Exhibit 10.51



Recording requested by
and when recorded mail to:

Macdonald, Halsted & Laybourne
Citicorp Plaza, 36th Floor
725 S. Figueroa Street
Los Angeles, California  90017
Attention:  Juliana Stamato, Esq.
- --------------------------------------------------------------------------------

     THIS AGREEMENT REGARDING OVERRIDING ROYALTY (this "Agreement") is made as
of this 5th day of May, 1988, by and between Coso Energy Developers, a
California general partnership ("CED"), and Coso Land Company ("CLC"), a joint
venture between California Energy Company, Inc., a Delaware corporation
("CECI"), and Caithness Geothermal 1980 Ltd., a New Jersey Limited Partnership.

                                   RECITALS:
                                   --------

     A.   Pursuant to that certain Assignment of Record Title Interest in a
Lease for Oil and Gas or Geothermal Resources dated April 15, 1988, CLC assigned
to Coso Geothermal Company ("CGC"), a joint venture between CECI, CLC, Pacific
Geothermal Ltd., L.P., a New Jersey limited partnership, Mt. Whitney Geothermal
Limited Partnership, a New Jersey limited partnership, and Mojave Joint Venture
(a joint venture between West Coast Geothermal Ltd. and Caithness Geothermal
1980 Limited - Special Group 1, both New Jersey limited partnerships), all of
CLC's record title interest in and to that certain Offer to Lease and Lease for
Geothermal Resources dated April 19, 1985, effective May 1, 1985 (the "BLM
Lease"), between the Bureau of Land Management (the "BLM"), as lessor, and CECI,
as lessee. The BLM Lease covers the lands located in Inyo County, California, as
more particularly described in Exhibit A attached hereto and made a part hereof
(the "BLM Project Area").

     B.   CGC subsequently assigned all of its record title interest in the BLM
Lease to CED pursuant to that certain Assignment of Record Title Interest in a
Lease for Oil and Gas or Geothermal Resources dated April 15, 1988, effective
May 1, 1988.


     C.   CLC, CGC and CED contemplated that CLC would have an overriding
royalty interest in the steam produced from the BLM Project Area.  CED now
desires to grant to CLC such an overriding royalty interest.

     NOW, THEREFORE, in consideration of the foregoing Recitals, which are by
this reference incorporated herein, and for other good and valuable
consideration, the receipt of which is hereby acknowledged, the parties hereto
agree as follows:

     Section 1.  Royalty.  CED shall pay to CLC an overriding royalty in an
     ---------   -------
amount equal to five percent (5%) of the value of the steam produced from the
BLM Project Area.  The value of the steam shall be equal to the steam value used
in calculating the royalty payable to the BLM under the BLM Lease.  The
overriding royalty shall be due and payable on the last day of the month
following the month in which the production occurs.

     Section 2.  Certification and Acknowledgment of CLC.  CLC certifies that it
     ---------   ---------------------------------------
is a citizen of the United States, an association of such citizens or an
association of corporations and partnerships organized under the laws of the
United States or of any State thereof.  CLC acknowledges and understands that an
overriding royalty may not be less than or greater than the percentages
specified in 43 Code of Federal Regulations Section 3241, as may be amended from
time to time.  CLC further acknowledges and understands that the certification
and acknowledgment of CLC contained in this Section 2 are for the benefit of and
may be relied upon by CED and the BLM.

     Section 3.  Further Assurances.  CLC and CED agree that, at any time and
     ---------   ------------------
from time to time, upon the written request of the other, such party will
promptly and duly execute and deliver any and all such further instruments and
documents and take such further action as the other party may reasonably request
in order to obtain the full benefits of this Agreement.

     Section 4.  Severability.  Any provision of this Agreement which is
     ---------   ------------
prohibited, unenforceable or not authorized in any jurisdiction shall, as to
such jurisdiction, be ineffective to the extent of such prohibition,
unenforceability or non-authorization, without invalidating the remaining
provisions hereof or affecting the validity, enforceability or legality of such
provision in any other jurisdiction.

     Section 5.  Notices.  All notices, certificates, requests and other
     ---------   -------
communications to any party hereunder shall be in writing (including bank wire,
facsimile or similar writing) and shall be given to such party, addressed to it,
at its address or facsimile number set forth below, or such other address or
number as such party may hereafter specify for such purpose by

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notice to the other party in accordance herewith.  Each such notice,
certificate, request or communication shall be effective (i) when presented
personally, (ii) if give by mail, five (5) days after such communication is
deposited in the U.S. mails, registered, return receipt requested, with first
class postage prepaid, addressed as aforesaid or (iii) if given by any other
means, when delivered at the address specified below.  The telecopy (facsimile)
numbers provided below are for convenience of the parties only.  Transmission by
telecopy shall constitute provision of notice under this Agreement only if
receipt thereof is acknowledged by the recipient.

