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                          REGISTRATION RIGHTS AGREEMENT

         THIS REGISTRATION RIGHTS AGREEMENT (this "Agreement") is entered into
as of the ___nd day of __________, 2004, by and among: Tremisis Energy
Acquisition Corporation, a Delaware corporation (the "Company"); and the
undersigned parties listed under Investor on the signature page hereto (each, an
"Investor" and collectively, the "Investors").

         WHEREAS, the Investors currently hold all of the issued and outstanding
securities of the Company;

         WHEREAS, the Investors and the Company desire to enter into this
Agreement to provide the Investors with certain rights relating to the
registration of shares of Common Stock held by them;

         NOW, THEREFORE, in consideration of the mutual covenants and agreements
set forth herein, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

1.       DEFINITIONS.  The following capitalized terms used herein have the
following meanings:

                  "Agreement" means this Agreement, as amended, restated,
supplemented, or otherwise modified from time to time.

                  "Commission" means the Securities and Exchange Commission, or
any other federal agency then administering the Securities Act or the Exchange
Act.

                  "Common Stock" means the common stock, par value $0.0001 per
share, of the Company.

                  "Company" is defined in the preamble to this Agreement.

                  "Demand Registration" is defined in Section 2.1.1.

                  "Demanding Holder" is defined in Section 2.1.1.

                  "Exchange Act" means the Securities Exchange Act of 1934, as
amended, and the rules and regulations of the Commission promulgated thereunder,
all as the same shall be in effect at the time.

                  "Form S-3" is defined in Section 2.3.

                  "Indemnified Party" is defined in Section 4.3.

                  "Indemnifying Party" is defined in Section 4.3.

                  "Investor" is defined in the preamble to this Agreement.

                  "Investor Indemnified Party" is defined in Section 4.1.


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                  "Maximum Number of Shares" is defined in Section 2.1.4.

                  "Notices" is defined in Section 6.3.

                  "Piggy-Back Registration" is defined in Section 2.2.1.

                  "Register," "registered" and "registration" mean a
registration effected by preparing and filing a registration statement or
similar document in compliance with the requirements of the Securities Act, and
the applicable rules and regulations promulgated thereunder, and such
registration statement becoming effective.

                  "Registrable Securities" mean all of the shares of Common
Stock owned or held by Investors. Registrable Securities include any warrants,
shares of capital stock or other securities of the Company issued as a dividend
or other distribution with respect to or in exchange for or in replacement of
such shares of Common Stock. As to any particular Registrable Securities, such
securities shall cease to be Registrable Securities when: (a) a Registration
Statement with respect to the sale of such securities shall have become
effective under the Securities Act and such securities shall have been sold,
transferred, disposed of or exchanged in accordance with such Registration
Statement; (b) such securities shall have been otherwise transferred, new
certificates for them not bearing a legend restricting further transfer shall
have been delivered by the Company and subsequent public distribution of them
shall not require registration under the Securities Act; (c) such securities
shall have ceased to be outstanding, or (d) the Securities and Exchange
Commision makes a definitive determination to the Company that the Registrable
Securities are salable under Rule 144(k).

                  "Registration Statement" means a registration statement filed
by the Company with the Commission in compliance with the Securities Act and the
rules and regulations promulgated thereunder for a public offering and sale of
Common Stock (other than a registration statement on Form S-4 or Form S-8, or
their successors, or any registration statement covering only securities
proposed to be issued in exchange for securities or assets of another entity).

                  "Release Date" means the date on which shares of Common Stock
are disbursed from escrow pursuant to Section 3 of that certain Stock Escrow
Agreement dated as of _______, 2004 by and among the parties hereto and American
Stock Transfer & Trust Company.

                  "Securities Act" means the Securities Act of 1933, as amended,
and the rules and regulations of the Commission promulgated thereunder, all as
the same shall be in effect at the time.

                  "Underwriter" means a securities dealer who purchases any
Registrable Securities as principal in an underwritten offering and not as part
of such dealer's market-making activities.

         2.       REGISTRATION RIGHTS.

                  2.1      Demand Registration.


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                  2.1.1. Request for Registration. At any time and from time to
time on or after the Release Date, the holders of a majority-in-interest of the
Registrable Securities held by the Investors or the transferees of the
Investors, may make a written demand for registration under the Securities Act
of all or part of their Registrable Securities (a "Demand Registration"). Any
demand for a Demand Registration shall specify the number of shares of
Registrable Securities proposed to be sold and the intended method(s) of
distribution thereof. The Company will notify all holders of Registrable
Securities of the demand, and each holder of Registrable Securities who wishes
to include all or a portion of such holder's Registrable Securities in the
Demand Registration (each such holder including shares of Registrable Securities
in such registration, a "Demanding Holder") shall so notify the Company within
fifteen (15) days after the receipt by the holder of the notice from the
Company. Upon any such request, the Demanding Holders shall be entitled to have
their Registrable Securities included in the Demand Registration, subject to
Section 2.1.4 and the provisos set forth in Section 3.1.1. The Company shall not
be obligated to effect more than an aggregate of two (2) Demand Registrations
under this Section 2.1.1 in respect of Registrable Securities.

