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                                                                    EXHIBIT 4.15

================================================================================



                               GUARANTEE AGREEMENT

                                     between



                                TECO ENERGY, INC.

                                 (as Guarantor)

                                       and

                              THE BANK OF NEW YORK

                             (as Guarantee Trustee)

                                   dated as of

                               _____________, 20__



================================================================================







<PAGE>   2




                                TABLE OF CONTENTS

<TABLE>
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                                                                                          PAGE
<S>                                                                                       <C>
Article I         DEFINITIONS...............................................................1

        Section 1.1   Definitions...........................................................1

Article II        TRUST INDENTURE ACT.......................................................4

        Section 2.1   Trust Indenture Act; Application......................................4

        Section 2.2   List of Holders.......................................................4

        Section 2.3   Reports by the Guarantee Trustee......................................5

        Section 2.4   Periodic Reports to the Guarantee Trustee.............................5

        Section 2.5   Evidence of Compliance with Conditions Precedent......................5

        Section 2.6   Events of Default; Waiver.............................................5

        Section 2.7   Event of Default; Notice..............................................6

        Section 2.8   Conflicting Interests.................................................6

Article III       POWERS, DUTIES AND RIGHTS OF THE GUARANTEE TRUSTEE........................6

        Section 3.1   Powers and Duties of the Guarantee Trustee............................6

        Section 3.2   Certain Rights of Guarantee Trustee...................................8

        Section 3.3   Indemnity............................................................10

Article IV        GUARANTEE TRUSTEE........................................................10

        Section 4.1   Guarantee Trustee: Eligibility.......................................10

        Section 4.2   Appointment, Removal and Resignation of the Guarantee Trustee........10

Article V         GUARANTEE................................................................11

        Section 5.1   Guarantee............................................................11

        Section 5.2   Waiver of Notice and Demand..........................................11

        Section 5.3   Obligations Not Affected.............................................11

        Section 5.4   Rights of Holders....................................................12

        Section 5.5   Guarantee of Payment.................................................13

        Section 5.6   Subrogation..........................................................13

        Section 5.7   Independent Obligations..............................................13

Article VI        COVENANTS AND SUBORDINATION..............................................13

        Section 6.1   Subordination........................................................13

        Section 6.2   Pari Passu Guarantees................................................13
</TABLE>

                                       -i-

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                                TABLE OF CONTENTS
                                   (CONTINUED)


<TABLE>
<CAPTION>
                                                                                          PAGE
<S>                                                                                       <C>
Article VII       TERMINATION..............................................................14

        Section 7.1   Termination..........................................................14

Article VIII      MISCELLANEOUS............................................................14

        Section 8.1   Successors and Assigns...............................................14

        Section 8.2   Amendments...........................................................14

        Section 8.3   Notices..............................................................14

        Section 8.4   Benefit..............................................................15

        Section 8.5   Interpretation.......................................................15

        Section 8.6   Governing Law........................................................16
</TABLE>



                                      -ii-



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                               GUARANTEE AGREEMENT

        This GUARANTEE AGREEMENT, dated as of ______________, 20__, is executed
and delivered by TECO ENERGY, INC. (the "Guarantor"), a Florida corporation
having its principal office at TECO Plaza, 702 North Franklin Street, Tampa,
Florida, 33602, and THE BANK OF NEW YORK, a New York banking corporation, as
trustee (the "Guarantee Trustee"), for the benefit of the Holders (as defined
herein) from time to time of the Company Preferred Securities (as defined
herein) of TECO Funding Company ___, LLC, a Delaware limited liability company
(the "LLC").

        WHEREAS, pursuant to an Amended and Restated Trust Agreement (the "Trust
Agreement"), dated as of _____________, 2000 among the trustees named therein
(the "Trustees"), the LLC, as Depositor, and the Holders from time to time of
undivided beneficial ownership interests in the assets of TECO Capital Trust ___
(the "Issuer"), a Delaware statutory business trust, the Issuer is issuing up to
$_____________ aggregate liquidation preference of its __% Trust Preferred
Securities (liquidation preference __ per preferred security) (the "Trust
Preferred Securities") representing undivided beneficial ownership interests in
the assets of the Issuer and having the terms set forth in the Trust Agreement;

        WHEREAS, the Guarantee Trustee will use the proceeds of the Trust
Preferred Securities to purchase the preferred securities of the LLC (the
"Company Preferred Securities"), and the proceeds of the Company Preferred
Securities will be used to purchase $_________ of the ____% __________ Notes due
_______ (the "Notes") of the Guarantor which will constitute the principal
assets of the LLC; and

        WHEREAS, as incentive for the Guarantee Trustee to purchase the Company
Preferred Securities, the Guarantor desires irrevocably and unconditionally to
agree, to the extent set forth herein, to pay to the Holders of the Company
Preferred Securities the Guarantee Payments (as defined herein) and to make
certain other payments on the terms and conditions set forth herein;

        NOW, THEREFORE, in consideration of the purchase by the Guarantee
Trustee and each Holder of Company Preferred Securities, which purchase the
Guarantor hereby agrees shall benefit the Guarantor, the Guarantor executes and
delivers this Guarantee Agreement for the benefit of the Holders from time to
time of the Company Preferred Securities.

