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                                                            HECO Exhibit 10.5(b)


              PERFORMANCE AGREEMENT AND FOURTH AMENDMENT TO THE
            PURCHASE POWER CONTRACT DATED MARCH 24, 1986 AS AMENDED


     THIS PERFORMANCE AGREEMENT AND FOURTH AMENDMENT ("Performance Agreement" or
"Fourth Amendment") is made as of this 12th day of February 1996 ("Execution
Date"), by and between HAWAII ELECTRIC LIGHT COMPANY, INC. (the "Company" or
"HELCO"), and PUNA GEOTHERMAL VENTURE (the "Seller" or "PGV").

     WHEREAS, the Company is an operating electric public utility on the Island
of Hawaii subject to the Hawaii Public Utilities Law (Hawaii Revised Statutes,
Chapter 269) and the rules and regulations of the Hawaii Public Utilities
Commission (the "PUC" or "Commission");

     WHEREAS, the Company has entered into a Purchase Power Contract for
Unscheduled Energy Made Available From a Qualifying Facility (the "Unscheduled
Energy Contract"), dated March 24, 1986, with Thermal Power Company ("Thermal
Power") which was approved by the PUC by Decision and Order No. 8692, dated
March 25, 1986, in Docket No. 5525;

     WHEREAS, Thermal Power assigned the Unscheduled Energy Contract to AMOR
VIII and AMOR VIII assigned the Unscheduled Energy Contract to PGV;

     WHEREAS, HELCO and PGV have entered into that certain Firm Capacity
Amendment to Purchase Power Contract, dated July 28, 1989 ("Firm Capacity
Amendment"), which amended the Unscheduled Energy Contract, and was approved by
the PUC by Decision and Order No. 10519, dated February 14, 1990, in Docket No.
6498;

     WHEREAS, by Amendment to Purchase Power Contract, As Amended ("Second
Amendment"), HELCO and PGV amended the Unscheduled Energy Contract and Firm
Capacity Amendment;

     WHEREAS, a number of issues arose between the Company and Seller which they
settled in a Settlement Agreement dated March 7, 1995 ("Settlement Agreement");

     WHEREAS, as part of the Settlement Agreement, the Company and Seller agreed
to a third amendment ("Third Amendment") to the Unscheduled Energy Contract,
Firm Capacity Amendment, and the Second Amendment (the Unscheduled Energy
Contract as amended by the Firm Capacity Amendment, the Second Amendment, and
the Third Amendment and as may be amended from time to time, is referred to as
the "Amended PPC") (The Third Amendment was approved on an interim basis by the
PUC by Interim Decision and Order No. 13876, dated May 5, 1995, in Docket No.
95-0074);
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     WHEREAS, Seller presently provides to the Company, and the Company
presently purchases from Seller, twenty-five (25) megawatts ("MW") of firm
capacity from Seller's Facility pursuant to the Amended PPC;

     WHEREAS, the Seller desires to sell to the Company an additional five (5)
MW of firm capacity generated by the Facility above the twenty-five (25) MW of
firm capacity presently supplied, and the Company wishes to purchase such Energy
from the Seller, upon the terms and conditions set forth herein;

     WHEREAS, the Seller's Facility will continue to be throughout the term of
this Performance Agreement either (1) a qualifying, small power production
facility under Subchapter 2 of the PUC's Standards for Small Power Production
and Cogeneration in the State of Hawaii, Chapter 74 of Title 6 of the State's
Administrative Rules, or (2) a "non-fossil fuel producer" within the meaning of
Section 269-27.2, Hawaii Revised Statutes;

     NOW, THEREFORE, in consideration of the premises and the respective
promises herein, the Company and the Seller hereby agree as follows:

I.   THE PROJECT

     A.   Enhancement and Operation of Seller's Facility

          1.  Seller agrees to provide the Company with five (5) megawatts of
firm capacity in addition to the twenty-five (25) megawatts of firm capacity
currently being provided pursuant to the Amended PPC (for a total of thirty
megawatts of firm capacity) and 18,600 kvar of reactive under this Agreement.
The reactive shall be in proportion to power in the range of 0.85 lagging to 1.0
unity power factor and shall be dispatched by the Company to keep the Seller's
generator within the limits of plus or minus 5% of the generator voltage.

          2.  Attached as Exhibit A, is a description of the proposed
enhancements (the "Project") to Seller's Facility to enable Seller to provide an
additional five (5) MW of firm capacity (a total of thirty megawatts of firm
capacity) and 18,600 kvar of reactive. Seller's Facility as modified by the
Project is referred to hereinafter as "Seller's Facility".

          3.  Seller shall be responsible for all costs associated in any way
with Seller's Facility and/or the Project.

          4.  Seller shall be responsible for obtaining all permits, licenses,
approvals and any other requirements 

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reasonably required for Seller to provide the additional five (5) megawatts of
firm capacity pursuant to this Performance Agreement.

          5.  Within sixty (60) days of the Execution Date, a final (1) a 
single-line diagram of Seller's Facility, (2) relay list, and (3) trip scheme,
all as may be modified by the Project, shall be prepared and, subject to the
review and acceptance thereof by both parties, signed and attached to Attachment
B To The Fourth Amendment as Exhibit 1 to Appendix B and made a part thereof.
Such single line diagram shall expressly identify the final location on the
Point of Interconnection.

          6.  Within sixty (60) days of the Execution Date, the design and
specifications for protective equipment to protect HELCO's system, as may be
modified by the Project, shall be prepared and, subject to the review and
acceptance thereof by both parties, signed and attached to Amended PPC and made
a part thereof.

          7.  Attached hereto as Exhibit B is a project schedule relating to the
Project.

          8.  Prior to the Commercial Operation Date (as defined below) of the
Seller's Facility to produce the additional five (5) megawatts of firm capacity
(for a total of thirty (30) megawatts of firm capacity), Seller shall inform
HELCO on the third business day of every month of the status of the Seller's
Project as of the last day of the prior month, including but not limited to, any
revisions to the date of installation, the date of operation in parallel with
the Company's System, and the anticipated Commercial Operation Date (as defined
below) of the Seller's Facility for the additional five (5) megawatts of Firm
Capacity.

     B.  Acceptance Tests.  The Company shall conduct acceptance tests as part
of the determination of when Firm Capacity payments related to the additional
five (5) megawatts of firm capacity should begin.

          1.  Upon completion and testing of Seller's Facility as modified by
the Project by Seller for the additional five (5) megawatts of firm capacity,
Seller shall give HELCO seven (7) days prior notice of the time and date when
Seller will be ready to begin the 100 continuous hours acceptance test for the
additional five (5) megawatts of firm capacity.

          2.  Upon the agreed upon time and date, the Company shall conduct the
100 continuous hours acceptance test for the additional five (5) megawatts of
firm capacity ("Acceptance Test").  At a minimum, Seller must be able to deliver
to the  

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Company l00% of the Seller's Firm Capacity Obligation (30,000 kw of capacity and
18,600 kvar of reactive) for 100 consecutive hours under Company's Dispatch (as
defined in Attachment E to the Fourth Amendment). The Acceptance Test may be
started and/or completed prior to the Effective Date (as defined below) of this
Performance Agreement.

          3.  As the last step of the Acceptance Test, Seller shall ramp
Seller's Facility down to simulate a sudden loss of system load.  Seller shall
decrease power output from thirty (30) megawatts to ten (10) megawatts at an
average ramp rate of one (1) megawatt per minute.  Seller shall ramp Seller's
Facility up in power output to simulate an increase in demand on the Facility.
Seller shall increase power output from eighteen and one-half (18.5) megawatts
to thirty (30) megawatts at an average ramp rate of one (1) MW/minute.  In
addition, during the Acceptance Test, the Seller shall demonstrate the ability
to adjust kvars from 1,500 to 18,600.

          4.  The Seller's performance throughout the Acceptance Test shall be
monitored remotely through the SCADA system and recorded.  In addition, the
Seller shall also allow HELCO representatives to be stationed at Seller's
Facility to verify all data and ensure that all operational changes made at the
request of HELCO were done within the bounds of good engineering and operating
practices.

          5.  Upon successful completion of the Acceptance Test, HELCO will
notify Seller in writing of the acceptance of the additional 5 MW of firm
capacity and Seller will immediately acknowledge in writing such acceptance by
HELCO.  The date on which Seller's Facility is deemed to be capable of reliable
delivery of the additional five (5) megawatts of firm capacity pursuant to this
Performance Agreement after the successful completion of the Acceptance Test is
referred to herein as the "Commercial Operation Date".

II.  PROJECT COMPLETION

     A.  Commercial Operation Date.  The Commercial Operation Date shall occur
prior to or within six (6) months after the later of PUC Approval (as defined
below in Section IV.A) or Bank's Consent (as defined in Section IV.B. below).

     B.  Penalties For Not Meeting Commercial Operation Date Deadline.  If the
Commercial Operation Date for the additional five (5) megawatts does not occur
within nine (9) months of the later of the date of PUC Approval or Bank's
Consent (the "Commercial Operation Date Deadline"), then:
 
         1.  Seller shall pay HELCO one cent ($0.01) per on-peak hour for each
kilowatt deficiency until Seller 

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satisfies the Acceptance Test. Kilowatt deficiency is the difference in
kilowatts at any given time between the 5,000 kilowatts PGV is required to
produce hereunder and the actual amount produced by PGV pursuant to this
Performance Agreement.
 
          2. Seller shall pay to HELCO late charges in the amount of $1,380.00
per day for each day commencing on the Commercial Operation Date Deadline until
the Commercial Operation Date.
 
          3. Any penalties incurred under this Section II.B. shall cease to
accrue one year after the Commercial Operation Date Deadline.
     
III.  INTERCONNECTION FACILITIES
 
     A.  The parties believe that there are no additional interconnection
facilities required for HELCO's system to accept the additional five (5)
megawatts of Energy to be provided by Seller pursuant to this Performance
Agreement.
 
     B.  If it is later determined that additional interconnection facilities
are needed, then Seller shall be responsible for cost and construction of all
interconnection facilities required to deliver the additional 5 MW of firm
capacity from Seller's Facility to the Company's System.
 
     C.  Seller shall be responsible for one hundred percent (100%) of the
maintenance costs associated with any upgrade of existing interconnection
facilities.

IV.  APPROVALS REQUIRED PRIOR TO EFFECTIVE DATE

     A.  Public Utilities Commission Approval.

          1.  The parties will use their best efforts, including without
limitation, participation in any PUC proceeding at the request of the other
party, to obtain an appropriate decision and order satisfactory to the Company
("PUC Approval") that approves this Agreement and authorizes the Company to
include payments made to the Seller hereunder in the Company's Energy Cost
Adjustment Clause pursuant to Rule 6-60-6, Standards For Electric and Gas
Utility Service, Title 6, Chapter 60, of the Hawaii Administrative Rules, and in
the Company's Firm Capacity Surcharge pursuant to Section 269-27.2(d), Hawaii
Revised Statutes, or in the Company's base rates pursuant to Section 269-16(b),
Hawaii Revised Statutes, whichever occurs first.

          2.  The Company shall be responsible for submitting the application
for PUC Approval and for all of the Company's costs associated thereto.  Seller
shall cooperate with the  

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Company in any reasonable manner to assist the Company in the application for
PUC Approval and Seller shall be responsible for its costs in providing such
cooperation and assistance.

          3.  Notwithstanding anything in this Performance Agreement to the
contrary, in the event that the Commission denies the Company's application to
include all payments to Seller hereunder in the Company's Energy Cost Adjustment
Clause pursuant to Rule 6-60-6, Standards For Electric and Gas Utility Service,
Title 6, Chapter 60, of the Hawaii Administrative Rules, and the Company's Firm
Capacity Surcharge pursuant to Section 269-27.2(d), Hawaii Revised Statutes, or
in the Company's base rates pursuant to Section 269-16(b), Hawaii Revised
Statutes, then this Fourth Amendment, at HELCO's option and in HELCO's sole
discretion, shall be null and void and of no further force and effect.  HELCO
shall have thirty (30) days from the date the PUC decision and order denying the
Company's application becomes final and non-appealable to terminate this
Agreement pursuant to this Section IV.A.

