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                                                                     EXHIBIT 5.1


                    [LETTERHEAD OF COVINGTON & BURLING]

                                                                   April 4, 2002


Calpine Corporation
50 West San Fernando Street
San Jose, CA 95113

Calpine Canada Energy Finance ULC
Suite 800, Purdy's Wharf, Tower 1
1959 Upper Water Street
P.O. Box 997
Halifax, Nova Scotia B3J 3N2

Calpine Canada Energy Finance II ULC
Suite 800, Purdy's Wharf, Tower 1
1959 Upper Water Street
P.O. Box 997
Halifax, Nova Scotia B3J 3N2

Calpine Capital Trust IV
c/o Calpine Corporation
50 West San Fernando Street
San Jose, CA 95113

Calpine Capital Trust V
c/o Calpine Corporation
50 West San Fernando Street
San Jose, CA 95113

Ladies and Gentlemen:

             We are acting as counsel to Calpine Corporation, a Delaware
corporation (the "Company"), Calpine Canada Energy Finance ULC, an unlimited
liability company organized under the laws of Nova Scotia, Canada ("Energy
Finance"), Calpine Canada Energy Finance II ULC, an unlimited liability company
organized under the laws of Nova Scotia, Canada ("Energy Finance II"), Calpine
Capital Trust IV, a Delaware business trust ("Capital Trust IV"), and Calpine
Capital Trust V, a Delaware business trust ("Calpine Trust V"), in connection
with the shelf registration under the Securities Act of 1933, as amended
(the "Securities Act"), pursuant to the Registration Statement on Form S-3
(File No. 333-76880) initially filed with the Securities and Exchange
Commission (the "Commission") on January 17, 2002 and amended on April 4, 2002
(such Registration Statement, which includes, pursuant to Rule 429(a) under the
Securities Act, the various securities identified on the cover page of
Amendment No. 1 and in Footnote 8 to the Calculation of Registration Fee table
therein, as the same may be amended or supplemented from time to time, is
herein referred to as the "Registration Statement") with respect to, among
other
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securities, (i) the Company's common stock, par value $.001 per share (the
"Common Securities"), preferred stock, par value $.001 per share (the "Preferred
Securities"), unsecured debt securities (the "Debt Securities") and depositary
shares (the "Depositary Shares"), evidenced by depositary receipts (the
"Depositary Receipts"), each representing a fractional interest in a share of
Preferred Securities, (ii) unsecured debt securities of Energy Finance (the
"Energy Finance Debt Securities") fully and unconditionally guaranteed by the
Company, (iii) unsecured debt securities of Energy Finance II (the "Energy
Finance II Debt Securities") fully and unconditionally guaranteed by the Company
and (iv) the associated guarantees issued by the Company with respect to the
Energy Finance Debt Securities (the "Energy Finance Guarantees") and the Energy
Finance II Debt Securities (the "Energy Finance II Guarantees" and, together
with the Energy Finance Guarantees, the "Guarantees").  The Debt Securities are
to be issued pursuant to an Indenture (the "Indenture"), dated as of
August 10, 2000, between the Company and Wilmington Trust Company, as Trustee
(the "Trustee"), which is incorporated by reference as an exhibit to the
Registration Statement.  The Depositary Shares will be issued under a Deposit
Agreement (the "Deposit Agreement"), among the Company, a financial institution
to be determined, as Depositary (the "Depositary"), and the holders from time to
time of the Depositary Receipts, the form of which has been filed as an exhibit
to the Registration Statement.  The Energy Finance Debt Securities are to be
issued pursuant to an Amended and Restated Indenture (as so amended and
restated, the "Energy Finance Indenture"), dated as of October 16, 2001, between
Energy Finance and the Trustee, which is incorporated by reference as an exhibit
to the Registration Statement.  The Energy Finance II Debt Securities are to be
issued pursuant to an Indenture, dated as of October 18, 2001, between Energy
Finance II and the Trustee, as supplemented by the First Supplemental Indenture,
dated as of October 18, 2001, thereto (as so supplemented, the "Energy
Finance II Indenture" and, together with the Energy Finance I Indenture, the
"Subsidiary Indentures"), which is incorporated by reference as an exhibit to
the Registration Statement.  The Energy Finance Guarantees are to be issued by
the Company pursuant to a Guarantee Agreement, dated as of April 25, 2001, as
amended by the First Amendment to Guarantee Agreement, dated as of
October 16, 2001 (as so amended, the "Energy Finance Guarantee Agreement")
between the Company and the Trustee, which is incorporated by reference as an
exhibit to the Registration Statement.  The Energy Finance II Guarantees are to
be issued by the Company pursuant to a Guarantee Agreement, dated as of
October 18, 2001, as amended by the First Amendment to Guarantee Agreement,
dated as of October 18, 2001 (as so amended, the "Energy Finance II Guarantee
Agreement" and, together with the Energy Finance Guarantee Agreement, the
"Guarantee Agreements") between the Company and the Trustees, which is
incorporated by reference as an exhibit to the Registration Statement.