                  2.1.2. Effective Registration. A registration will not count
as a Demand Registration until the Registration Statement filed with the
Commission with respect to such Demand Registration has been declared effective
and the Company has complied with all of its obligations under this Agreement
with respect thereto; provided, however, that if, after such Registration
Statement has been declared effective, the offering of Registrable Securities
pursuant to a Demand Registration is interfered with by any stop order or
injunction of the Commission or any other governmental agency or court, the
Registration Statement with respect to such Demand Registration will be deemed
not to have been declared effective, unless and until, (i) such stop order or
injunction is removed, rescinded or otherwise terminated, and (ii) a
majority-in-interest of the Demanding Holders thereafter elect to continue the
offering; provided, further, that the Company shall not be obligated to file a
second Registration Statement until a Registration Statement that has been filed
is counted as a Demand Registration or is terminated.

                  2.1.3. Underwritten Offering. If a majority-in-interest of the
Demanding Holders so elect and such holders so advise the Company as part of
their written demand for a Demand Registration, the offering of such Registrable
Securities pursuant to such Demand Registration shall be in the form of an
underwritten offering. In such event, the right of any holder to include its
Registrable Securities in such registration shall be conditioned upon such
holder's participation in such underwriting and the inclusion of such holder's
Registrable Securities in the underwriting to the extent provided herein. All
Demanding Holders proposing to distribute their securities through such
underwriting shall enter into an underwriting agreement in customary form with
the Underwriter or Underwriters selected for such underwriting by a
majority-in-interest of the holders initiating the Demand Registration.

                  2.1.4. Reduction of Offering. Subject to the rights of the

holders of securities issued or issuable upon exercise of those certain Unit
Purchase Options to be issued to EarlyBirdCapital, Inc. or its designees in
connection with the Company's initial public offering in ________ 2004, if the
managing Underwriter or Underwriters for a Demand Registration that is to be an
underwritten offering advises the Company and the Demanding Holders in writing
that the dollar amount or number of shares of Registrable Securities which the
Demanding Holders desire to sell, taken together with all other shares of Common
Stock or other securities

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which the Company desires to sell and the shares of Common Stock, if any, as to
which registration has been requested pursuant to written contractual piggy-back
registration rights held by other shareholders of the Company who desire to
sell, exceeds the maximum dollar amount or maximum number of shares that can be
sold in such offering without adversely affecting the proposed offering price,
the timing, the distribution method, or the probability of success of such
offering (such maximum dollar amount or maximum number of shares, as applicable,
the "Maximum Number of Shares"), then the Company shall include in such
registration: (i) first, the Registrable Securities as to which Demand
Registration has been requested by the Demanding Holders (pro rata in accordance
with the number of shares of Registrable Securities which such Demanding Holder
has requested be included in such registration, regardless of the number of
shares of Registrable Securities held by each Demanding Holder) that can be sold
without exceeding the Maximum Number of Shares; (ii) second, to the extent that
the Maximum Number of Shares has not been reached under the foregoing clause
(i), the shares of Common Stock or other securities that the Company desires to
sell that can be sold without exceeding the Maximum Number of Shares; (iii)
third, to the extent that the Maximum Number of Shares has not been reached
under the foregoing clauses (i) and (ii), the shares of Common Stock for the
account of other persons that the Company is obligated to register pursuant to
written contractual arrangements with such persons and that can be sold without
exceeding the Maximum Number of Shares; and (v) fourth, to the extent that the
Maximum Number of Shares have not been reached under the foregoing clauses (i),
(ii), and (iii), the shares of Common Stock that other shareholders desire to
sell that can be sold without exceeding the Maximum Number of Shares.

                  2.1.5. Withdrawal. If a majority-in-interest of the Demanding
Holders disapprove of the terms of any underwriting or are not entitled to
include all of their Registrable Securities in any offering, such
majority-in-interest of the Demanding Holders may elect to withdraw from such
offering by giving written notice to the Company and the Underwriter or
Underwriters of their request to withdraw prior to the effectiveness of the
Registration Statement filed with the Commission with respect to such Demand
Registration. If the majority-in-interest of the Demanding Holders withdraws
from a proposed offering relating to a Demand Registration, then such
registration shall not count as a Demand Registration provided for in Section
2.1.1.

          2.2     Piggy-Back Registration.
                  -----------------------

                  2.2.1. Piggy-Back Rights. If at any time on or after the
Release Date the Company proposes to file a Registration Statement under the
Securities Act with respect to an offering of equity securities, or securities
or other obligations exercisable or exchangeable for, or convertible into,
equity securities, by the Company for its own account or for shareholders of the
Company for their account (or by the Company and by shareholders of the Company
including, without limitation, pursuant to Section 2.1), other than a
Registration Statement (i) filed in connection with any employee stock option or
other benefit plan, (ii) for an exchange offer or offering of securities solely
to the Company's existing shareholders, (iii) for an offering of debt that is
convertible into equity securities of the Company or (iv) for a dividend
reinvestment plan, then the Company shall (x) give written notice of such
proposed filing to the holders of Registrable Securities as soon as practicable
but in no event less than ten (10) days before the anticipated filing date,
which notice shall describe the amount and type of securities to be included in
such offering, the intended method(s) of distribution, and the name of the
proposed

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managing Underwriter or Underwriters, if any, of the offering, and (y) offer to
the holders of Registrable Securities in such notice the opportunity to register
the sale of such number of shares of Registrable Securities as such holders may
request in writing within five (5) days following receipt of such notice (a
"Piggy-Back Registration"). The Company shall cause such Registrable Securities
to be included in such registration and shall use its best efforts to cause the
managing Underwriter or Underwriters of a proposed underwritten offering to
permit the Registrable Securities requested to be included in a Piggy-Back
Registration to be included on the same terms and conditions as any similar
securities of the Company and to permit the sale or other disposition of such
Registrable Securities in accordance with the intended method(s) of distribution
thereof. All holders of Registrable Securities proposing to distribute their
securities through a Piggy-Back Registration that involves an Underwriter or
Underwriters shall enter into an underwriting agreement in customary form with
the Underwriter or Underwriters selected for such Piggy-Back Registration.