     B.  Consent of Bank

          1.  Seller, at its own expense, shall use its best efforts to obtain
from Credit Suisse, a bank organized and existing under the laws of Switzerland,
as Agent and Collateral Agent for the benefit of its own account and such other
financial institutions as may participate in the funding and other risks
associated with the Facility (the "Bank"), a Consent of the Bank to this Fourth
Amendment, related documents, and the transactions and obligations of Seller
herein, substantially in the form attached hereto as Exhibit C ("Bank's
Consent").

          2.  Notwithstanding anything in this Performance Agreement to the
contrary, in the event that the Bank does not execute the Bank's Consent, then
this Fourth Amendment shall be null and void and of no further force and effect.

V.  EFFECTIVE DATE/CONDITIONS PRECEDENT

     A.  Effective Date.  The obligations of the parties under Section IV and
Section VI of this Performance Agreement shall become effective on the Execution
Date.  The remaining provisions of this Performance Agreement (excluding Section
IV and Section VI) shall not become effective until the later of (1) the date of
obtaining PUC Approval, or (2) the date of obtaining the Bank's Consent (the
"Effective Date").

     B.  Conditions Precedent.  In addition to Section V.A., except for the
obligations of the parties under Section IV and Section VI of this Performance
Agreement, in no event shall the 

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Company be obligated under this Performance Agreement until the fulfillment of
the following conditions:

          1.  The Company obtains PUC Approval as specified in Section IV.A.
above;

          2.  Seller shall obtain and deliver to HELCO Bank's Consent,
substantially in the form attached hereto as Exhibit C;

          3.  Seller successfully completes to HELCO's satisfaction the
Acceptance Test described in Section I.B.;

          4.  Seller fulfills all of its In-Kind Obligations (as defined in the
Settlement Agreement) under the Settlement Agreement; and

          5.  Each party shall have delivered or cause to be delivered to the
other party, such documents which may be reasonably required pursuant to this
Performance Agreement.

     C.  Term.  This Performance Agreement shall remain in effect for the same
period of time as the Amended PPC, unless otherwise provided in this Performance
Agreement.

VI.  TERMINATION/DEFAULT

     A.  This Performance Agreement will terminate:

          1.  if the Bank's Consent is not received prior to June 1, 1996;

          2.  at HELCO's option, to be exercised by written notice to Seller by
June 15, 1997, if PUC Approval satisfactory to HELCO is not received prior to
May 1, 1997;

          3.  at HELCO's option, to be exercised by written notice to Seller,
pursuant to Section IV.A.3.;

          4.  at the option of a non-defaulting party to be exercised by written
notice to the other party if the other party commits any Event of Default and
fails to cure such default in accordance with Sections VI.D. or VI.E. below; or

          5.  upon the termination of the Amended PPC.

     B.  The occurrence of any of the following events at anytime during this
Agreement shall constitute an "Event of Default" under this Performance
Agreement by the Company:

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          1.   in the event of nonperformance by the Company of any material
obligation under this Performance Agreement;

          2.  failure of the Company to pay any amounts due and payable under
this Performance Agreement within sixty (60) days after receipt of invoice;

          3.  the Company shall (1) be dissolved, be adjudicated as bankrupt, or
become subject to an order for relief under any bankruptcy law; (2) fail to pay,
or admit in writing its inability to pay, its debts generally as they become
due; (3) make an assignment for the benefit of creditors; (4) apply for, seek,
consent to, or acquiesce in the appointment of a receiver, custodian, trustee,
examiner, liquidator or similar official for itself or any substantial part of
its property; (5) institute any proceedings seeking an order for relief or to
adjudicate it as bankrupt or insolvent, or seeking dissolution, winding up,
liquidation, reorganization, arrangement, adjustment or composition of it or its
debts under any law relating to bankruptcy, insolvency, reorganization, or
relief of debtors; or (6) take any action to authorize or effect any of the
foregoing actions;

          4.  without the application, approval, or consent of the Company, a
receiver, trustee, examiner, liquidator or similar official shall be appointed
for the Company or any part of its property, or a proceeding described in
Section VI.B.3. above shall be instituted against the Company and such
appointment shall continue undischarged or such proceeding shall continue
undismissed or unstayed for a period of 60 consecutive days or the Company shall
fail to file timely and answer or other pleading denying the material
allegations filed against it in any such proceeding;

          5.  as provided for in Appendix E of the Amended PPC.

     C.  The occurrence of any one of the following events at anytime during
this Performance Agreement shall constitute an "Event of Default" under this
Performance Agreement by Seller:

          1.  if Seller has failed to (a) have the injection pumps (as defined
in Exhibit A attached hereto) on-site within twenty-three (23) weeks after the
later of PUC Approval or the Bank's Consent or (b) have the injection pumps
installed within twenty-six (26) weeks after the later of PUC Approval or the
Bank's Consent.

          2.  if Seller cannot satisfactorily complete the Acceptance Test
described in Section I.B within twenty-one (21) months after the later of PUC
Approval or the Bank's Consent;

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          3.   if Seller cannot satisfactorily fulfill its In-Kind Obligations
under the Settlement Agreement and related documents within twenty-one (21)
months after the later of PUC Approval or the Bank's Consent, provided that, in
the event that HELCO declines to take Energy from PGV pursuant to Section
II.B.2.c. of the Settlement Agreement from the Effective Date of this
Performance Agreement, then the twenty-one (21) month period shall be extended
by adding one day to the twenty-one (21) month period for each one hundred (100)
megawatthours ("mwh") (rounded to the nearest increment of 100 mwh) of Energy
HELCO declines to accept under Section II.B.2.c. of the Settlement Agreement,
provided further that, notwithstanding anything to the contrary, any Energy
offered to HELCO by PGV above 30 MW per hour during on-peak periods and/or above
25 MW per hour during off-peak periods, and declined by HELCO, shall not be
included in calculating any extension of the twenty-one (21) month period;

          4.  in the event of nonperformance by Seller of any material
obligation in this Performance Agreement;

          5.  failure of Seller to pay any amounts due and payable under this
Performance Agreement within sixty (60) days after receipt of invoice;

          6.  abandonment of the Project or the discontinuance by the Seller of
services covered under this Performance Agreement for a period of twelve (12)
consecutive months unless such discontinuance is caused by Force Majeure under
Section VIII below or an Event of Default by the Company;

          7.  if Seller shall (1) be dissolved, be adjudicated as bankrupt, or
become subject to an order for relief under any bankruptcy law; (2) fail to pay,
or admit in writing its inability to pay, its debts generally as they become
due; (3) make an assignment for the benefit of creditors other than the Bank;
(4) apply for, seek, consent to, or acquiesce in the appointment of a receiver,
custodian, trustee, examiner, liquidator or similar official for itself or any
substantial part of its property; (5) institute any proceedings seeking an order
for relief or to adjudicate it as bankrupt or insolvent, or seeking dissolution,
winding up, liquidation, reorganization, arrangement, adjustment or composition
of it or its debts under any law relating to bankruptcy, insolvency,
reorganization, or relief of debtors; or (6) take any action to authorize or
effect any of the foregoing actions;

          8.  without the application, approval, or consent of Seller, a
receiver, trustee, examiner, liquidator or similar official shall be appointed
for Seller or any part of its property, or a proceeding described in Section
VI.C.7. above shall be instituted against Seller and such appointment shall

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continue undischarged or such proceeding shall continue undismissed or unstayed
for a period of 60 consecutive days or Seller shall fail to file timely and
answer or other pleading denying the material allegations filed against it in
any such proceeding;

          9.  the failure to keep in force and effect all permits, approvals,
licenses, permits and the like, reasonably required for Seller to provide the
additional five (5) megawatts of firm capacity under this Performance Agreement;

          10.  the failure to maintain qualification of Seller's Facility
pursuant to Section IX.E; or

          11.  as provided for in Appendix E of the Amended PPC.

     D.  If an Event of Default, other than failure to make any payment due and
payable within sixty (60) days after receipt of invoice, by either party shall
extend for a period of sixty days after receipt of written notice of such Event
of Default from the non-defaulting party, then the non-defaulting party may, at
its option, terminate this Performance Agreement by delivering written notice of
such termination to the party in default and/or may institute such legal action
or proceedings or resort to such other remedies as it deems necessary; provided,
however, that the party not in default shall not terminate this Performance
Agreement at the end of such sixty day period if the party in default has
corrected or commenced appropriate steps to correct such default and is
diligently prosecuting same to completion.  Such termination shall be effective
on the date of written notice of termination to the party in default and shall
not prejudice any rights of the non-defaulting party.

     E.  If the Event of Default is based on a party's failure to make any
payment that is due and payable under this Performance Agreement, the party
claiming such Event of Default shall give written notice to the non-paying party
stating that such payment is deemed payable.  The non-paying party shall have
ten (10) days from the receipt of such notice to make the required payment and
if payment is not made within such ten (10 day period, the non-defaulting party
may terminate this Performance Agreement pursuant to written notice provided in
accordance with Section VI.D. above.

     F.  Rights And Obligations Of The Parties Upon Default.  If this
Performance Agreement is terminated pursuant to this Section VI, the parties
shall have no further obligations to each other hereunder except for such
obligations as have been incurred hereunder prior to such termination.

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     Notwithstanding the foregoing, in the event of default, the non-defaulting
party may exercise whatever legal or equitable remedies may be available to it
against the defaulting party.  However, the parties further agree that in no
event shall either party be liable to the other for lost profits.

     G.  Interpretation of Amended PPC.  In the event this Performance Agreement
is terminated, but the Amended PPC is still in effect, then the Amended PPC
shall be interpreted as if the amendments to the Amended PPC described in
Section VII below were never effective.

     H.  No Cross Default.  A breach of or default under this Performance
Agreement shall not constitute a breach of or default under the Amended PPC.  No
Event of Default under this Performance Agreement shall constitute an Event of
Default under the Amended PPC unless such event is specifically enumerated as an
Event of Default under the Amended PPC.

VII.  AMENDMENT OF THE AMENDED PPC

     A.  Upon the fulfillment of the conditions precedent set forth in Sections
V.A. and V.B. above, the Amended PPC shall be amended as follows:

     1.  Appendix A, Description Of Seller's Generation And Conversion
Facilities, of the Amended PPC is deleted in its entirety and replaced by
Attachment A, which is attached hereto and made a part hereof.

     2.  Appendix B, Facilities Owned By The Seller, of the Amended PPC is
deleted in its entirety and replaced by Attachment B, which is attached hereto
and made a part hereof.

     3.  Appendix C, Interconnection Facilities Owned By The Company, of the
Amended PPC is deleted in its entirety and replaced by Attachment C, which is
attached hereto and made a part hereof.

     4.  Appendix D, Power Purchases By Company, of the Amended PPC is deleted
in its entirety and replaced by Attachment D, which is attached hereto and made
a part hereof.

     5.  Appendix F, Definitions, of the Amended PPC is deleted in its entirety
and replaced by Attachment E, which is attached hereto and made a part hereof.

     6.  Section 15, Force Majeure, of the Amended PPC is deleted in its
entirety and replaced by Attachment F, which is attached hereto and made a part
hereof.

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     B.   Upon the fulfillment of the conditions precedent set forth in Section
V.B. above and the amendment of the Amended PPC as specified in Section VII.A.
above, HELCO shall begin to make Firm Capacity payments pursuant to Paragraph
3(d) of Appendix B and Paragraph B.2. of Appendix D of the Amended PPC as
amended by this Performance Agreement.

VIII.  FORCE MAJEURE

     A.  If either party shall be wholly or partially prevented from performing
any of its obligations under this Performance Agreement by reason of an event of
force majeure reasonably beyond its control and not attributable to its neglect,
then and in any such event, such party shall be excused from whatever
performance is prevented by such event to the extent so prevented, and such
party shall not be liable for any damage or loss resulting therefrom.  Events of
force majeure shall include accidents, lightning, rain, earthquake, wind, wind-
blown water, riots, fire, flood, invasion, insurrection, lava flow or volcanic
activity, tidal wave, civil commotion, the order of any court, judge or civil
authority, war, and any act of God or the public enemy or any other cause beyond
the reasonable control of the party relying on such cause to excuse its
performance hereunder to the extent to which the party cannot remedy the problem
by exercise of due diligence, including, but not limited to, the expenditure of
all reasonable sums of money; provided that inadequate or extreme reservoir
pressures, temperature, or the presence of foreign substances therein shall not
be considered to be an event of force majeure except as provided in Section
VIII.C. below.

