CONFIDENTIAL TREATMENT REQUESTED. CONFIDENTIAL PORTIONS OF THIS DOCUMENT HAVE
BEEN REDACTED AND HAVE BEEN SEPARATELY FILED WITH THE COMMISSION.

                                                                 Exhibit 10.4.23

                         GEOTHERMAL LEASE AND AGREEMENT

     THIS LEASE AND AGREEMENT is made this 15th day of February, 1977, by and
between the undersigned WALTER J. HOLTZ, as Lessor, and MAGMA ENERGY, INC., a
corporation, as Lessee.

     1. WITNESSETH: For and in consideration of ten dollars ($10.00) to the
Lessor paid and other good and valuable consideration, the receipt of which is
hereby acknowledged and in consideration of the covenants and agreements as
herein provided, the Lessor does grant, lease, let and demise unto the Lessee,
its successors and assigns, the land and premises hereinafter described, with
the sole and exclusive right to the Lessee to enter upon and to use and occupy
the said land to explore for, drill for, develop, mine, produce and utilize
geotherma1 steam, geotherma1 fluids, hot water, brines, electric energy and the
heat and energy of the Earth in all its forms (hereinafter called "Geothermal
Resources"), and by-products thereof and products associated therewith (except
oil, gas and other hydrocarbons), and to take, store, remove, dispose of and use
same and for uses and purposes incidental thereto, together with the right to
utilize the leased land and to construct, maintain and use any and all
facilities thereon and therein as may be necessary for Lessee's operations on
the leased land or other land in the vicinity of the leased land and for
utilization of the geotherma1 resources and other products produced therefrom,
including but not limited to well sites, pipelines, power stations and
transmission lines, roads, structures and installations relating thereto,
service facilities,




tanks, ponds, wells for injection or reinjection of waste geothermal resources,
gases and other residual products.

     2. Lessor reserves the exclusive right to utilize said land for all other
purposes which do not unreasonably interfere with Lessee's operations. If
Lessee's operations on the land cause damage or loss of stock, crops, or
property, Lessee shall compensate the injured party for such loss within 90 days
after demand therefore, Lessee agrees to indemnify and hold Lessor harmless from
any loss or injury to any party not a party hereto, by reason of any act or
omission of Lessee during its tenancy hereunder. Lessee before commencing any
operations on the leased land shall procure public liability and property damage
insurance with limits not less than $500,000.00 as to public liability and
$100,000.00 as to property damage, naming Lessor as a co-insured and shall
deliver a certificate of such insurance to Lessor. Lessee through its actions
shall not permit any mechanics lien, or other claim of any kind to become an
encumbrance upon Lessor's title to the leased land. If Lessee fails to take
action to remove any lien or claim that may be filed within 30 days after demand
by Lessor, Lessor at its option, may terminate this lease upon 10 days written
notice.

     3. This lease shall be for a period of five (5) years from the date hereof
(hereinafter called "primary term") and so long thereafter as rent or royalty is
being paid hereunder or any of the aforesaid substances is produced therefrom or
from land pooled or unitized therewith, or drilling, development, testing or
producing operations are conducted thereon, or excused under the terms hereof.

                                       2


     4. In addition to the initial consideration, the first year's rental of
$*** will be paid to Lessor upon the execution of this Lease. Thereafter,
commencing with the first anniversary of the term hereof, Lessee shall pay to
Lessor as rental yearly in advance the sum of *** dollars ($***) per acre per
year for so much of said land as may then still be under this Lease, until such
time as royalties paid to Lessor are equal to or greater than *** dollars ($***)
per acre per year.

     5. The land covered hereby is described in Exhibit "A" attached hereto and
made a part hereof.

     6. Notwithstanding any other provision of this Lease, it is specifically
understood and agreed that if at the end of five (5) years from date of
expiration of the primary term hereof, Lessee has not commenced production and
sale in commercial quantities of geothermal resources, or any other upon which
royalty is payable to Lessor hereunder, or if after commencing production and
sale of such substances, Lessee shall discontinue same for a period of six
months in any calendar year, then Lessee shall default under this Lease and at
Lessor's Option, this Lease may be terminated if Lessee shall fail to remedy
such default as herein provided or written notice of default from Lessor to
Lessee; provided, however, that no default shall be deemed to exist where such
discontinuance of production or sale is caused by governmental regulations or
restrictions, shutdown for repairs, maintenance, modification or enlargement of
Lessee's electric generating facilities, or because of any of the conditions as
set forth in paragraph 15 below.

