Document:

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

                                       20CONFIDENTIAL TREATMENT REQUESTED. CONFIDENTIAL PORTIONS OF THIS DOCUMENT HAVE
BEEN REDACTED AND HAVE BEEN SEPARATELY FILED WITH THE COMMISSION.

                                                                 EXHIBIT 10.4.24

                                GEOTHERMAL LEASE

         THIS LEASE is made this 31st day of August, 1983, by and between MAGMA
ENERGY, INC., ("Lessor") a Nevada corporation, as Lessor, and HOLT GEOTHERMAL
COMPANY, ("Lessee") a California corporation, as Lessee.

                                    Recitals

         Lessor has heretofore drilled certain wells and developed certain
geothermal resources on the land and premises hereinafter described. Lessee
desires to undertake to develop additional geothermal resources on said land and
to construct thereon facilities to utilize geothermal resources for the
generation of electric power, utilizing the Magmamax power process, a
proprietary and patented process owned by Lessor for generating electric power
utilizing geothermal resources, the U.S. patent number thereon being 3,757,516,
Lessee desires, in addition to a non-exclusive license to utilize on and limited
to the leased land the Magmamax power process, to use a portion of said land for
electric power generating facilities and to obtain, on a continuing basis and
subject to License Agreement, the benefit of Lessor's continuing knowledge and
experience with respect to the Magmamax process and to have the non-exclusive
right to utilize any new developments or improvements of the Magmamax process on
and limited to the leased land.

         1. WITNESSETH: that in consideration of the agreements contained
herein, the parties hereby enter into a lease of the hereinafter described land
(the "leased land") by Lessor to Lessee and concurrently herewith, and as part
of one integrated transaction, the parties shall enter into a License Agreement
with respect to the leased land and with respect to the use by Lessee of the
Magmamax power process. In consideration of the agreements contained herein, the
Lessor does grant, lease, let and demise unto the Lessee, its successors and
assigns, the leased land with the sole and exclusive right to the Lessee to
enter upon and to use and occupy the leased land to explore for, drill for,
develop, mine, produce and use the natural heat of the earth, the energy, in
whatever form, below the surface of the earth present in, resulting from, or
created by, or which may be extracted from, such natural heat, and all minerals
in solution or other products obtained from naturally heated fluids, brines,
associated gases, and steam, in whatever form, found below the surface of the
earth ("geothermal resources") and to take, store, remove, dispose of and use
same and for uses and purposes incidental thereto, together with the right to
use the leased land and to construct and maintain any and all facilities thereon
and therein as may be necessary for Lessee's operations on the leased land or
other lands in the vicinity of the leased land, and for use of the geothermal
resources including but not limited to well sites, pipelines, power plants,
power transmission lines, power stations, tanks, ponds, wells for injection or
reinjection of waste water, gases and other residual products, roads, and other
structures and installations. Lessor retains all rights to use and occupy the
surface and subsurface of the leased land for all purposes, provided that such
use or occupancy shall not unreasonably interfere with the rights of Lessee
under this Lease.

         2. Description. The leased land is described in Exhibit "A" attached
hereto and made a part hereof. In addition to the above-described leased land,
this Lease also covers

                                       -2-

accretions and any small strips or parcels of land now or here after owned by
Lessor which are contiguous or adjacent to the above-described leased land.
Lessor agrees to execute at Lessee's request any additional or supplemental
instruments for a more complete or accurate description of the land so covered.

         3. Term. TO HAVE AND TO HOLD the leased land for a period of thirty
(30) years from the date hereof ("primary term") and so long thereafter as any
geothermal resources are produced therefrom, or are capable of being produced
therefrom, or drilling or producing operations are conducted thereon, or excused
under the terms hereof.

         4. Commencement of Operations. Within eighteen (18) months after the
effective date of this Lease, Lessee shall Commence and diligently continue the
drilling of one or more wells for production of geothermal resources from the
leased land until Lessee shall have satisfied itself that sufficient geothermal
resources are obtainable to supply the needs of a Power plant or power plants of
a gross capacity of ten (10) or more megawatts. If, within six (6) months after
commencement of drilling the first well on the leased land, Lessee determines in
its sole judgment that it is not able to develop on the leased land a sufficient
quantity of geothermal resources to warrant installation of one or more power
plants for generating electricity therefrom, Lessee may, upon notice given to
Lessor within thirty (30) days after expiration of such six (6) month period,
terminate and be freed of all obligations under this Lease. If Lessee elects not
to so terminate this Lease, Lessee shall proceed with the drilling of such well
or wells as it deems appropriate to supply the requisite quantity of geothermal
resources for operation of a power plant or power plants and shall proceed
diligently and in good faith with construction of a power plant or power plants
on the leased land for generation of electricity utilizing the geothermal
resources.

5. Royalty. Lessee shall pay to Lessor as royalty during the full term of this
Lease compensations as follows: (a) As to electricity generated by facilities
having a gross rated capacity of ten (10) megawatts or less, Lessee shall pay to
Lessor *** percent (***%) of the gross proceeds received by Lessee. The said
payment shall be deemed to embrace a payment of *** percent (***%) of gross
proceeds for geothermal resources produced from the leased land and utilized for
the generation of electricity thereon and *** percent (***%) of gross proceeds
as payment for the said non-exclusive license, for surface land use and for
Lessee's agreement to make available to Lessor subject to License Agreement its
continuing knowledge and experience with respect to the Magmamax power process
and the right to utilize new developments or improvements thereof on the leased
land; (b) As to electricity generated by facilities having a gross rated
capacity in excess of ten (10) megawatts, Lessee shall pay to Lessor *** percent
(***%) of the gross proceeds received by Lessee. The said payment shall be
deemed to embrace a payment of *** percent (***%) of gross proceeds for
geothermal resources produced and utilized for the generation of electricity and
*** percent (***%) of gross proceeds as payment for the said non-exclusive
license, for surface land use and for Lessor's agreement to make available to
Lessee subject to License Agreement its continuing knowledge and experience with
respect to the Magmamax power process and the right to utilize new developments
or improvements thereof on the leased land; (c) The payment by Lessee to Lessor
of the total compensations provided for in subparagraphs (a) and (b) hereof,
when due, for the full term of this Lease is a condition to the continuation of
Lessee's rights under this Lease and its right to use or occupy the leased land
or any part thereof. In the event Lessee Shall

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

                                      -3-

default under any covenant or condition of this Lease and fail to remedy such
default or to commence in good faith remedy such default, if such default cannot
be remedied within the notice period, Lessor shall have the right, upon
expiration of sixty (60) days written notice of default, to terminate this Lease
and all of Lessee's rights hereunder. The term "gross proceeds" means the amount
received from the sale to others of electricity produced on the leased land from
geothermal resources therein by the Lessee. Lessee shall pay to Lessor royalty
on the last day of each month for accrued royalties for the preceding calendar
month. If the geothermal resources produced from the leased land are
insufficient for operation of Lessee's plant or plants at a gross capacity of
ten (10) megawatts, at the request of Lessee, Lessor may supply geothermal
resources from other land and the ***% royalty rate shall apply to gross
proceeds produced therefrom. If Lessor is unable to provide sufficient
geothermal resources, Lessee may secure geothermal resources from other lands
without paying royalty to Lessor on the geothermal resources so secured. Lessee
shall have the right to commingle the geothermal resources with geothermal
resources produced from other lands 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 pay royalty on any electricity generated
on the leased land and used by it in its operations under this Lease.

         6. License Agreement. Lessor agrees to grant to Lessee, by separate
agreement entered into concurrently herewith, a non-exclusive license to utilize
on and limited to the leased land for the term of this Lease Lessor's patented
Magmamax power process and improvements thereof. Together with said license,
Lessor will agree to make available to Lessee without additional consideration,
Lessor's continuing knowledge and experience with respect to said process. In
the event Lessee shall develop any patentable improvements to the Magmamax power
process, Lessor shall be entitled to a non-exclusive royalty free license with
respect thereto.

         7. Plant Expansion. Lessee shall have the right to increase the
capacity of its plant or build additional plants on the leased land if
operations under this Lease demonstrate the availability of an adequate supply
of geothermal resources on the same terms and conditions as set forth herein.
Lessee shall have the right of first refusal for the development of electricity
available from geothermal resources on adjacent or nearby lands leased or
otherwise controlled by Lessor, in the event Lessee's operation proves the
adequacy of the geothermal resources and the commercial feasibility of producing
electricity therefrom. Lessee shall have four (4) years from the date of firm
operation of the plant to determine if an increase in plant and production
capacity is warranted by the geothermal resources underlying the leased land on
the basis of its operations. Lessee will notify Lessor of its determination on
or before the fourth anniversary of said date. If an increase in the size of the
plant or construction of additional plants is not warranted in Lessee's sole
judgment, Lessee will relinquish its rights to the surface area not actually
used for the original plant or plants, gathering and injection lines, and wells,
Lessor shall assume full responsibility for compliance with any necessary
governmental approvals of such a relinquishment by Lessee. A release of surface
rights to any part of the leased land shall not constitute a release of any part
of the geothermal resources underlying the leased land.

         8. Reinjection. Lessee shall have the right to drill such well or wells
on the leased land as Lessee may deem desirable, including wells for injection
or reinjection purposes, and shall have the right to dispose in any such wells
waste brine, water and other substances, waste

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

                                      -4-

products from a well, or wells, power plants or other facilities, located on the
leased land or from wells, power plants or other facilities, located in the
vicinity of the leased land. Lessee shall have the right to freely transfer
geothermal resources from wells located on the leased land, or other lands in
the vicinity of the leased land, to and from the leased land and to inject
geothermal resources into a well or wells located on the leased land.