                  2.2.2. Reduction of Offering. Subject to the rights of the
holders of securities issued or issuable upon exercise of those certain Unit
Purchase Options to be issued to EarlyBirdCapital, Inc. or its designees in
connection with the Company's initial public offering in ________ 2004, if the
managing Underwriter or Underwriters for a Piggy-Back Registration that is to be
an underwritten offering advises the Company and the holders of Registrable
Securities in writing that the dollar amount or number of shares of Common Stock
which the Company desires to sell, taken together with shares of Common Stock,
if any, as to which registration has been demanded pursuant to written
contractual arrangements with persons other than the holders of Registrable
Securities hereunder, the Registrable Securities as to which registration has
been requested under this Section 2.2, and the shares of Common Stock, if any,
as to which registration has been requested pursuant to the written contractual
piggy-back registration rights of other shareholders of the Company, exceeds the
Maximum Number of Shares, then the Company shall include in any such
registration:

                         (i) If the registration is undertaken for the Company's
account: (A) first, the shares of Common Stock or other securities that the
Company desires to sell that can be sold without exceeding the Maximum Number of
Shares; (B) second, to the extent that the Maximum Number of Shares has not been
reached under the foregoing clause (A), the shares of Common Stock, if any,
including the Registrable Securities, as to which registration has been
requested pursuant to written contractual piggy-back registration rights of
security holders (pro rata in accordance with the number of shares of Common
Stock which each such person has actually requested to be included in such
registration, regardless of the number of shares of Common Stock with respect to
which such persons have the right to request such inclusion) that can be sold
without exceeding the Maximum Number of Shares; and

                         (ii) If the registration is a "demand" registration
undertaken at the demand of persons other than the holders of Registrable
Securities pursuant to written contractual arrangements with such persons, (A)
first, the shares of Common Stock for the account of the demanding persons that
can be sold without exceeding the Maximum Number of Shares; (B) second, to the
extent that the Maximum Number of Shares has not been reached under the
foregoing clause (A), the shares of Common Stock or other securities that the
Company desires to sell that can be sold without exceeding the Maximum Number of
Shares; and (C) third, to the extent that the Maximum Number of Shares has not
been reached under the


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<PAGE>

foregoing clauses (A) and (B), the Registrable Securities as to which
registration has been requested under this Section 2.2 (pro rata in accordance
with the number of shares of Registrable Securities held by each such holder);
and (D) fourth, to the extent that the Maximum Number of Shares has not been
reached under the foregoing clauses (A), (B) and (C), the shares of Common
Stock, if any, as to which registration has been requested pursuant to written
contractual piggy-back registration rights which such other shareholders desire
to sell that can be sold without exceeding the Maximum Number of Shares.

                  2.2.3. Withdrawal. Any holder of Registrable Securities may
elect to withdraw such holder's request for inclusion of Registrable Securities
in any Piggy-Back Registration by giving written notice to the Company of such
request to withdraw prior to the effectiveness of the Registration Statement.
The Company may also elect to withdraw a registration statement at any time
prior to the effectiveness of the Registration Statement. Notwithstanding any
such withdrawal, the Company shall pay all expenses incurred by the holders of
Registrable Securities in connection with such Piggy-Back Registration as
provided in Section 3.3.

              2.3 Registrations on Form S-3. The holders of Registrable
Securities may at any time and from time to time, request in writing that the
Company register the resale of any or all of such Registrable Securities on Form
S-3 or any similar short-form registration which may be available at such time
("Form S-3"); provided, however, that the Company shall not be obligated to
effect such request through an underwritten offering. Upon receipt of such
written request, the Company will promptly give written notice of the proposed
registration to all other holders of Registrable Securities, and, as soon as
practicable thereafter, effect the registration of all or such portion of such
holder's or holders' Registrable Securities as are specified in such request,
together with all or such portion of the Registrable Securities of any other
holder or holders joining in such request as are specified in a written request
given within fifteen (15) days after receipt of such written notice from the
Company; provided, however, that the Company shall not be obligated to effect
any such registration pursuant to this Section 2.3: (i) if Form S-3 is not
available for such offering; or (ii) if the holders of the Registrable
Securities, together with the holders of any other securities of the Company
entitled to inclusion in such registration, propose to sell Registrable
Securities and such other securities (if any) at any aggregate price to the
public of less than $500,000. Registrations effected pursuant to this Section
2.3 shall not be counted as Demand Registrations effected pursuant to Section
2.1.