             We have reviewed such corporate records, certificates and other
documents, and such questions of law, as we have considered necessary or
appropriate for the purposes of this opinion.  We have assumed that each of the
parties (other than the Company) has duly authorized, executed and delivered
the documents to which it is a party.  We have further assumed that each of
Energy Finance and Energy Finance II is an unlimited liability company duly
organized, validly existing and in good standing under the laws of the Province
of Nova Scotia and has all requisite power, authority and legal right to
execute, deliver and perform the applicable Subsidiary Indenture and Energy
Finance Debt Securities or Energy Finance II Debt Securities, as applicable,
and that, insofar as the law of the Province of Nova Scotia is concerned, each
of the Subsidiary Indentures, the Energy Finance Debt Securities and the Energy
Finance II Debt Securities constitutes the valid and binding obligation of
Energy Finance or Energy Finance II, as applicable, enforceable in accordance
with its terms.
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             We have relied as to certain matters on information obtained from
public officials, officers of the Company, Energy Finance and Energy Finance II
and other sources believed by us to be responsible.

         Based upon the foregoing, and subject to the qualifications set forth
below, we are of the opinion that:

(1)   The Company is a corporation duly incorporated, validly existing and in
      good standing under the laws of the State of Delaware.

(2)   When, as and if:  (i) the Registration Statement shall have become
      effective pursuant to the Securities Act, (ii) the appropriate corporate
      action has been taken by the Company to authorize the issuance of the
      Common Securities and fix or otherwise determine the consideration to be
      received for such Common Securities, (iii) any legally required consents,
      approvals, authorizations and other orders of the Commission and other
      regulatory authorities are obtained, (iv) such Common Securities with
      terms so fixed shall have been duly sold, issued and delivered by the
      Company against payment therefor in accordance with such corporate
      action and as contemplated by the Registration Statement and assuming
      compliance with the Securities Act, and (v) certificates evidencing
      shares of the Common Securities have been duly executed by the duly
      authorized officers of the Company in accordance with applicable law,
      then, upon the happening of such events, such Common Securities will be
      validly issued, fully paid and nonassessable.

(3)   When, as and if:  (i) the Registration Statement shall have become
      effective pursuant to the provisions of the Securities Act, (ii)
      appropriate corporate action has been taken by the Company to authorize
      the issuance of Preferred Securities, to fix the terms thereof and to
      authorize the execution and filing of a Certificate of Designations
      relating thereto with the Secretary of State of the State of Delaware,
      (iii) such Certificate of Designations shall have been executed by duly
      authorized officers of the Company and so filed by the Company, all in
      accordance with the laws of the State of Delaware, (iv) any legally
      required consents, approvals, authorizations and other orders of the
      Commission and any other regulatory authorities are obtained, (v) such
      Preferred Securities with terms so fixed shall have been duly sold,
      issued and delivered by the Company against payment therefor in
      accordance with such corporate action and as contemplated by the
      Registration Statement and assuming compliance with the Securities Act,
      and (vi) certificates evidencing shares of Preferred Securities
      have been duly executed by the duly authorized officers of the Company in
      accordance with applicable law, then, upon the happening of such events,
      such Preferred Securities will be validly issued, fully paid and
      nonassessable.

(4)   When, as and if:  (i) the Registration Statement shall have become
      effective pursuant to the provisions of the Securities Act, (ii)
      appropriate corporate action has been taken by the Company to authorize
      and approve the execution and delivery of the Deposit Agreement
      substantially in the form filed as an exhibit to the Registration
      Statement and to authorize the issuance of Depositary Shares and to fix
      the terms thereof, (iii) such Deposit Agreement shall have been executed
      and delivered by a duly authorized officer of the Company and duly
      executed and delivered by the Depositary, (iv) the Depositary Receipts
      shall have been duly executed by the Depositary and the registrar
      therefor in accordance with the Deposit Agreement, (iv) validly issued
      shares of Preferred Securities
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      have been deposited with the Depositary in accordance with the Deposit
      Agreement, (v) any legally required consents, approvals, authorizations
      and other orders of the Commission and any other regulatory authorities
      have been obtained, and (vi) such Depositary Shares shall have been duly
      sold, issued and delivered by the Company against payment therefor in
      accordance with such corporate action and as contemplated by the
      Registration Statement and assuming compliance with the Securities Act,
      then, upon the happening of such events, such Depositary Shares will
      represent legal and valid interests in such Preferred Securities and the
      Depositary Receipts will constitute valid evidence of such interest in
      such Preferred Securities.