         Notwithstanding the foregoing, however, force majeure does not include
any labor dispute, any failure of Seller to obtain and/or maintain any permit or
any full or partial curtailment of the electric output of the Facility that is
caused by or arises from a mechanical or equipment breakdown, even if the
breakdown occurs without the fault or negligence of Seller, unless such
breakdown is caused by any of the specific force majeure events listed above and
could not have been reasonably prevented.

     B.  The party claiming an event of force majeure shall give prompt written
notice of such event to the other party within 30 days of the date such party
claiming force majeure knew or should have known of the event of force majeure.
In addition, such party shall use reasonable diligence, to the extent
practicable, to limit the impact of such event on the performance of its
obligations under this Performance Agreement.  Notwithstanding the foregoing,
this Section VIII.B. shall not excuse any payment obligation that has
theretofore accrued under this Performance Agreement.

     C.  Inadequate or extreme reservoir pressures, temperatures, or the
presence of foreign substances therein,

                                       12
<PAGE>
 
shall not be an event of force majeure unless the Seller has taken reasonable
actions to avoid or mitigate any adverse impact on the Seller's ability to meet
its obligations under this Performance Agreement including the expenditure of
all reasonable sums of money.

     D.  Any obligation of either party under this Performance Agreement shall
be excused only to the extent and for the period that the party's inability to
perform is caused by a force majeure event.  The party so excused shall make all
reasonable efforts including all reasonable expenditures of necessary funds to
cure, mitigate or remedy a force majeure event.  Any payments due as
compensation for the obligation so excused shall also be excused for so long as
the obligation is not performed due to force majeure.

     E.  In the event that the Commercial Operation Date of the additional five
(5) megawatts is delayed because of an event or events of force majeure, the
time periods specified in Sections II.A and II.B shall be extended on a day-for-
day basis to match the duration of the event of force majeure.

     F.  Notwithstanding any other provision of this Performance Agreement, if a
party is prevented from substantially performing its obligations under this
Performance Agreement by an event of force majeure that continues for a period
of twelve (12) consecutive months, the other party may terminate the Performance
Agreement without further liability of either party to the other hereunder.
Such termination shall be effective upon 90 days written notice given any time
after the twelve month period has expired but prior to the resumption of
substantial performance; provided, however, that if substantial performance is
resumed during that 90 day period, such termination shall not be effective.

IX.  MISCELLANEOUS PROVISIONS

     A.  Transmission Line Agreement.  If, upon fulfillment of the conditions
precedent of Section V.B. of this Performance Agreement, Seller is or thereafter
becomes obligated to supply HELCO an amount of Energy equal to the remaining
Transmission Line Obligation (as defined in the Settlement Agreement) pursuant
to Section II.C.5 of the Settlement Agreement, then HELCO and PGV agree that the
remaining Transmission Line Obligation shall be paid by offsetting any amounts
owed by HELCO to PGV for energy payments for Energy provided to HELCO above 25
MW during on-peak periods and above 22 MW during off-peak periods.  Presently,
the remaining Transmission Line Obligation is Two Million Nine Hundred Eighteen
Thousand Seven Hundred And No/100 Dollars ($2,918,700.00).

     B.  Entire Agreement.  Subject to Section VI.G. herein, this Performance
Agreement, the Amended PPC and the Settlement  

                                       13
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Agreement, including any and all attachments, exhibits and related documents
(including, without limitation, the Transmission Line Agreement) constitute the
entire understanding between the parties, supersedes any and all previous
understandings between the parties, and binds and inures to the benefit of the
parties, their successors and assigns. The parties have entered into this
Performance Agreement in reliance upon the representations and mutual
undertakings contained herein and not in reliance upon any oral or written
representation or information provided to one party by any representative of the
other party. No modification, amendment or waiver of all or any part of this
Performance Agreement shall be valid unless it is in writing and signed by both
parties.

     C.  Continuing Effect.  To the extent not amended by this Performance
Agreement, the Amended PPC shall remain in full force and effect.

     D.  Authority.  All action on the part of the parties to authorize the
execution, delivery and performance of this Performance Agreement and the
consummation of the transactions contemplated herein, shall have been duly and
validly taken by each party and that this Performance Agreement constitutes a
valid and binding obligation of each party.

     E.  Further Performance.  Each party hereto shall and does hereby agree to
make, execute, deliver and cooperate with each other, as the case may be, any
and all agreements, instruments, documents, records and/or funds, as the case
may be, whatsoever required, necessary and/or convenient to effect and
consummate this Performance Agreement and to permit performance of all acts
required hereunder.

     F.  Defined Terms.  Capitalized terms not otherwise defined in this
Performance Agreement shall have the meaning ascribed to them in the Amended
PPC.

     G.  Electric Service Supplied By HELCO.  This Performance Agreement and the
Amended PPC do not provide for any electric services by HELCO to Seller.  If
Seller requires any electric services from HELCO, Seller shall receive such
service in accordance with HELCO's tariff.

     H.  Affiliated Interest.  The Seller shall not sell or transfer more than a
10% equity interest to any person or entity, or enter into any other transaction
that would make the Seller an Affiliated Interest with the Company as defined by
Section 269-19.5, Hawaii Revised Statutes, without first notifying the Company
and receiving appropriate PUC approval, if any is required.  If the PUC (or any
other entity which has the authority to do so) finds that the Seller is an
Affiliated Interest with the Company, the Seller shall have 60 days to take
whatever action may be appropriate to render the  

                                       14
<PAGE>
 
relationship not to be an Affiliated Interest. The Company shall have the right
to terminate the Amended PPC, including this Fourth Amendment and any future
amendments, if the PUC prohibits the Company from recovering any payments made
to the Seller under this Amended PPC, as amended herein and from time to time,
due to the effect of Section 269-19.5, Hawaii Revised Statutes, relating to
affiliated interests.

     I.  Qualification Of Seller's Facility.  Seller's Facility will continue to
be throughout the term of this Performance Agreement either (1) a qualifying,
small power production facility under Subchapter 2 of the PUC's Standards for
Small Power Production and Cogeneration in the State of Hawaii, Chapter 74 of
Title 6 of the State's Administrative Rules, or (2) a "non-fossil fuel producer"
within the meaning of Section 269-27.2, Hawaii Revised Statutes.

     J.  Governing Law.  This Performance Agreement shall be subject to,
governed by, construed and enforced in accordance with the laws of the State of
Hawaii, without regard to choice of law principles, and each of the parties
hereto shall and does hereby agree to submit to the personal jurisdiction and
venue of the Circuit Court of the Third Circuit of the State of Hawaii or the
United States District Court for the District of Hawaii, as the case may be.

     K.  Headings.  The headings herein are inserted only for convenience and
reference, and shall in no way define, limit or describe the scope or intent of
any provision of this Performance Agreement.

     L.  No Party Deemed Drafter.  This Performance Agreement reflects the
results of negotiations between the parties hereto and, therefore, no party
shall be deemed to be the drafter of this Performance Agreement.  This
Performance Agreement or any provision hereof shall not be construed or
interpreted by any Circuit or Federal Court or other authority of competent
jurisdiction before which this Performance Agreement is properly presented
against any party as drafter.

      M.  Severability.  If any term or provision of this Performance Agreement
or the application thereof to any person, entity or circumstance shall to any
extent be invalid or unenforceable, the remainder of this Performance Agreement,
or the application of such term or provision to persons, entities or
circumstances other than those as to which it is invalid or unenforceable, shall
not be affected thereby, and each term and provision of this Performance
Agreement shall be valid and enforceable to the fullest extent permitted by law.

     N.  Waiver.  The failure of either party to enforce at any time any of the
provisions of this Performance Agreement, or to require at any time performance
by the other party of any of the provisions hereof, shall in no way be construed
to be a  

                                       15
<PAGE>
 
waiver of such provisions, nor in any way to affect the validity of this
Performance Agreement or any part hereof, or the right of such party thereafter
to enforce every such provision.

     O.  Notice.  Unless otherwise provided, all notices, requests, demands and
other communications hereunder shall be in writing and shall be deemed given if
(1) delivered personally, or (2) by facsimile transmission (followed with a hard
copy by first class mail, postage prepaid), or (3) three (3) Business Days after
being mailed by certified or registered mail, postage prepaid, return receipt
requested, to the parties at the following addresses or at such other addresses
as the parties shall have specified by notice hereunder:

     If to HELCO:

         HAWAII ELECTRIC LIGHT COMPANY, INC.
         1200 Kilauea Avenue
         Hilo, Hawaii  96720-4295
 
         ATTN: President
 
         FAX No.: (808) 969-0100

     If to PGV:

         PUNA GEOTHERMAL VENTURE
         14-3860 Kapoho Pahoa Road
         Pahoa, Hawaii  96778
 
     or
 
         P. O. Box 30
         Pahoa, Hawaii  96778
 
         ATTN: General Manager

         FAX No.: (808) 965-7254

 
     P.  Counterparts/Facsimile Signatures.  This Performance Agreement may be
executed and delivered by the parties hereto in any number of counterparts, each
of which shall be delivered an original or duplicate original, and all of which
together shall constitute one and the same instrument or agreement.
Counterparts may be exchanged by facsimile, which facsimile signatures shall be
effective for all purposes and treated in the same manner as physical
signatures.  Notwithstanding the foregoing, the party using facsimile signatures
agrees that it will promptly forward physically signed copies of this
Performance Agreement to the other party.

                                       16
<PAGE>
 
     IN WITNESS WHEREOF, the Company and the Seller have executed this
Performance Agreement as of the day and year first above written.


     HAWAII ELECTRIC LIGHT COMPANY, INC.
 
 
     By:  /s/ Warren H.W. Lee
 
     Name: Warren H.W. Lee
 
     Title: President
 
 
 
     By:  /s/ Edward Y. Hirata
 
     Name: Edward Y. Hirata
 
     Title: Vice President
 
 
 
     PUNA GEOTHERMAL VENTURE
 
 
     By AMOR VIII CORPORATION,
      a Delaware corporation,
      Its General Partner
 
 
        By:  /s/ J. B. Fahrendorf
 
        Name: J. B. Fahrendorf
 
        Title: President
 
 
     By CE PUNA L.P.,
      a Maryland limited partnership,
      Its General Partner
 
        By CE PUNA I, INC.,
        a Maryland corporation,
        Its General Partner
 
            By:  /s/ John R. Farrell
    
            Name: John R. Farrell
 
            Title: Vice President

                                       17
<PAGE>
 
STATE OF HAWAII               )
                              ) SS.
CITY AND COUNTY OF HONOLUL    )


     On this 8th day of February, 1996, before me personally appeared WARREN
H.W. LEE to me personally known, who, being by me duly sworn, did say that
he/she is the PRESIDENT, of HAWAII ELECTRIC LIGHT COMPANY, INC., a Hawaii
corporation, and that foregoing Performance Agreement was signed on behalf of
HAWAII ELECTRIC LIGHT COMPANY, INC. by authority of its Board of Directors, and
said officers acknowledged said Performance Agreement to be the free act and
deed of HAWAII ELECTRIC LIGHT COMPANY, INC.


                                    /s/ Ann A. Okuno
                                    Notary Public, State of Hawaii

                                    My Commission expires: 3/22/98

<PAGE>
 
STATE OF HAWAII              )
                             ) SS.
CITY AND COUNTY OF HONOLULU  )

     On this 5th day of February, 1996, before me personally appeared Edward Y.
Hirata to me personally known, who, being by me duly sworn, did say that he/she
is the Vice President, of HAWAII ELECTRIC LIGHT COMPANY, INC., a Hawaii
corporation, and that foregoing Performance Agreement was signed on behalf of
HAWAII ELECTRIC LIGHT COMPANY, INC. by authority of its Board of Directors, and
said officers acknowledged said Performance Agreement to be the free act and
deed of HAWAII ELECTRIC LIGHT COMPANY, INC.