         9. Inspection by Lessor. Lessor, or its agents, at Lessor's sole risk,
may during hours of operation examine the leased land and the workings,
installations and structures thereto and operations of Lessee thereon, and may
at reasonable times inspect the books and records of Lessee with respect to
production and operations and matters pertaining to the payment of royalties to
Lessor. Lessee shall make available to Lessor all of Lessee's information and
operating experience as to producing and injection wells and the installed
electric generating facilities. Lessee shall also furnish to Lessor all
drilling, engineering and geological reports, tests and logs as to all wells
drilled on said land. Lessor retains the right to utilize the leased land for
any and all purposes provided that such use shall not unreasonably interfere
with Lessee's operations thereon. Lessor, its employees, representatives and
permittees retain the right at all times to enter upon the leased land and to
view all operations and activities of Lessee thereon, provided that Lessee shall
not be liable to Lessor or to any such persons for personal injury or property
damage not resulting from any negligent act or omission of Lessee. Lessor shall
maintain all information gained by such inspection in strict confidence and
shall not disclose any of such information to third parties without advance
written permission of Lessee.

         10. Warranty of Title. Lessor hereby warrants that it has clear title
to the leased land and the geothermal resources contained therein, agrees to
defend title conveyed to Lessee under this Lease, and agrees that Lessee, at
Lessee's option, may pay and discharge any taxes, mortgages or liens existing,
levied or assessed on or against the leased land. If Lessee exercises such
option, Lessee shall be subrogated to the rights of the party to whom payment is
made to the extent of all payments costs and expenses, including attorneys'
fees, and, in addition to its other rights, may reimburse itself out of any
royalties otherwise payable to Lessor. In the event Lessee is made aware of any
claim inconsistent with Lessor's title, Lessee may suspend the payment of
royalties under this Lease, without interest, until Lessee has been furnished
satisfactory evidence that such claim has been resolved.

         11. Lesser Interest. If the Lessor or any party Lessor owns a lesser
interest in the geothermal resources under this Lease than the entire and
undivided fee estate herein, then the royalty herein provided as to geothermal
resources shall be paid to the Lessor or such party Lessor only in the
proportion which his ownership bears to the whole and undivided fee. Lessor
shall bear the entire cost of any underlying royalty interest in the fee estate
or otherwise.

         12. Removal. Lessee shall have the right at any time and from time to
time to remove from the leased land any and all casing, machinery, equipment,
structures, installations and property of every kind and character placed upon
the leased land by or pursuant to permission of Lessee, provided that if such
removal should occur after termination of all rights granted herein, it shall be
completed within a reasonable time thereafter. Lessee agrees after termination
of this Lease to leave the leased land in a clean condition and to level sump
holes or excavations.

                                      -5-

         13. Implied Covenants. This Lease constitutes and expresses the entire
agreement between the parties and no implied covenant of any kind shall be read
into it and in particular there shall not be read into it any implied covenant
requiring Lessee to commence or to continue to conduct more drilling or other
operations on the leased land or to drill more wells thereon or fixing any
greater measure of diligence than Lessee has herein expressly agreed to.

         14. Ancillary Rights. In exploring for, developing, producing, using
and marketing geothermal resources on the leased land, Lessee shall have the
right of ingress and egress along with the right to conduct such operations on
the leased land as may be reasonably necessary for such purposes, including but
not limited to geophysical operations, the drilling of wells, and the
construction and use of roads, canals, pipelines, tanks, water wells, disposal
wells, injection wells, pits, electric and telephone lines, power stations and
plants, and other facilities deemed necessary by Lessee to discover, produces,
store, treat or transport geothermal resources and easements necessary thereto.
Lessee may use in such operations, free of cost, any water or other substances
produced on the leased land. The right of ingress and egress granted hereby
shall apply to the entire leased land described, notwithstanding any partial
release or other termination of this Lease with respect thereto.

         15. Breach or Default. In the event at any time after four (4) years
from the date hereof Lessee shall sell electrical power from said leased land in
any amount less than two (2) megawatts gross generating capacity and if such
condition continues for a period of one (1) year (the generating output would be
computed on an average for said one year), Lessor shall have the right to
consider the aforesaid event a default under this Lease, provided that Lessee
shall not be required to produce and sell electricity in excess of the reservoir
capability of the leased land. If Lessee at any time during the term of this
Lease and Agreement determines in good faith that it is uneconomic or not
feasible to continue its operations on the leased land, Lessee shall have the
right to terminate this Lease and to relinquish its rights under this lease. In
the event of termination Lessee shall execute and deliver appropriate
instruments to clear title to the leased land and shall remove surface
facilities and provide for wells as herein provided in the event of termination
due to Lessee's default. No litigation shall be initiated by Lessor with respect
to any breach or default by Lessee under this Lease, for a period of at least
ninety (90) days after Lessor has given Lessee written notice fully describing
the breach or default, and then only if Lessee fails to begin to remedy the
breach or default within such period. In the event the matter is litigated and
there is a final judicial determination that a breach has occurred, this Lease
shall not be forfeited or cancelled in whole or in part unless Lessee is given a
reasonable time after such judicial determination to remedy the breach or
default and Lessee fails to do so.

         16. Forbearance by Lessor. If any default shall occur which entitles
Lessor to terminate this Lease, Lessor shall have no right to terminate this
Lease unless, following the expiration of the period of time given to Lessee to
cure such default, Lessor shall notify any beneficiary under a deed of trust
covering all or any part of the leased land ("Mortgagee") of Lessor's intent to
so terminate at least thirty (30) days in advance of the proposed effective date
of such termination (the "Termination Notice"). Lessor shall have no right to
terminate this Lease if after delivering the Termination Notice to Mortgagee any
of the following occurs: (a) In the case of a default in the payment of
royalties, Mortgagee shall notify Lessor of Mortgagee's desire to cure such
default, and Mortgagee shall pay or cause to be paid all royalties, and any
other payments then due and in arrears as specified in the Termination Notice,
as well as such

                                      -6-

sums which may become due during such thirty day period, or extended period as
provided in subsection (c) below; (b) In the case of a default which does not
involve the payment of money but is reasonably susceptible of being cured by
Mortgagee, Mortgagee shall notify Lessor of Mortgagee's desire to cure such
default, and Mortgagee shall comply, or in good faith and with reasonable
diligence commence to comply, with all such nonmonetary requirements of this
Lease then in default and diligently pursue such cure to completion, subject to
paragraph 17; (a) In the case of a default not reasonably susceptible of being
cured by Mortgagee, including failure of production, or in the event Mortgagee
is complying with the requirements of subsections (a) or (b) above, this Lease
shall not terminate provided (i) within ninety (90) days after the giving by
Lessor of the Termination Notice, Mortgagee gives written notice to Lessor of
Mortgagee's intention to foreclose its deed of trust, and (ii) Mortgagee, within
ninety (90) days after the giving of the Termination Notice commences
foreclosure or similar proceedings under its deed of trust for the purpose of
acquiring Lessee's interest in this Lease and thereafter diligently prosecutes
the same (provided however, that if Mortgagee is restrained by a court of
competent jurisdiction from so proceeding, the time periods set forth above
shall be tolled), and (iii) either Mortgagee or any other purchaser of Lessee's
interest under this Lease, within a reasonable time after the acquisition of
such interest, commences production, or otherwise cures all defaults hereunder
susceptible of being cured by Mortgagee or such purchaser. No cancellation,
surrender or modification of this Lease shall be effective unless consented to
in writing by any Mortgagee.

         17. Force Majeure. Lessee's obligations under this Lease shall be
suspended until expiration of ninety (90) days after removal of cause for
suspension and the term of this Lease and the period for removal of Lessee's
property in the event of termination shall be extended while Lessee is prevented
from complying therewith by strikes, lockouts, riots, action of the elements,
accidents, delays in transportation, inability to secure labor or materials in
the open market, laws, rules, or regulations of any Federal, State, Municipal or
other governmental agency, authority, or representative having jurisdiction,
inability to secure or absence of a market for commercial sale of geothermal
resources from the leased land; or by other matters or conditions beyond the
reasonable control of Lessee, whether or not similar to the conditions or
matters specifically enumerated in this Paragraph.

         18. Liens, Taxes and Insurance. Lessee shall hold harmless, indemnify
and defend Lessor against all claims, demands, actions and causes of action for
injury or death to persons, damage or destruction of property unless caused by
the negligence or misconduct of Lessor, mechanic's and material man's liens
arising out of or by virtue of Lessee's rights or exercise of any rights under
this Lease, operations on the leased land or any acts or omissions by Lessee,
and Lessee undertakes and agrees to obtain and maintain insurance coverage,
naming Lessor as additional insured, in an amount not less than ten million
dollars ($10,000,000) principal amount to protect Lessor against any such
claims. Lessee shall pay all taxes levied and assessed against all structures,
improvements and personal property placed upon the leased land by Lessee. Lessor
shall pay all taxes levied and assessed against the leased land as such
including the geothermal resources and the right to production thereof and
against any rights therein not covered by this Lease and shall pay all taxes
levied and assessed against all structures and improvements placed on the leased
land by Lessor. Lessee, at its own expense, prior to commencing operations on
the leased land, shall obtain, and thereafter while this Lease is in effect
shall maintain, adequate Workers' Compensation Insurance.

                                      -7-

         19. Assignment. Except as provided in this Paragraph, the interest of
either Lessor or Lessee under this Lease may be assigned, devised or otherwise
transferred in whole or in part, by area and by depth or zone and the rights and
obligations shall extend to their respective heirs, devisees, executors,
administrators, successors and assigns. No change in Lessor's ownership shall
have the effect of reducing the rights or enlarging the obligations of Lessee
under this Lease and no change in ownership shall be binding on Lessee until
sixty (60) days after Lessee has been furnished the original or certified or
duly authenticated copies of the documents establishing such change of ownership
to the satisfaction of Lessee, Lessee shall not transfer, assign or reassign its
interest in whole or in part in this Lease without the consent of Lessor, which
consent shall not be unreasonably withheld, provided that this Lease may be
hypothecated for the benefit of any creditor of Lessee or Lessee's successor in
interest. If Lessee transfers its interest under this Lease in whole or in part,
Lessee shall be relieved of all obligations thereafter arising with respect to
the transferred interest, and failure of the transferee to satisfy such
obligations with respect to the transferred interest shall not affect the rights
of Lessee with respect to any interest not so transferred.

         20. Notice. Any notice from the Lessor to the Lessee must be given by
sending the same by registered or certified mail, postage prepaid, addressed to
its office at 1301 Chelton Way, South Pasadena, California 91030, and any notice
from the Lessee to the Lessor must be given in the same manner addressed to the
Lessor at 631 South Witmer Street, Los Angeles, California 90017. The parties
may, upon notice, change their said respective addresses for notice.