     3.       REGISTRATION PROCEDURES.

              3.1 Filings; Information. Whenever the Company is required to
effect the registration of any Registrable Securities pursuant to Section 2, the
Company shall use its best efforts to effect the registration and sale of such
Registrable Securities in accordance with the intended method(s) of distribution
thereof as expeditiously as practicable, and in connection with any such
request:

                  3.1.1. Filing Registration Statement. The Company shall, as
expeditiously as possible and in any event within sixty (60) days after receipt
of a request for a Demand Registration pursuant to Section 2.1, prepare and file
with the Commission a Registration Statement on any form for which the Company
then qualifies or which counsel for


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the Company shall deem appropriate and which form shall be available for the
sale of all Registrable Securities to be registered thereunder in accordance
with the intended method(s) of distribution thereof, and shall use its best
efforts to cause such Registration Statement to become and remain effective for
the period required by Section 3.1.3; provided, however, that the Company shall
have the right to defer any Demand Registration for up to thirty (30) days, and
any Piggy-Back Registration for such period as may be applicable to deferment of
any demand registration to which such Piggy-Back Registration relates, in each
case if the Company shall furnish to the holders a certificate signed by the
Chief Executive Officer of the Company stating that, in the good faith judgment
of the Board of Directors of the Company, it would be materially detrimental to
the Company and its shareholders for such Registration Statement to be effected
at such time; provided further, however, that the Company shall not have the
right to exercise the right set forth in the immediately preceding proviso more
than once in any 365-day period in respect of a Demand Registration hereunder.

                  3.1.2. Copies. The Company shall, prior to filing a
Registration Statement or prospectus, or any amendment or supplement thereto,
furnish without charge to the holders of Registrable Securities included in such
registration, and such holders' legal counsel, copies of such Registration
Statement as proposed to be filed, each amendment and supplement to such
Registration Statement (in each case including all exhibits thereto and
documents incorporated by reference therein), the prospectus included in such
Registration Statement (including each preliminary prospectus), and such other
documents as the holders of Registrable Securities included in such registration
or legal counsel for any such holders may request in order to facilitate the
disposition of the Registrable Securities owned by such holders.

                  3.1.3. Amendments and Supplements. The Company shall prepare
and file with the Commission such amendments, including post-effective
amendments, and supplements to such Registration Statement and the prospectus
used in connection therewith as may be necessary to keep such Registration
Statement effective and in compliance with the provisions of the Securities Act
until all Registrable Securities and other securities covered by such
Registration Statement have been disposed of in accordance with the intended
method(s) of distribution set forth in such Registration Statement (which period
shall not exceed the sum of one hundred eighty (180) days plus any period during
which any such disposition is interfered with by any stop order or injunction of
the Commission or any governmental agency or court) or such securities have been
withdrawn.

                  3.1.4. Notification. After the filing of a Registration
Statement, the Company shall promptly, and in no event more than two (2)
business days after such filing, notify the holders of Registrable Securities
included in such Registration Statement of such filing, and shall further notify
such holders promptly and confirm such advice in writing in all events within
two (2) business days of the occurrence of any of the following: (i) when such
Registration Statement becomes effective; (ii) when any post-effective amendment
to such Registration Statement becomes effective; (iii) the issuance or
threatened issuance by the Commission of any stop order (and the Company shall
take all actions required to prevent the entry of such stop order or to remove
it if entered); and (iv) any request by the Commission for any amendment or
supplement to such Registration Statement or any prospectus relating thereto or
for additional information or of the occurrence of an event requiring the
preparation of a supplement or amendment to such prospectus so that, as
thereafter delivered to the purchasers of


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the securities covered by such Registration Statement, such prospectus will not
contain an untrue statement of a material fact or omit to state any material
fact required to be stated therein or necessary to make the statements therein
not misleading, and promptly make available to the holders of Registrable
Securities included in such Registration Statement any such supplement or
amendment; except that before filing with the Commission a Registration
Statement or prospectus or any amendment or supplement thereto, including
documents incorporated by reference, the Company shall furnish to the holders of
Registrable Securities included in such Registration Statement and to the legal
counsel for any such holders, copies of all such documents proposed to be filed
sufficiently in advance of filing to provide such holders and legal counsel with
a reasonable opportunity to review such documents and comment thereon, and the
Company shall not file any Registration Statement or prospectus or amendment or
supplement thereto, including documents incorporated by reference, to which such
holders or their legal counsel shall object.

                  3.1.5. State Securities Laws Compliance. The Company shall use
its best efforts to (i) register or qualify the Registrable Securities covered
by the Registration Statement under such securities or "blue sky" laws of such
jurisdictions in the United States as the holders of Registrable Securities
included in such Registration Statement (in light of their intended plan of
distribution) may request and (ii) take such action necessary to cause such
Registrable Securities covered by the Registration Statement to be registered
with or approved by such other Governmental Authorities as may be necessary by
virtue of the business and operations of the Company and do any and all other
acts and things that may be necessary or advisable to enable the holders of
Registrable Securities included in such Registration Statement to consummate the
disposition of such Registrable Securities in such jurisdictions; provided,
however, that the Company shall not be required to qualify generally to do
business in any jurisdiction where it would not otherwise be required to qualify
but for this paragraph (e) or subject itself to taxation in any such
jurisdiction.

