EXHIBIT 5.1

                                 GRAUBARD MILLER
                                600 THIRD AVENUE
                          NEW YORK, NEW YORK 10016-2097


                                                                April 27, 2004




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

Dear Sirs:


         Reference is made to the Registration Statement on Form S-1
("Registration Statement") filed by Tremisis Energy Acquisition Corporation
("Company"), a Delaware corporation, under the Securities Act of 1933, as
amended ("Act"), covering (i) 5,500,000 Units, with each Unit consisting of one
share of the Company's common stock, par value $.0001 per share (the "Common
Stock"), and warrants to purchase two shares of the Company's Common Stock (the
"Warrants") to the underwriters for whom EarlyBirdCapital, Inc. is acting as
representative (collectively, the "Underwriters"), (ii) up to 825,000 Units (the
"Over-Allotment Units") which the Underwriters will have a right to purchase
from the Company to cover over-allotments, if any, (iii) up to 275,000 Units
(the "Purchase Option Units") which EarlyBirdCapital, Inc. will have the right
to purchase ("Purchase Option") for its own account or that of its designees,
(iv) all shares of Common Stock and all Warrants issued as part of the Units,
Over-Allotment Units and the Purchase Option Units and (v) all shares of Common
Stock issuable upon exercise of the Warrants included in the Units,
Over-Allotment Units and Purchase Option Units.



         We have examined such documents and considered such legal matters as we
have deemed necessary and relevant as the basis for the opinion set forth below.
With respect to such examination, we have assumed the genuineness of all
signatures, the authenticity of all documents submitted to us as originals, the
conformity to original documents of all documents submitted to us as reproduced
or certified copies, and the authenticity of the originals of those latter
documents. As to questions of fact material to this opinion, we have, to the
extent deemed appropriate, relied upon certain representations of certain
officers and employees of the Company.

         Based upon the foregoing, we are of the opinion that:

         1. The Units, the Over-Allotment Units, the Purchase Option Units, the
Warrants and the Common Stock to be sold to the Underwriters, when issued and
sold in accordance with and in the manner described in the plan of distribution
set forth in the Registration Statement, will be duly authorized, validly
issued, fully paid and non assessable.

         2. Each of the Purchase Option and Warrants constitutes legal, valid
and binding obligations of the Company, enforceable against it in accordance
with its terms, except (i) as limited by applicable bankruptcy, insolvency,
reorganization, moratorium, and other laws of general application affecting
enforcement of creditors' rights generally, (ii) as limited by laws relating to
the availability of specific performance, injunctive relief, or other equitable
remedies, and (iii) to the extent indemnification provisions contained such
documents, if any, may be limited by applicable federal or state law and
consideration of public policy.

         We are opining solely on all applicable statutory provisions of
Delaware corporate law, including the rules and regulations underlying those
provisions, all applicable provisions of the Delaware Constitution and all
applicable judicial and regulatory determinations. We hereby consent to the use
of this opinion as an exhibit to the Registration Statement, to the use of our
name as your counsel and to all




references made to us in the Registration Statement and in the Prospectus
forming a part thereof. In giving this consent, we do not hereby admit that we
are in the category of persons whose consent is required under Section 7 of the
Act, or the rules and regulations promulgated thereunder.

                                 Very truly yours,



                                 /s/ Graubard Miller