         21. Severability. If any provision of this Lease shall be found or
declared to be null, void or unenforceable for any reason whatsoever by any
Court of competent jurisdiction, then and in such event only such provision
shall be affected thereby, and such finding, ruling or decision shall not in any
way affect the remainder of this instrument or any of the other terms or
conditions hereof, which remaining terms and conditions shall remain binding,
valid and subsisting and in full force and effect between the parties, it being
specifically understood and agreed that the provisions of this Lease are
severable for the purposes of the provisions of this Paragraph. This Lease shall
not in any event extend beyond such term as may be legally permissible under
applicable laws, and should any such applicable law limit the term to less than
that provided in Paragraph 3, then this Lease shall not be void but shall be
deemed to be in existence for such term and no longer.

         22. Integration. This Lease constitutes the entire agreement between
the parties and supersedes all other agreements and understandings, whether oral
or written, the parties may have in connection therewith, including the March 3,
1982, Letter of Intent to enter into this Lease, and say be modified or
terminated only by a writing signed by the parties.

         23.      Binding  Effect.  This Lease shall extend to and be binding
upon the heirs,  executors, administrators, grantees, successors and assigns of
the parties.

     IN WITNESS WHEREOF the parties hereto have executed this Lease effective
as of the date first written above.

HOLT GEOTHERMAL COMPANY                     MAGMA ENERGY, INC.

By: /s/ Indecipherable                      By: /s/ Indecipherable
    ----------------------------                ----------------------------
    President                                   Chairman

Attest: /s/ W.E. Viney                      Attest: /s/ Indecipherable
        ------------------------                    ------------------------
        Secretary                                   Secretary

STATE OF CALIFORNIA     )
                        )  ss.
COUNTY OF LOS ANGELES   )

     On 31 August 1983 before me, the undersigned, a Notary Public in and for
said County and State, personally appeared Ben Holt, known to me to be the
President, and W.E. Viney, known to me to be the Secretary of Holt Geothermal
Company, the corporation that executed the within Instrument, known to me to be
the persons who executed the within Instrument on behalf of the corporation
therein named, and acknowledged to me that such corporation executed the within
instrument pursuant to its by-laws or resolution of its board of directors.

/s/ Betty J. Peterson
---------------------------
Betty J. Peterson

STATE OF CALIFORNIA     )
                        )  ss.
COUNTY OF LOS ANGELES   )

     On August 31, 1983 before me, the undersigned, a Notary Public in and for
said County and State, personally appeared B.C. McCabe, known to me to be the
Chairman, and Joseph W. Aidlin, known to me to be Secretary of Magma Energy,
Inc., the corporation that executed the within Instrument, known to me to be the
persons who executed the within Instrument on behalf of the corporation therein
named, and acknowledged to me that such corporation executed the within
instrument pursuant to its by-laws or resolution of its board of directors.

WITNESSETH my hand and offical seal.

/s/ April L. Wogatzke
---------------------------
April L. Wogatzke

                                  EXHIBIT "A-2"
                    EXISTING PLANT BASELINE REVENUE FORECAST

                                                BASELINE
                                                 REVENUE
       CAPACITY     NET    ENERGY   AGREEMENT   FORECAST
        PRICE     MW HRS    PRICE     PRICE       (Sm)
       --------   ------   ------   ---------   --------
1987     .0194    70,000    .0700     .0894       6,258
1988     .0194    70,000    .0700     .0894       6,258
1989     .0194    70,000    .0700     .0894       6,258
1990     .0194    70,000    .0700     .0894       6,258
1991     .0194    70,000    .0700     .0894       6,258
1992     .0194    70,000    .0700     .0894       6,258
1993     .0194    70,000    .0700     .0894       6,258
1994     .0194    70,000    .0700     .0894       6,258
1995     .0194    70,000    .0700     .0894       6,258
1996     .0194    68,273    .0630     .0824       5,626
                  70,000*                         5,768*
1997     .0194    68,273    .0668     .0862       5,884
                  70,000*                         6,034*
1998     .0194    68,273    .0708     .0902       6,157
                  70,000*                         6,314*
1999     .0194    68,273    .0750     .0944       6,447
                  70,000*                         6,608*
2000     .0194    68,273    .0795     .0989       6,755
                  70,000*                         6,923*
2001     .0194    68,273    .0843     .1037       7,080
                  70,000*                         7,259*
2002     .0194    68,273    .0894     .1088       7,426
                  70,000*                         7,616*
2003     .0194    68,273    .0947     .1141       7,792
                  70,000*                         7,987*
2004     .0194    68,273    .1004     .1198       8,180
                  70,000*                         8,386*
2005     .0194    68,273    .1064     .1258       8,591
                  70,000*                         8,806*
2006     .0194    68,273    .1128     .1322       9,027
                  70,000*                         9,254*
2007     .0194    68,273    .1196     .1390       9,489
                  70,000*                         9,730*
2008     .0194    68,273    .1268     .1462       9,979
                  70,000*                        10,234*
2009     .0194    68,273    .1344     .1538      10,499
                  70,000*                        10,766*
2010     .0194    68,273    .1424     .1618      11,049
                  70,000*                        11,326*
2011     .0194    68,273    .1510     .1704      11,633
2012     .0194    68,273    .1600     .1794      12,251
2013     .0194    68,273    .1696     .1890      12,907
2014     .0194    68,273    .1798     .1992      13,602
2015     .0194    68,273    .1906     .2100      14,338
2016 and for the balance of the term of the Lease to be calculated using the
same bases.

For purposes of this Exhibit "A-2", the figures noted with an asterisk (*) for
the period between and including 1996 and 2010 shall be the effective figures
for their corresponding years only until such time as ***% of the amount of the
cumulative gross revenues attributable to the increment of magawatt hours sold
each year by the Existing Plant between and including *** MW hours and *** MW
hours equals $***, plus simple interest at a rate of 7% per annum beginning
January 1, 1990 (on the full amount of $*** and not on the declining balance
thereof). Thereafter, the numbers not noted with asterisk (*) during such period
shall become effective for their corresponding years.

         The remaining amount representing ***% of the cumulative gross revenues
attributable to the increment of megawatt hours sold each year by the Existing
Plant between and including *** MW hours and *** MW hours shall be paid to
Lessor as additional Existing Plant Base Royalty, in addition to (l) the
Existing Plant Base Royalty to be Paid to Lessor pursuant to Paragraph 5.1 of
the Lease and (2) Bonus Royalty to be paid to Lessor pursuant to Paragraph 5.3
of the Lease.

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

                                  Exhibit "A-1"
                       New Plant Baseline Revenue Forecast
                                Revised June 1991

                     BASELINE
                      REVENUE
                     FORECAST
YEAR                   (SM)
----                 --------
1991                   8,829
1992                   9,650
1993                  10,457
1994                  11,272
1995                  12,177
1996                  13,018
1997                  14,021
1998                  15,051
1999                  16,072
2000                  16,072
2001                   9,958
2002                  10,448
2003                  10,967
2004                  11,518
2005                  12,101
2006                  12,720
2007                  13,376
2008                  14,071
2009                  14,808
2010                  15,589
2011                  16,417
2012                  17,294
2013                  18,225
2014                  19,211
2015                  20,256
2016                  21,364
2017                  22,538
2018                  23,783
2019                  25,104
2020                  26,506
2021                  27,993
2022 and for the      To be calculated
balance of the        using the same
term of the Lease.    bases.

                                 FIRST AMENDMENT
                               TO GEOTHERMAL LEASE

         THIS FIRST AMENDMENT TO GEOTHERMAL LEASE (the "Amendment") is made and
entered into effective as of April 30, 1987 (the "Effective Date") by and
between Magma Energy, Inc., a Nevada corporation (the "Lessor") and
Mammoth-Pacific, a California general partnership (the "Lessee"), collectively
referred to herein as the "Parties".

                                    Recitals

         WHEREAS, the Parties made and entered into that certain Geothermal
Lease dated the 31st day of August, 1983, by and between Lessor and Holt
Geothermal Company, to which Lessee is the successor-in-interest as Lessee (the
"Lease"), a copy of which is attached as Exhibit "A" to this Amendment and
incorporated by reference herein; and

         WHEREAS, the Parties now desire to modify the Lease with respect to the
royalties to be paid by Lessee to Lessor in connection with the operation of one
or more electric power plants fueled by geothermal resources underlying the
leased land, the expansion of the existing electric power plant and the
construction of additional electric power plants, and any other matters referred
to herein.

         NOW THEREFORE, in consideration of the mutual promises and covenants
contained herein, and other good and valuable consideration, receipt and
sufficiency of which are hereby acknowledged, Lessor and Lessee agree to amend
the Lease as follows:

         1. Paragraph 3 of the Lease is hereby deleted in its entirety and a new
Paragraph 3, reading as follows, is substituted in its place instead:

         3. Term. TO HAVE AND TO HOLD the leased land for a period of thirty
(30) years from the date hereof (the "primary term") and so long thereafter as
electricity is produced on the leased land from the geothermal resources
therein, or excused under the terms of Paragraph 17 of this Lease.

         2. Paragraph 5 of the Lease is hereby deleted in its entirety and a new
Paragraph 5, reading as follows, is substituted in its place instead:

         5. Royalty. Lessee shall pay to Lessor as royalty during the balance of
the full term of this Lease compensation as follows:

         5.1 Existing Plant Base Royalty. As to electricity or other energy
generated by all facilities in commercial operation on or before the Effective
Date of this Amendment ("the Existing Plant") Lessee shall pay to Lessor as
royalties during the balance of the full term of the Lease the following
percentage of the "Gross Proceeds", as such term is defined below, received by
Lessee from each such facility (the "Existing Plant Base Royalty"), together
with applicable "Bonus Royalties" as such term is defined at Subparagraph 5.3
below:

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

         (a) From April 1, 1987, and for a period of twenty-four (24)
consecutive months thereafter, the higher of (i) *** percent (***%) or (ii)
*** percent (***%) of "Baseline Revenue" *** as such term is defined at
Subparagraph 5.3 below, and applicable "Bonus Royalties" as such term is defined
at Subparagraph 5.3 below;

         (b) From the date following the conclusion of the period set out in
Subparagraph 5.1(a), above, and for a period of twelve (12) consecutive, months
thereafter, the higher of (i) *** percent (***%), or (ii) *** percent (***%) of
"Baseline Revenue", as such term is defined at Subparagraph 5.3 below, and
applicable "Bonus Royalties" as such term is defined at Subparagraph 5.3 below;

         (c) From the date following the conclusion of the period set out in
Subparagraph 5.1(b), above, and for a period of twelve (12) consecutive months
thereafter, the higher of (i) *** percent (***%), or (ii) *** percent (***%) of
"Baseline Revenue", and applicable "Bonus Royalties" as such term is defined at
Subparagraph 5.3 below; and,

         (d) From the date following the conclusion of the period set out in
Subparagraph 5.1(c), above, and for the balance of the term of this Lease, ***
percent (***%), together with applicable "Bonus Royalties" as such term is
defined at Subparagraph 5.3 below.

