Exhibit
10.13.2

EXECUTION COPY

FIRST SUPPLEMENTAL
INDENTURE

FIRST SUPPLEMENTAL INDENTURE (this
‘‘Supplemental Indenture’’) dated as of
June  14,  2006, among Orcal Geothermal Inc., a Delaware
corporation (the ‘‘Issuer’’), and Union Bank of
California, N.A., as trustee (the ‘‘Trustee’’)
and as collateral agent (the ‘‘Collateral
Agent’’), in each case, under the lndenture referred to
below.

W I T N E S S E T H

WHEREAS, the Issuer and the
guarantors named therein have heretofore executed and delivered to the
Trustee an indenture (the ‘‘Indenture’’) and a
First Series Supplemental Indenture (the ‘‘First Series
Supplemental Indenture’’), each dated as of December
8,  2005, and together providing for the issuance of $165,000,000
in aggregate principal amount of 6.21% Senior Secured Notes due
2020 (the ‘‘Initial Notes’’);

WHEREAS,
the Indenture provides that under certain circumstances the Indenture
may be supplemented or amended by the Issuer, the Trustee and the
Collateral Agent; and

WHEREAS, pursuant to Article VllI of the
Indenture, the Trustee is authorized to execute and deliver this
Supplemental Indenture.

NOW, THEREFORE, in consideration of the
foregoing and for other good and valuable consideration, the receipt of
which is hereby acknowledged, the parties hereto mutually covenant and
agree for the equal and ratable benefit of the Holders of the Initial
Notes as follows:

1.    CAPITALIZED TERMS.    Capitalized
terms used herein without definition shall have the meaning assigned to
them in the Indenture.

2.    AMENDMENT.    The parties hereby
agree to amend Section 2.04 of the Indenture by deleting Section 2.O4
and replacing it in its entirety with the following new
provision:

‘‘Section 2.04
Denominations.    The Senior Secured Notes shall be issuable
only in registered form without coupons and in denominations of $1,000
and any integral multiple of $1,000 in excess thereof. Any repayments
(either scheduled or pursuant to any redemption) of any Senior Secured
Note shall be made only in the denomination or integral multiple
thereof set forth above. Notwithstanding the foregoing, any repayments
(either scheduled or pursuant to any redemption) and any transfers or
exchanges of any Initial Note shall be made in a denomination rounded
to the nearest $0.01.’’









3.    REFERENCES TO AND EFFECT ON
INDENTURE.    (a) On and after the execution of this Supplemental
Indenture, each reference in the Indenture to ‘‘this
Indenture,’’ ‘‘hereunder,’’
‘‘hereof’’ or words of like import referring to
the Indenture, shall mean and be a reference to the Indenture, as
amended by this Supplemental Indenture.

(b)    The Indenture,
as specifically amended by this Supplemental Indenture, is and shall
continue to be in full force and effect and is hereby in all respects
ratified and confirmed.

4.    EFFECTIVENESS.    This
Supplemental Indenture shall be effective upon execution hereof by the
Issuer, the Trustee and the Collateral Agent.

5.    BENEFITS OF
THIS SUPPLEMENTAL INDENTURE.    Nothing in this Supplemental
Indenture, express or implied, shall give to any person, other than the
parties to the Indenture and their respective successors thereunder and
the Holders of the Notes, any benefit or any legal or equitable right,
remedy or claim under this Supplemental
Indenture.

6.    GOVERNING LAW.    THE INTERNAL LAW OF THE
STATE OF NEW YORK SHALL GOVERN AND BE USED TO CONSTRUE THIS
SUPPLEMENTAL INDENTURE WITHOUT GIVING EFFECT TO APPLICABLE PRINCIPLES
OF CONFLICTS OF LAW TO THE EXTENT THAT THE APPLICATION OF THE LAWS OF
ANOTHER JURISDICTION WOULD BE REQUIRED
THEREBY.

7.    COUNTERPARTS.    The parties may sign any
number of copies of this Supplemental Indenture. Each signed copy shall
be an original, but all of them together represent the same
agreement.

8.    EFFECT OF HEADINGS.    The Section
headings herein are for convenience only and shall not affect the
construction hereof.

9.    THE TRUSTEE.    The Trustee shall
not be responsible in any manner whatsoever for or in respect of the
validity or sufficiency of this Supplemental Indenture or for or in
respect of the recitals contained herein, all of which recitals are
made solely by the Issuer.









IN WITNESS WHEREOF, the parties hereto have
caused this Supplemental Indenture to be duly executed and attested,
all as of the date first above written.

Dated: June 14, 2006






							
	 			ORCAL
GEOTHERMAL
INC.
	 			 			 
	 			By:			/s/
Yehudit
Bronicki   
	 			 			Name:
	 			 			Title:
	 			UNION BANK OF
CALIFORNIA, N.A., as
Trustee
	 			 			 
	 			By:			 /s/
JAMES
MYERS
	 			 			Name:   JAMES
MYERS
	 			 			Title:     VICE
PRESIDENT
	 			UNION BANK OF
CALIFORNIA, N.A., as Collateral
Agent
	 			 			 
	 			By:			 /s/
JAMES
MYERS
	 			 			Name:   JAMES
MYERS
	 			 			Title:     VICE
PRESIDENT
	






[Signature Page to First
Supplemental Indenture]