/s/ Anita J. Rocker
Notary Public State of Hawaii

My Commission expires: 6-7-97

<PAGE>
 
STATE OF MARYLAND       )
                        ) SS.
COUNTY OF HARTFORD      )


     On this 9th day of February, 1996, before me appeared John R. Farrell, to
me personally known, who, being by me duly sworn, did say that he/she is the
Vice President of CE PUNA I, INC., a Maryland corporation; that said corporation
is a general partner of CE Puna Limited Partnership, a Maryland limited
partnership; that said CE Puna Limited Partnership is a general partner of Puna
Geothermal Venture, a Hawaii general partnership named in the foregoing
Performance Agreement; that said Performance Agreement was executed by said
corporation as the duly authorized general partner of and on behalf of CE Puna
Limited Partnership, as the duly authorized general partner of and on behalf of
Puna Geothermal Venture, and acknowledged that the seal affixed to the foregoing
Performance Agreement is the corporate seal of said corporation, and that said
Performance Agreement was signed and sealed on behalf of said corporation by
authority of its Board of Directors and in the name of and on behalf of CE Puna
Limited Partnership and in the name of and on behalf of Puna Geothermal Venture,
and said officer acknowledged said Performance Agreement to be the free act and
deed of said corporation and as said general partner of CE Puna Limited
Partnership as the general partner of Puna Geothermal Venture.


/s/ Janet R. Cunningham
Notary Public State of Maryland
My Commission expires:  5/1/96 

<PAGE>
 
STATE OF OREGON          )
                         ) SS.
COUNTY OF CLACKAMAS      )


     On this 12th day of FEBRUARY, 1996, before me personally appeared JOSEPH B.
FAHRENDORF to me personally known, who, being by me duly sworn, did say that
he/she is the PRESIDENT of AMOR VIII CORPORATION, a Delaware corporation; that
said corporation is a general partner of Puna Geothermal Venture, a Hawaii
general partnership, named in the foregoing Performance Agreement; that said
Performance Agreement was executed by said corporation as the duly authorized
general partner of and on behalf of Puna Geothermal Venture, and acknowledged
that the seal affixed to the foregoing Performance Agreement is the corporate
seal of said corporation, and that said Performance Agreement was signed and
sealed on behalf of said corporation by authority of its Board of Directors and
in the name of and on behalf of Puna Geothermal Venture, and said officer and
acknowledged said Performance Agreement to be the free act and deed of AMOR VIII
Corporation as general partner of PUNA GEOTHERMAL VENTURE.


/s/ Penny J. Brower
Notary Public State of OREGON

My Commission expires: 10/16/99

<PAGE>
 
                                                           ATTACHMENT A
                                                              TO THE
                                                         FOURTH AMENDMENT


                                  APPENDIX A

          DESCRIPTION OF SELLER'S GENERATION AND CONVERSION FACILITIES

1.    Name of facility:      Puna Geothermal Venture
 
             (a)  Location:  Honuaula, Puna, County of Hawaii, State of Hawaii

             (b)  Telephone number (for system emergencies) System
                  Emergencies:
                     (808) 965-7485
                  Switch Board
                     (808) 965-6233

             (c)  Company billing account number: 06 686 520 01
 
2.    Owner:                Puna Geothermal Venture
 
3.    Operator/1/:          Puna Geothermal Venture
 
4.    Name of person to whom payments are to be made:
 
      (a)      Mailing address:      Puna Geothermal Venture
                                     P. O. Box 30
                                     Pahoa, Hawaii  96778

      (b) Hawaii Gross Excise Tax License Number: 30067799

5.    Equipment:
 
      (a)  Type of facility and conversion equipment: Back pressure steam
           turbines integrated with air-cooled organic rankine cycle Ormat
           Energy Converters.

      (b)  Design capacity:/2/   Total 30 MW

-------------
/1/  Attach a letter signed by an officer of the Seller warranting that the
     Seller is in good standing with the Hawaii Department of Commerce and
     Consumer Affairs. 

/2/  The "Design Capacity" may exceed 30 MW to the extent necessary for Seller
     to furnish up to 30 MW of "Allowed Capacity" as defined in Appendix F,
     provided that the "Allowed Capacity" of this Contract shall be 30 MW.
<PAGE>
 
                                                           ATTACHMENT A
                                                              TO THE
                                                         FOURTH AMENDMENT


     (c)  Single or 3 phase: 3 phase

     (d)  Name of manufacturer: Ormat or equivalent

     (e)  Date of interconnection: December 31, 1989

6.   Projected date of operation in parallel to company's System ("Operational
     Date"):  First 25 MW - July 1, 1990
              Next 5 MW - Nine (9) months
              after the later of PUC
              Approval or Bank's Consent

7.   Date Firm Capacity Begins:     First 25 MW - June 26, 1993
                                    Next 5 MW - Upon the fulfillment of the
                                    conditions precedent set forth in
                                    Sections V.A. and V.B. of the Performance 
                                    Agreement

8.   Insurance carrier:  Attached hereto as Exhibit 1 to Appendix A

9.   If the owner is not the operator, a copy of the agreement between the owner
     and the operator which allows the operator to use the facility and which
     establishes the scope of operations by the operator and the respective
     rights of the owner and the operator with respect to the sale of electric
     energy from the Seller's facility shall be provided to HELCO.

10.  If the land on which the facilities are located is not owned by the
     facility's owner, a copy of the agreement with the owner of the land which
     establishes the right of the facility's owner to put the facility on the
     land and the existence of required rights of way and easements shall be
     provided to HELCO.

                                      2 
<PAGE>
 
                                                           ATTACHMENT A
                                                              TO THE
                                                         FOURTH AMENDMENT



                            Exhibit 1 To Appendix A
                            -----------------------

                                COSI PUNA, INC.
                                       &
                            PUNA GEOTHERMAL VENTURE

                         Addendum to Executive Summary


LIABILITY
---------

1.   Commercial General Liability - Provides protection for those sums you
     become legally obligated to pay as damages because of Bodily Injury or
     Property Damage to a third party, caused by an occurrence, and arising out
     of the insured premises and/or those operations necessary or incidental to
     your business.  Coverage also includes products and completed operations,
     contractual liability, independent contractors coverage, personal and
     advertising injury, fire legal liability and medical payments.

     Named
     Insured:                 Puna Geothermal Venture;
                              COSI Puna, Inc.

     Insurance
     Company:                 Lexington Insurance Company

     Policy
     Number:                  CGL 553 55 81
 
     Limits of
     Liability:               $1,000,000   Each Occurrence
                              $1,000,000   Personal and Advertising Injury
                              $   10,000   Medical Payments per Person
                              $  100,000   Fire Legal Liability
                              $1,000,000   Products/Completed
                                           Operations Aggregate
                              $2,000,000   General Aggregate
 
    Deductible:               $   25,000   each occurrence BI & PD Liability
 
    Policy Term:              March 31, 1995 to March 31, 1996
<PAGE>
 
                                                           ATTACHMENT A
                                                              TO THE
                                                         FOURTH AMENDMENT


                            Exhibit 1 To Appendix A
                            -----------------------



LIABILITY
---------

2.   Business Automobile Liability and Physical Damage - Provides protection for
     those sums you become legally obligated to pay as damages because of Bodily
     Injury or Property Damage to a third party, arising from the ownership,
     maintenance, or use of any owned, hired, or non-owned automobile, as
     outlined in the policy.  Other coverages include uninsured motorists,
     medical payments and physical damage (Comprehensive and Collision for owned
     and hired vehicles).

     Insurance
     Company:          Gulf Insurance Company
 
     Policy
     Number:           BA 543 69 52
 
     Limits of
     Liability:        $1,000,000   Bodily injury
                       $1,000,000   Property Damage
                       $1,000,000   Uninsured Motorists
                       $   20,000   Personal Injury Protection
                       $1,000,000   Hired and Non-Owned Automobile
 
     Deductible:       $    1,000   Comprehensive
                       $    1,000   Collision
 
     Policy Term:      8/1/95 - 8/1/96

     Note:             Schedule of vehicles on file with Company.

                                      2 
<PAGE>
 
                                                           ATTACHMENT A
                                                              TO THE
                                                         FOURTH AMENDMENT


                            Exhibit 1 To Appendix A
                            -----------------------

3.   Workers Compensation and Employers Liability - Provides protection to your
     employees for any injury, death, or disease arising out of and in the
     course of employment, as outlined in the policy.  Benefits are paid
     according to the Workers Compensation Law and Occupational Disease Law of
     each State or Territory.

     Insurance
     Company:                 The Travelers Insurance Company

     Policy
     Number:                  BUB599K4B4294

     Limits of
     Liability:

     Coverage A:              Workers Compensation - Statutory
     Coverage B:              Employers Liability -
                              $1,000,000  B|by Accident
                              $1,000,000  B|by Disease Policy Limit
                              $1,000,000  B|by Disease Each Employee

     Policy Term:             11/22/94 - 11/22/95

                                       3
<PAGE>
 
                                                           ATTACHMENT A
                                                              TO THE
                                                         FOURTH AMENDMENT


                            Exhibit 1 To Appendix A
                            -----------------------



4.   Umbrella Liability - Protects against catastrophic third party liability
     losses by providing excess limits of liability over and above the following
     General Liability, Automobile Liability, and the Employers Liability
     portion of the Worker's Compensation policy.  Coverage is subject to terms,
     conditions and exclusions of the following policy:

     Named
     Insured:           Puna Geothermal Venture;
                        COSI Puna, Inc.

     Insurance
     Company:           Lexington Insurance Company
 
     Policy
     Number:            8667359
 
     Limit of
     Liability:         $25,000,000   Each Occurrence
                        $25,000,000   General Aggregate
 
     Self
     Insured
     Retention:         $25,000
 
     Policy Term:       March 31, 1995 to March 31, 1996

                                       4
<PAGE>
 
                                                           ATTACHMENT A
                                                              TO THE
                                                         FOURTH AMENDMENT


                            Exhibit 1 To Appendix A
                            -----------------------



     Control of Well - Provides protection for cost to gain control of well; the
     expense to redrill and/or restore the well to the condition prior to the
     blowout and cleanup and pollution expenses resulting from a blowout.  A
     separate endorsement extends the policy to cover contractor's equipment
     (not rigs) in the insured's care, custody or control.

     Named
     Insured:          Puna Geothermal Venture;
                       COSI Puna, Inc.
 
     Insurance
     Company:          Underwriter's at Lloyd's London and Certain
                       Insurance Companies (through GSR)
 
     Policy
     Number:           62741
 
     Limits:           $20,000,000   Ea. Occurrence, OEE (100%)
                       $ 1,000,000   Care, Custody & Control (100%)
 
     Deductible:       $    25,000   Each Occurrence, per Section
                                     OEE (100%)
                       $    25,000   Care, Custody & Control (100%)
 
     Policy Term:      March 31, 1995 to March 31, 1996

     Note:             Premium Subject to Audit

                                       5
<PAGE>
 
                                                           ATTACHMENT A
                                                              TO THE
                                                         FOURTH AMENDMENT


                            Exhibit 1 To Appendix A
                            -----------------------

PROPERTY
--------

     Property Damage - Provides repair or replacement cost coverage for damage
     to all real and personal property, including Business Interruption
     resulting from a covered peril.  Provides coverage for fire and extended
     coverages, flood, earthquake, and transit, all subject to policy terms,
     conditions and exclusions.

     Boiler & Machinery - Provides repair or replacement cost coverage,
     including Business Interruption, resulting from sudden and accidental
     damage to objects, or parts thereof, subject to policy exclusions.  Objects
     include, but are not limited to, pressure, mechanical, and electrical
     apparatus, including turbine generators.

