Document:

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                                                                     Exhibit 4.1

     NUMBER                                                         UNITS
U-__________

  SEE REVERSE FOR         TREMISIS ENERGY ACQUISITION CORPORATION
CERTAIN DEFINITIONS

                                                        CUSIP __________________

         UNITS CONSISTING OF ONE SHARE OF COMMON STOCK AND TWO WARRANTS
                   EACH TO PURCHASE ONE SHARE OF COMMON STOCK

THIS CERTIFIES THAT
                   -------------------------------------------------------------
is the owner of                                                           Units.
                ---------------------------------------------------------

Each Unit ("Unit") consists of one (1) share of common stock, par value $.0001
per share ("Common Stock"), of Tremisis Energy Acquisition Corporation, a
Delaware corporation (the "Company"), and two warrants (the "Warrants"). Each
Warrant entitles the holder to purchase one (1) share of Common Stock for $5.00
per share (subject to adjustment). Each Warrant will become exercisable on the
later of (i) the Company's completion of a merger, capital stock exchange, asset
acquisition or other similar business combination or (ii) ______________, 2005
and will expire unless exercised before 5:00 p.m., New York City Time, on
____________, 2008, or earlier upon redemption (the "Expiration Date"). The
Common Stock and Warrants comprising the Units represented by this certificate
are not transferable separately prior to __________, 2004, subject to earlier
separation in the discretion of EarlyBirdCapital, Inc. The terms of the Warrants
are governed by a Warrant Agreement, dated as of _______, 2004, between the
Company and American Stock Transfer & Trust Company, as Warrant Agent, and are
subject to the terms and provisions contained therein, all of which terms and
provisions the holder of this certificate consents to by acceptance hereof.
Copies of the Warrant Agreement are on file at the office of the Warrant Agent
at 59 Maiden Lane, New York, New York 10038, and are available to any Warrant
holder on written request and without cost.

    This certificate is not valid unless countersigned by the Transfer Agent and
Registrar of the Company.

    Witness the facsimile seal of the Company and the facsimile signature of its
duly authorized officers.

By

                                        [SEAL]
-------------------------------------              -----------------------------
                Chairman of the Board              Secretary

<PAGE>

                     TREMISIS ENERGY ACQUISITION CORPORATION

         The Company will furnish without charge to each stockholder who so
requests, a statement of the powers, designations, preferences and relative,
participating, optional or other special rights of each class of stock or series
thereof of the Company and the qualifications, limitations, or restrictions of
such preferences and/or rights.

         The following abbreviations, when used in the inscription on the face
of this certificate, shall be construed as though they were written out in full
according to applicable laws or regulations:

<TABLE>
<S>                 <C>                                           <C>
         TEN COM -  as tenants in common                          UNIF GIFT MIN ACT - ______ Custodian _______
         TEN ENT -  as tenants by the entireties                                      (Cust)          (Minor)
         JT TEN -   as joint tenants with right of survivorship                 under Uniform Gifts to Minors
                    and not as tenants in common                                Act ______________
                                                                                        (State)
</TABLE>

Additional Abbreviations may also be used though not in the above list.

         For value received, ___________________________ hereby sell, assign and
transfer unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
    IDENTIFYING NUMBER OF ASSIGNEE

----------------------------------------

----------------------------------------

--------------------------------------------------------------------------------
 (PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE)

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--------------------------------------------------------------------------------

                                                                        Units
-----------------------------------------------------------------------

represented by the within Certificate, and do hereby irrevocably constitute and

appoint                                                               Attorney
        -------------------------------------------------------------

to transfer the said Units on the books of the within named Company will full
power of substitution in the premises.

Dated
      ---------------                 ------------------------------------------
                                      NOTICE:  The signature to this assignment
                                               must correspond with the name as
                                               written upon the face of the
                                               certificate in every particular,
                                               without alteration or enlargement
                                               or any change whatever.