(5)   When, as and if:  (i) the Registration Statement shall have become
      effective pursuant to the provisions of the Securities Act, (ii) the
      appropriate corporate action has been taken by the Company to authorize
      the form, terms, execution and delivery of any series of Debt Securities,
      (iii) such series of Debt Securities shall have been sold and issued in
      substantially the form and containing the terms described in the
      Indenture and such corporate action and as contemplated by the
      Registration Statement and assuming compliance with the Securities Act,
      (iv) any legally required consents, approvals, authorizations and other
      orders of the Commission and any other regulatory authorities with
      respect to such series of Debt Securities are obtained and (v)
      certificates evidencing such series of Debt Securities have been
      authenticated by the Trustee, then, upon the happening of such events,
      such series of Debt Securities, when issued, will be binding obligations
      of the Company, enforceable against the Company in accordance with their
      respective terms, subject to bankruptcy, insolvency, fraudulent transfer,
      reorganization, moratorium and other laws of general applicability
      relating to or affecting creditors' rights and to general equity
      principles.

(6)   When, as and if: (i) the Registration Statement shall have become
      effective pursuant to the provisions of the Securities Act, (ii) the
      appropriate corporate action has been taken by Energy Finance to
      authorize the form, terms, execution and delivery of any series of Energy
      Finance Debt Securities, (iii) such series of Energy Finance Debt
      Securities shall have been sold and issued in substantially the form and
      containing the terms described in the Energy Finance Indenture and such
      corporate action and as contemplated by the Registration
      Statement and assuming compliance with the Securities Act, (iv) any
      legally required consents, approvals, authorizations and other orders of
      the Commission and any other regulatory authorities with respect to such
      series of Energy Finance Debt Securities are obtained and (v)
      certificates evidencing such series of Energy Finance Debt Securities
      have been duly authenticated by the Trustee, then, upon the happening of
      such events, such series of Energy Finance Debt Securities, when issued,
      will be valid and binding obligations of Energy Finance, enforceable
      against Energy Finance in accordance with their respective terms, subject
      to bankruptcy, insolvency, fraudulent transfer, reorganization,
      moratorium and other laws of general applicability relating to or
      affecting creditors' rights and to general equity principles.

(7)   When, as and if: (i) the Registration Statement shall have become
      effective pursuant to the provisions of the Securities Act, (ii) the
      appropriate corporate action has been taken by Energy Finance II to
      authorize the form, terms, execution and delivery of any series of Energy
      Finance II Debt Securities, (iii) such series of Energy Finance II Debt
      Securities shall have been sold and issued in substantially the form and
      containing the terms described in the Energy Finance II Indenture and
      such corporate action and as contemplated by the Registration Statement
      and assuming compliance with the Securities
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      Act, (iv) any legally required consents, approvals, authorizations and
      other orders of the Commission and any other regulatory authorities with
      respect to such series of Energy Finance II Debt Securities are obtained
      and (v) certificates evidencing such series of Energy Finance II Debt
      Securities have been duly authenticated by the Trustee, then, upon the
      happening of such events, such series of Energy Finance II Debt
      Securities, when issued, will be valid and binding obligations of Energy
      Finance II, enforceable against Energy Finance II in accordance with
      their respective terms, subject to bankruptcy, insolvency, fraudulent
      transfer, reorganization, moratorium and other laws of general
      applicability relating to or affecting creditors' rights and to general
      equity principles.

(8)   When, as and if: (i) the Registration Statement shall have become
      effective pursuant to the provisions of the Securities Act, (ii) the
      appropriate corporate action has been taken by the Company to authorize
      the form, terms, execution and delivery of the Guarantees, (iii) the
      Guarantees shall have been issued in substantially the form and
      containing the terms described in the Guarantee Agreements and such
      corporate action and as contemplated by the Registration Statement and
      assuming compliance with the Securities Act, and (iv) any legally
      required consents, approvals, authorizations and other orders of the
      Commission and any other regulatory authorities with respect to the
      Guarantees are obtained, then, upon the happening of such events, the
      Guarantees, when issued, will be valid and binding obligations of the
      Company, enforceable against the Company in accordance with their
      respective terms, subject to bankruptcy, insolvency, fraudulent transfer,
      reorganization, moratorium and other laws of general applicability
      relating to or affecting creditors' rights and to general equity
      principles.

        The foregoing opinion is subject to the qualifications that we express
no opinion as to (i) waivers of defenses or statutory or constitutional rights
or waivers of unmatured claims or rights, (ii) rights to indemnification,
contribution or exculpation to the extent that they purport to indemnify any
party against, or release or limit any party's liability for, its own breach or
failure to comply with statutory obligations, or to the extent such provisions
are contrary to public policy, or (iii) rights to collection of liquidated
damages or penalties.

        We are members of the bar of the State of New York.  We do not purport
to be experts in, and do not express any opinion on, any laws other than the
law of the State of New York, the Delaware General Corporation Law and the
Federal law of the United States of America.

        We hereby consent to the filing of this opinion as Exhibit 5.1 to the
Registration Statement and to the reference to our firm under the heading "Legal
Matters" in the Prospectus contained in the Registration Statement.  In giving
such consent, we do not thereby admit that we are in the category of persons
whose consent is required under Section 7 of the Securities Act.

                                  Very truly yours,

                                  /s/ Covington & Burling

