EXHIBIT 10.8

MEMBERSHIP INTEREST REDEMPTION
SUBORDINATED PROMISSORY NOTE

Up to $24,500,000    December 4, 2009      New York, New York 

     FOR VALUE RECEIVED, and subject to and effective upon the occurrence of the
Redemption Date (as defined in the Redemption Agreement), THERMO NO. 1 BE-01,
LLC, a Delaware limited liability company (the "Company"), hereby promises to
pay to MERRILL LYNCH, PIERCE, FENNER & SMITH INCORPORATED, a Delaware
corporation (the "MLP"), the principal sum of Twenty Four Million Five Hundred
Thousand Dollars ($24,500,000) (or such lesser amount as shall constitute
Redemption Consideration under the Redemption Agreement), in lawful money of the
United States of America and in immediately available funds, on the dates and in
the principal amounts provided herein.

     This Note is the Redemption Note referenced in that certain Membership
Interest Redemption Agreement dated as of December 4, 2009 by and among the
Company, Raser, IRP and MLP (as amended, supplemented or otherwise modified in
accordance with the terms thereof and in effect from time to time, the
"Redemption Agreement"), evidences Redemption Consideration paid by the Company
to MLP under the Redemption Agreement, and is expressly made subject to and
effective upon the occurrence of the Redemption Date (as defined in the
Redemption Agreement). Capitalized terms used but not defined in this Note have
the respective meanings assigned to them in the Redemption Agreement.

     The payment hereunder will be due and payable on the Guaranteed Final
Completion Date, but in no event prior to (i) the payment of the Buy-Down CA
Redemption Amount plus expenses of the Lenders, and (ii) when and as otherwise
permitted under Section 3.9.3.2.6 of the Account and Security Agreement, as
amended. This Note and the obligations of the Company evidenced hereby shall
terminate, whether or not full payment of amounts due hereunder is made, as
provided in Section 2.2.2 of the Redemption Agreement.

No amounts hereunder may be prepaid. This Note shall not bear interest.

For purposes of this Note, the following terms shall have the following
meanings:

“Senior Credit Agreement” means that certain Credit Agreement, dated as of
August 31, 2008, among the Company, the Lenders and the Administrative Lender
(as such terms are defined in Schedule Z to the thereto (“Schedule Z”)) party
thereto and Deutsche Bank Trust Company Americas, as Administrative Agent and
Collateral Agent, as the same may hereafter be amended, restated, supplemented
or otherwise modified from time to time.

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“Senior Credit Documents” means collectively the Senior Credit Agreement and the
other Financing Documents (as defined in Schedule Z), each as from time to time
in effect, together with any amendments, supplements, modifications,
replacements or refinancings thereof.

“Senior Debt” means and includes all obligations (whether now outstanding or
hereafter incurred), for the payment of which the Company is responsible or
liable as obligor, guarantor or otherwise in respect of all obligations of the
Company under the Senior Credit Agreement, the Advances (as defined in Schedule
Z) and the Notes (as defined in Schedule Z) in respect of principal, interest,
Make-Whole Amount (as defined in Schedule Z), fees, indemnities and expenses,
whether now owing or hereafter incurred (including any interest accruing
subsequent to the commencement of an Insolvency Proceeding (as defined below)
whether or not the claims of holders of such payment obligations for such
interest are allowed in any such proceeding).

“Senior Debt Default” means any Credit Agreement Default or Credit Agreement
Event of Default (each as defined in Schedule Z).

“Subordinated Debt” means and includes all obligations (whether now outstanding
or hereafter incurred), for the payment of which the Company is responsible or
liable as obligor, guarantor or otherwise in respect of all obligations of the
Company under the Redemption Agreement, this Note or any Transaction Document
(as defined in Schedule Z), whether now owing or hereafter incurred.

     Anything in this Note to the contrary notwithstanding, all amounts owing to
the holder of this Note pursuant to the provisions herein are subordinated and
junior to all Senior Debt to the extent set forth herein as follows:

(i)      In the event of any insolvency, bankruptcy, liquidation, reorganization
or other similar proceedings, or any receivership proceedings in connection
therewith, relative to the Company (an “Insolvency Proceeding”), and in the
event of any proceedings for voluntary liquidation, dissolution or other winding
up of the Company, whether or not involving insolvency or bankruptcy
proceedings, then all Senior Debt shall first be paid in full in cash before the
payment of any Subordinated Debt in any such proceeding.   (ii)      In any
proceeding described in subsection (i), above, any payment which may be payable
or deliverable in respect of this Note shall be paid or delivered directly to
the holders of Senior Debt (or to a banking institution selected by the court or
person making the payment or delivery or designated by any holder of Senior
Debt), unless and until all of the Senior Debt shall have been paid in full in
cash.   (iii)      The holder of this Note, to the extent such holder is
otherwise entitled to do so, will not pursue any remedy to enforce payment
during the period commencing at the initial time when such holder is not
permitted to receive any payment with respect to this Note (a “Note Payment”)
continuing until the earliest of (i) the date on which such Note Payment is
permitted by the applicable provisions of the  

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  Account and Security Agreement, (ii) the date of the repayment in full in cash
of all of the Senior Debt, or (iii) the date upon which any Insolvency
Proceeding is commenced.   (iv)      If any payment shall be received by the
holder of this Note in contravention of any of the terms of subsections (i)
through (iii) above, such payment shall be received in trust for the benefit of
the holders of the Senior Debt and shall forthwith be paid over or delivered and
transferred to the holders of Senior Debt.  

     The provisions contained herein may not be amended in any respect without
the consent of all holders of the Senior Debt and shall be deemed a continuing
offer to all holders of the Senor Debt to act in reliance on such provisions
(but no such reliance shall be required to be proven to receive the benefits
hereof) and may be enforced by such holders, and no right of any present or
future holder of the Senior Debt to enforce subordination as provided herein
shall be prejudiced or impaired by any act or failure to act on the part of the
Company or by any act or failure to act by any such holder, or by any
non-compliance by the Company with the terms and provisions of this Note or the
terms, provisions and covenants of the Senior Credit Documents.

     The Company hereby waives notice of presentment, demand, protest or notice
of any other kind hereunder.

     THIS NOTE SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAW
OF THE STATE OF NEW YORK APPLICABLE TO CONTRACTS MADE AND TO BE PERFORMED WITHIN
THE STATE OF NEW YORK.

THERMO NO. 1 BE-01, LLC,
a Delaware limited liability company

By:    Intermountain Renewable Power, LLC  Its:    Managing Member        By:   
/s/ Richard D. Clayton      Name:    Richard D. Clayton      Title:    Manager 

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