         For all purposes herein, the term "Gross Proceeds" shall mean (i) with
respect to the Existing Plant, all accounts received by Lessee, directly or
indirectly, from the sale to others of electricity, including energy and
capacity payments, or energy in any other form, produced on the leased land from
the geothermal resources therein or, if applicable, the "Adjacent Lease", as
such term is defined at Subparagraph 5.8 below, and (ii) with respect to the
"New Plants", as such term is defined at Subparagraph 5.2 below, all accounts
received by Lessee, directly and indirectly, from the sale to others of
electricity, including energy and capacity payments, or energy in any other form
produced from any lands or geothermal resources without regard to ownership
thereof.

         5.2 New Plant Base Royalty. As to electricity or other energy generated
by all additional plants utilizing the "Standard Offer Number Four Contracts",
as such term is defined at Subparagraph 7.1 below (the "New Plants") Lessee
shall pay to Lessor for the balance of the full term of the Lease *** percent
(***%) of the Gross Proceeds received by Lessee (the "New Plant Base Royalty"),
together with applicable "Bonus Royalties" as such term is defined at
Subparagraph 5.3 below.

         5.3 Bonus Royalties. The Existing Plant Base Royalty and New Plant Base
Royalty payable by Lessee to Lessor with respect to the Existing Plant and each
new Plant pursuant to Subparagraphs 5.1 and 5.2 above, shall be augmented by
additional royalties (the "Bonus Royalties") calculated in accordance with the
procedure set forth in Appendix "A" attached to this Amendment and incorporated
by reference herein. Except as otherwise provided at Subparagraph 5.1(a), (b)
and (c) above, the Existing Plant Base Royalty for the Existing Plant and the
New Plant Base Royalty for each New Plant (collectively, the "Base Royalties")
shall be applied to all Gross Proceeds for each such plant at or below the
"Baseline Revenue" in any year. The term "Baseline Revenue" for each such plant
shall mean the forecasts of annual revenues

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

                                      -9-

determined as set forth in Appendix "A" to this Amendment. For all Gross
Proceeds from the Existing Plant and each of the New Plants, respectively in
excess of the Baseline Revenue (the "Additional Revenue") for such plants, the
Bonus Royalties shall be applied to calculate the total amount of royalty
payable to Lessor.

         5.4 Inflation Adjustment. The applicable Baseline Revenue for each of
the plants shall not be subject to adjustment during the fixed price period of
any power purchase agreement associated with such plant. The Baseline Revenue
for each of the plants shall be adjusted annually for all years after expiration
of the period of firm prices provided in the power purchase agreement associated
with such plant to account for the difference between an assumed inflation rate
of five percent (5%) per annum and the actual inflation experienced (the
"Inflation Adjustment"). For the purpose of the Inflation Adjustment, the
"Actual Inflation" shall be determined from comparison of the value of the
Producer Price Index for Finished Goods Excluding Food (the "Inflation Index")
on December 31st of the then current year to the value of the Inflation Index on
December 31, 1986. The Actual Inflation shall be equal to the ratio of the value
of the Inflation Index on December 31, of the then current year to the value of
the Inflation Index on December 31, 1986. The "Assumed Inflation" shall be equal
to one and five hundredths ("1.05") raised to a power equal to the number of
years between 1986 and the then current year. The "Inflation Adjustment Factor"
shall be equal to the Actual Inflation divided by the Assumed Inflation. The
"Adjusted Baseline Revenue" for each year shall be determined by multiplying the
Baseline Revenue for each year by the Inflation Adjustment Factor.

         In determining the foregoing Inflation Adjustment, the percentage of
increase or decrease in the Inflation Index shall be calculated to the nearest
one hundredth of one percent (1/100th of 1%). Percentage changes in the
Inflation Index shall be calculated based on the original released United States
Department of Labor, Bureau of Labor Statistics published data with the base
"1967-100" until a new base period is established. Calculations shall be made
based on data on the new base period from that time forward. If, for any reason,
the statistics complied by the United States Department of Labor, Bureau of
Labor Statistics and referred to above, are not available for use for the
foregoing adjustment, an adjustment shall be made by mutual agreement of Lessor
and Lessee. If the United States Department of Labor, Bureau of Labor Statistics
designates an index with a new title and/or code number as being continuous with
the Inflation Index then such new index shall be used for the foregoing
adjustment.

         5.5 Consequences of Default by Lessee. The payment when due by Lessee
to Lessor of the total compensation provided for in this Paragraph 5, for the
balance of the full term of the Lease, is a condition to the continuation of
Lessee's rights under the Lease and its right to use or occupy the leased land
or any part thereof. In the event that Lessee shall default under any covenant
or condition of the Lease and shall fail to remedy such default or to commence
in good faith to remedy such default, if such default cannot be remedied within
the notice period, Lessor shall have the right, upon expiration of sixty (60)
days written notice of default, to terminate the Lease and all of Lessee's
rights hereunder.

         5.6 Payment of Royalties. Lessee shall pay to Lessor the Base
Royalties, and any applicable Bonus Royalties, on the last day of each month for
accrued royalties for the preceding calendar month. Lessee shall calculate the
amount of actual Bonus Royalties due under the Lease at the end of each calendar
year during the term of the Lease, and shall make payment of

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

                                      -10-

any underpayment to Lessor or Lessor shall make payment of any overpayment to
Lessee, as the case may be, for any amount due (the "Additional Royalties") and
payable no later than forty-five (45) days after the end of each calendar year
during the term of the Lease. When applicable under Subparagraph 5.4 above,
Inflation Adjustments to the Baseline Revenue resulting from application of the
Inflation Index shall be made on a dollar basis by each January 31st during the
term of the Lease before calculating the actual Bonus Royalties. The Baseline
Revenue for the first year of operation for any New Plant shall be prorated from
the date of first delivery to the end of the calendar year to adjust for
differences in actual and forecasted revenue set forth in the schedules of
Baseline Revenue established for such plant.

         5.7 Insufficiency of Geothermal Resources. (a) With respect to both the
Existing Plant and any New Plants or any "Additional Plants," as such term is
defined at Subparagraph 5.9 below, built on the leased land or the "Adjacent
Lease", as such term is defined at Subparagraph 5.8 below, Lessee shall utilize
geothermal resources produced from the leased land and/or the "Adjacent Lease".
If the geothermal resources obtainable from the leased land and the Adjacent
Lease are insufficient for operation of the Existing Plant, any New Plant, or
any Additional Plant at their respective average capacity during the preceding
three (3) calendar years, Lessor may, but shall not be obligated to, make
available geothermal resources from other lands at the applicable royalty rates
provided in Subparagraphs 5.1, 5.2 and 5.3 above. In such cast, Lessor shall pay
all underlying, overriding, or other form of royalty or production payment, net
revenue interest, or other form of compensation payable to the United States of
America or any other third party on geothermal resources supplied from such
other land. If Lessor is unwilling or unable, as provided above, to make
available sufficient geothermal resources for the Existing Plant or for any such
New Plant or any such Additional Plant, Lessee may secure geothermal resources
from other lands ("Other Lands") for any such plant without paying royalty to
Lessor on the geothermal resources so secured. In such a case, Lessee shall have
the right to commingle the geothermal resources provided with geothermal
resources provided from such Other Lands and to pay Lessor's royalty on the
basis of production allocable to the leased land and the Adjacent Lease, and the
Other Lands made available by Lessee, as determined by metering or gauging same.

         (b) With respect to any New Plant built on land other than the leased
land or the Adjacent Lease, Lessee shall pay Lessor the full royalty due under
Subparagraphs 5.2 and 5.3 above regardless of the source of the geothermal
resources, in accordance with definition of Gross Proceeds in Subparagraph 5.1
above and the last sentence of Subparagraph 7.1 below, and the provisions of
Subparagraph 5.7 (a) above shall have no application.

         5.8 Unitization of Geothermal Resources. Lessor may not voluntarily
commit federal Geothermal Lease Number CA-11667-A (the "Adjacent Lease") to any
unit or cooperative agreement without the prior written consent of Lessee and
shall cooperate fully with Lessee, at no cost to Lessor, in accepting or
opposing, as determined by Lessee any attempt to compel unitization or other
form of joinder, of the Adjacent Lease pursuant to applicable laws and
regulations including, but not limited to, the Geothermal Steam Act of 1970, and
implementing regulations published at Title 43 Code of Federal Regulations, Part
3200, et seq., with all reasonable expenses thereof to be borne by Lessee. In
the event that the Adjacent Lease becomes unitized or otherwise joined with any
other land leased or otherwise controlled by Lessee, Lessor may not propose, or
make any election with respect to, any "Participating Area",

                                      -11-

as such term is defined in applicable laws and regulations without the prior
written consent of Lessee.

         5.9 Additional Plants. As to electricity or other energy generated by
all additional plants built on the leased land or, if applicable, the Adjacent
Lease from geothermal resources therein, other than the Existing Plant or the
New Plants (the "Additional Plants"), Lessee shall pay to Lessor during the
remainder of the full term of the Lease, royalties as provided at Subparagraphs
5.2, 5.3, 5.4, 5.6 and 5.7 above.