          If to CED:          Coso Energy Developers
                              c/o Coso Hotsprings Intermountain Power, Inc.
                              601 California Street
                              San Francisco, California  94108
                              Attention:  Chief Financial Officer
                              Telecopy:  (415) 391-8989

          with copies to:     Macdonald, Halsted & Laybourne
                              Citicorp Plaza, 36th Floor
                              725 South Figueroa Street
                              Los Angeles, California  90017
                              Attention:  Jay M. Davis, Esq.
                              Telecopy:  (213) 629-7206

                              Caithness Geothermal 1980 Ltd.
                              c/o Caithness Corporation
                              380 Lexington Avenue
                              New York, New York  10017
                              Attention:  Mr. James D. Bishop
                              Telecopy:  (212) 557-1587

                              Milbank, Tweed, Hadley & McCloy
                              One Chase Manhattan Plaza
                              New York, New York  10005
                              Attention:  Ola T. Hox, Esq.
                              Telecopy:  (212) 530-5219

          If to CLC:          Coso Land Company
                              c/o California Energy Company, Inc.
                              601 California Street
                              San Francisco, California  94108
                              Attention:  Chief Financial Officer
                              Telecopy:  (415) 391-8989

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          with copies to:     Macdonald, Halsted & Laybourne
                              Citicorp Plaza, 36th Floor
                              725 South Figueroa Street
                              Los Angeles, California  90017
                              Attention:  Jay M. Davis, Esq.
                              Telecopy:  (213) 629-7206

                              Caithness Geothermal 1980 Ltd.
                              c/o Caithness Corporation
                              380 Lexington Avenue
                              New York, New York  10017
                              Attention:  Mr. James D. Bishop
                              Telecopy:  (212) 557-1587

                              Milbank, Tweed, Hadley & McCloy
                              One Chase Manhattan Plaza
                              New York, New York  10005
                              Attention:  Ola T. Hox, Esq.
                              Telecopy:  (212) 530-5219


     Section 6.  Successors and Assigns.  Whenever in this Agreement any of the
     ---------   ----------------------
parties hereto is named or referred to, successors and assigns of such party
shall be deemed to be included and all covenants, promises and agreements in
this Agreement by and on behalf of the respective parties hereto shall be
binding upon and inure to the benefit of the respective successors and permitted
assigns of such parties, whether so expressed or not.

     Section 7.  Governing Law.  This Agreement shall be governed by,
     ---------   -------------
interpreted under, and construed and enforced in accordance with the laws of the
State of California.  Nothing contained herein, however, shall preclude either
party from bringing any legal suit, action or proceeding arising out of or
relating to this Agreement in the courts of any place where the other party or
any of its property or assets, or the property or assets of any of its general
partners, may be found or located.

To the extent permitted by applicable law, such party hereby irrevocably submits
to the jurisdiction of any such court expressly waives, in respect of any such
suit, action or proceeding, the jurisdiction of any other court or courts now or
hereafter, by reason of its present or future domicile, or otherwise, may be
available to it.

     Section 8.  Amendments and Waivers.  This Agreement may be amended only by
     ---------   ----------------------
a writing signed by the parties hereto.

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No amendment or waiver of any provision of this Agreement nor consent by either
party or any departure by the other party herefrom shall in any event be
effective unless the same shall be in writing and signed by the party to be
charged thereby.  Any such waiver or consent shall be effective only in the
specific instance and for the specific purpose for which given.  No failure on
the part of any party hereto to exercise, and no delay in exercising, any right
hereunder shall operate as a waiver thereof (except as expressly provided
herein) nor shall any single or partial exercise or any right hereunder preclude
any other or further exercise thereof or the exercise of any other right. The
remedies herein provided are cumulative and not exclusive of any remedies
provided by law.  This Agreement supersedes all prior agreements among the
parties hereto with respect to the matters addressed herein.

     Section 9.  Headings.  The section headings in this Agreement are included
     ---------   --------
herein for convenience of reference only and shall not constitute a part of this
Agreement for any other purpose.

     Section 10.  Counterparts.  This Agreement may be executed in any number of
     ----------   ------------
counterparts, each of which shall be an original, with the same effect as if the
signatures thereto and hereto were upon the same instrument.

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     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the date first shown above.

                         COSO ENERGY DEVELOPERS

                         By:  COSO HOTSPRINGS INTERMOUNTAIN POWER, INC.,
                              A general partner

                              By:   /s/ Richard A. Nishkian
                                    -----------------------
                                    Name:     Richard A. Nishkian
                                    Title:    Chief Financial Officer

                         By:  CAITHNESS COSO HOLDINGS,
                              A general partner

                              By:   CAITHNESS NAVY II GROUP, L.P.,
                                    A general partner

                                    By:  MOJAVE POWER III, INC.,
                                         A general partner

                                         By:  /s/ Hiram A. Bingham
                                              --------------------
                                              Name:     Hiram A. Bingham
                                              Title:    President

                              By:   CAITHNESS CORPORATION,
                                    A general partner

                                    By:  /s/ Hiram A. Bingham
                                         --------------------
                                         Name:     Hiram A. Bingham
                                         Title:    President

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                         By:  CAITHNESS BLM GROUP, L.P.,
                              A general partner

                              By:   MOJAVE POWER III, INC.,
                                    A general partner

                                    By:  /s/ Hiram A. Bingham
                                         --------------------
                                         Name:     Hiram A. Bingham
                                         Title:    President

                              By:   CAITHNESS CORPORATION,
                                    A general partner

                                    By:  /s/ Hiram A. Bingham
                                         --------------------
                                         Name:     Hiram A. Bingham
                                         Title:    President

                    COSO LAND COMPANY,
                    a California Joint Venture

                    By:  California Energy Company, Inc.,
                         a Delaware Corporation, General Partner

                         By:  /s/ Richard A. Nishkian
                              -----------------------
                              Name:      Richard A. Nishkian
                              Title:     Senior Vice President and
                                    Chief Financial Officer

                    By:  Caithness Geothermal 1980 Ltd.,
                         a New Jersey Limited Partnership
                         A general partner

                         By:  Caithness Corporation
                              a Delaware Corporation
                              A general partner

                              By:   /s/ Hiram A. Bingham
                                    --------------------
                                    Hiram A. Bingham
                                    President

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