*** Confidential material redacted and filed separately with the Commission.

                                       3


     7. Any lands required by Lessee for location of well or wells, easements,
rights of way, egress, ingress, pipelines, or other surface or subsurface
facilities of any kind, hereinafter called "Occupied Land", excepting, however,
those facilities referred to in paragraph 9 below, shall be submitted to Lessor
for his consent and approval before operations on such lands or use thereof are
commenced. Unless Lessor dissents to the location or locations submitted within
five days, and offers a substitute location within 10 days of receiving notice
of Lessee's proposed location, Lessee may consider the request as submitted
approved and may proceed with its planned locations on such lands or use
thereof. Lessor shall not be unreasonable or arbitrary as to the selection or
approval of such sites.

     Should Lessor cause the leased land or any portion thereof to be used for
other than agricultural purposes he shall have the right, at his expense, with
the exception of any well or wells, to cause the aforesaid easements, _______ to
be relocated. Any well site shall consist of not more than two sites and there
shall be a limit of one site per 40 acres of leased land. ____________ Lessee
shall continue to pay all royalties attributable to Occupied site.

     8. Lessee shall pay Lessor yearly rental for Occupied Land adjusted
annually, equal to farming rentals being paid per acre to owners of adjacent or
adjoining farm land, but in no case less than $*** per acre per year. The
parties acknowledge that said farming rental is presently $*** per acre per
year.

*** Confidential material redacted and filed separately with the Commission.

                                       4


     9. Lessor shall also make available to the Lessee one site of not more than
five acres in size for a facility or facilities for the generation of electric
power and/or the processing of geothermal resources or by-products thereof. The
location of said site shall be submitted to Lessor for his consent and approval
as provided for in paragraph 7 above in the same manner as though said site
constituted "Occupied Land". In such event, Lessee shall purchase said site,
paying to the Lessor the fair market value thereof. Said fair market value shall
be based upon the highest and best use of said site notwithstanding the fact
that the same may then be devoted to agricultural purposes. If the parties
cannot agree upon the fair market value of such land within 30 days after
exercise of Lessee's option, such value shall be determined by three qualified
appraisers, one to be selected by each of the parties and the third by any judge
of the Imperial County Superior Court. The rules of the American Arbitration
Association shall apply and be binding upon the parties as to any such
valuation. In the event of such sale Lessor shall retain all geothermal and
mineral rights under said site.

     10. Lessee shall pay to Lessor as royalty *** of the gross proceeds
received by Lessee from the sale of Geothermal resources, or by-products hereof.
Should Lessee process its *** before sale, Lessor's royalties shall bear its
proportionate share of ***. Lessee shall pay to Lessor said royalty on the 25th
day of each month for accrued royalties for the preceding calendar month. Lessee
shall have the right to co-mingle the geothermal resources and other substances
produced from the leased land or lands pooled therewith with such substances
produced from other lands

*** Confidential material redacted and filed separately with the Commission.


                                       5


and to pay Lessor's royalty on the basis of production allocable to the leased
land as determined by metering or gauging same. Lessee shall not be required to
account to the Lessor for, or pay royalty on, any product produced by Lessee
from said land and used by it in its operations hereunder. Except for taxes
chargeable to Lessor no deduction from royalties due Lessor will be made without
written approval of Lessor, except as herein provided.

     11. It is understood and agreed by and between the parties hereto that at
any time during the primary term of this Agreement if Lessee shall acquire by
purchase or assignment an interest in any lease executed after the date of this
Agreement and covering lands located within five miles of the land covered
hereby, which lease shall contain a greater Lessor's royalty or a greater annual
per acre rental than is provided by this Agreement, the Lessee shall immediately
increase the corresponding terms of this Agreement so as to afford the Lessor
herein equal terms. In the event of such increase, the Lessee shall promptly
tender to the Lessor for his execution an instrument in writing which shall
contain such increased terms.

     12. In valuing amounts realized or received by Lessee for any thing or
substance sold, utilized or disposed of by Lessee upon which royalty is payable
to Lessor, such amount in no event shall be less than would be obtained as
between parties dealing at arms length and not under substantial common control.

     13. If the Lessor or any party Lessor owns a less interest in the
geothermal resources or by-products hereunder than the entire and undivided fee
estate therein, then


                                       6


the royalty and rental herein provided shall be paid the Lessor or such party
Lessor only in the proportion which his ownership bears to the whole and
undivided fee.