                  3.1.6. Agreements for Disposition. The Company shall enter
into customary agreements (including, if applicable, an underwriting agreement
in customary form) and take such other actions as are reasonably required in
order to expedite or facilitate the disposition of such Registrable Securities.
The representations, warranties and covenants of the Company in any underwriting
agreement which are made to or for the benefit of any Underwriters, to the
extent applicable, shall also be made to and for the benefit of the holders of
Registrable Securities included in such registration statement. No holder of
Registrable Securities included in such registration statement shall be required
to make any representations or warranties in the underwriting agreement except,
if applicable, with respect to such holder's organization, good standing,
authority, title to Registrable Securities, lack of conflict of such sale with
such holder's material agreements and organizational documents, and with respect
to written information relating to such holder that such holder has furnished in
writing expressly for inclusion in such Registration Statement.

                  3.1.7. Cooperation. The principal executive officer of the
Company, the principal financial officer of the Company, the principal
accounting officer of the Company and all other officers and members of the
management of the Company shall cooperate fully in any offering of Registrable
Securities hereunder, which cooperation shall include, without limitation, the
preparation of the Registration Statement with respect to such offering and all
other offering

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materials and related documents, and participation in meetings with
Underwriters, attorneys, accountants and potential investors.

                  3.1.8. Records. The Company shall make available for
inspection by the holders of Registrable Securities included in such
Registration Statement, any Underwriter participating in any disposition
pursuant to such registration statement and any attorney, accountant or other
professional retained by any holder of Registrable Securities included in such
Registration Statement or any Underwriter, all financial and other records,
pertinent corporate documents and properties of the Company, as shall be
necessary to enable them to exercise their due diligence responsibility, and
cause the Company's officers, directors and employees to supply all information
requested by any of them in connection with such Registration Statement.

                  3.1.9. Opinions and Comfort Letters. The Company shall furnish
to each holder of Registrable Securities included in any Registration Statement
a signed counterpart, addressed to such holder, of (i) any opinion of counsel to
the Company delivered to any Underwriter and (ii) any comfort letter from the
Company's independent public accountants delivered to any Underwriter. In the
event no legal opinion is delivered to any Underwriter, the Company shall
furnish to each holder of Registrable Securities included in such Registration
Statement, at any time that such holder elects to use a prospectus, an opinion
of counsel to the Company to the effect that the Registration Statement
containing such prospectus has been declared effective and that no stop order is
in effect.

                  3.1.10. Earnings Statement. The Company shall comply with all
applicable rules and regulations of the Commission and the Securities Act, and
make available to its shareholders, as soon as practicable, an earnings
statement covering a period of twelve (12) months, beginning within three (3)
months after the effective date of the registration statement, which earnings
statement shall satisfy the provisions of Section 11(a) of the Securities Act
and Rule 158 thereunder.

                  3.1.11. Listing. The Company shall use its best efforts to
cause all Registrable Securities included in any registration to be listed on
such exchanges or otherwise designated for trading in the same manner as similar
securities issued by the Company are then listed or designated or, if no such
similar securities are then listed or designated, in a manner satisfactory to
the holders of a majority of the Registrable Securities included in such
registration.

              3.2 Obligation to Suspend Distribution. Upon receipt of any notice
from the Company of the happening of any event of the kind described in Section
3.1.4(iv), or, in the case of a resale registration on Form S-3 pursuant to
Section 2.3 hereof, upon any suspension by the Company, pursuant to a written
insider trading compliance program adopted by the Company's Board of Directors,
of the ability of all "insiders" covered by such program to transact in the
Company's securities because of the existence of material non-public
information, each holder of Registrable Securities included in any registration
shall immediately discontinue disposition of such Registrable Securities
pursuant to the Registration Statement covering such Registrable Securities
until such holder receives the supplemented or amended prospectus contemplated
by Section 3.1.4(iv) or the restriction on the ability of "insiders" to transact
in the Company's securities is removed, as applicable, and, if so directed by
the Company, each such holder will


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<PAGE>


deliver to the Company all copies, other than permanent file copies then in such
holder's possession, of the most recent prospectus covering such Registrable
Securities at the time of receipt of such notice.

              3.3 Registration Expenses. The Company shall bear all costs and
expenses incurred in connection with any Demand Registration pursuant to Section
2.1, any Piggy-Back Registration pursuant to Section 2.2, and any registration
on Form S-3 effected pursuant to Section 2.3, and all expenses incurred in
performing or complying with its other obligations under this Agreement, whether
or not the Registration Statement becomes effective, including, without
limitation: (i) all registration and filing fees; (ii) fees and expenses of
compliance with securities or "blue sky" laws (including fees and disbursements
of counsel in connection with blue sky qualifications of the Registrable
Securities); (iii) printing expenses; (iv) the Company's internal expenses
(including, without limitation, all salaries and expenses of its officers and
employees); (v) the fees and expenses incurred in connection with the listing of
the Registrable Securities as required by Section 3.1.11; (vi) National
Association of Securities Dealers, Inc. fees; (vii) fees and disbursements of
counsel for the Company and fees and expenses for independent certified public
accountants retained by the Company (including the expenses or costs associated
with the delivery of any opinions or comfort letters requested pursuant to
Section 3.1.9); (viii) the fees and expenses of any special experts retained by
the Company in connection with such registration and (ix) the fees and expenses
of one legal counsel selected by the holders of a majority-in-interest of the
Registrable Securities included in such registration. The Company shall have no
obligation to pay any underwriting discounts or selling commissions attributable
to the Registrable Securities being sold by the holders thereof, which
underwriting discounts or selling commissions shall be borne by such holders.
Additionally, in an underwritten offering, all selling shareholders and the
Company shall bear the expenses of the underwriter pro rata in proportion to the
respective amount of shares each is selling in such offering.