     Insurance Company:       Insurance Company of North
                              America (INA)

     Policy Number:           EUTFD835821-7

     Policy Term:             8/1/95 - 8/1/96

     Highlights of Limits:

     Combined Property Damage and Boiler & Machinery including:  Business
     Interruption, Flood, Pollution Cleanup & Removal, Errors & Omissions, and
     Debris Removal

          Combined Unit       $102,916,000 per occurrence

     Sub-Limits applicable to Property Damage:
     -----------------------------------------

          Earthquake                $40,000,000
 
          Accounts Receivable       $ 5,000,000
 
          Valuable Papers           $ 5,000,000
 
          Demolition/Increased
          Cost of Construction      $ 5,000,000
 
          Extra Expense             $ 5,000,000

                                       6
<PAGE>
 
                                                           ATTACHMENT A
                                                              TO THE
                                                         FOURTH AMENDMENT


                            Exhibit 1 To Appendix A
                            -----------------------

          Property in Transit                          $ 5,000,000
 
          Newly Acquired Property                      $ 5,000,000
           (90 days)
 
          Transmission/
          Distribution Lines                           $ 1,500,000
 
     Sub-Limits applicable to Boiler & Machinery:
     --------------------------------------------
 
          Business Interruption                        $13,514,000
 
          Service Interruption                         $ 5,000,000
 
          Extra Expense                                $ 5,000,000
 
          Expediting Expense                           $ 1,000,000
 
          Hazardous Substance                          $ 1,000,000
 
          Ammonia Contamination                        $ 1,000,000
 
          Water Damage                                 $ 1,000,000
 
     Deductibles:
 
          Property Damage                              $    50,000   except
 
          Transmission/
          Distribution Lines                           $   250,000
 
          Named Windstorms                             $   250,000
 
          Earthquake                                   $   100,000   or 2% 
                                                            whichever is greater

          Business Interruption                        30 day waiting period 
                                                       except;

          Service Interruption                         48 hour waiting period

                                       7
<PAGE>
 
                                                                  ATTACHMENT B
                                                                     TO THE
                                                                FOURTH AMENDMENT


                                   APPENDIX B

                         FACILITIES OWNED BY THE SELLER

1.   Seller's Facility

     (a)  A final (1) a single-line diagram of Seller's Facility, (2) relay
          list, and (3) trip scheme shall be prepared and, subject to the review
          and acceptance thereof by both parties, signed and attached hereto as
          Exhibit 1 to Appendix B and made a part hereof. Such single-line
          diagram expressly identifies the final location of the Point of
          Interconnection.

          Material changes or additions to the Seller's Facility reflected in
          the single-line diagram, relay list, and trip scheme shall not be made
          without the prior written consent of the Company pursuant to Section 3
          of the Contract. If any changes in or additions to such Facility,
          records, and operating procedures are required by the Company, the
          Company shall specify such changes to the Seller in writing, and
          except in the case of an emergency, Seller shall have the opportunity
          to review any such change or addition in advance.

     (b)  The Seller shall furnish, install, operate and maintain facilities
          such as breakers, relay, switches, synchronizing equipment, monitoring
          equipment and control and protective devices acceptable to the Company
          as suitable for parallel operation with the Company's System.  Such
          facilities shall be accessible at all times to authorized Company
          personnel.

     (c)  The Seller shall furnish, install and maintain in accordance with the
          Company's requirements all conductors, service switches, fuses, meter
          sockets, meter and instrument transformer housing and mounting,
          switchboard meter test buses, meter panels and similar devices
          required for service connections and meter installations on the
          Seller's premises.

     (d)  Seller shall install transducers, metering, AC and DC sources,
          telephone lines, and provide interconnecting wiring for supervisory
          and communications equipment.

     (e)  The Company has reviewed and accepted the design drawings and Bill of
          Material for the Seller's electrical equipment required to
          interconnect with
<PAGE>
 
                                                                  ATTACHMENT B
                                                                     TO THE
                                                                FOURTH AMENDMENT


          the Company's System.  The type of electrical equipment, the type of
          protective relaying equipment (which equipment shall be mutually
          agreeable to the parties) and the settings that affect the reliability
          and safety of operation of the Company's and Seller's interconnected
          system shall be acceptable to the Company.  The Company, at its
          option, may request to witness operation of control, synchronizing,
          and protection schemes.

     (f)  The Seller shall provide a manual disconnect device which provides a
          visible break to separate the Seller's Facility from the Company's
          System.  Such disconnect device shall be lockable in the OPEN position
          and be readily accessible to Company personnel at all times.

     (g)  In order to allow Seller's Facility to remain on-line and to assist in
          restart of parallel operation thereof with the Company's System,
          Seller may provide automatic equipment to isolate Seller's Facility
          from the Company's System during large system disturbances; provided
          that such automatic equipment has been approved by the Company prior
          to installation for compatibility with Company's System.

2.  Operating Procedures

     (a)  The Company may require periodic reviews of the Seller's Facility,
          maintenance records, available operating procedures and policies, and
          relay settings, and may request changes it deems necessary to protect
          the Company's System from damages resulting from the Seller's parallel
          operation.

     (b)  Logs shall be kept by the Seller for information on unit availability,
          including reasons for planned and forced outages; circuit breaker trip
          operations; relay operations, including target initiation; and other
          unusual events.  The Company shall have the right to review these
          logs, especially in analyzing system disturbances.  The Seller will
          provide the Company with subsequent written confirmation any time the
          Seller experiences a unit trip.  Such confirmation will include the
          date and time of the occurrence as well as the cause of the unit trip.

     (c)  Seller shall limit its Facility's ramp rate to less than 2 MW/min.

     (d)  The Company's Load Dispatcher shall specify the power factor at which
          energy is delivered by the Seller to

                                       2
<PAGE>
 
                                                                  ATTACHMENT B
                                                                     TO THE
                                                                FOURTH AMENDMENT

          the Company.  Typical power factor requirements will normally 
          operate in a range of O.85 lagging to 1.0.

     (e)  If Seller is separated from the Company's System for any reason, the
          Seller, under no circumstances, shall reclose into the Company's
          system without first obtaining specific approval to do so from the
          Company's Load Dispatcher.  Such approval shall be withheld only when
          such reclosing is not in accordance with Section 17(a) of this
          Contract and the Company's standard practices, policies and
          procedures.

     (f)  The Company's Load Dispatcher will notify the Seller whenever the
          Seller must be separated from the Company's System pursuant to
          Sections 6 and 7 of this Contract.  When possible, reasonable advance
          notice will be given to the Seller by the Company's Load Dispatcher,
          provided this provision does not limit the Company's obligation to
          give notice under Section 6(b) of this Contract.

     (g)  The Seller shall submit the next five-year maintenance requirement in
          writing to the Company each year no later than June 30 of the previous
          year.  The Company shall specify the maintenance schedule for the
          five-year period and inform the Seller in writing no later than
          September 30 of the same year.  The Company shall not unreasonably
          delay maintenance of the Seller's Facility and will cooperate with
          Seller in establishing a reasonable schedule for the Seller's
          maintenance requirements.

     (h)  The Seller shall notify the Company's Load Dispatcher prior to
          synchronizing a generator onto or taking a generator off the system.
          Such notification should be as far in advance as reasonably possible
          under the circumstances causing the action.

     (i)  Company Dispatch - The Company shall have the sole and absolute right,
          through supervisory equipment or otherwise, to control, from moment to
          moment, within the limits of sound engineering practices, the rate of
          delivery of energy and capacity subject to a Legally Enforceable
          Obligation to a maximum of the Seller's Firm Capacity Obligation.

3.  Seller's Firm Capacity Obligation

     (a)  Firm Capacity Obligation.  The Seller shall furnish the Company 30,000
          kw of capacity and 18,600 kvar of reactive from the Effective Date of
          the Fourth

                                       3
<PAGE>
 
                                                                  ATTACHMENT B
                                                                     TO THE
                                                                FOURTH AMENDMENT


          Amendment until the end of the contract term pursuant to a Legally
          Enforceable Obligation, under the Company's Dispatch during the entire
          term hereof except for the "annual overhaul period" set forth in
          Paragraph 3(b) of this Appendix B.  The reactive shall be in
          proportion to power in the range of 0.85 lagging to 1.0 unity power
          factor and shall be dispatched by the Company to keep the Seller's
          generator within the limits of plus or minus 5% of the generator
          voltage.

     (b)  Plant Shutdown Period.  The Seller may shut its facility down and
          shall have no obligation to furnish the Company the capacity described
          in Paragraph 3(a) of this Appendix B during the "Annual Overhaul
          Period."  During each contract year the Annual Overhaul Period shall
          not be longer than 28 days and shall be taken during the period
          beginning May 15 and ending September 30, the specific days to be
          determined each contract year with the Company's approval, which
          approval shall not be unreasonably withheld, and shall not be in
          conflict with the schedule established for the Company's other firm
          capacity contracts.

     (c)  Minimum Delivery Guarantee By The Company.  The Company shall accept
          as much of the power made available from the Seller as possible, given
          the limitations resulting from the Company's obligations to purchase
          minimum amounts of firm capacity from other firm capacity sellers, the
          Company's existing obligations to purchase As-Available Energy, the
          Company's need to keep a minimum number of its own generating units
          on-line at least at a reasonable minimum loading, the Company's load
          during certain times of the day and other operating reasons, provided
          that the Company shall accept 25,000 kw during the on-peak hours (7:00
          a.m. to 9:00 p.m.), and 20,000 kw in 1990 and 22,000 kw after 1990
          during the off-peak hours.  The Company shall purchase a minimum of
          178,000,000 kwh each year from the Seller under the Company's Dispatch
          subject to the provisions of Section 6 and 7 of the Contract.  The
          178,000,000 kwh amount shall be reduced by the Energy (kwh) that the
          Seller should have delivered to the Company but could not due to
          reasons other than the Annual Overhaul Period and force majeure.

     (d)  Capacity Payments.  The Company shall pay the Seller for the Firm
          Capacity under Company Dispatch subject to a Legally Enforceable
          Obligation that the Seller is obligated to deliver to the Company
          pursuant to

                                       4
<PAGE>
 
                                                                  ATTACHMENT B
                                                                     TO THE
                                                                FOURTH AMENDMENT


          Paragraph 3 of this Appendix B as provided for by Paragraph B of 
          Appendix D of this Contract.

     (e)  Sanctions for Non-Performance.  The Seller shall pay the sanctions
          provided for by Paragraph D of Appendix D of this Contract if it fails
          to satisfy its firm capacity obligations under this Contract.

4.  Access to Facility

     (a)  Seller hereby grants HELCO the right, but not the obligation, for the
          term of this Contract to enter upon the Facility with such prior
          notice as is reasonable under the circumstances to take such action as
          may be necessary in the reasonable opinion of HELCO (i) to maintain,
          inspect, read and test meters and other HELCO equipment, and (ii) to
          interconnect, interrupt, monitor or measure electrical generation
          produced at Seller's Facility.

     (b)  PGV shall provide in the first month of every year on an annual basis
          throughout the term of this Contract, information and geothermal data
          in substantially the form attached hereto as Exhibit 2 to Appendix B.
          In addition, at HELCO's request, PGV shall meet with HELCO and provide
          such data, information and access to PGV's Facility reasonably
          required to update the December 12, 1995 "Geothermal Resource
          Assessment, Puna Geothermal Venture Expansion, Kilauea East Rift,
          Hawaii" by Gerald Niimi of Therma Source, Inc. and the January 15,
          1996 "Analysis of Fluid Compositions at the Puna Geothermal Venture 30
          mWe Geothermal Facility" by Donald Thomas of G-Tech Services, and/or
          provide a similar analysis to these reports.