         5.10 Minimum Royalty. Notwithstanding Subparagraph 5.7 hereof, Lessee
shall pay to Lessor during the remainder of the full term of the Lease, a
minimum royalty of 3% of gross proceeds from the sale to others of electricity,
including energy and capacity payments, or energy in any other form generated by
plants built on the leased land or when applicable, the Adjacent Lease.

         5.11 No Guaranteed Internal Rate of Return. Lessor shall not be deemed
to have guaranteed Lessee a minimum internal rate of return with respect to the
Existing Plant, any New Plant, or any Additional Plant.

         3. Paragraph 7 of the Lease is hereby deleted in its entirety and a new
Paragraph 7, reading as follows, is substituted in its place instead.

         7. Plant Expansion. Lessee shall have the right to expand its
operations on the leased land, the Adjacent Lease, or any other lands without
regard to ownership thereof beyond the capacity of the Existing Plant as
follows:

         7.1 Plant Expansion. Subject to the provisions of Subparagraph 7.2
below, Lessee shall have the right to increase the capacity of the Existing
Plant or build the New Plants on the leased land, if operations under the Lease
demonstrate the availability of an adequate supply of geothermal resources, on
the terms and conditions set forth herein. Subject to the provisions of
Subparagraph 7.2 below and the first and second provisos to this sentence,
Lessee shall have the right of first refusal for the development of electricity
available from utilization of geothermal resources underlying the Adjacent
Lease; provided that Lessee's operation proves the adequacy of the geothermal
resources and the commercial feasibility of producing electricity therefrom; and
provided further, that Lessee shall have committed to construction of or more of
the New Plants associated with the Standard Offer Number Four Power Purchase
Contracts between Lessee and Southern California Edison Company bearing Document
Numbers 2433H and 2435H (the "Standard Offer Number Four Contracts") or expanded
the Existing Plant in an amount of no less than ten (10) megawatts nameplate
rating prior to the expiration of the Standard Offer Number Four Contracts.

         Lessee hereby agrees to exercise good faith efforts to obtain all
necessary governmental permits, authorizations, and approvals to build and
operate two (2) New Plants on the leased land or on adjacent land leased or
otherwise controlled by Lessor and, if it obtains governmental permits,
authorizations, and approvals which, in its sole discretion, are such that make
construction of the two New Plants economically viable, agrees to seek all
necessary internal corporate and partnership authorizations, and sufficient
financing for the construction of such

                                      -12-

two New Plants. In the event that Lessee is unable, in the exercise of good
faith efforts, to obtain all necessary external and internal permits,
authorizations, approval and financing to build and operate any New Plants or
determine not to build any New Plants for any reason or no reason, Lessee shall
proceed in accordance with the terms of Subparagraph 7.2, below. Regardless of
ownership of the land or geothermal resource dedicated to any New Plant, Lessee
shall pay Lessor royalties on the Gross Proceeds of such New Plants as provided
in Subparagraphs 5.2 and 5.3, above.

         7.2 Consequences of Failure to Expand. If Lessee shall fail to complete
prior to the expiration of the Standard Offer Number Four Contracts an increase
in the capacity of the Existing Plant of no less than ten (10) megawatts
nameplate rating or the construction of at least one (1) New Plant, Lessee shall
relinquish to Lessor its rights under the Lease to the surface and subsurface
area not actually used for the Existing Plant, gathering and injection lines,
and wells and shall further relinquish its right to use the geothermal resource
underlying the leased land or the Adjacent Lease for any purpose other than
operating the Existing Plant as provided herein. If Lessee so relinquishes its
rights to the surface and subsurface area and the geothermal resource, with
respect to the surface and subsurface actually used for the Existing Plant,
gathering and injection lines and wells, Lessee and Lessor shall jointly hold
such rights on a non-interference basis. If Lessee so relinquishes the foregoing
rights, Lessor shall have the right to utilize (i) the surface and subsurface
not actually used for the Existing Plant, gathering and injection lines, and
wells and the geothermal resources underlying the leased land, and (ii) the
Adjacent Lease, for any purpose; provided, however, Lessor may not exercise any
of the foregoing reserved rights which, in the reasonable opinion of Lessee,
might interfere with the operation of the Existing Plant.

         4.  A new Paragraph number 24 is hereby added to the Lease as follows:

         24. Upon request, Lessee shall provide Lessor with full access to
review, and, with respect to Lessor operations on the leased land or Adjacent
Lease, to use without charge all geotechnical data, geotechnical reports, and
documents containing geotechnical information of any kind related to Lessee's
operations on the leased land.

         5. A new Paragraph number 25 is hereby added to the Lease as follows:

         25. Lessee hereby waives, discharges and releases Lessor from any and
all claims of Lessee against Lesser, its directors, officers, employees or
agents which have accrued prior to April 1, 1987 and which arose out of, in
connection with, or relate to the negotiations of Lessees entering into, or
Lessor's performance or nonperformance of the Lease.

         6. As modified or added to by the terms of this Amendment, all terms
and conditions of the Lease shall remain in full force and effect. All
capitalized terms contained herein, unless otherwise defined, shall have the
meaning ascribed to such terms in the Lease.

         IN WITNESS WHEREOF, this Amendment has been executed on the first date
written above by the duly authorized representatives of the parties.

                                      -13-

         MAGMA ENERGY, INC., Lessor MAMMOTH-PACIFIC, Lessee

                                          By: PACIFIC GEOTHERMAL COMPANY,
                                              general partner of MAMMOTH-PACIFIC

         By: /s/ Indecipherable           By: /s/ Indecipherable
            --------------------------       --------------------------------

         Title: President & CEO           Title: President
               -----------------------          -----------------------------

                                      -14-

                                  Appendix "A"

                       Calculation of Additional Royalties

     As provided in Paragraph 5 of the Amendment to which this Appendix "A" is
attached, the basic structure of the royalty arrangement for the Existing Plant
and each New Plant includes a mutually agreed upon baseline revenue forecast
(the "Baseline Revenue") and a two-tier royalty rate. For all Gross Proceeds, as
such term is defined at Subparagraph 5.1 of the Lease, as amended by the
Amendment, in a given year in excess of the applicable Baseline Revenue for a
plant (the "Additional Revenues"), additional royalties (the "Bonus Royalties")
equal to ***% of such Additional Revenue shall be paid. The procedure set forth
below details the steps to be followed in the calculation of Bonus Royalties for
the Existing Plant and each New Plant. Calculations shall be made separately for
the Existing Plant and each New Plant.

     1. The Schedule of Baseline Revenue attached as Exhibit "A-1" to this
Appendix "A" has been established in accordance with mutually agreed upon
parameters for the New Plant scheduled to be completed first (see Paragraph 4
below). If the actual date of "Firm Operation", as such term is defined in any
applicable power purchase agreement, is other than that used in the agreed upon
parameters, the Baseline Revenue for the first year of operation and the tenth
year of operation (when energy pricing switches from the fixed price schedule to
as-available pricing) will be adjusted to reflect the actual date of Firm
Operation. The Baseline Revenue for any additional New Plants will be
established utilizing substantially the same bases as those utilized in
calculating the Baseline Revenue for the first New Plant. The Schedule of
Baseline Revenue attached as Exhibit "A-2" to this Appendix "A" has been
established for the Existing Plant in accordance with mutually agreed upon
parameters.

     2. Bonus Royalites will be calculated separately for the Existing Plant and
each New Plant and will be paid when earned. During any month in a given
calendar year in which the aggregate Gross Proceeds for a plant exceed the
applicable Baseline Revenue for that plant, Bonus Royalites will become payable
and will be paid at the same time that the Baseline Royalties for the plant are
to be paid. The Bonus Royalties for a plant will be calculated by multiplying
the Additional Revenues received during that month for that plant by the Bonus
Royalty Percentage.

     3. No later than forty-five (45) days after the end of each calendar year,
Lessee will calculate the amount of the actual Bonus Royalites due during such
year, and shall

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

                                       -1-

make payment of any underpayment to Lessor, or Lessor shall make payment of any
overpayment to Lessee, as the case may be. Calculation of actual *** will be
based on following formulas:

     (a)  Adjusted Baseline Revenue.

          During the period commencing on the date of Firm Operation of each New
          Plant and ending ten years thereafter, and during the period
          commencing on January 1, 1987, and ending on December 31, 1995 for the
          Existing Plant (the "First Period"), the Adjusted Baseline Revenue
          shall equal the Baseline Revenue.

          After the expiration of the First Period, the Baseline Revenue shall
          be adjusted annually by the Inflation Adjustment Factor to reflect the
          difference between the assumed inflation index used in the calculation
          of the Baseline Revenue (the "Assumed inflation"} and the actual
          inflation rate as reported by the Producer Price Index for Finished
          Goods Excluding Food published by the department of Labor, Bureau of
          Labor Statistics for December of each year (the "Inflation Index").
          The method of adjustment is as follows:

                                   Baseline Revenue(n)       Inflation Index(n)
Adjusted Baseline Revenue(n) = -------------------------- X ---------------------
                               Assumed Inflation Index(n)   Inflation Index(1986)

          where "n" is the year of adjustment, and the Assumed Inflation Index
          for such year is taken from the following table:

                             Assumed Inflation Index

       Index          Index          Index
Year   Value   Year   Value   Year   Value
----   -----   ----   -----   ----   -----
1986   1.000   1997   1.710   2008   2.925
1987   1.050   1998   1.796   2009   3.072
1988   1.103   1999   1.886   2010   3.225
1989   1.158   2000   1.980   2011   3.386
1990   1.216   2001   2.079   2012   3.556
1991   1.276   2002   2.183   2013   3.733
1992   1.340   2003   2.292   2014   3.920
1993   1.407   2004   2.407   2015   4.116
1994   1.477   2005   2.527   2016   4.322
1995   1.551   2006   2.653   2017   4.538
1996   1.629   2007   2.786   2018   4.765

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

                                       -2-

     (b)  Additional Revenue = Gross Proceeds - Adjusted
          ------------------
          Baseline Revenue

          except that if Gross Proceeds for any year is less than Adjusted
          Baseline Revenue for such year, then

          Additional Revenue = 0

     (c)  Except as provided in Subparagraphs 5.1(a), (b) and (c),
          Base Royalties = Base Royalties percentage of 12% or 12.5%, as
                           the case may be, X Adjusted Baseline Revenue

          except that if Gross Proceeds for any year is less than Adjusted
          Baseline Revenue for such year, then

Base Royalties= Base Royalties percentage of ***% or ***%, as the case may be, X
                                 Gross Proceeds

     (d) Bonus Royalties= Bonus Royalties percentage of ***% X Additional
         Revenue

     (e) Total Royalites= Base Royalties + Bonus Royalties

     (f) Additonal Royalties= Total Royalties - Base Royalties Paid

     4. The Schedule of Baseline Revenue attached as Exhibit "A-1" to this
Appendix "A" has been established for a New Plant consisting of a 12MW facility
with a Firm Operation date of November, 1988. Bases include: 85% load factor
after Firm Operation; energy revenue at the applicable Standard Offer Number
Four Contract rate for ten years, and then fixed at 50% of the standard Offer
Number Four Contract rate in 1999, and escalating at 6% thereafter, and 100% of
the capacity revenue based on the Standard Offer Number Four Contract
as-available capacity schedule through 1998, and then fixed at the 1998 price
thereafter.