     14. Lessee may, at any time during the life of this Lease, pool, unitized
or combine all or any part of the leased land into a unit (hereinafter called
"Unit") with any other land or lands or leases adjacent, adjoining or in the
immediate vicinity of the leased land for drilling, development, producing or
operating purposes, provided that the total acreage within any such drilling or
operating unit shall not exceed 5,120 acres, plus or minus 10%. Such a Unit
shall be created upon Lessee's filing with the County Recorder, in the county
where the leased land is located, a notice or declaration of creation of such
unit, describing the lands and acreage to be embraced there, and the names of
the lessors and the dates of the respective leases covering such lands. Notice
of and a copy of the creation of a Unit shall be sent to Lessor.

     15. Production as to which royalty is payable from any wells drilled upon
any such Unit, whether located upon the leased land or other lands, shall be
credited to the leased land in the proportion that the acreage of the leased
land in such Unit bears to the total acreage of such Unit. The royalty paid as
herein provided shall be deemed to be the royalty payable to Lessor with respect
to the leased lands hereunder, and all drilling, developing, producing or other
operation by Lessee on any of the unitized land shall for purposes of this
Lease, be deemed to be performed on the leased land.

     16. The obligations of Lessee hereunder shall be suspended, and the Primary
Term shall be extended until expiration of ninety (90) days after removal of
cause for


                                       7


suspension, while the Lessee is prevented or delayed from complying therewith,
in whole or in part, by strikes, lockouts, actions of the elements, accidents,
inability to obtain services or equipment, rules, regulations or restrictions of
any federal, state, municipal or other governmental entity or agency, procedures
relating to environmental matters, the delay in issuance of permits to Lessee
required with respect to any of Lessee's operations hereunder, provided that
application for any such permits shall have been made not less than 30 days
prior to the time for performing any act required of Lessee hereunder or matters
or conditions beyond the reasonable control of the Lessee (including, but not
limited to, inability to obtain a market for the geothermal resources produced
from the leased land) whether or not similar to the matters or conditions herein
specifically enumerated.

     17. Lessee will keep Occupied Land in a clean and weed-free condition at
all times. If Lessor so desires, he may do the work required and bill Lessee for
his actual costs.

     18. Lessee agrees to put forward its best efforts in overcoming obstacles
that may prevent or delay the expeditious and successful geothermal development
of the leased lands.

     19. The Lessee shall pay all property taxes on its improvements and
property and ninety percent (90%) of the taxes if any, levied against Geothermal
Resources rights and rights as to other products covered by this lease. Lessor
shall pay all taxes levied and assessed against the land as such and Lessor's
property and ten percent (10%) of the taxes


                                       8


levied and assessed against Geothermal Resources rights and rights as to other
products covered by this lease. In the event the State, United States, or any
municipality or other governmental agency levies a license, severance,
production or other tax on the products hereunder, or on Lessee's right to
operate or produce or sell products, then and in that event the Lessee shall pay
ninety percent (90%) of such tax and Lessor shall pay ten percent (10%) thereof.
Lessee is hereby authorized to pay any taxes and assessments on behalf of Lessor
and may, if it so desires, deduct the amount so paid from royalties or monies
due Lessor hereunder. Any taxes (other than taxes on the leased land as such and
Lessor's improvements), a portion of which are chargeable to Lessor under this
Lease, which are levied against the Unit or the pooled lands as a Unit, shall be
chargeable to Lessor only in the proportion thereof that the share of production
from such Unit is allocated to the leased land.

     20. In the event any taxes are levied or assessed against Geothermal
Resources rights or rights as to other products covered by this lease prior to
the production and sale of geothermal resources or by-products thereof, then
Lessee shall pay all said taxes levied and assessed against said rights for
Lessor's account, until such time as geothermal resources or any of the
substances covered by the lease are produced and sold in commercial quantities.

     21. The Lessee or the owner thereof shall have the right at any time to
remove from said land all machinery, equipment, pipes, casing, structures and
other property and improvements belonging to or placed on the land by or under
agreement with the Lessee,


                                       9


providing that such removal shall be completed no later than a reasonable time
after the termination of this lease . Lessee agrees after termination of this
lease to return said land to as near its original condition as is practical.

