L.P. ("Related Party"), shall be allowed
to charge the Company an allocable share of Related Party's overhead, up to
$2,500 per month, to compensate it for the Company's use of Related Party's
offices, utilities and personnel. Related Party and the undersigned shall also
be entitled to reimbursement from the Company for their 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

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Tremisis Energy Acquisition Corporation
EarlyBirdCapital, Inc.
March 3, 2004
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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.

                     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 the Secretary and Treasurer and 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 Secretary and Treasurer and 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
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Tremisis Energy Acquisition Corporation
EarlyBirdCapital, Inc.
March 3, 2004
Page 4


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.

                  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.

                                                     Isaac Kier
                                                     ----------
                                                     Print Name of Insider


                                                     /s/ Isaac Kier
                                                     --------------
                                                     Signature


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                                    EXHIBIT A

ISAAC KIER has been a member of our board of directors and our secretary and
treasurer since our inception. Since February 2000, Mr. Kier has served as a
general partner of Coqui Capital Patners L.P., a venture capital firm, which
invests primarily in early stage companies. Mr. Kier has been a director of
eDiets.com, Inc., a Nasdaq-listed leading provider of online diet and fitness
programs and related products and services, since November 1999. Since October
1997, he has been a principal and managing partner of First Americas Partners,
LLC, an investment partnership focusing on investments in North and South
America. From 1987 to 1997, he served as the managing partner of the Alabama 8
Market, a non-wireline cellular licensee. From 1982 until its sale in 1995, Mr.
Kier served as the chairman of the board and chief executive officer of Lida,
Inc., a Nasdaq-listed company engaged in textile production and printing. Mr.
Kier also serves on the board of directors of several private companies
including Hudson Health Sciences, Caribbean Storage, Inc., Montebello Brand
Liquors, Inc. and Islanet, Inc. Mr. Kier received a B.A. in Economics from
Cornell University and a J.D. from George Washington University Law School.