     5. The Schedule of Baseline Revenue attached as Exhibit "A-2" to this
Appendix "A" has been established for the Existing Plant. Bases include: 70,000
MWh of energy sold per year through December 31, 1995, and 68,268 MWh per year
through December 31, 2015; energy and capacity revenues at rates provided in the
Amended and Restated Power Purchase and Sales Agreement for the Existing Plant,
dated December 12, 1986 through December 31, 1995; and then at 50% of the
Standard Offer Number Four Contract energy payment rate in 1996, and escalating
at 6% thereafter; and 100% of the capacity revenue payment rate of $.0194/Kwh
thereafter.

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

                                       -3-

                                  Exhibit "A-l"
                       New Plant Baseline Revenue Forecast

                     BASELINE
                      REVENUE
                     FORECAST
YEAR                   ($M)
----                 --------
1988                   1,776
1989                   7,782
1990                   8,302
1991                   8,829
1992                   9,650
1993                  10,457
1994                  11,272
1995                  12,177
1996                  13,018
1997                  14,021
1998                  14,921
1999                   9,059
2000                   9,495
2001                   9,958
2002                  10,448
2003                  10,967
2004                  11,518
2005                  12,101
2006                  12,720
2007                  13,376
2008                  14,071
2009                  14,808
2010                  15,589
2011                  16,417
2012                  17,294
2013                  18,225
2014                  19,211
2015                  20,256
2016                  21,364
2017                  22,538
2018                  23,783
2019 and for the      To be calculated
balance of the        using the same
term of the Lease.    bases.

                                  EXHIBIT "A-2"
                    EXISTING PLANT BASELINE REVENUE FORECAST

                                                BASELINE
                    NET                          REVENUE
       CAPACITY   MW HRS   ENERGY   AGREEMENT   FORECAST
         PRICE     SOLD     PRICE     PRICE       ($M)
       --------   ------   ------   ---------   --------
1987     .0194    70,000    .0700     .0894       6,258
1988     .0194    70,000    .0700     .0894       6,258
1989     .0194    70,000    .0700     .0894       6,258
1990     .0194    70,000    .0700     .0894       6,258
1991     .0194    70,000    .0700     .0894       6,258
1992     .0194    70,000    .0700     .0894       6,258
1993     .0194    70,000    .0700     .0894       6,258
1994     .0194    70,000    .0700     .0894       6,258
1995     .0194    70,000    .0700     .0894       6,258
1996     .0194    68,273    .0630     .0824       5,626
1997     .0194    68,273    .0668     .0862       5,884
1998     .0194    68,273    .0708     .0902       6,157
1999     .0194    68,273    .0750     .0944       6,447
2000     .0194    68,273    .0795     .0989       6,755
2001     .0194    68,273    .0843     .1037       7,080
2002     .0194    68,273    .0894     .1088       7,426
2003     .0194    68,273    .0947     .1141       7,792
2004     .0194    68,273    .1004     .1198       8,180
2005     .0194    68,273    .1064     .1258       8,591
2006     .0194    68,273    .1128     .1322       9,027
2007     .0194    68,273    .1196     .1390       9,489
2008     .0194    68,273    .1268     .1462       9,979
2009     .0194    68,273    .1344     .1538      10,499
2010     .0194    68,273    .1424     .1618      11,049
2011     .0194    68,273    .1510     .1704      11,633
2012     .0194    68,273    .1600     .1794      12,251
2013     .0194    68,273    .1696     .1890      12,907
2014     .0194    68,273    .1798     .1992      13,602
2015     .0194    68,273    .1906     .2100      14,338
2016 and for the balance of the term of the Lease to be calculated using the
same bases.

RECORDING REQUESTED BY
AND WHEN RECORDED RETURN TO:

RALPH B. KOSTANT, ESQ.
WEISSBURG and ARONSON, INC.
2049 Century Park East, 32nd Floor
Los Angeles, California 90067-3271

                      SECOND AMENDMENT TO GEOTHERMAL LEASE

     THIS AMENDMENT TO GEOTHERMAL LEASE ("Amendment") is made and entered into
effective as of January 1, 1990, by and among MAGMA POWER COMPANY, a Nevada
corporation ("Lessor") and MAMMOTH-PACIFIC, L.P., a California limited
partnership ("Lessee"), with reference to the following facts:

     A. Magma Energy, Inc., a Nevada corporation, and Holt Geothermal Company, a
California corporation, entered into that certain Geothermal Lease dated August
31, 1983, and recorded in memorandum form on September 6, 1983, in Book 389,
Page 37 of Official Records of Mono County, California (the "Lease").

     B. Magma Energy, Inc. has merged with and into Lessor, and Lessor is the
successor-in-interest to Magma Energy, Inc., by operation of law, as fee owner
of the real property covered by the Lease.

     C. By an Assignment of Lease dated August 31, 1983, and recorded in
memorandum form on September 20, 1983, in Book 390, Page 90 of Official Records
of Mono County, California, Holt Geothermal Company assigned all of it right,
title and interest in the Lease to Mammoth-Pacific, a California general
partnership.

     D. The Lease was previously amended by the First Amendment to Geothermal
Lease dated April 30, 1987 between Magma Energy, Inc. and Mammoth-Pacific, a
California general partnership.

                                      -15-

     E. Pacific Geothermal Company, a California corporation and a general
partner of Lessee, subsequently succeeded to all of Mammoth-Pacific, a
California general partnership's right, title and interest in the Lease. By an
assignment dated January 29, 1990 and recorded in memorandum form on January 29,
1990 as Instrument No. 665, Official Records of Mono County, California, Pacific
Geothermal Company assigned an undivided 50% of all of its right, title and
interest in the Lease to Lessee, and the remaining undivided fifty percent (50%)
of all of its right, title and interest in the Lease in equal shares to CD
Mammoth Lakes I, Inc., a Maryland corporation and _______ Mammoth Lakes II,
Inc., a Maryland corporation (collectively, the CD Companies); and the CD
Companies in the same assignment subsequently assigned all of such right, title
and interest in the Lease to Lessee.

     F. Exhibit "A" to the Lease contains the following exception in the
description of Parcel B of the leased premises EXCEPTING THEREFROM the surface
of the Southwesterly three (3) acres, more or less, occupied by a lumberyard as
of the date of this Lease.

     The area covered by this exception is referred to in this Amendment as the
"Excepted Acreage."

     G. Lessor and Lessee desire to amend the Lease to include the Excepted
Acreage in the leased premises, without, however, any warranty of title by
Lessor.

     NOW, THEREFORE, in consideration of the above-referenced facts, the
agreements of Lessor and Lessee contained herein, and for other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, Lessor and Lessee agree as follows:

     1. The following language is deleted from Exhibit "A" to the Lease:

                                      -16-

     EXCEPTING THEREFROM the surface of the Southwesterly three (3) acres, more
or less, occupied by a lumberyard as of the date of this Lease.

     2. From and after the date of this Amendment, the Excepted Acreage shall be
part of the leased premises covered by the Lease, subject to all of the terms
and conditions of the Lease, as amended, except as provided in paragraph 3
below.

     3. Notwithstanding anything set forth in the Lease, Lessor is leasing the
Excepted Acreage to Lessee without any warranties or representations of title
whatsoever, including, without limitation, any warranty or representation that
the Excepted Acreage is free and clear of leases and tenancies by others.

     EVIDENCING their agreement, Lessor and Lessee have executed this Amendment
as of the date first written above.

     LESSOR:

     MAGMA POWER COMPANY, a Nevada
     corporation

     By: /s/ Jon R. Peele
     Name: (print): Jon R. Peele
     Title: Senior Vice President

     By: /s/ Wallace C. Dieckmann
     Name: (print) Wallace C. Dieckmann
     Title: Assistant Secretary

     LESSEE:

     MAMMOTH-PACIFIC, L.P., a California limited partnership

     By Pacific Geothermal Company, a California corporation, its Managing
     General Partner

     By: /s/ Claude Harvey
     Name: (print) Claude Harvey
     Title: Sr. Vice President

                                      -17-

                       THIRD AMENDMENT TO GEOTHERMAL LEASE

     THIS THIRD AMENDMENT TO GEOTHERMAL LEASE (the "Third Amendment") is made
and entered into as of April 12, 1991, by and between MAGMA POWER COMPANY, a
Nevada corporation ("Lessor") and MAMMOTH-PACIFIC, L.P., a California limited
partnership ("Lessee") with reference to the foregoing facts:

     A. Magma Energy, Inc., a Nevada corporation, and Holt Geothermal Company, a
California corporation, entered into that certain Geothermal Lease dated August
31, 1983, and recorded in memorandum form on September 6, 1983, in Book 389,
Page 37 of Official Records of Mono County, California (the "Original Lease").

     B. Magma Energy, Inc. has merged with and into Lessor, and Lessor is the
successor-in-interest to Magma Energy, Inc., by operation of law, as fee owner
of the real property covered by the Original Lease.

     C. By an Assignment of Lease dated August 31, 1983, and recorded in
memorandum form on September 20, 1983, in Book 390, Page 90 of the Official
Records of Mono County, California, Holt Energy Company assigned all of its
right, title and interest in the Original Lease to Mammoth-Pacific, a California
general partnership ("MPGP").