     22. If Lessee shall violate any provision, condition or covenant hereof,
Lessee shall take corrective action to diligently remedy such violation within
60 days of written notice thereof by Lessor. If Lessee shall fail to do so,
Lessor at his option may cancel this lease by written notice to Lessee, and all
rights of the Lessee in and to said land shall be at an end, save and excepting
each well completed or being drilled and one surrounding each such well, and
saving and excepting rights of way, easements, surface areas and ingress and
egress to surface areas necessary for Lessee's operation for operation and
maintenance of such wells and operation and maintenance of electric generating
and power transmission facilities or other facilities for utilization or
processing of other products covered hereby, and as to which the person or
persons owning or operating such facilities are not in default under the
agreement or agreements pursuant to which such facilities were installed on the
leased land. If, upon termination of this lease, Lessee does not, within 30 days
thereafter, leave the leased land in a clean and farmable condition and remove
from said land all machinery, equipment, pipes, structures and other property or
improvements placed on the land by Lessee and not permitted to remain thereon,
then Lessor shall have the right to remove all such items and Lessee will pay to
Lessor actual cost for such removal and disposal.

                                       10


     23. Lessee may, at any time and upon payment of the sum of $10.00 to Lessor
as and for fixed and liquidated damages, quitclaim to the Lessor all of the
right, title and interest of Lessee in and to the leased lands or any part
thereof, and thereupon all rights and obligations of the parties hereto one to
the other shall cease and terminate as to the premises quitclaimed, except:

     a. No quitclaim shall relieve Lessee of any debt or obligation for the
payment of money due Lessor at time of quitclaim, or any indemnity or old
harmless obligation in Lessor's favor or any obligation of Lessee to restore or
repair the land quitclaimed in accordance with the provisions of this lease.

     b. Quitclaims will not reduce Lessor's percentage in a unit formed prior to
date of quitclaim; and, in the event no Unit has been created, will not reduce
the royalty payments to which he would otherwise be entitled.

     24. In the event of any litigation under this lease, the prevailing party
shall be entitled to reasonable attorney's fees and costs of suit as fixed by
the court.

     25. This Lease and Agreement supersedes that certain lease and agreement
between the parties dated December 10, 1971, a short form of which was recorded
in Book 1321, Page 1194, Official Records of Imperial County, California. It is
understood and agreed that the wells, property, facilities and improvements
heretofore drilled or placed on the leased land by Lessee under said lease and
agreement dated December 10, 1971, are and shall continue to be the property of
Lessee and subject to the provisions of this Lease and Agreement.

                                       11


     26. This lease and all its terms, conditions and provisions shall extend to
and be binding upon the heirs, executors, administrators, grantees, successors
and assigns of the parties hereto.

     27. Any notice from the Lessor to the Lessee must be given by sending the
same by registered or certified mail, postage prepaid, addressed to the office
of Lessee at 631 South Witmer Street, Los Angeles, California 90017; and any
notice from the Lessee to Lessor must be given in the same manner addressed to
the Lessor at 1550 Orange Avenue, El Centro, California 92243. The parties may,
upon notice, change their said respective addresses for notice.

/s/ Walter J. Holtz
---------------------------------
Walter J. Holtz


                                              MAGMA ENERGY, INC.



                                              By: /s/ B.C. McCabe
                                                 -------------------------------
                                              B.C. McCabe              President



                                              By: /s/ Joseph W. Aidlin
                                                 -------------------------------
                                              Joseph W. Aidlin         Secretary


                                       12



                                    EXHIBIT A

     The land which is the subject of the herein Geothermal Lease and Agreement
is that certain land situate in the County of Imperial, State of California,
more particularly described as follows, to wit:

     Tract 40, Township 16 South, Range 14 East, S. B. M. in
     the County of Imperial, State of California, as per Map of
     the re-survey, approved and filed in the United States Land
     Office at Los Angeles, California.

     EXCEPTING THEREFROM that portion thereof described as follows:

     BEGINNING at the Northwest Corner of said Tract 40;
     Thence East along the North line thereof, 208.72 feet;
     Thence South 208.72 feet; thence West 208.72 feet to a
     point in the West line of said Tract 40; Thence North along
     said West line, 208.72 feet to the Point of Beginning.





     Including all rights in and under easements, roadways and canals
appurtenant to the said land.


                                       13



Recording Requested by

NEW ALBION RESOURCES CO.