                                       5
<PAGE>
 
                                                                  ATTACHMENT B
                                                                     TO THE
                                                                FOURTH AMENDMENT


                            Exhibit 1 To Appendix B



[To Be Attached  -- Attach hereto a copy of a single-line diagram of the
Seller's Facility, relay list, and trip scheme within sixty (60) days of the
Execution Date (as defined in the Performance Agreement) pursuant to the
Performance Agreement.]
<PAGE>
 
                                                                  ATTACHMENT B
                                                                     TO THE
                                                                FOURTH AMENDMENT


                            Exhibit 2 To Appendix B



PUNA GEOTHERMAL VENTURE

KS10 PRODUCTION WELL DATA
<TABLE>
<CAPTION>
                                                  AVERAGE     AVERAGE
                                                 WELLHEAD    WELLHEAD
                HOURS                            PRESSURE      TEMP
 Mo. Total     ON PROD   STEAM   BRINE   TOTAL    (PSIG)      (DEG F)
<S>            <C>       <C>     <C>     <C>     <C>         <C>
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
 
<CAPTION> 
 
KS09 PRODUCTION WELL DATA
 
                                                 AVERAGE     AVERAGE
                                                 WELLHEAD    WELLHEAD
                HOURS                            PRESSURE      TEMP
Mo. Total      ON PROD   STEAM   BRINE   TOTAL    (PSIG)     (DEG F)
<S>            <C>       <C>     <C>     <C>     <C>         <C>
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
</TABLE>
<PAGE>
 
                                                                  ATTACHMENT B
                                                                     TO THE
                                                                FOURTH AMENDMENT

                            Exhibit 2 to Appendix B



PUNA GEOTHERMAL VENTURE

COMBINED INJECTION DATA
QUANTITIES OF FLUID INJECTED (K POUNDS)


<TABLE>
<CAPTION>
 
 
 Mo. Total     GEOFLUID
<S>            <C>
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
</TABLE>

                                       2
<PAGE>
 
                                                                  ATTACHMENT C
                                                                    TO THE
                                                                FOURTH AMENDMENT


                                   APPENDIX C

                Interconnection Facilities Owned By The Company


1.   The Company will design, construct, own, operate and maintain all
     facilities on the Company's side of the Point of Interconnection required
     to interconnect the Company's System with the Seller's Facility at 69 kv,
     including, without limitation, the following equipment at the Seller's
     Facility:

     (a)  Necessary instrument transformers, test facilities (except switchboard
          meter test buses), meters, and protective line relays.

     (b)  Supervisory and communication equipment for remote control and
          metering (a Remote Terminal Unit) at the Seller's Facility.

     (c)  Provided, however, that PGV will construct the permanent switching
          station at the Point of Interconnection.

     (d)  The Seller shall be responsible for the costs to design, permit,
          construct, and install the interconnection facilities owned by the
          Company.

2.   The terms relating to the design, permitting, construction and operation of
     certain Interconnection Facilities, including power transmission lines,
     required to be installed in order to accept Energy from Seller's Facility
     have been determined by separate agreements between the parties.  This
     Contract is subject in all respects to the parties' conclusion of
     satisfactory terms regarding the construction, installation and operation
     of such Interconnection Facilities and the payment therefor.  To the extent
     a portion of such costs is to be paid by Seller, an allocation shall be
     agreed to by the parties that reflects benefits to Buyer's System of
     constructing or upgrading such Interconnection Facilities or portions
     thereof that are not required solely to interconnect Seller's Facility.
     Such cost allocation shall be subject to review and approval by the PUC.

     Presently, the Company and Seller's have entered into a Transmission Line
     Agreement, dated March 7, 1995, which is pending before the PUC for
     approval.  The Transmission Line Agreement is incorporated herein by
     reference.
<PAGE>
 
                                                                  ATTACHMENT C
                                                                    TO THE
                                                                FOURTH AMENDMENT

3.   The Seller shall reimburse the Company for any costs incurred in operating,
     maintaining, replacing, or relocating Company-owned Interconnection
     Facilities to the extent that such costs exceed Company's cost if the
     Seller were not interconnected to the Company's System.

4.   The Company shall maintain full and complete information logs and records
     of (i) all meter readings; (ii) the calculation of amounts due to Seller;
     (iii) the operation and maintenance of the Interconnection Facilities; and
     (iv) information to verify events described in Section 6(a), 6(b), and 7 of
     this Contract, including but not limited to, unit availability (including
     reasons for planned and forced outages), circuit breaker trip operations,
     and relay operations (including target initiation).

5.   The Seller shall be allowed to review the information logs and records
     maintained by the Company pursuant to Section 4 of this Appendix C, above,
     during the Company's normal business hours in accordance with the Company's
     rules for service to its customers.

                                       2
<PAGE>
 
                                                                  ATTACHMENT D
                                                                    TO THE
                                                                FOURTH AMENDMENT


                                   APPENDIX D

                           POWER PURCHASES BY COMPANY
                                  (For 30 MW)


A.  ENERGY PURCHASES BY THE COMPANY

     1.   Subject to the other provisions of this Contract, including but not
          limited to Sections 6 and 7 of this Contract:

          a.   The Company shall accept and pay for the first twenty-five (25)
               megawatts of on-peak Energy and the first twenty-two (22)
               megawatts of off-peak Energy generated by the Seller's Facility
               and delivered by the Seller to the Company at the higher of:  (a)
               the respective on-peak and off-peak energy rates set forth in
               Paragraph A.3.a. of this APPENDIX D, or (b) $0.0656/kilowatthour
               ("kwh") on-peak or $0.0543/kwh off-peak; provided, however, that
               the rate of delivery of such Energy under this Paragraph A.1.a
               shall not exceed twenty-five (25) megawatts on-peak and twenty-
               two (22) megawatts off-peak at any given time.

          b.   The Company shall accept and pay for an additional five (5)
               megawatts of on-peak Energy (above the twenty-five (25) megawatts
               delivered pursuant to Paragraph A.1.a above) generated by the
               Seller's Facility and delivered by the Seller to the Company at
               the higher of:  (a) the on-peak energy rate set forth in
               Paragraph A.3.b. of this APPENDIX D, or (b) the Minimum Purchase
               Rate set forth in Paragraph A.4. of this APPENDIX D; provided,
               however, that the rate of delivery of such Energy under this
               Paragraph A.1.b shall not exceed five (5) megawatts at any given
               time.

          c.   At the Company's sole discretion, the Company may accept and pay
               for any additional on-peak Energy provided above the thirty (30)
               megawatts of on-peak Energy (delivered pursuant to Paragraphs
               A.1.a. and A.1.b. above) at the higher of:  (a) the on-peak
               energy rate set forth in Paragraph A.3.b. of this APPENDIX D, or
               (b) the Minimum Purchase Rate set forth in Paragraph A.4. of this
               APPENDIX D.
<PAGE>
 
                                                                  ATTACHMENT D
                                                                    TO THE
                                                                FOURTH AMENDMENT

          d.   At the Company's sole discretion, the Company may accept and pay
               for any additional off-peak Energy above the twenty-two (22)
               megawatts of off-peak Energy (delivered pursuant to Paragraph
               A.1.a. above) generated by the Seller's Facility and delivered by
               the Seller to the Company at the higher of:  (a) the Energy
               Rate/kwh calculated for on-peak energy set forth in Paragraph
               A.3.b. of this APPENDIX D less $0.01/kwh, or (b) $0.02/kwh.

          e.   The Company agrees that it will not enter into any new contracts
               with independent power producers or amend any existing contracts
               with independent power producers that would obligate the Company
               to take any more off-peak As-Available Energy than the Company is
               presently obligated to take under an existing agreement without
               first agreeing to take an additional 5 megawatts of off-peak
               Energy from Seller.  This provision shall not apply to the
               purchase, either in a new or existing contract with an
               independent power producer, of any additional amount of off-peak
               energy required in such contract because of the reasonable
               minimum operating requirements of an independent power producer.

     2.   Energy furnished by Seller to the Company shall be metered by a time-
          of-day meter that measures Energy delivery on at least one hour
          intervals.  The Company shall not pay for any Energy that may be
          delivered by the Seller prior to installation and operation of the
          Company's meters.  The on-peak hours shall be those between 7:00 a.m.
          and 9:00 p.m. daily, and the off-peak hours shall be those between
          9:00 p.m. on one day and 7:00 a.m. on the following day.

     3.   Energy Rates

          a.   The on-peak energy rate for the first 25 MW of on-peak Energy and
               the off-peak energy rate for the first 22 MW of off-peak Energy
               delivered pursuant to Paragraph A.1.a. above shall be one hundred
               percent (100%) of the Company's respective on-peak and off-peak
               Avoided Energy Costs (including avoided costs of fuel and
               operation and maintenance) in cents per kilowatthour, calculated
               in accordance with the provisions of the PUC's Standards, on file
               with the PUC and in effect for the month in which such Energy is
               delivered.

                                       2
<PAGE>
 
                                                                  ATTACHMENT D
                                                                    TO THE
                                                                FOURTH AMENDMENT

          b.   The on-peak energy rate for the next 5 MW of on-peak Energy
               (above 25 MW) delivered pursuant to Paragraph A.1.b. above shall
               be:

     On-Peak Energy
                    Rate/kwh =   [Fuel Rate (Base Charge) x A] + [Variable O & M
                                  Rate (Base Charge) x (GDPIPD (current)/GDPIPD
                                  (base))]

The terms in the above formula shall have the following meanings as stated:

     Fuel Rate (Base Charge):  $0.038/kwh

A =  Fuel Actual (Diesel)/Fuel Base (Diesel) where:

Fuel Actual (Diesel) is the average of each of the Thursday high and low Pacific
                     Northwest Spot 0.5% No. 2 prices for Diesel Fuel ("PNW No.
                     2 prices"), as reported by Oil Price Information Service
                     ("OPIS") from the 21st day of the second preceding month to
                     the 20th day of the month preceding the month Energy is
                     delivered to HELCO (Computation Month), expressed in
                     dollars per gallon, rounded to the fourth decimal place;
                     and

Fuel Base (Diesel) is the average of each of the Thursday high and low PNW No. 2
                     prices as reported by OPIS from the 21st day of November
                     1995 to the 20th day of December 1995, expressed in dollars
                     per gallon, rounded to the fourth decimal place and which
                     the parties agreed is $0.5444/gallon.

If OPIS is not published or does not publish a high and low price for a
                     particular Thursday during the relevant one month period,
                     the high and low prices for the closest preceding day for
                     which OPIS publishes a price report will be used.

In the event that PNW No. 2 prices are not published by OPIS then the parties
                     agree to use another publication that publishes PNW No. 2
                     prices. In the event that PNW No. 2 prices are not
                     published or otherwise available, the parties agree to
                     adjust the

                                       3
<PAGE>
 
                                                                  ATTACHMENT D
                                                                    TO THE
                                                                FOURTH AMENDMENT


Fuel Rate (Base Charge) by a new index, which, to the extent practicable, shall
                    be applied in the same fashion as the index represented by
                    the term "A" in the above formula.

                    Variable O & M Rate (Base Charge) = $0.0029/kwh

                    GDPIPD (current)  =  the final Gross Domestic Product
                                         Implicit Price Deflator ("GDPIPD")
                                         (there are four categories of GDPIPD --
                                         advance, preliminary, final and revised
                                         final) as published by the United
                                         States Department of Commerce,
                                         Economics and Statistics
                                         Administration, Bureau of Economic
                                         Analysis ("Department of Commerce") for
                                         the third quarter of the calendar year
                                         preceding the calendar year in which
                                         the Energy is delivered.

                   GDPIPD (base)      =  the final GDPIPD as published by the
                                         Department of Commerce for the third
                                         quarter of 1995.

In the event that GDPIPD is not published by Department of Commerce, the parties
               agree to adjust the Variable O & M Rate (Base Charge) by another
               index mutually agreed upon by the parties.

When adjusting the Variable O&M Rate (Base Charge), the adjustment shall apply
               to the energy delivered by Seller to HELCO in the month of the
               adjustment date (January 1) and then invoiced for payment in the
               following month. In other words, the annual adjustment factor
               will be first applied to the energy delivered in January to be
               invoiced in February.

An example of the On-Peak Energy calculation is attached hereto as Exhibit 1 to
               Appendix D.

4.   The Minimum Purchase Rate, as defined in APPENDIX F of this Contract, shall
     apply to the five (5) megawatts of Energy delivered by Seller under

                                       4
<PAGE>
 
                                                                  ATTACHMENT D
                                                                    TO THE
                                                                FOURTH AMENDMENT

          Paragraph A.1.b. above to the Company during the term of this
          Contract.

     5.   During each payment period Seller shall be credited at the rate of
          $0.002 per kilovarhour for each kilovarhour furnished by the Seller to
          the Company in excess of .62 x kwh.  The kvarh meters shall be
          adjusted to prevent reversal in the event the power factor is leading.