              3.4 Information. The holders of Registrable Securities shall
provide such information as may reasonably be requested by the Company, or the
managing Underwriter, if any, in connection with the preparation of any
Registration Statement, including amendments and supplements thereto, in order
to effect the registration of any Registrable Securities under the Securities
Act pursuant to Section 2 and in connection with the Company's obligation to
comply with federal and applicable state securities laws.

     4.       INDEMNIFICATION AND CONTRIBUTION.

              4.1 Indemnification by the Company. The Company agrees to
indemnify and hold harmless each Investor and each other holder of Registrable
Securities, and each of their respective officers, employees, affiliates,
directors, partners, members, attorneys and agents, and each person, if any, who
controls an Investor and each other holder of Registrable Securities (within the
meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act)
(each, an "Investor Indemnified Party"), from and against any expenses, losses,
judgments, claims, damages or liabilities, whether joint or several, arising out
of or based upon any untrue statement (or allegedly untrue statement) of a
material fact contained in any Registration Statement under which the sale of
such Registrable Securities was registered under the Securities Act, any
preliminary prospectus, final prospectus or summary prospectus contained in the


                                       10

<PAGE>


Registration Statement, or any amendment or supplement to such Registration
Statement, or arising out of or based upon any omission (or alleged omission) to
state a material fact required to be stated therein or necessary to make the
statements therein not misleading, or any violation by the Company of the
Securities Act or any rule or regulation promulgated thereunder applicable to
the Company and relating to action or inaction required of the Company in
connection with any such registration; and the Company shall promptly reimburse
the Investor Indemnified Party for any legal and any other expenses reasonably
incurred by such Investor Indemnified Party in connection with investigating and
defending any such expense, loss, judgment, claim, damage, liability or action;
provided, however, that the Company will not be liable in any such case to the
extent that any such expense, loss, claim, damage or liability arises out of or
is based upon any untrue statement or allegedly untrue statement or omission or
alleged omission made in such Registration Statement, preliminary prospectus,
final prospectus, or summary prospectus, or any such amendment or supplement, in
reliance upon and in conformity with information furnished to the Company, in
writing, by such selling holder expressly for use therein. The Company also
shall indemnify any Underwriter of the Registrable Securities, their officers,
affiliates, directors, partners, members and agents and each person who controls
such Underwriter on substantially the same basis as that of the indemnification
provided above in this Section 4.1.

              4.2 Indemnification by Holders of Registrable Securities. Each
selling holder of Registrable Securities will, in the event that any
registration is being effected under the Securities Act pursuant to this
Agreement of any Registrable Securities held by such selling holder, indemnify
and hold harmless the Company, each of its directors and officers and each
underwriter (if any), and each other person, if any, who controls such selling
holder or such underwriter within the meaning of the Securities Act, against any
losses, claims, judgments, damages or liabilities, whether joint or several,
insofar as such losses, claims, judgments, damages or liabilities (or actions in
respect thereof) arise out of or are based upon any untrue statement or
allegedly untrue statement of a material fact contained in any Registration
Statement under which the sale of such Registrable Securities was registered
under the Securities Act, any preliminary prospectus, final prospectus or
summary prospectus contained in the Registration Statement, or any amendment or
supplement to the Registration Statement, or arise out of or are based upon any
omission or the alleged omission to state a material fact required to be stated
therein or necessary to make the statement therein not misleading, if the
statement or omission was made in reliance upon and in conformity with
information furnished in writing to the Company by such selling holder expressly
for use therein, and shall reimburse the Company, its directors and officers,
and each such controlling person for any legal or other expenses reasonably
incurred by any of them in connection with investigation or defending any such
loss, claim, damage, liability or action. Each selling holder's indemnification
obligations hereunder shall be several and not joint and shall be limited to the
amount of any net proceeds actually received by such selling holder.

              4.3 Conduct of Indemnification Proceedings. Promptly after receipt
by any person of any notice of any loss, claim, damage or liability or any
action in respect of which indemnity may be sought pursuant to Section 4.1 or
4.2, such person (the "Indemnified Party") shall, if a claim in respect thereof
is to be made against any other person for indemnification hereunder, notify
such other person (the "Indemnifying Party") in writing of the loss, claim,
judgment, damage, liability or action; provided, however, that the failure by
the Indemnified