                                    ARTICLE I

                                   DEFINITIONS

        SECTION 1.1 DEFINITIONS.

        As used in this Guarantee Agreement, the terms set forth below shall,
unless the context otherwise requires, have the following meanings. Capitalized
or otherwise defined terms used but not otherwise defined herein shall have the
meanings assigned to such terms in the Trust Agreement as in effect on the date
hereof.

        "Affiliate" of any specified Person means any other Person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified

<PAGE>   5

Person; provided, however, that an Affiliate of the Guarantor shall not be
deemed to include the Issuer. For the purposes of this definition, "control"
when used with respect to any specified Person means the power to direct the
management and policies of such Person, directly or indirectly, whether through
the ownership of voting securities, by contract or otherwise; and the terms
"controlling" and "controlled" have meanings correlative to the foregoing.

        "Event of Default" means a default by the Guarantor on any of its
payment or other obligations under this Guarantee Agreement; provided, however,
that, except with respect to a default in payment of any Guarantee Payments, the
Guarantor shall have received notice of default and shall not have cured such
default within 90 days after receipt of such notice.

        "Guarantee Payments" means the following payments or distributions,
without duplication, with respect to the Company Preferred Securities, to the
extent not paid or made by or on behalf of the LLC; (i) any accumulated and
unpaid Dividends (as defined in the LLC Agreement) required to be paid on such
Company Preferred Securities, to the extent the LLC shall have funds on hand
available therefor at such time, (ii) the redemption price, including all
accumulated and unpaid Dividends to the date of redemption (the "Redemption
Price"), with respect to the Company Preferred Securities called for redemption
by the LLC to the extent the LLC shall have funds on hand available therefor at
such time, and (iii) upon a voluntary or involuntary termination, winding up or
liquidation of the LLC, unless Notes are distributed to the Holders, the lesser
of (a) the aggregate of the liquidation preference of $___ per Company Preferred
Security plus accumulated and unpaid Dividends on the Company Preferred
Securities to the date of payment to the extent the LLC shall have funds on hand
available to make such payment at such time and (b) the amount of assets of the
LLC remaining available for distribution to Holders in liquidation of the LLC
(in either case, the "Liquidation Distribution").

        "Guarantee Trustee" means The Bank of New York, until a Successor
Guarantee Trustee has been appointed and has accepted such appointment pursuant
to the terms of this Guarantee Agreement and thereafter means each such
Successor Guarantee Trustee.

        "Holder" means any holder, as registered on the books and records of the
Issuer, of any Trust Preferred Securities or, as registered on the books of the
LLC, of any Company Preferred Securities, as the context may require; provided,
however, that in determining whether the holders of the requisite percentage of
Trust Preferred Securities or Company Preferred Securities have given any
request, notice, consent or waiver hereunder, "Holder" shall not include the
Guarantor, the Guarantee Trustee, or any Affiliate of the Guarantor or the
Guarantee Trustee.

        "Indebtedness" means, with respect to a Person, (i) the principal of and
premium, if any, and interest, if any, on, (A) indebtedness of such Person for
money borrowed and (B) indebtedness evidenced by securities, notes, debentures,
bonds or other similar instruments issued by such Person; (ii) all capital lease
obligations of such Person; (iii) all obligations of such Person issued or
assumed as the deferred purchase price of property, all conditional sale
obligations of such Person and all obligations of such Person under any
conditional sale or title retention agreement (but excluding trade accounts
payable and accrued liabilities in the ordinary course of business); (iv) all
obligations, contingent or otherwise, of such Person in respect of any letters
of credit, banker's acceptance, security purchase facilities or similar credit
transactions; (v) all obligations in respect of interest rate swap, cap, floor,
collar or other agreements, interest

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<PAGE>   6

rate future or option contracts, currency swap agreements, currency future or
option contracts and other similar agreements; and (vi) all obligations of the
type referred to in clauses (i) through (v) of others for the payment of which
such Person is responsible or liable as obligor, guarantor or otherwise.

        "Indenture" means the Indenture, dated as of August 17, 1998, between
the Guarantor and The Bank of New York, as Trustee, together with the _______
Supplemental Indenture dated as of _______, 20__ relating to the Notes, each as
amended or supplemented from time to time.

        ["Junior Subordinated Indebtedness" means all the Indebtedness of the
Guarantor subordinate and junior to Subordinated Indebtedness and Senior
Indebtedness].

        "List of Holders" has the meaning specified in Section 2.2(a).

        "LLC Agreement" means the Amended and Restated Limited Liability Company
Agreement of the LLC dated as of ________, 20__, as the same may be amended from
time to time.

        "Majority in liquidation preference of the Company Preferred Securities"
means, except as provided by the Trust Indenture Act, a vote by the Holder(s),
voting separately as a class, of more than 50% of the liquidation preference of
all then outstanding Company Preferred Securities issued by the LLC.