     6.   This paragraph intentionally left blank.

     7.   The Seller shall deliver Energy under Company Dispatch pursuant to a
          Legally Enforceable Obligation as follows:

          a.   On-Peak Period.  During the 14 hour period from 7:00 a.m. to 9:00
               p.m. each day, the Seller shall be obligated to deliver Energy
               under the Company's Dispatch at a rate equal to the Seller's Firm
               Capacity Obligation described in Paragraph 3.(a) of APPENDIX B of
               this Contract.

          b.   Off-Peak Period.  During the 10 hour period from midnight to 7:00
               a.m. and 9:00 p.m. to midnight each day, the Seller shall be
               obligated to deliver energy under the Company's Dispatch at a
               rate not greater than the Seller's Firm Capacity Obligation
               described in Paragraph 3.(a) of APPENDIX B of this Contract and
               not less than the Minimum Delivery Guarantee.

B.   CAPACITY PURCHASES BY THE COMPANY

     1.   As compensation for providing the Firm Capacity under Company Dispatch
          as described in Paragraph 3(a) of APPENDIX B, the Company will pay the
          Seller a capacity payment, payable monthly within 20 days after the
          last day of the calendar month in which the firm capacity was
          provided, of 1/12 of the Annual Capacity Payment Rate.

     2.   The Capacity Payment Rate shall be:

          a.   $4,000,000 per year for the first twenty-five (25) megawatts of
               firm capacity under Company Dispatch as described in Paragraph 3
               of APPENDIX B beginning on June 26, 1993; and subject to the
               sanction provision of Paragraph D.1. of APPENDIX D; and

                                       5
<PAGE>
 
                                                                  ATTACHMENT D
                                                                    TO THE
                                                                FOURTH AMENDMENT

          b.   $504,750 per year for the next five (5) megawatts of firm
               capacity under Company Dispatch above the first twenty-five (25)
               megawatts of firm capacity in Subsection B.2.a. as described in
               Paragraph 3 of APPENDIX B beginning on the date of the
               fulfillment of the conditions precedent set forth in Sections
               V.A. and V.B. of the Fourth Amendment; provided that the Seller
               has satisfied the Acceptance Test requirement of Section I.B. of
               the Fourth Amendment; and subject to the sanction provision of
               Paragraph D.1. of APPENDIX D.  If the first year of operation for
               the additional 5 MW of firm capacity is a partial calendar year
               then the amount of the Capacity Payment ($504,750) shall be
               prorated on a daily basis ($1,380 per day) from the date of the
               fulfillment of the conditions precedent set forth in Sections
               V.A. and V.B. of the Fourth Amendment through December 31 of that
               year.

     3.   The Company shall not be required to pay any additional capacity
          payment for any additional power supplied by the Seller, either at the
          Company's or the Seller's request.

     4.   A failure by the Seller to provide the required Firm Capacity to the
          Company shall result in the reduction in the capacity payment due to
          the Seller from the Company in accordance with Paragraph D of APPENDIX
          D of this Contract.  The Company shall not have any obligation to pay
          capacity payments to the Seller for periods in excess of twenty-four
          hours in which the Seller is unable to fulfill its obligations under
          the Contract, including but not limited to (i) circumstances which are
          subject to Paragraph 15 of this Contract relating to Force Majeure
          without fault, or (ii) for periods in which the Seller does not
          fulfill its obligations under Paragraph 3 of APPENDIX B of this
          Contract due to the Seller's "default," as such term is defined in
          APPENDIX E of this Contract.

     5.   If the Seller does not satisfy its firm capacity obligations as
          described in Paragraph 3 of APPENDIX B and Paragraph C of this
          APPENDIX D of this Contract, it shall pay sanctions as described in
          Paragraph D of this APPENDIX D.


                                       6
<PAGE>
 
                                                                  ATTACHMENT D
                                                                    TO THE
                                                                FOURTH AMENDMENT

C.   PERFORMANCE STANDARDS

     1.   The Seller acknowledges and agrees that the Seller's generating
          facility is expected to meet the following minimum standards for
          satisfactory day-to-day performance during each contract year:  (i) an
          On-peak Availability (excluding the four-week annual maintenance
          period and downtime due to a catastrophic equipment failure) of 95
          percent or better; (ii) not more than 6 Plant Trips per year; and
          (iii) a forced outage rate of 5 percent or less.

     2.   The "On-peak Availability" of the Seller's Facility (in percent) is to
          be computed by adding the total on-peak Energy under Company's
          Dispatch subject to a Legally Enforceable Obligation available from
          the Seller's Facility during the contract year, and dividing by the
          product of 4,718 on-peak hours per 48 week year (4,732 for leap years)
          times the Firm Capacity Obligation (prorated on a daily basis, if
          necessary) and multiplying the total by 100 percent.

     3.   "Catastrophic Equipment Failure" means a sudden, unexpected failure of
          a major piece of equipment which (i) substantially reduces or
          eliminates the capability of the Seller's Facility to produce power,
          (ii) is beyond the reasonable control of the Seller and could not have
          been prevented by the exercise of due diligence by the Seller, and
          (iii) despite the exercise of all reasonable efforts, requires more
          than sixty (60) days to repair.

     4.   "Plant Trip" means the sudden and immediate removal of the Seller's
          Facility from service as a result of an immediate
          mechanical/electrical/hydraulic control system trip or operator
          initiated trip/shutdown which requires the Company to take immediate
          steps to place an unscheduled generator on line to make up for the
          loss of output of the Seller's Facility; provided, however, that a
          Plant Trip shall not include:  (i) any such removal which occurs
          within forty-eight (48) hours of the time at which the Seller's
          Facility is restarted following an outage; (ii) trips caused or
          initiated by the Company; or (iii) trips occurring during periods when
          the Seller has continued to furnish capacity to the Company at the
          request of the Company's Production Manager after the Seller has
          notified the Company's Production Manager that the Seller's Facility
          is likely to trip.


                                       7
<PAGE>
 
                                                                  ATTACHMENT D
                                                                    TO THE
                                                                FOURTH AMENDMENT

     5.   The "Forced Outage Rate" of the Seller's Facility during a contract
          year is to be computed by totaling the average megawatts unavailable
          for service due to forced outages or deratings on an hourly basis,
          multiplying the total by 100, and dividing by the product of 8,760
          hours per year times the weighted average of the Seller's firm
          capacity obligation (prorated on a daily basis, if necessary).

D.   SANCTIONS

     1.   The capacity payment is to be made on the basis of the full
          availability of the Seller's Firm Capacity Obligation.  When the
          Seller's full Firm Capacity Obligation is not available, the Seller
          shall pay the Company $0.0214 per on-peak hour for each kilowatt of
          deficiency based on annual capacity payments of $504,750 and 4,718 on-
          peak hours in a year for the first five (5) megawatts of deficiency
          and the Seller shall pay the Company $0.0339 per on-peak hour for each
          kilowatt of deficiency in excess of five (5) megawatts of deficiency
          based on annual capacity payments of $4 million and 4,718 on-peak
          hours in a year.

     2.   For each contract year in which the On-peak Availability of the
          Seller's Facility is less than 95 percent, unless the shortfall is due
          to a catastrophic equipment failure, the Seller shall pay $7,992 to
          the Company for each full percentage point of the shortfall less than
          95 percent to and including 80 percent, and the Seller will pay
          $11,875 to the Company for each full percentage point of the shortfall
          less than 80 percent.

     3.   For each Plant Trip in excess of 6 per contract year, the Seller shall
          pay $10,000 to the Company.

     4.   The Company shall have the right to offset any payment due from the
          Seller under this Paragraph against any payments due to the Seller.

     5.   This paragraph intentionally left blank.

     6.   Each party may exercise whatever legal or equitable remedies may be
          available to enforce the obligations of this Contract in the event of
          a default by the other party.


                                       8
<PAGE>
 
                                                                  ATTACHMENT D
                                                                    TO THE
                                                                FOURTH AMENDMENT

                            Exhibit 1 To Appendix D

                                Illustration of
                          On-Peak Energy Payment Rate
 
On-Peak Energy Payment Rate    = Fuel Component + Variable O&M Component
 
Where:
Fuel Component                 = Fuel Rate (Base Charge) x Fuel Index
 
Variable O&M Component         = Variable O&M Rate (Base Charge) x Variable O&M
                                 Index
Fuel Rate (Base Charge)        = $0.038/kwh
 
Fuel Index                     = PNW (current)/PNW (base)
 
Variable O&M Rate
(Base Charge)                  = $0.0029/kwh
 
Variable O&M Index             = GDP IPD (current)/GDP IPD (base)
 
On-Peak Energy Payment Rate    = [$0.038/kwh x PNW (current)/PNW (base)] +
                                 [$0.0029 x GDP IPD (current)/GDP IPD (base)]

     Where:
     PNW (current)             =  the average of each of the Thursday high and
                                  low Pacific Northwest Spot 0.5% No. 2 prices
                                  for Diesel Fuel ("PNW"), as reported by Oil
                                  Price Information Service ("OPIS") from the
                                  21st day of the second preceding month to the
                                  20th day of the month energy is delivered by
                                  PGV to HELCO, expressed in $/gallon

     PNW (base)                =  $0.5444/gallon, the average of the Thursday
                                  high and low Pacific Northwest Spot 0.5% No. 2
                                  prices for Diesel Fuel, as reported by OPIS
                                  from the 21st day of November 1995 to the 20th
                                  day of December 1995, expressed in $/gallon

     GDP IPD (current)         =  final GDP IPD for the 3rd Quarter of the year
                                  preceding the year that the Variable O&M Index
                                  will be used

     GDP IPD (base)            =  the final GDP IPD for the third quarter of
                                  1995 (Note: 107.9 is the "preliminary"
                                  estimate used only for this illustration - the
                                  "final" shall be used in the actual
                                  calculation)

On-Peak Energy Payment Rate    =  [$0.038/kwh x PNW (current)/$0.5444/gal] +
                                  [$0.0029 x GDP IPD (current)/107.9]
<PAGE>
 
                                                                  ATTACHMENT D
                                                                    TO THE
                                                                FOURTH AMENDMENT

                            Exhibit 1 To Appendix D
<TABLE>
<CAPTION>
                                   OPIS
   PRICE                    PACIFIC NORTHWEST       CUSA/HECO   CUSA/HECO
    FOR                        DIESEL PRICE          WEEKLY      MONTHLY
 MONTH OF       DATE      LOW      HIGH     AVG       PRICE      AVERAGE
<S>           <C>        <C>      <C>      <C>      <C>         <C>
DEC 1995      10/26/95   0.5800   0.5850   0.5825      0.5825
              11/02/95   0.5775   0.5850   0.5813      0.5813
              11/09/95   0.5900   0.5950   0.5925      0.5925
              11/16/95   0.5625   0.5700   0.5663      0.5663      0.5806
 
JAN 1996      11/22/95   0.5550   0.5650   0.5600      0.5600
              11/30/95   0.5400   0.5500   0.5450      0.5450
              12/07/95   0.5350   0.5450   0.5400      0.5400
              12/14/95   0.5300   0.5350   0.5325      0.5235      0.5444
 
</TABLE>


                                       2
<PAGE>
 
                                                                  ATTACHMENT E
                                                                    TO THE
                                                                FOURTH AMENDMENT


                                   APPENDIX F

                                  DEFINITIONS

1.   Allowed Capacity:  The maximum Capacity agreed upon between Company and
Seller that may be delivered to Company at any one time by the Seller, unless
Company requests otherwise, which shall be thirty megawatts (30 MW).

2.   As-Available Energy:  Energy provided to Company on an unscheduled basis as
it becomes available, rather than at prearranged times and in prearranged
amounts, and which is not subject to a Legally Enforceable Obligation.

3.   Avoided Energy Costs:  The energy costs that the Company avoids by
purchasing Energy from Seller, as defined in and calculated in accordance with
the PUC's Standards.

4.   Capacity:  Electric power expressed in kilowatts or megawatts.

5.   Company's Dispatch:  Company's sole and absolute right to control, from
moment to moment, through supervisory equipment, or otherwise, and in accordance
with good engineering practice in the electric utility industry, the rate of
delivery of Energy offered by Seller to Company.

6.   Company's Fuel Adjustment Clause:  The provision in the Company's rate
schedules that allows Company to pass through to its customers the Company's
costs of fuel and purchased power.

7.   Company's System:  The electric system owned and operated by the Company on
the Island of Hawaii consisting of power plants, transmission and distribution
lines, and related equipment for the production and delivery of electric power
to the public.

8.   Company's System Load Dispatcher:  The authorized representative of Company
who is responsible for carrying out Company's Dispatch.