                                       11

<PAGE>


Party to notify the Indemnifying Party shall not relieve the Indemnifying Party
from any liability which the Indemnifying Party may have to such Indemnified
Party hereunder, except and solely to the extent the Indemnifying Party is
actually prejudiced by such failure. If the Indemnified Party is seeking
indemnification with respect to any claim or action brought against the
Indemnified Party, then the Indemnifying Party shall be entitled to participate
in such claim or action, and, to the extent that it wishes, jointly with all
other Indemnifying Parties, to assume control of the defense thereof with
counsel satisfactory to the Indemnified Party. After notice from the
Indemnifying Party to the Indemnified Party of its election to assume control of
the defense of such claim or action, the Indemnifying Party shall not be liable
to the Indemnified Party for any legal or other expenses subsequently incurred
by the Indemnified Party in connection with the defense thereof other than
reasonable costs of investigation; provided, however, that in any action in
which both the Indemnified Party and the Indemnifying Party are named as
defendants, the Indemnified Party shall have the right to employ separate
counsel (but no more than one such separate counsel) to represent the
Indemnified Party and its controlling persons who may be subject to liability
arising out of any claim in respect of which indemnity may be sought by the
Indemnified Party against the Indemnifying Party, with the fees and expenses of
such counsel to be paid by such Indemnifying Party if, based upon the written
opinion of counsel of such Indemnified Party, representation of both parties by
the same counsel would be inappropriate due to actual or potential differing
interests between them. No Indemnifying Party shall, without the prior written
consent of the Indemnified Party, consent to entry of judgment or effect any
settlement of any claim or pending or threatened proceeding in respect of which
the Indemnified Party is or could have been a party and indemnity could have
been sought hereunder by such Indemnified Party, unless such judgment or
settlement includes an unconditional release of such Indemnified Party from all
liability arising out of such claim or proceeding.

    4.4      Contribution.

              4.4.1. If the indemnification provided for in the foregoing
Sections 4.1, 4.2 and 4.3 is unavailable to any Indemnified Party in respect of
any loss, claim, damage, liability or action referred to herein, then each such
Indemnifying Party, in lieu of indemnifying such Indemnified Party, shall
contribute to the amount paid or payable by such Indemnified Party as a result
of such loss, claim, damage, liability or action in such proportion as is
appropriate to reflect the relative fault of the Indemnified Parties and the
Indemnifying Parties in connection with the actions or omissions which resulted
in such loss, claim, damage, liability or action, as well as any other relevant
equitable considerations. The relative fault of any Indemnified Party and any
Indemnifying Party shall be determined by reference to, among other things,
whether the untrue or alleged untrue statement of a material fact or the
omission or alleged omission to state a material fact relates to information
supplied by such Indemnified Party or such Indemnifying Party and the parties'
relative intent, knowledge, access to information and opportunity to correct or
prevent such statement or omission.

              4.4.2. The parties hereto agree that it would not be just and
equitable if contribution pursuant to this Section 4.4 were determined by pro
rata allocation or by any other method of allocation which does not take account
of the equitable considerations referred to in the immediately preceding Section
4.4.1. The amount paid or payable by an Indemnified Party as a result of any
loss, claim, damage, liability or action referred to in the immediately
preceding

                                       12

<PAGE>



paragraph shall be deemed to include, subject to the limitations set forth
above, any legal or other expenses incurred by such Indemnified Party in
connection with investigating or defending any such action or claim.
Notwithstanding the provisions of this Section 4.4, no holder of Registrable
Securities shall be required to contribute any amount in excess of the dollar
amount of the net proceeds (after payment of any underwriting fees, discounts,
commissions or taxes) actually received by such holder from the sale of
Registrable Securities which gave rise to such contribution obligation. No
person guilty of fraudulent misrepresentation (within the meaning of Section
11(f) of the Securities Act) shall be entitled to contribution from any person
who was not guilty of such fraudulent misrepresentation.

     5.       UNDERWRITING AND DISTRIBUTION.

              5.1 Rule 144. The Company covenants that it shall file any reports
required to be filed by it under the Securities Act and the Exchange Act and
shall take such further action as the holders of Registrable Securities may
reasonably request, all to the extent required from time to time to enable such
holders to sell Registrable Securities without registration under the Securities
Act within the limitation of the exemptions provided by Rule 144 under the
Securities Act, as such Rules may be amended from time to time, or any similar
Rule or regulation hereafter adopted by the Commission.

     6.       MISCELLANEOUS.

              6.1 Other Registration Rights. The Company represents and warrants
that no person, other than a holder of the Registrable Securities, has any right
to require the Company to register any shares of the Company's capital stock for
sale or to include shares of the Company's capital stock in any registration
filed by the Company for the sale of shares of capital stock for its own account
or for the account of any other person.

              6.2 Assignment; No Third Party Beneficiaries. This Agreement and
the rights, duties and obligations of the Company hereunder may not be assigned
or delegated by the Company in whole or in part. This Agreement and the rights,
duties and obligations of the holders of Registrable Securities hereunder may be
freely assigned or delegated by such holder of Registrable Securities in
conjunction with and to the extent of any transfer of Registrable Securities by
any such holder. This Agreement and the provisions hereof shall be binding upon
and shall inure to the benefit of each of the parties and their respective
successors and the permitted assigns of the Investor or holder of Registrable
Securities or of any assignee of the Investor or holder of Registrable
Securities. This Agreement is not intended to confer any rights or benefits on
any persons that are not party hereto other than as expressly set forth in
Article 4 and this Section 6.2.