        "Officers' Certificate" means, with respect to any Person, a certificate
signed by the Chairman or a Vice Chairman of the Board, the President or a Vice
President, and by the Treasurer, an Assistant Treasurer, the Secretary or an
Assistant Secretary of such Person, and delivered to the Guarantee Trustee. Any
Officers' Certificate delivered with respect to compliance with a condition or
covenant provided for in this Guarantee Agreement shall include:

                (a)     a statement that each officer signing the Officers'
        Certificate has read the covenant or condition and the definitions
        relating thereto;

                (b)     a brief statement of the nature and scope of the
        examination or investigation undertaken by each officer in rendering the
        Officers' Certificate;

                (c)     a statement that each officer has made such examination
        or investigation as, in such officer's opinion, is necessary to enable
        such officer to express an informed opinion as to whether or not such
        covenant or condition has been complied with; and

                (d)     a statement as to whether, in the opinion of each
        officer, such condition or covenant has been complied with.

        "Person" means a legal person, including any individual, corporation,
estate, partnership, joint venture, association, joint stock company, limited
liability company, trust, unincorporated association, or government or any
agency or political subdivision thereof, or any other entity of whatever nature.


                                        3
<PAGE>   7

        "Responsible Officer" means, with respect to the Guarantee Trustee, any
Senior Vice President, any Vice President, any Assistant Vice President, any
Assistant Secretary, any Assistant Treasurer, any trust officer or assistant
trust officer or any other officer of the Corporate Trust Department of the
above designated officers and also means, with respect to a particular corporate
trust matter, any other officer to whom such matter is referred because of that
officer's knowledge of and familiarity with the particular subject.

        ["Senior Indebtedness" means ________________________.]

        ["Subordinated Indebtedness" means all Indebtedness of the Guarantor
which is subordinated and junior in right of payment to Senior Indebtedness, but
does not include Junior Subordinated Indebtedness.]

        "Successor Guarantee Trustee" means a successor Guarantee Trustee
possessing the qualifications to act as Guarantee Trustee under Section 4.1.

        "Trust Indenture Act" means the Trust Indenture Act of 1939, as amended.


                                   ARTICLE II

                               TRUST INDENTURE ACT

        SECTION 2.1 TRUST INDENTURE ACT; APPLICATION.

                (a)     This Guarantee Agreement is subject to the provisions of
        the Trust Indenture Act that are required to be part of this Guarantee
        Agreement and shall, to the extent applicable, be governed by such
        provisions.

                (b)     If and to the extent that any provision of this
        Guarantee Agreement limits, qualifies or conflicts with the duties
        imposed by Sections 310 to 317, inclusive, of the Trust Indenture Act,
        such imposed duties shall control.

        SECTION 2.2    LIST OF HOLDERS.

                (a)     The Guarantor shall furnish or cause to be furnished to
        the Guarantee Trustee (a) quarterly, on or before January 1, April 1,
        July 1 and October 11 of each year, a list, in such form as the
        Guarantee Trustee may reasonably require, of the names and addresses of
        the Holders of the Company Preferred Securities ("List of Holders") as
        of a date not more than 15 days prior to the delivery thereof, and (b)
        at such other times as the Guarantee Trustee may request in writing,
        within 30 days after the receipt by the Guarantor of any such request, a
        List of Holders as of a date not more than 15 days prior to the time
        such list is furnished, in each case to the extent such information is
        in the possession or control of the Guarantor and is not identical to a
        previously supplied list of Holders or has not otherwise been received
        by the Guarantee Trustee in its capacity as


---------------------------------
(1) These dates are 15 days before the interest payment dates.



                                        4

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        such. The Guarantee Trustee may destroy any List of Holders previously
        given to it on receipt of a new List of Holders.

                (b)     The Guarantee Trustee shall comply with its obligations
        under Section 311(a), Section 311(b) and Section 312(b) of the Trust
        Indenture Act.

        SECTION 2.3 REPORTS BY THE GUARANTEE TRUSTEE.

        Not later than May 15 of each year, commencing May 15, 2001 the
Guarantee Trustee shall provide to the Holders of the Company Preferred
Securities such reports as are required by Section 313 of the Trust Indenture
Act, if any, in the form and in the manner provided by Section 313 of the Trust
Indenture Act. The Guarantee Trustee shall also comply with the requirements of
Section 313(d) of the Trust Indenture Act.

        A copy of each such report shall, at the time of such transmission to
Holders, be filed by the Guarantee Trustee with each national stock exchange,
the NASDAQ National Market or such other interdealer quotation system or
self-regulatory organization upon which the Company Preferred Securities are
listed or traded, with the Commission and with the Guarantor. The Guarantor will
promptly notify the Guarantee Trustee when any Company Preferred Securities are
listed on any stock exchange and of any delisting thereof.

        SECTION 2.4 PERIODIC REPORTS TO THE GUARANTEE TRUSTEE.

        The Guarantor shall provide to the Guarantee Trustee, the Securities and
Exchange Commission and the Holders such documents, reports and information, if
any, as required by Section 314 of the Trust Indenture Act and the compliance
certificate required by Section 314 of the Trust Indenture Act, in the form, in
the manner and at the times required by Section 314 of the Trust Indenture Act.

        SECTION 2.5 EVIDENCE OF COMPLIANCE WITH CONDITIONS PRECEDENT.

        The Guarantor shall provide to the Guarantee Trustee such evidence of
compliance with such conditions precedent, if any, provided for in this
Guarantee Agreement that relate to any of the matters set forth in Section
314(c) of the Trust Indenture Act. Any certificate or opinion required to be
given by an officer pursuant to Section 314(c)(1) may be given in the form of an
Officers' Certificate.

        SECTION 2.6 EVENTS OF DEFAULT; WAIVER.