When Recorded Return To:

NEW ALBION RESOURCES CO.
P.O. Box 168
San Diego, California 92112

Fee
$7.00

                   AMENDMENT TO GEOTHERMAL LEASE AND AGREEMENT

     This Amendment to Geothermal Lease and Agreement ("Amendment") is entered
into this 14th day of April, 1982, by and between WALTER J. HOLTZ ("Holtz") and
NEW ALBION RESOURCES CO., a California corporation ("NARCO"), with reference to
the following facts:

     A. On February 15, 1977, Holtz entered into a "Geothermal Lease and
Agreement" (the "Holtz Lease") with Magma Energy, Inc , a corporation, for the
lands therein described, to explore for, drill for, develop, mine, produce and
utilize geothermal resources and by-products and products associated therewith.
A short form of the Holtz Lease was recorded April 29, 1977, at Book 1400, Page
1487 of Official Records of Imperial County, California. The Holtz Lease was
assigned by Magma Energy, Inc , to NARCO by "Assignment of Interest in Lease,"
dated February 15, 1978, and recorded February 22, 1978, at Book 1412, Page 1083
of Official Records of Imperial County, California.

                                       14


     B. The "primary term" of the Holtz Lease is for a period of five years,
commencing February 15, 1977.

     C. The parties desire to extend the primary term of the Holtz Lease for an
additional one-year period, commencing February 15, 1982, and amend the Holtz
Lease in other respects.

     NOW, THEREFORE, in consideration of the promise of rent to be paid, the
mutual covenants of the parties herein contained, and other good and valuable
consideration, the parties agree as follows:

     1. The "primary term" of the Holtz Lease, set forth in Paragraph 3 of said
lease, is hereby extended for a twelve-month period commencing February 15,
1982, and terminating at Midnight, February 14, 1983.

     2. The following is hereby added to the Holtz Lease as Paragraph 28
thereof:

     "28. Subject to Lessor's right under Paragraph 6 hereof
     and notwithstanding anything else to the contrary
     contained herein, or in the Holtz Lease, if Lessee
     completes a well or wells or a processing plant on the
     leased lands or on the Unit area capable of producing
     or processing Geothermal Resources in quantities and
     quality deemed paying quantities by Lessee, Lessee may
     continue to pay or tender to Lessor, annually in
     advance of each lease anniversary date, rental until
     Lessee has made a sale of Geothermal Resources produced
     from or allocated to the leased lands. So long as such
     annual rental payments are paid or tendered, this Lease
     shall remain in force and effect even though extended
     thereby beyond the primary term, and all payments so
     paid or tendered after the expiration of said primary
     term shall be deemed advance royalties, and so long as
     same are paid, each well or wells shall be deemed to be
     actually producing Geothermal Resources in paying


                             15


     quantities under the terms hereof. The entire amount of
     any such advance royalty(ies) paid to Lessor may be
     retained by Lessor and shall not be subject to
     recapture by Lessee. Lessee agrees to exercise due
     diligence in the development and drilling of wells and
     the production of Geothermal Resources in paying
     quantities; provided, however, that Unit Operations
     conducted under the terms of the Heber Geothermal Unit
     Agreement, recorded in Book 1437, Page 1272, Imperial
     County, California, without a cessation of 180
     consecutive days for reasons other than those stated in
     Article 14 of said Unit Agreement, shall be considered
     as due diligence under this Paragraph 28.

     3. Notwithstanding any provision herein or in the Holtz Lease to the
contrary, and notwithstanding extension hereby of the "primary term" of the
Holtz Lease (i) the five (5) year period described in Paragraph 6 of the Holtz
Lease shall not be hereby extended beyond February 15, 1987, as originally set
forth in the Holtz Lease, and (ii) Paragraph 11 of the Holtz Lease shall remain
in full force and effect throughout the primary term as extended hereby.

     4. The signature original of this Amendment may be filed for recordation by
either party in the Office of the County Recorder for Imperial County,
California.

     5. This Amendment to Geothermal Lease and Agreement shall bind and inure to
the benefit of the respective heirs, executors, administrators, successors and
assigns of the parties hereto.

     6. The Holtz Lease as hereby amended is confirmed.

     The parties have executed this Amendment to Geothermal Lease and Agreement
at San Diego, California, as of the date sat forth at the beginning hereof.