     D. The Original Lease was previously amended by the First Amendment to
Geothermal Lease dated as of April 30, 1987 between Magma Energy, Inc and MPGP
(the "First Amendment") and by the Second Amendment to Geothermal Lease dated as
of January 1, 1990 between Lessor and MPGP (the "Second Amendment") (the
Original Lease, the First Amendment and the Second Amendment are referred to
collectively herein as the "Lease").

     E. MPGP has dissolved and, as a result of such dissolution, Pacific
Geothermal Company, a California corporation ("PGC"), succeeded to 100% of
MPGP's interest in the Lease.

     F. PGC is a general partner of Lessee, holding not less than 50% interests
in both partnership capital and profits.

     G. By an Assignment and Assumption Agreement dated as of January , 1990
(the "Assignment Agreement"), PGC assigned an undivided 50% interest in the
Lease to Lessee and an undivided 50% in the Lease to the CD Companies (as
defined in the Assignment Agreement) (the "CD Companies"). Said Assignment
Agreement was recorded in memorandum form on January 29, 1990 in Book 548, Page
592 of the Official Records of Mono County, California.

     H. Concurrently with the Assignment to the CD Companies described in
Recital G, the CD Companies assigned their entire interest in the Lease to
Lessee.

     I. Lessor and Lessee now desire to modify the Lease for purpose of, among
other things, modifying and/or clarifying certain rights and obligations of
Lessor and Lessee under the Lease.

                                      -18-

     NOW, THEREFORE, in consideration of the mutual promises and covenants
contained herein, and for other good and valuable consideration the receipt and
sufficiency of which are hereby acknowledged, Lessor and Lessee agree to amend
the Lease as follows:

     1. Definitions. All capitalized terms contained herein, unless otherwise
defined, shall have the meanings ascribed to such terms in the Lease.

     2. Modification of Exhibit "A-1". Lessor and Lessee agree to amend Exhibit
"A-1" to the First Amendment promptly upon the occurrence of "firm operation" of
each New Plant, which amendment(s) shall be prepared on the basis of the same
assumptions used for purposes of initially preparing said Exhibit "A-1", but
which amendment(s) shall accurately reflect the appropriate commencement date
for the effectiveness thereof.

     3. Modification of Exhibit "A-2". Exhibit "A-2" to the First Amendment is
hereby deleted in its entirety and Exhibit "A-2" hereto is substituted in its
place.

     4. Property Taxes. Paragraph 18 of the Lease is hereby amended by adding
the following before the last sentence of Paragraph 18:

     In this regard, all property taxes assessed by the Assessor on the
respective property interests of the parties hereunder in respect of the leased
land shall be shared by Lessee and Lessor in proportion to which the Assessor
allocates the assessment of value among structures, improvements and personal
property made or placed upon the leased land by Lessee, on the one hand, and the
leased land as such (including the geothermal resources and the right to
production thereof), on the other hand; provided, however, that any increase in
tax assessments which arise after the date hereof by reason change in control of
or ownership interests in Lessee shall be paid by "Lessee", and/"Lessee" shall
indemnify and hold Lessor harmless therefor, including, without limitation,
changes in control or of ownership interests in Lessee arising by reason of
redemptions or transfers of interest. In addition, from and after January 1,
1990, Lessor and Lessee shall cooperate in good faith to pursue a joint strategy
of settling on an agreed-upon methodology with the Assessor for valuation and
allocation of property taxes, both historically and prospectively during the
term of this Lease. Lessor and Lessee agree that each party shall represent its
own interests as they shall appear and shall bear its own fees and costs, but
shall seek, in good faith and to the extent reasonably practicable, to present a
common position to the Assessor in a good faith effort to achieve the lowest
overall property tax assessment applicable to both parties.

     5. Indemnification. Paragraph 18 of the Lease is hereby further amended by
adding the following after the first sentence of Paragraph 18:

     Without limiting the generality of the foregoing or any other provision of
this Lease (including, without limitation, Paragraphs 12 and 15 hereof) and in
furtherance thereof, Lessee acknowledges that Lessor has not itself utilized or
monitored Lessee's activities on the leased land and Lessee (i) acknowledges and
agrees that Lessee is relying solely on its own investigation of the leased land
with respect to the effect of (a) the presence, if any, of any underground tanks
on the leased land or of any "hazardous substances", "hazardous materials" or
"hazardous wastes" (as defined under federal or California Law) (collectively,
the "Hazardous Materials"), (ii) assumes the risk of all liabilities, claims,
demands, actions and causes of action arising out of any such storage tanks or
Hazardous Materials on, at, in, under or about the leased

                                      -19-

land whether placed there now or at any point in the future while this Lease is
in affect and, (iii) agrees to hold harmless, indemnify and defend Lessor
against all claims with respect to the foregoing.

     6. Assignment of BLM Lease. Concurrently with the execution and delivery
hereof, Lessor is assigning to Lessee all of Lessor's right, title and interest
in and to that certain Geothermal Resource Lease (Mono-Long Valley Parcel #12)
dated March 1, 1982, between the United States and Magma Energy, as assigned to
Lessor (the "BLM Lease"). In consideration for such Assignment, Lessee shall pay
to Lessor, on the date hereof, the amount of $89,468.06 by wire transfer of
immediately available funds.

     7. BLM Approval. Lessee shall, within 180 days following the date hereof,
obtain from the Department of Interior, Bureau of Land Management ("BLM") such
approvals to the Assignment of the BLM Lease described in Paragraph 6 of this
Third Amendment as may be required in accordance with 43 C.F.R. 3241.2, and
either (a) Lessee shall post a bond satisfactory to BLM if required thereby or
(b) if Lessor has heretofore posted a bond with BLM, then Lessee shall replace
such bond and cause such bond to be released to Lessor. In the event Lessee
fails to perform its obligations under this Paragraph 7, Lessee shall, upon
request of Lessor, assign the BLM Lease to Lessor.

     8. Cross Default. Lessee shall be deemed to be in material breach of the
Lease, as amended hereby, in the event Lessee fails for any reason whatsoever to
pay within five (5) days when due all royalties payable by Lessee for Lessor
under the Lease, as amended hereby, in respect of the BLM Lease, including
without limitation in the event the payment of all or any part of said royalties
are determined to constitute impermissible overriding royalties. If Lessee or
any lender or other party holding a beneficial interest in the BLM Lease fails
to pay any royalty due under the ELM Lease within sixty (60) days after such
royalty comes due, Lessor shall have the right to terminate the Lease upon
written notice to Lessee.

     9. BLM Lease Property Taxes. From and after the date hereof, Lessee shall
pay all property taxes payable in respect of the BLM Lease property and all
rental and royalties payable under the BLM Lease, as though Lessee were the
direct and original lessee thereunder, and lessee shall indemnify and hold
harmless Lessor for all losses, liabilities, costs and expenses (including
without limitation reasonable attorneys' fees) in respect thereof.

     10. Matters Concerning the BLM Leases. To the best of Lessor's knowledge,
without any review of title reports but based solely on Lessor's not having
received any notice, certificate or document to the contrary, Lessor has no
reason to believe there are any defects in Lessor's title to the BLM Lease. In
addition, Lessor represents that all rental Payments and taxes attributable to
the BLM Lease which have become due and payable have been paid in full.

     11. Effectiveness of Third Amendment. This Third Amendment shall be
effective and become of full force and effect only upon receipt by Lessor of
insurance binders or certificates in a form reasonably satisfactory to Lessor
evidencing the maintenance by Lessee of all policies of insurance required to be
maintained pursuant to Paragraph 18 of the Lease.

     12. Continued Effectiveness. Except as specifically provided in this Third
Amendment, the Lease shall remain in full force and effect in accordance with
its original terms

                                      -20-

and conditions, except that the term "Lease" as used in the Lease shall
hereafter mean the Lease as amended hereby.

     13. Counterparts. This Third Amendment may be executed simultaneously in
two or more counterparts, each of which shall be deemed an original, but all of
which together shall constitute a single original instrument.

     14. Entire Agreement-Amendments. This Third Amendment, together with the
Lease and those certain letter agreements date of even date herewith, between
Lessor and Lessee, constitute the entire agreement of the parties with respect
to the matters set forth herein, and the provisions hereof, together with the
other documents enumerated in this Paragraph 14, shall supersede any and all
prior agreements or understandings relating to the same subject matter. The
Lease, as amended hereby, may be further amended only by a writing signed by a
duly authorized representative of both parties.

     IN WITNESS WHEREOF, the parties hereto have caused this Third Amendment to
be signed by their duly authorized officers as of the day and year first above
written.

                                           LESSOR:

                                           MAGMA POWER COMPANY, a Nevada
                                           corporation

                                           By: /s/ Jon R. Peele
                                              --------------------------------
                                           Name:  Jon R. Peele
                                           Its:  Senior Vice President

                                           By: /s/ Wallace C. Dieckmann
                                              --------------------------------
                                           Name:  Wallace C. Dieckmann
                                           Its:  Assistant Secretary

                                           LESSEE:

                                           MAMMOTH-PACIFIC, L.P., a California
                                           limited partnership

                                           By:  Pacific Geothermal Company,
                                           a California corporation,
                                           General Partner

                                           By: /s/ Claude Harvey
                                              --------------------------------
                                           Name: Claude Harvey
                                                ------------------------------
                                           Title: Sr. Vice President
                                                 -----------------------------

                                           Recording Requested By and
                                           When Recorded Return To:

                                           WILLILAM E. VINEY, ESQ.
                                           530 West 6th Street, Suite 623
                                           Los Angeles, California 90014

                                           By: CD Mammoth Lakes I Inc.,
                                              --------------------------------
                                               a Maryland Corporation
                                              --------------------------------
                                               General Partner

                                           By: /s/ Terry L. Ogletree
                                              --------------------------------
                                           Name: Terry L. Ogletree
                                                ------------------------------
                                           Its: President
                                               -------------------------------

                                      -21-

                                  Exhibit "A-1"
                       New Plant Baseline Revenue Forecast
                                Revised June 1991

                                          BASELINE
                                           REVENUE
                                          FORECAST
                     YEAR                   ($M)
                     ----                 --------
                     1991                   8,829
                     1992                   9,650
                     1993                  10,457
                     1994                  11,272
                     1995                  12,177
                     1996                  13,018
                     1997                  14,021
                     1998                  15,051
                     1999                  16,072
                     2000                  16,072
                     2001                   9,958
                     2002                  10,448
                     2003                  10,967
                     2004                  11,518
                     2005                  12,101
                     2006                  12,720
                     2007                  13,376
                     2008                  14,071
                     2009                  14,808
                     2010                  15,589
                     2011                  16,417
                     2012                  17,294
                     2013                  18,225
                     2014                  19,211
                     2015                  20,256
                     2016                  21,364
                     2017                  22,538
                     2018                  23,783
                     2019                  25,104
                     2020                  26,506
                     2021                  27,993
                     2022 and for the      To be calculated
                     balance of the        using the same
                     term of the Lease.    bases.