        The Holders of a Majority in liquidation preference of the Company
Preferred Securities may, by vote, on behalf of the Holders, waive any past
Event of Default and its consequences. Upon such waiver, any such Event of
Default shall cease to exist, and any Event of Default arising therefrom shall
be deemed to have been cured, for every purpose of this Guarantee Agreement, but
no such waiver shall extend to any subsequent or other default or Event of
Default or impair any right consequent therefrom.


                                       5

<PAGE>   9

        SECTION 2.7 EVENT OF DEFAULT; NOTICE.

                (a)     The Guarantee Trustee shall, within 90 days after the
        occurrence of an Event of Default known to the Guarantee Trustee,
        transmit by mail, first class postage prepaid, to the Holders of the
        Company Preferred Securities, notices of all such Events of Default
        unless such defaults have been cured or waived before the giving of such
        notice; provided, that, except in the case of a default in the payment
        of a Guarantee Payment, the Guarantee Trustee shall be protected in
        withholding such notice if and so long as the Board of Directors, the
        executive committee or a trust committee of directors and/or Responsible
        Officers of the Guarantee Trustee in good faith determines that the
        withholding of such notice is in the interests of the Holders.

                (b)     The Guarantee Trustee shall not be deemed to have
        knowledge of any Event of Default unless the Guarantee Trustee shall
        have received written notice, or a Responsible Officer charged with the
        administration of the Trust Agreement shall have obtained written
        notice, of such Event of Default.

        SECTION 2.8 CONFLICTING INTERESTS.

        The Trust Agreement shall be deemed to be specifically described in this
Guarantee Agreement for the purposes of clause (i) of the first proviso
contained in Section 310(b) of the Trust Indenture Act.

                                   ARTICLE III

               POWERS, DUTIES AND RIGHTS OF THE GUARANTEE TRUSTEE

        SECTION 3.1    POWERS AND DUTIES OF THE GUARANTEE TRUSTEE.

                (a)     This Guarantee Agreement shall be held by the Guarantee
        Trustee for the benefit of the Holders of the Company Preferred
        Securities, and the Guarantee Trustee shall not transfer this Guarantee
        Agreement to any Person except a Holder exercising his or her rights
        pursuant to Section 5.4(iv) or to a Successor Guarantee Trustee on
        acceptance by such Successor Guarantee Trustee of its appointment to act
        as Successor Guarantee Trustee. The right, title and interest of the
        Guarantee Trustee shall automatically vest in any Successor Guarantee
        Trustee, upon acceptance by such Successor Guarantee Trustee of its
        appointment hereunder, and such vesting and cessation of title shall be
        effective whether or not conveyancing documents have been executed and
        delivered pursuant to the appointment of such Successor Guarantee
        Trustee.

                (b)     If an Event of Default has occurred and is continuing,
        the Guarantee Trustee shall enforce this Guarantee Agreement for the
        benefit of the Holders of the Company Preferred Securities.

                (c)     The Guarantee Trustee, before the occurrence of any
        Event of Default and after the curing or waiver of all Events of Default
        that may have occurred, shall undertake to perform only such duties as
        are specifically set forth in this Guarantee Agreement, and no implied
        covenants shall be read into this Guarantee Agreement against the
        Guarantee


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<PAGE>   10

        Trustee. In case an Event of Default has occurred (that has not been
        cured or waived pursuant to Section 2.6), the Guarantee Trustee shall
        exercise such of the rights and powers vested in it by this Guarantee
        Agreement, and use the same degree of care and skill in its exercise
        thereof, as a prudent person would exercise or use under the
        circumstances in the conduct of his or her own affairs.

                (d)     No provision of this Guarantee Agreement shall be
        construed to relieve the Guarantee Trustee from liability for its own
        negligent action, its own negligent failure to act or its own willful
        misconduct, except that:

                        (i)     prior to the occurrence of any Event of Default
        and after the curing or waiving of all such Events of Default that may
        have occurred:

                                (A)     the duties and obligations of the
                        Guarantee Trustee shall be determined solely by the
                        express provisions of this Guarantee Agreement, and the
                        Guarantee Trustee shall not be liable except for the
                        performance of such duties and obligations as are
                        specifically set forth in this Guarantee Agreement; and

                                (B)     in the absence of bad faith on the part
                        of the Guarantee Trustee, the Guarantee Trustee may
                        conclusively rely, as to the truth of the statements and
                        the correctness of the opinions expressed therein, upon
                        any certificates or opinions furnished to the Guarantee
                        Trustee and conforming to the requirements of this
                        Guarantee Agreement; but in the case of any such
                        certificates or opinions that by any provision hereof or
                        of the Trust Indenture Act are specifically required to
                        be furnished to the Guarantee Trustee, the Guarantee
                        Trustee shall be under a duty to examine the same to
                        determine whether or not they conform to the
                        requirements of this Guarantee Agreement;

                        (ii)    the Guarantee Trustee shall not be liable for
        any error of judgment made in good faith by a Responsible Officer of the
        Guarantee Trustee, unless it shall be proved that the Guarantee Trustee
        was negligent in ascertaining the pertinent facts upon which such
        judgment was made;