Signature(s) Guaranteed:

--------------------------------------------------------------------------------
THE SIGNATURE(S) SHOULD BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION
(BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH
MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM, PURSUANT TO
S.E.C. RULE 17Ad-15.<PAGE>

<TABLE>
<CAPTION>

                                                                                                                      EXHIBIT 4.2

<S>                                            <C>                                                            <C>
               NUMBER                             (SEE REVERSE SIDE FOR LEGEND)                                         SHARES

         ______C

                                             TREMISIS ENERGY ACQUISITION CORPORATION

                                        INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE

                                                            COMMON STOCK

                                                                                                                 SEE REVERSE FOR
                                                                                                             CERTAIN DEFINITIONS

                  THIS CERTIFIES THAT                                                             CUSIP ______________

                  IS THE OWNER OF

                        FULLY PAID AND NON-ASSESSABLE SHARES OF THE PAR VALUE OF $.0001 EACH OF THE COMMON STOCK OF

                                                 TREMISIS ENERGY ACQUISITION CORPORATION

                 transferable on the books of the Corporation in person or by duly authorized attorney upon surrender of
                      this certificate properly endorsed. This certificate is not valid unless countersigned by the
                            Transfer Agent and registered by the Registrar. Witness the seal of the Corporation
                                        and the facsimile signatures of its duly authorized officers.

                  Dated:

                                                            [LOGO OMITTED]
         --------------------------------------------                               ----------------------------------------------
         CHAIRMAN                                                                   SECRETARY
</TABLE>

<PAGE>

         The following abbreviations, when used in the inscription on the face
of this certificate, shall be construed as though they were written out in full
according to applicable laws or regulations:

<TABLE>
<CAPTION>

<S>                      <C>                                         <C>
         TEN COM -         as tenants in common                       UNIF GIFT MIN ACT - _____   Custodian ______
         TEN ENT -         as tenants by the entireties                                   (Cust)            (Minor)
         JT TEN -          as joint tenants with right of survivorship         under Uniform Gifts to Minors
                           and not as tenants in common                            Act ______________
                                                                                          (State)
</TABLE>

    Additional Abbreviations may also be used though not in the above list.

                     TREMISIS ENERGY ACQUISITION CORPORATION

         The Corporation will furnish without charge to each stockholder who so
requests the powers, designations, preferences and relative, participating,
optional or other special rights of each class of stock or series thereof of the
Corporation and the qualifications, limitations, or restrictions of such
preferences and/or rights. This certificate and the shares represented thereby
are issued and shall be held subject to all the provisions of the Certificate of
Incorporation and all amendments thereto and resolutions of the Board of
Directors providing for the issue of shares of Preferred Stock (copies of which
may be obtained from the secretary of the Corporation), to all of which the
holder of this certificate by acceptance hereof assents.

         For value received, ___________________________ hereby sell, assign and
transfer unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
    IDENTIFYING NUMBER OF ASSIGNEE

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|                                     |
|                                     |
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________________________________________________________________________________
 (PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE)

________________________________________________________________________________

________________________________________________________________________________

_________________________________________________________________________ shares

of the capital stock represented by the within Certificate, and do hereby
irrevocably constitute and appoint ____________________________________________
______________________________________Attorney to transfer the said stock on the
books of the within named Corporation will full power of substitution in the
premises.

Dated _________________

                               _________________________________________________
                               NOTICE:  The signature to this assignment must
                                        correspond with the name as written
                                        upon the face of the certificate in
                                        every particular, without alteration or
                                        enlargement any change whatever.
Signature(s) Guaranteed:

________________________________________________________
THE SIGNATURE(S) SHOULD BE GUARANTEED BY AN ELIGIBLE GUARANTOR
INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS
AND CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE
GUARANTEE MEDALLION PROGRAM, PURSUANT TO S.E.C. RULE 17Ad-15.

The holder of this certificate shall be entitled to receive funds from the trust
fund only in the event of the Company's liquidation or if the holder seeks to
convert his respective shares into cash upon a business combination which he
voted against and which is actually completed by the Company. In no other
circumstances shall the holder have any right or interest of any kind in or to
the trust fund.

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