9.   Commercial Operation:  For the first twenty-five (25) megawatts of
Capacity, Commercial Operation is the date (June 26, 1993) on which Seller's
Facility was deemed by Seller to be capable of reliable delivery of firm
capacity.  For the additional five (5) megawatts of capacity delivered under the
Fourth Amendment, Commercial Operation is the date on which Seller's Facility is
deemed by Seller to be capable of reliable delivery of an additional five (5)
megawatts of firm capacity after the successful completion of the 100 hour
Acceptance Test as stated in the Fourth Amendment.

10.  Energy:  Electric power expressed in kilowatthours.
<PAGE>
 
                                                                  ATTACHMENT E
                                                                    TO THE
                                                                FOURTH AMENDMENT

11.  Energy Cost Adjustment Clause:  Same as Company's Fuel Adjustment Clause.

12.  Firm Capacity:  Thirty megawatts (30 MW) of reliable electrical Capacity
and 18,600 kvar of reactive which the Seller has agreed to make available to
HELCO from Seller's Facility at the Point of Interconnection under the Company's
Dispatch.

13.  Firm Capacity Obligation:  Seller's Legally Enforceable Obligation to
provide Firm Capacity as described in Section 3(a) of APPENDIX B of this
Contract.

14.  Fourth Amendment:  That certain PERFORMANCE AGREEMENT AND FOURTH AMENDMENT
TO THE PURCHASE POWER CONTRACT DATED MARCH 24, 1986 AS AMENDED dated February
__, 1996, by and between Hawaii Electric Light Company, Inc. and Puna Geothermal
Venture.

15.  Interconnection Facilities:  The equipment and devices required to permit
Seller's power plant to operate in parallel with and deliver electric power to
Company's System, such as, but not limited to, transmission lines, transformers,
switches, and circuit breakers.

16.  Legally Enforceable Obligation:  A binding commitment to supply Energy or
Capacity at prearranged times and in prearranged amounts under Company's
Dispatch, with sanctions for noncompliance.

17.  Minimum Purchase Rate:  The minimum rate payable by Company to Seller for
on-peak Energy delivered by Seller to Company under this Contract shall be equal
to the on-peak Energy Rate calculated pursuant to Paragraph A.3.b. of APPENDIX D
on the date of PUC Approval (as defined in the Fourth Amendment).

18.  Operational Date:  The date(s) on which the respective generating units of
Seller's Facility are projected for planning purposes to begin parallel
operation with Company's System.

19.  Point of Interconnection:  The point of delivery of Energy and/or Capacity
supplied by Seller to Company where Seller's Facility interconnects with
Company's System.

20.  PUC's Standards:  Standards for Small Power Production and Cogeneration in
the State of Hawaii, issued by the Hawaii Public Utilities Commission, Chapter
74 of Title 6, Hawaii Administrative Rules, currently in effect and as may be
amended from time to time.


                                       2
<PAGE>
 
                                                                  ATTACHMENT E
                                                                    TO THE
                                                                FOURTH AMENDMENT

21.  "Seller's Facility" or the "Facility":  All real estate, fixtures and
property owned, controlled, operated or managed by Seller in connection with, or
to facilitate, the production, generation, transmission, delivery or furnishing
of electricity by Seller to Company and required to interconnect with Company's
System, except Seller's geothermal wellfield, pipelines, and other equipment
located upstream from Seller's power plant.


                                       3
<PAGE>
 
                                                                  ATTACHMENT F
                                                                     TO THE
                                                                FOURTH AMENDMENT


15.  Force Majeure
 
     (a)  If either party shall be wholly or partially prevented from performing
          any of its obligations under this Contract by reason of an event of
          force majeure reasonably beyond its exclusive control and not
          attributable to its neglect, then and in any such event, such party
          shall be excused from whatever performance is prevented by such event
          to the extent so prevented, and such party shall not be liable for any
          damage or loss resulting therefrom.  Events of force majeure shall
          include but not be limited to the following:  accidents, action or
          inaction of any governmental agency (including the inability to obtain
          permits or authorization), lightning, rain, earthquake, wind, wind-
          blown water, riots, fire, flood, invasion, insurrection, lava flow or
          volcanic activity, tidal wave, civil commotion, the order of any
          court, judge or civil authority, war, and any act of God or the public
          enemy; provided that inadequate or extreme reservoir pressures,
          temperature, or the presence of foreign substances therein shall not
          be considered to be an event of force majeure except as provided in
          Subsection (c) of this paragraph.

     (b)  The party claiming an event of force majeure shall give prompt written
          notice of such event to the other party within 30 days of the date
          such party claiming force majeure knew or should have known of the
          event of force majeure.  In addition, such party shall use reasonable
          diligence, to the extent practicable, to limit the impact of such
          event on the performance of its obligations under this Contract.
          Notwithstanding the foregoing, this Subsection 15(b) shall not excuse
          any payment obligation that has theretofore accrued under this
          Contract.

     (c)  Inadequate or extreme reservoir pressures, temperatures, or the
          presence of foreign substances therein, shall not be an event of force
          majeure unless the Seller has taken reasonable actions to avoid or
          mitigate any adverse impact on the Seller's ability to meet its
          obligations under this Contract.
<PAGE>
 
                                                                EXHIBIT A
                                                                  TO THE
                                                           PERFORMANCE AGREEMENT


                          DESCRIPTION OF ENHANCEMENTS



The enhancements will increase the site electrical generating output by
increasing the flow to the three existing injection wells.  This will be
accomplished mainly by the installation of three injection pumps ("injection
pumps").  These injection pumps will increase injection pressure, thus
increasing system flow and electric generation output.  In addition, it is
contemplated that condensate flows will be redirected from 4" and 6" lines
currently in use to an existing 14" line.  This change is intended to enhance
process efficiency.
<PAGE>
 
                                                                EXHIBIT B
                                                                  TO THE
                                                           PERFORMANCE AGREEMENT


                                PROJECT SCHEDULE



The timetable for completion of the project activities are expressed in weeks
from the date of the later of PUC Approval or Bank's Consent of the Performance
Agreement.  The first number is the week in which the activity is expected to
begin and the second number is the week in which the activity is expected to be
completed.

Description of Activity                Timetable
 
Engineering                            Week 0 to Week 12
 
Procurement                            Week 0 to Week 21
 
Installation                           Week 10 to Week 26
 
Power Output                           Week 26

Major Milestone

     PGV expects to have its injection pumps on site no later than 23 weeks
after the later of PUC Approval or Bank's Consent of the Performance Agreement.
<PAGE>
 
                                                                EXHIBIT C
                                                                  TO THE
                                                           PERFORMANCE AGREEMENT



                              _____________, 1996



Hawaii Electric Light
 Company, Inc.
1200 Kilauea Avenue
Hilo, Hawaii  96720-4295

        RE:  Consent To Performance Agreement

Gentlemen:

          We refer to that certain Performance Agreement And Fourth Amendment To
The Purchase Power Contract Dated March 24, 1986 as Amended ("Performance
Agreement"), dated as of __________________, 1996, by and between Hawaii
Electric Light Company, Inc. ("HELCO"), incorporated under the laws of the
Republic of Hawaii, and Puna Geothermal Venture ("PGV"), a Hawaii general
partnership.  Capitalized terms used herein and not otherwise defined shall have
the meaning set forth in the Performance Agreement and, if none, then as set
forth in the Confirmation Agreement (as defined below).

          CREDIT SUISSE, a bank organized and existing under the laws of
Switzerland, as Agent and Collateral Agent for the benefit of its own account
and such other financial institutions as may participate in the funding and
other risks associated with the Loan as defined below (hereinafter collectively
referred to as "Credit Suisse"), the Lenders (as defined in the Confirmation
Agreement) and PGV have entered into (i) a Credit Agreement-Construction Loan
and Term Loan Facility, and (ii) an Assignment and Security Agreement
("Assignment"), pursuant to which Credit Suisse has agreed to make a loan
("Loan") to PGV for the purpose of constructing the PGV facility.

          Pursuant to the Assignment, PGV has granted to Credit Suisse a
security interest in the HELCO-PGV Agreements, for the benefit of the Lenders,
as security for the payment of all sums to become due and payable to Credit
Suisse and the Lenders.
<PAGE>
 
                                                                EXHIBIT C
                                                                  TO THE
                                                           PERFORMANCE AGREEMENT

Hawaii Electric Light
 Company, Inc.
Page 2



          The Assignment requires PGV to obtain Credit Suisse's written consent
prior to amending, canceling or terminating the HELCO-PGV Agreements.  Pursuant
to the Confirmation of Purchase Power Contract and Agreement ("Confirmation
Agreement"), dated June 29, 1990, by and between HELCO, PGV and Credit Suisse,
HELCO is also required to obtain the written consent of Credit Suisse prior to
amending, canceling or terminating the HELCO-PGV Agreements.

          Under the Performance Agreement, PGV has agreed to provide, and HELCO
has agreed to accept and pay for, an additional five (5) megawatts of firm
capacity.  In order to provide the additional firm capacity, the Performance
Agreement requires amending certain of the HELCO-PGV Agreements, which in turn,
requires the consent of Credit Suisse and Banque Nationale de Paris, a bank
organized and existing under the laws of the Republic of France ("BNP").

Consent

          Credit Suisse and BNP have each reviewed the Performance Agreement and
each hereby consent to PGV's and HELCO's execution of the Performance Agreement
and the performance of the terms, conditions and obligations of the parties
thereunder.

          This Consent shall be subject to, governed by, construed and enforced
in accordance with the laws of the State of Hawaii, without regard to principles
of choice of law.

          The individuals executing this Consent represent and warrant that they
are duly authorized to do so on behalf of Credit Suisse and BNP, as the case
maybe, and that this Consent, once executed, shall be fully binding upon Credit
Suisse and BNP, as the case maybe, and their respective
<PAGE>
 
                                                                EXHIBIT C
                                                                  TO THE
                                                           PERFORMANCE AGREEMENT


Hawaii Electric Light
 Company, Inc.
Page 3



successors, agents, representatives, administrators, trustees and assigns.


Consented to and agreed
to as the date first
above written:


CREDIT SUISSE

     By:                     ___________________________

     Name:                   ___________________________

     Title:                  ___________________________



     By                      ___________________________

     Name:                   ___________________________

     Title:                  ___________________________



BANQUE NATIONALE de PARIS


     By:                     ___________________________

     Name:                   ___________________________

     Title:                  ___________________________


     By:                     ___________________________

     Name:                   ___________________________

     Title:                  ___________________________
<PAGE>
 
                                                                EXHIBIT C
                                                                  TO THE
                                                           PERFORMANCE AGREEMENT


STATE OF ____________        )
                             )  SS.
COUNTY OF ___________        )


               On this ______ day of _______________, 199___, before me appeared
     ______________________________ and ______________________________, to me
     personally known, who, being by me duly sworn, did say that they are
     ______________________________ and ______________________________,
     respectively, of CREDIT SUISSE, a bank organized and existing under the
     laws of Switzerland, as Agent and Collateral Agent; that the seal affixed
     to the foregoing instrument is the corporate seal of said bank; that said
     instrument was signed and sealed in behalf of said corporation by authority
     of its Board of Directors; and said ______________________________ and
     ______________________________ acknowledged said instrument to be the free
     act and deed of said bank.



     ___________________________________
     Notary Public, State of ___________

     My Commission expires: ____________
<PAGE>
 
                                                                EXHIBIT C
                                                                  TO THE
                                                           PERFORMANCE AGREEMENT



STATE OF ____________        )
                             )  SS.
COUNTY OF ___________        )


          On this ______ day of _______________, 199___, before me appeared
______________________________ and ______________________________, to me
personally known, who, being by me duly sworn, did say that they are
______________________________ and ______________________________, respectively,
of BANQUE NATIONALE de PARIS, a bank organized and existing under the laws of
the Republic of France; that the seal affixed to the foregoing instrument is the
corporate seal of said bank; that said instrument was signed and sealed in
behalf of said corporation by authority of its Board of Directors; and said
______________________________ and ______________________________ acknowledged
said instrument to be the free act and deed of said bank.



___________________________________
Notary Public, State of ___________

My Commission expires: ____________