                        (iii)   the Guarantee Trustee shall not be liable with
        respect to any action taken or omitted to be taken by it in good faith
        in accordance with the direction of the Holders of not less than a
        Majority in liquidation preference of the Company Preferred Securities
        relating to the time, method and place of conducting any proceeding for
        any remedy available to the Guarantee Trustee, or exercising any trust
        or power conferred upon the Guarantee Trustee under this Guarantee
        Agreement; and

                        (iv)    no provision of this Guarantee Agreement shall
        require the Guarantee Trustee to expend or risk its own funds or
        otherwise incur personal financial liability in the performance of any
        of its duties or in the exercise of any of its rights or powers, if the
        Guarantee Trustee shall have reasonable grounds for


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<PAGE>   11

        believing that the repayment of such funds or liability is not
        reasonably assured to it under the terms of this Guarantee Agreement or
        adequate indemnity against such risk or liability is not reasonably
        assured to it.

        SECTION 3.2 CERTAIN RIGHTS OF GUARANTEE TRUSTEE.

        (a)     Subject to the provisions of Section 3.1:

                (i)     The Guarantee Trustee may conclusively rely and shall be
        fully protected in acting or refraining from acting upon any resolution,
        certificate, statement, instrument, opinion, report, notice, request,
        direction, consent, order, bond, debenture, note, other evidence of
        indebtedness or other paper or document reasonably believed by it to be
        genuine and to have been signed, sent or presented by the proper party
        or parties.

                (ii)    Any direction or act of the Guarantor contemplated by
        this Guarantee Agreement shall be sufficiently evidenced by an Officer's
        Certificate unless otherwise prescribed herein.

                (iii)   Whenever, in the administration of this Guarantee
        Agreement, the Guarantee Trustee shall deem it desirable that a matter
        be proved or established before taking, suffering or omitting to take
        any action hereunder, the Guarantee Trustee (unless other evidence is
        herein specifically prescribed) may, in the absence of bad faith on its
        part, request and rely upon an Officers' Certificate which, upon receipt
        of such request from the Guarantee Trustee, shall be promptly delivered
        by the Guarantor.

                (iv)    The Guarantee Trustee may consult with legal counsel of
        its selection, and the written advice or opinion of such legal counsel
        with respect to legal matters shall be full and complete authorization
        and protection in respect of any action taken, suffered or omitted to be
        taken by it hereunder in good faith and in accordance with such advice
        or opinion. Such legal counsel may be legal counsel to the Guarantor or
        any of its Affiliates and may be one of its employees. The Guarantee
        Trustee shall have the right at any time to seek instructions concerning
        the administration of this Guarantee Agreement from any court of
        competent jurisdiction.

                (v)     The Guarantee Trustee shall be under no obligation to
        exercise any of the rights or powers vested in it by this Guarantee
        Agreement at the request or direction of any Holder, unless such Holder
        shall have provided to the Guarantee Trustee such adequate security and
        indemnity as would satisfy a reasonable person in the position of the
        Guarantee Trustee, against the costs, expenses (including attorneys'
        fees and expenses) and liabilities that might be incurred by it in
        complying with such request or direction, including such reasonable
        advances as may be requested by the Guarantee Trustee; provided that,
        nothing contained in this Section 3.2(a)(v) shall be taken to relieve
        the Guarantee Trustee, upon the


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<PAGE>   12

        occurrence of an Event of Default, of its obligation to exercise the
        rights and powers vested in it by this Guarantee Agreement.

                (vi)    The Guarantee Trustee shall not be bound to make any
        investigation into the facts or matters stated in any resolution,
        certificate, statement, instrument, opinion, report, notice, request,
        direction, consent, order, bond, debenture, note, other evidence of
        indebtedness or other paper or document, but the Guarantee Trustee, in
        its discretion, may make such further inquiry or investigation into such
        facts or matters as it may see fit, and if the Guarantee Trustee shall
        determine to make such further inquiry or investigation, it shall be
        entitled to examine the books, records and premises of the Guarantor,
        personally or by agent or attorney.

                (vii)   The Guarantee Trustee may execute any of the trusts or
        powers hereunder or perform any duties hereunder either directly or by
        or through its agents or attorneys, and the Guarantee Trustee shall not
        be responsible for any misconduct or negligence on the part of any such
        agent or attorney appointed with due care by it hereunder.

                (viii)  Any action taken by the Guarantee Trustee or its agents
        hereunder shall bind the Holders, and the signature of the Guarantee
        Trustee or its agents alone shall be sufficient and effective to perform
        such action. No third party shall be required to inquire as to the
        authority of the Guarantee Trustee to so act or as to its compliance
        with any of the terms and provisions of this Guarantee Agreement, both
        of which shall be conclusively evidenced by the Guarantee's or its
        agent's taking such action.

                (ix)    Whenever in the administration of this Guarantee
        Agreement the Guarantee Trustee shall deem it desirable to receive
        instructions with respect to enforcing any remedy or right or taking any
        other action hereunder, the Guarantee Trustee (A) may request
        instructions from the Holders of a Majority in Liquidation Amount of the
        Company Preferred Securities, (B) may refrain from enforcing such remedy
        or right or taking such other action until such instructions are
        received, and (C) shall be protected in acting in accordance with such
        instructions.