              6.3 Notices. All notices, demands, requests, consents, approvals
or other communications (collectively, "Notices") required or permitted to be
given hereunder or which are given with respect to this Agreement shall be in
writing and shall be personally served, delivered by reputable air courier
service with charges prepaid, or transmitted by hand delivery, telegram, telex
or facsimile, addressed as set forth below, or to such other address as such
party shall have specified most recently by written notice. Notice shall be
deemed given on the date of service or transmission if personally served or
transmitted by telegram, telex or facsimile;

                                       13

<PAGE>

provided, that if such service or transmission is not on a business day or is
after normal business hours, then such notice shall be deemed given on the next
business day. Notice otherwise sent as provided herein shall be deemed given on
the next business day following timely delivery of such notice to a reputable
air courier service with an order for next-day delivery.


                           To the Company:

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

                           with a copy to:

                           Bingham McCutchen LLP
                           399 Park Avenue
                           New York, New York 10022
                           Attn: Floyd I. Wittlin, Esq.; and

                           Graubard Miller
                           600 Third Avenue
                           New York, NY 10016-2097
                           Attention: David Miller


                           To an Investor, to:

                           Lawrence S. Coben
                           1775 Broadway, Suite 604
                           New York, New York 10019

                           Isaac Kier
                           1775 Broadway, Suite 604
                           New York, New York 10019

                           David A. Preiser
                           c/o Houlihan Lokey Howard & Zukin
                           685 Third Avenue
                           New York, New York 10016

                           Jon Schotz
                           c/o Saybrook Capital, LLC
                           401 Wilshire Boulevard, Suite 850
                           Santa Monica, California 9040

                                       14
<PAGE>

                           with a copy to:

                           Graubard Miller
                           600 Third Avenue
                           New York, NY 10016-2097
                           Attention: David Miller


              6.4 Severability. This Agreement shall be deemed severable, and
the invalidity or unenforceability of any term or provision hereof shall not
affect the validity or enforceability of this Agreement or of any other term or
provision hereof. Furthermore, in lieu of any such invalid or unenforceable term
or provision, the parties hereto intend that there shall be added as a part of
this Agreement a provision as similar in terms to such invalid or unenforceable
provision as may be possible and be valid and enforceable.

              6.5 Counterparts. This Agreement may be executed in multiple
counterparts, each of which shall be deemed an original, and all of which taken
together shall constitute one and the same instrument.

              6.6 Entire Agreement. This Agreement (including all agreements
entered into pursuant hereto and all certificates and instruments delivered
pursuant hereto and thereto) constitute the entire agreement of the parties with
respect to the subject matter hereof and supersede all prior and contemporaneous
agreements, representations, understandings, negotiations and discussions
between the parties, whether oral or written.

              6.7 Modifications and Amendments. No amendment, modification or
termination of this Agreement shall be binding upon any party unless executed in
writing by such party.

              6.8 Titles and Headings. Titles and headings of sections of this
Agreement are for convenience only and shall not affect the construction of any
provision of this Agreement.

              6.9 Waivers and Extensions. Any party to this Agreement may waive
any right, breach or default which such party has the right to waive, provided
that such waiver will not be effective against the waiving party unless it is in
writing, is signed by such party, and specifically refers to this Agreement.
Waivers may be made in advance or after the right waived has arisen or the
breach or default waived has occurred. Any waiver may be conditional. No waiver
of any breach of any agreement or provision herein contained shall be deemed a
waiver of any preceding or succeeding breach thereof nor of any other agreement
or provision herein contained. No waiver or extension of time for performance of
any obligations or acts shall be deemed a waiver or extension of the time for
performance of any other obligations or acts.

              6.10 Remedies Cumulative. In the event that the Company fails to
observe or perform any covenant or agreement to be observed or performed under
this Agreement, the Investor or any other holder of Registrable Securities may
proceed to protect and enforce its rights by suit in equity or action at law,
whether for specific performance of any term contained in this Agreement or for
an injunction against the breach of any such term or in aid of the


                                       15

<PAGE>

exercise of any power granted in this Agreement or to enforce any other legal or
equitable right, or to take any one or more of such actions, without being
required to post a bond. None of the rights, powers or remedies conferred under
this Agreement shall be mutually exclusive, and each such right, power or remedy
shall be cumulative and in addition to any other right, power or remedy, whether
conferred by this Agreement or now or hereafter available at law, in equity, by
statute or otherwise.

              6.11 Governing Law. This Agreement shall be governed by,
interpreted under, and construed in accordance with the internal laws of the
State of New York applicable to agreements made and to be performed within the
State of New York, without giving effect to any choice-of-law provisions thereof
that would compel the application of the substantive laws of any other
jurisdiction.

              6.12 Waiver of Trial by Jury. Each party hereby irrevocably and
unconditionally waives the right to a trial by jury in any action, suit,
counterclaim or other proceeding (whether based on contract, tort or otherwise)
arising out of, connected with or relating to this Agreement, the transactions
contemplated hereby, or the actions of the Investor in the negotiation,
administration, performance or enforcement hereof.


                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

                                       16

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         IN WITNESS WHEREOF, the parties have caused this Registration Rights
Agreement to be executed and delivered by their duly authorized representatives
as of the date first written above.



                                                TREMISIS ENERGY
                                                ACQUISITION CORPORATION,
                                                a Delaware corporation


                                                By:_____________________________
                                                Name:  Lawrence S. Coben
                                                Title:   Chairman of the Board


INVESTORS
                                                ---------------------------
                                                Lawrence S. Coben


                                                ---------------------------
                                                Isaac Kier


                                                ---------------------------
                                                David A. Preiser


                                                ---------------------------
                                                Jon Schotz