                                  EXHIBIT "A-2"
                    EXISTING PLANT BASELINE REVENUE FORECAST

                                                BASELINE
                                                REVENUE
       CAPACITY    NET     ENERGY   AGREEMENT   FORECAST
         PRICE    MW HRS    PRICE     PRICE       ($m)
       --------   ------   ------   ---------   --------
1987     .0194    70,000    .0700     .0894       6,258
1988     .0194    70,000    .0700     .0894       6,258
1989     .0194    70,000    .0700     .0894       6,258
1990     .0194    70,000    .0700     .0894       6,258
1991     .0194    70,000    .0700     .0894       6,258
1992     .0194    70,000    .0700     .0894       6,258
1993     .0194    70,000    .0700     .0894       6,258
1994     .0194    70,000    .0700     .0894       6,258
1995     .0194    70,000    .0700     .0894       6,258
1996     .0194    68,273    .0630     .0824       5,626
                  70,000*                         5,768*
1997     .0194    68,273    .0668     .0862       5,884
                  70,000*                         6,034*
1998     .0194    68,273    .0708     .0902       6,157
                  70,000*                         6,314*
1999     .0194    68,273    .0750     .0944       6,447
                  70,000*                         6,608*
2000     .0194    68,273    .0795     .0989       6,755
                  70,000*                         6,923*
2001     .0194    68,273    .0843     .1037       7,080
                  70,000*                         7,259*
2002     .0194    68,273    .0894     .1088       7,426
                  70,000*                         7,616*
2003     .0194    68,273    .0947     .1141       7,792
                  70,000*                         7,987*
2004     .0194    68,273    .1004     .1198       8,180
                  70,000*                         8,386*
2005     .0194    68,273    .1064     .1258       8,591
                  70,000*                         8,806*
2006     .0194    68,273    .1128     .1322       9,027
                  70,000*                         9,254*
2007     .0194    68,273    .1196     .1390       9,489
                  70,000*                         9,730*
2008     .0194    68,273    .1268     .1462       9,979
                  70,000*                        10,234*
2009     .0194    68,273    .1344     .1538      10,499
                  70,000*                        10,766*
2010     .0194    68,273    .1424     .1618      11,049
                  70,000*                        11,326*
2011     .0194    68,273    .1510     .1704      11,633
2012     .0194    68,273    .1600     .1794      12,251
2013     .0194    68,273    .1696     .1890      12,907
2014     .0194    68,273    .1798     .1992      13,602
2015     .0194    68,273    .1906     .2100      14,338
2016 and for the balance of the term of the Lease to be calculated using the
same bases.

          For purposes of this Exhibit "A-2", the figures noted with an asterisk
(*) for the period between and including 1996 and 2010 shall be the effective
figures for their corresponding years only until such time as ***% of the amount
of the cumulative gross revenues attributable to the increment of megawatt hours
sold each year by the Existing Plant between and including *** MW hours and ***
MW hours equals $***, plus simple interest at a rate of 7% per annum beginning
January 1, 1990 (on the full amount of $*** and not on the declining balance
thereof). Thereafter, the numbers not noted with asterisk (*) during such period
shall become effective for their corresponding years.

          The remaining amount representing ***% of the cumulative gross
revenues attributable to the increment of megawatt hours sold each year by the
Existing plant between and including *** MW hours and *** MW hours shall be paid
to Lessor as additional Existing Plant Base Royalty, in addition to (1) the
Existing Plant Base Royalty to be paid to Lessor pursuant to Paragraph 5.1 of
the Lease and (2) Bonus Royalty to be paid to Lessor pursuant to Paragraph 5.3
of the Lease.

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

Recording Requested By and
When Recorded Return To:

WILLIAM E. VINEY, ESQ.
530 West 6th Street, Suite 623
Los Angeles, California 90014

                               MEMORANDUM OF LEASE

          THIS MEMORANDUM OF LEASE is made on August 31, 1983 between Magma
          Energy, Inc., a Nevada corporation ("Lessor"), and Holt Geothermal
          Company, a California corporation ("Lessee").

                                   WITNESSETH:

     The parties hereto have entered into a Geothermal Lease (the "Lease")
granting to Lessee the exclusive right to the geothermal resources produced from
the land subject to the Lease. Under the terms of the Lease, the Lessor shall
share in the revenues received from the use of the energy derived from the
geothermal resources.

     ACCORDINGLY, in consideration of the premises and the mutual covenants set
forth in the Lease, it is agreed between the parties as follows:

     1. Term and Premises. The Lessor hereby leases exclusively to Lessor, and
Lessee hereby leases for its exclusive use from Lessor all rights to the
geothermal resources

                                       -2-

produced from the real property located near the Casa Diablo Hot Springs, County
of Mono, State of California described in Exhibit A attached to this Memorandum
of Lease. The tern of the Lease is for thirty (30) years from and after the date
hereof and so long thereafter as any geothermal resources are produced
therefrom, or are capable of being produced therefrom, or drilling or producing
operations are conducted thereon or excused under the terms of the Lease. The
Lease also provides Lessee with a right to use a certain portion of the surface
of the real property, the right to conduct certain activities on the surface of
the real property, continuing access rights to the real property, all as more
specifically set forth in the Lease, which Lease is dated August 31, 1983. The
provisions of the Lease are incorporated into this Memorandum of Lease by
reference.

     2. Purpose of Memorandum of Lease. This memorandum of Lease is prepared for
the purpose of recordation, and it in no way modifies the provisions of the
Lease referred to in Section 1 hereof.

     IN WITNESS WHEREOF the parties hereto have executed this Memorandum of
Lease effective as of the date first written above.

HOLT GEOTHERMAL COMPANY                 MAGMA ENERGY, INC.

By: /s/ Illegible                       BY: /s/ Illegible
    -------------------------------         ------------------------------------
               President                                  Chairman

Attest: /s/ Illegible                   Attest: /s/ Illegible
        ---------------------------             --------------------------------
               Secretary                                  Secretary

                                       -3-

STATE OF CALIFORNIA,    )
                        ) ss.
COUNTY OF LOS ANGELES   )

     On August 31, 1983 before me, the undersigned, a Notary Public in and for
said County and State, personally appeared B.C. McCabe, known to me to be the
____________ and Joseph W. _______, known to me to be Secretary of Magma Energy,
Inc., the corporation that executed the within Instrument, known to me to be the
persons who executed the within Instrument on behalf of the corporation therein
named, and acknowledged to me that such corporation executed the within
instrument pursuant to its by-laws or resolution of its board of directors.

WITNESSETH my hand and official seal.

                                                           OFFICIAL SEAL
By: /s/ April L. Wogatzke                                 APRIL L WOGATZKE
    -------------------------------                  NOTARY PUBLIC - CALIFORNIA
    April L. Wogatzke                                     SAN DIEGO COUNTY
                                                   My comm. expires JUL 27, 1984

                                           P.O. Box 17780, Los Angeles, CA 90017

STATE OF CALIFORNIA,    )
                        ) ss.
COUNTY OF LOS ANGELES   )

     On 31 August 1983 before me, the undersigned, a Notary Public in and for
said County and State, personally appeared Ben Holt, known to me to be the
President, and W.E. Viney, known to me to be Secretary of Holt Geothermal
Company, the corporation that executed the within Instrument, known to me to be
the persons who executed the within Instrument on behalf of the corporation
therein named, and acknowledged to me that such corporation executed the within
instrument pursuant to its by-laws or resolution of its board of directors.

WITNESSETH my hand and official seal.

                                                            OFFICIAL SEAL
By: /s/ Betty J. Peterson                                 BETTY J PETERSON
    -------------------------------                _____________________________
    Betty J. Peterson                                    LOS ANGELES COUNTY
                                                   My comm. expires MAY 14, 1984

                                   EXHIBIT "A"

                                    Parcel A

     Those patented placer mining claims in the Mammoth Mining District, County
of Mono, State of California, known and described in the Patent as follows:

     WHITE OWL MO. 2 claim, embracing Section 32, West half of Northwest quarter
of Northeast quarter;

     WHITE OWL NO. 3 claim, embracing Section 32, Northwest quarter of Southwest
quarter of Northeast quarter, and

     WHITE OWL NO. 5 claim, embracing Section 32, North half of Southeast
quarter of Northwest quarter;

according to the official plat of said land approved January 28, 1857.

     EXCEPTING THEREFROM any veins or lodes of quartz, or other rock in place
bearing gold, silver, cinnabar, lead, tin, copper or other valuable deposits
within the land above described, which may have been discovered or known to
exist on or prior to November 20, 1950.

     Subject to rights of way, easements, and rights (other than ownership of or
rights to receive any rents or royalties on geothermal resources in, under or
that may be produced from said land) of record.

                                    Parcel B

     Southwest quarter of the Northwest quarter of Section 32, Township 3 South,
Range 28 East, M.D.M., in the County of Mono, State of California, according to
the official Plat thereof filed in the District Land office on June 23, 1857.

     EXCEPTING THEREFROM the surface of the Southwesterly three (3) acres, more
or less, occupied by a lumberyard as of the date of this Lease.

     Subject to rights of way, easements, and rights (other than ownership of or
rights to receive any rents or royalties on geothermal resources in, under or
that may be produced from said land) of record.

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