        (b)     No provision of this Guarantee Agreement shall be deemed to
impose any duty or obligation on the Guarantee Trustee to perform any act or
acts or exercise any right, power, duty or obligation conferred or imposed on it
in any jurisdiction in which it shall be illegal, or in which the Guarantee
Trustee shall be unqualified or incompetent in accordance with applicable law,
to perform any such act or acts or to exercise any such right, power, duty or
obligation. No permissive power or authority available to the Guarantee Trustee
shall be construed to be a duty to act in accordance with such power and
authority.


                                        9

<PAGE>   13

        SECTION 3.3 INDEMNITY.

        The Guarantor agrees to indemnify the Guarantee Trustee for, and to hold
it harmless against, any loss, liability or expense incurred without negligence
or bad faith on the part of the Guarantee Trustee, arising out of or in
connection with the acceptance or administration of this Guarantee Agreement,
including the costs and expenses of defending itself against any claim or
liability in connection with the exercise or performance of any of its powers or
duties hereunder. The Guarantee Trustee will not claim or exact any lien or
charge on any Guarantee Payments as a result of any amount due to it under this
Guarantee Agreement.

                                   ARTICLE IV

                                GUARANTEE TRUSTEE

        SECTION 4.1    GUARANTEE TRUSTEE: ELIGIBILITY.

                (a)     There shall at all times be a Guarantee Trustee which
        shall:

                        (i)     not be an Affiliate of the Guarantor; and

                        (ii)    be a Person that is eligible pursuant to the
                Trust Indenture Act to act as such and has a combined capital
                and surplus of at least $50,000,000, and shall be a corporation
                meeting the requirements of Section 310(c) of the Trust
                Indenture Act. If such corporation publishes reports of
                condition at least annually, pursuant to law or to the
                requirements of the supervising or examining authority, then,
                for the purposes of this Section and to the extent permitted by
                the Trust Indenture Act, the combined capital and surplus of
                such corporation shall be deemed to be its combined capital and
                surplus as set forth in its most recent report of condition so
                published.

                (b)     If at any time the Guarantee Trustee shall cease to be
        eligible to so act under Section 4.1(a), the Guarantee Trustee shall
        immediately resign in the manner and with the effect set out in Section
        4.2(c).

                (c)     If the Guarantee Trustee has or shall acquire any
        "conflicting interest" within the meaning of Section 310(b) of the Trust
        Indenture Act, the Guarantee Trustee and Guarantor shall in all respects
        comply with the provisions of Section 310(b) of the Trust Indenture Act.

        SECTION 4.2    APPOINTMENT, REMOVAL AND RESIGNATION OF THE GUARANTEE
        TRUSTEE.

                (a)     Subject to Section 4.2(b), the Guarantee Trustee may be
        appointed or removed without cause at any time by the Guarantor.

                (b)     The Guarantee Trustee shall not be removed until a
        Successor Guarantee Trustee has been appointed and has accepted such
        appointment by written instrument executed by such Successor Guarantee
        Trustee and delivered to the Guarantor.


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<PAGE>   14

                (c)     The Guarantee Trustee appointed hereunder shall hold
        office until a Successor Guarantee Trustee shall have been appointed or
        until its removal or resignation. The Guarantee Trustee may resign from
        office (without need for prior or subsequent accounting) by an
        instrument in writing executed by the Guarantee Trustee and delivered to
        the Guarantor, which resignation shall not take effect until a Successor
        Guarantee Trustee has been appointed and has accepted such appointment
        by instrument in writing executed by such Successor Guarantee Trustee
        and delivered to the Guarantor and the resigning Guarantee Trustee.

                (d)     If no Successor Guarantee Trustee shall have been
        appointed and accepted appointment as provided in this Section 4.2
        within 60 days after delivery to the Guarantor of an instrument of
        resignation, the resigning Guarantee Trustee may petition, at the
        expense of the Guarantor, any court of competent jurisdiction for
        appointment of a Successor Guarantee Trustee. Such court may thereupon,
        after prescribing such notice, if any, as it may deem proper, appoint a
        Successor Guarantee Trustee.

                                   ARTICLE V

                                    GUARANTEE

        SECTION 5.1 GUARANTEE.

        The Guarantor irrevocably and unconditionally agrees to pay in full to
the Holders of the Company Preferred Securities the Guarantee Payments (without
duplication of amounts theretofore paid by or on behalf of the LLC), as and when
due, regardless of any defense, right of setoff or counterclaim which the LLC
may have or assert. The Guarantor's obligation to make a Guarantee Payment may
be satisfied by direct payment of the required amounts by the Guarantor to the
Holders of the Company Preferred Securities or by causing the LLC to pay such
amounts to the Holders.

        SECTION 5.2 WAIVER OF NOTICE AND DEMAND.

        The Guarantor hereby waives notice of acceptance of the Guarantee
Agreement and of any liability to which it applies or may apply, presentment,
demand for payment, any right to require a proceeding first against the
Guarantee Trustee, LLC or any other Person before proceeding against the
Guarantor, protest, notice of nonpayment, notice of dishonor, notice of
redemption and all other notices and demands.

        SECTION 5.3 OBLIGATIONS NOT AFFECTED.