                                       16



                                                    /s/ Walter J. Holtz
                                                 -------------------------------
                                                        WALTER J. HOLTZ


                                                 NEW ALBION RESOURCES CO.,
                                                 a California corporation



                                                 By: /s/ Indecipherable
                                                    ----------------------------
                                                                  Vice President


                                                 Attest:


                                                 /s/ Indecipherable
                                                 -------------------------------
                                                                       Secretary


                                       17



                   AMENDMENT of GEOTHERMAL LEASE AND AGREEMENT

     THIS AGREEMENT, made this 14th day of March, 1986, between the party or
parties whose names are subscribed hereto under the designation of "Lessor",
hereinafter called "Lessor" (whether one or more), and CHEVRON GEOTHERMAL
COMPANY OF CALIFORNIA AND UNION OIL COMPANY OF CALIFORNIA, hereinafter called
"Lessee",

                              W I T N E S S E T H :

     THAT, REFERENCE IS HEREBY HAD to that certain Geothermal Lease and
Agreement dated February 15, 1977 (a short form of such lease being of record in
the Office of the County Recorder of Imperial County, California, in Book 1400,
at Page 1487 et seq., of Official Records), whereby Lessor did grant, let and
lease unto Magma Energy, Inc., a predecessor in interest to Lessee for the
purposes therein described certain lands situate in said County and State
particularly described in such lease and agreement, such lease and agreement
being hereinafter referred to as "said lease";

     AND, WHEREAS, by assignment dated February 15, 1978, recorded in Book 1412,
Page 1083 of said official records, Mamga Energy, Inc. assigned its interest in
said lease to New Albion Resources Co. ("NARCO");

     AND, WHEREAS, by asignment dated April 14, 1982, recorded in Book 1483,
page 678 of said official records, said lease was amended;

                                       18


     AND, WHEREAS, by assignment dated April 14, 1982, a memorandum of which was
recorded in Book 1488, Page 1749 of said official records, Narco assigned its
interest in said lease to Union Oil Company of California, ("UNION");

     AND, WHEREAS, by assignment dated September 1, 1982, a memorandum of which
was recorded in Book 1493, Page 601 of said official records, Union assigned a
67,238 percent undivided interest in said lease to Chevron Geothermal Company of
California;

     AND, WHEREAS, Lessor and Lessee have agreed to further amend said lease in
the particulars hereinafter set forth:

     NOW, THEREFORE, in consideration of the sum of ONE DOLLAR ($1.00) and other
valuable consideration paid to Lessor by Lessee, receipt of which is hereby
acknowledged, Lessor and Lessee agree as follows:

     1. The last sentence of Paragraph 8 of said lease which now reads as
follows: shall be and hereby is amended to read as follows:

     "The parties acknowledge that said farming rental is $*** per acre
     effective February 15, 1985. Commencing with the rental period that begins
     in 1986, the annual rental payment for occupied land for succeeding annual
     periods shall be determined by the increase, if any, in the Consumer Price
     Index, (All Urban Consumers, U.S. City Average, All Items) as reported by
     the U.S. Department of Labor, Bureau of Labor Statistics, for the last
     calendar month ending more than 60 days prior to the date of each such
     annual period ("Ending Index") as compared to the calendar month in which
     the 1985 rental payment was made ("Beginning Index"). In the event the
     Ending Index is a number greater than the Beginning Index, the amount of
     said rental payment shall be increased in the same ratio that the Ending
     Index bears to the Beginning Index."

*** Confidential material redacted and filed separately with the Commission.

                                       19


     2. To implement the foregoing, Lessor does hereby grant, demise, lease and
let unto Lessee all those certain lands particularly described in said lease for
the term and purposes and subject to all of the other provisions of said lease
as hereby amended. Lessor agrees that said lease as hereby amended is in good
standing and in full force and effect. Lessor acknowledges receipt of rental in
full under said lease to February 15, 1988.

     3. This agreement shall bind and inure to the benefit of the respective
heirs, executors, administrators, successors, and assigns of the parties hereto.

     IN WITNESS WHEREOF, this agreement has been executed as of the day and year
first herein written.


LESSEE

CHEVRON GEOTHERMAL COMPANY OF CALIFORNIA

By /s/ J.W. Davis
   ------------------------------------
   J.W. Davis, Vice-President


UNION OIL COMPANY OF CALIFORNIA

By /s/ Carol Otte
   ------------------------------------
   ITS ATTORNEY-IN-FACT
   CAREL OTTE


LESSOR

/s/ Walter J. Holtz
---------------------------------------
    WALTER J. HOLTZ

/s/ Toni F. Holtz
---------------------------------------
    TONI F. HOLTZ


                                       20