        The obligations, covenants, agreements and duties of the Guarantor under
this Guarantee Agreement shall in no way be affected or impaired by reason of
the happening from time to time of any of the following:

                (a)     the release or waiver, by operation of law or otherwise,
        of the performance or observance by the LLC of any express or implied
        agreement, covenant, term or condition relating to the Company Preferred
        Securities to be performed or observed by the LLC;



                                       11

<PAGE>   15

                (b)     the extension of time for the payment by the LLC of all
        or any portion of the Dividends (other than an extension of time for
        payment of Dividends that results from the extension of any interest
        payment period on the Notes as so provided in the Indenture), Redemption
        Price, Liquidation Distribution or any other sums payable under the
        terms of the Company Preferred Securities or the extension of time for
        the performance of any other obligation under, arising out of, or in
        connection with, the Company Preferred Securities;

                (c)     any failure, omission, delay or lack of diligence on the
        part of the Holders to enforce, assert or exercise any right, privilege,
        power or remedy conferred on the Holders pursuant to the terms of the
        Company Preferred Securities, or any action on the part of the LLC
        granting indulgence or extension of any kind;

                (d)     the voluntary or involuntary liquidation, dissolution,
        sale of any collateral, receivership, insolvency, bankruptcy, assignment
        for the benefit of creditors, reorganization, arrangement, composition
        or readjustment of debt of, or other similar proceedings affecting, the
        LLC or any of the assets of the LLC;

                (e)     any invalidity of, or defect or deficiency in, the
        Company Preferred Securities;

                (f)     the settlement or compromise of any obligation
        guaranteed hereby or hereby incurred; or

                (g)     any other circumstance whatsoever that might otherwise
        constitute a legal or equitable discharge or defense of a guarantor, it
        being the intent of this Section 5.3 that the obligations of the
        Guarantor hereunder shall be absolute and unconditional under any and
        all circumstances.

        There shall be no obligation of the Holders to give notice to, or obtain
the consent of, the Guarantor with respect to the happening of any of the
foregoing.

        SECTION 5.4 RIGHTS OF HOLDERS.

        The Guarantor expressly acknowledges that: (i) this Guarantee Agreement
will be deposited with the Guarantee Trustee to be held for the benefit of the
Holders of the Company Preferred Securities; (ii) the Guarantee Trustee has the
right to enforce this Guarantee Agreement on behalf of the Holders of the
Company Preferred Securities; (iii) the Holders of a Majority in liquidation
preference of the Company Preferred Securities have the right to direct the
time, method and place of conducting any proceeding for any remedy available to
the Guarantee Trustee in respect of this Guarantee Agreement or exercising any
trust or power conferred upon the Guarantee Trustee under this Guarantee
Agreement; and (iv) to the fullest extent permitted by law, without the need for
any other action of any person, including the Guarantee Trustee or any other
Holder of Trust Preferred Securities or Company Preferred Securities, each
Holder of Trust Preferred Securities or Company Preferred Securities will be
entitled to enforce the rights of the Holders of the Company Preferred
Securities under this Guarantee Agreement. The Guarantor waives, any right or
remedy to require that any action on this Guarantee Agreement be


                                       12

<PAGE>   16

brought first against the LLC or any other Person or entity before proceeding
directly against the Guarantor.

        SECTION 5.5 GUARANTEE OF PAYMENT.

        This Guarantee Agreement creates a guarantee of payment and not of
collection. This Guarantee Agreement will not be discharged except by payment of
the Guarantee Payments in full (without duplication of amounts theretofore paid
by the LLC) or upon distribution of Notes to Holders as provided in the LLC
Agreement and the Trust Agreement.

        SECTION 5.6 SUBROGATION.

        The Guarantor shall be subrogated to all (if any) rights of the Holders
against the LLC in respect of any amounts paid to the Holders by the Guarantor
under this Guarantee Agreement and shall have the right to waive payment by the
LLC pursuant to Section 5.1; provided, however, that the Guarantor shall not
(except to the extent required by mandatory provisions of law) be entitled to
enforce or exercise any rights which it may acquire by way of subrogation or any
indemnity, reimbursement or other agreement, in all cases as a result of payment
under this Guarantee Agreement, if at the time of any such payment, any amounts
are due and unpaid under this Guarantee Agreement. If any amount shall be paid
to the Guarantor in violation of the preceding sentence, the Guarantor agrees to
hold such amount in trust for the Holders of the Company Preferred Securities
and to pay over such amount to the Holders.

        SECTION 5.7 INDEPENDENT OBLIGATIONS.

        The Guarantor acknowledges that its obligations hereunder are
independent of the obligations of the LLC with respect to the Company Preferred
Securities and that the Guarantor shall be liable as principal and as debtor
hereunder to make Guarantee Payments pursuant to the terms of this Guarantee
Agreement notwithstanding the occurrence of any event referred to in subsections
(a) through (g), inclusive, of Section 5.3 hereof.

                                   ARTICLE VI

                           COVENANTS AND SUBORDINATION

        SECTION 6.1 [UNSECURED OBLIGATION][ SUBORDINATION].

        This Guarantee Agreement will constitute an unsecured obligation of the
Guarantor [and will rank subordinate and junior in right of payment to all
Senior Indebtedness and Subordinated Indebtedness of the Guarantor.]

        SECTION 6.2 PARI PASSU GUARANTEES.

        This Guarantee Agreement shall rank pari passu with any similar
Guarantee Agreements issued by the Guarantor on behalf of the Holders of Company
Preferred Securities issued by the LLC.


<PAGE>   17

                                   ARTICLE VII

                                   TERMINATION

        SECTION 7.1 TERMINATION.

        This Guarantee Agreement shall terminate and be of no further force and
effect upon (i) full payment of the Redemption Price of all Company Preferred
Securities, (ii) the distribution of Notes to the Holders in exchange for all of
the Company Preferred Securities or (iii) full payment of the amounts payable in
accordance with the Trust Agreement upon liquidation of the LLC, provided,
however, that the provisions of Section 3.3 hereof shall survive the termination
of this Guarantee Agreement. Notwithstanding the foregoing, this Guarantee
Agreement will continue to be effective or will be reinstated, as the case may
be, if at any time any Holder must restore payment of any sums paid with respect
to Company Preferred Securities or this Guarantee Agreement.

                                  ARTICLE VIII

                                  MISCELLANEOUS

        SECTION 8.1 SUCCESSORS AND ASSIGNS.

        All guarantees and agreements contained in this Guarantee Agreement
shall bind the successors, assigns, receivers, trustees and representatives of
the Guarantor and shall inure to the benefit of the Holders of the Company
Preferred Securities then outstanding. Except in connection with a
consolidation, merger or sale involving the Guarantor that is permitted under
Article Eight of the Indenture and pursuant to which the assignee agrees in
writing to perform the Guarantor's obligations hereunder, the Guarantor shall
not assign its obligations hereunder.

        SECTION 8.2 AMENDMENTS.

        Except with respect to any changes which do not adversely affect the
rights of the Holders of the Company Preferred Securities in any material
respect (in which case no consent of the Holders will be required), this
Guarantee Agreement may only be amended with the prior approval of the Holders
of not less than a Majority in liquidation preference of all the outstanding
Company Preferred Securities. The provisions of Article VIII of the LLC
Agreement concerning meetings of the Holders shall apply to the giving of such
approval.

        SECTION 8.3 NOTICES.

        Any notice, request or other communication required or permitted to be
given hereunder shall be in writing, duly signed by the party giving such
notice, and delivered, telecopied or mailed by first class mail as follows:

                (a)     if given to the Guarantee Trustee, at the Guarantee
        Trustee's mailing address set forth below (or such other address as the
        Guarantee Trustee may give notice of to the Guarantor and the Holders):



                                       14

<PAGE>   18

               The Bank of New York
               101 Barclay Street
               21st Floor West
               New York, New York 10286
               Attention:  Corporate Trust Department

                (b)     if given to the Guarantor, to the address set forth
        below or such other address, facsimile number or to the attention of
        such other Person as the Guarantor may give notice to the Holders of the
        Company Preferred Securities:

               TECO Energy, Inc.
               702 North Franklin Street
               Tampa, Florida 33602
               Attention:  Secretary

                (c)     if given to any Holder, at the address set forth on the
        books and records of the LLC.

        All notices hereunder shall be deemed to have been given when received
in person, telecopied with receipt confirmed, or mailed by first class mail,
postage prepaid, except that if a notice or other document is refused delivery
or cannot be delivered because of a changed address of which no notice was
given, such notice or other document shall be deemed to have been delivered on
the date of such refusal or inability to deliver.

        SECTION 8.4 BENEFIT.

        This Guarantee Agreement is solely for the benefit of the Holders of the
Company Preferred Securities and is not separately transferable from the Company
Preferred Securities.

        SECTION 8.5 INTERPRETATION.

        In this Guarantee Agreement, unless the context otherwise requires:

                (a)     capitalized terms used in this Guarantee Agreement but
        not defined in the preamble hereto have the respective meanings assigned
        to them in Section 1.1;

                (b)     a term defined anywhere in this Guarantee Agreement has
        the same meaning throughout;

                (c)     all references to "the Guarantee Agreement" or "this
        Guarantee Agreement" are to this Guarantee Agreement as modified,
        supplemented or amended from time to time;

                (d)     all references in this Guarantee Agreement to Articles
        and Sections are to Articles and Sections of this Guarantee Agreement
        unless otherwise specified;


                                       15

<PAGE>   19

                (e)     a term defined in the Trust Indenture Act has the same
        meaning when used in this Guarantee Agreement unless otherwise defined
        in this Guarantee Agreement or unless the context otherwise requires;

                (f)     a reference to the singular includes the plural and vice
        versa; and

                (g)     the masculine, feminine or neuter genders used herein
        shall include the masculine, feminine and neuter genders.

        SECTION 8.6    GOVERNING LAW.

        THIS GUARANTEE AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED AND
INTERPRETED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD
TO THE CONFLICT OF LAW PRINCIPLES THEREOF.

        This instrument may be executed in any number of counterparts, each of
which so executed shall be deemed to be an original, but all such counterparts
shall together constitute but one and the same instrument.

        THIS GUARANTEE AGREEMENT is executed as of the date first above written.

                              TECO ENERGY, INC.


                              By:
                                 -----------------------------------------------
                                  Name:
                                       -----------------------------------------
                                  Title:
                                        ----------------------------------------


                              THE BANK OF NEW YORK
                              as Guarantee Trustee


                              By:
                                 -----------------------------------------------
                                  Name:
                                       -----------------------------------------
                                  Title:
                                        ----------------------------------------



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