Exhibit
4.31
 HAZARDOUS SUBSTANCES
INDEMNITY AGREEMENT
  This
HAZARDOUS SUBSTANCES INDEMNITY AGREEMENT (the "Agreement") is made as of July
16, 2008, by VALCENT PRODUCTS
INC. a corporation organized under the laws of Alberta, Canada
("Valcent"), VALCENT USA
INC., a Nevada corporation, VALCENT MANUFACTURING,LTD., a Texas limited
partnership, VALCENT MANAGEMENTLLC, a Nevada
limited liability company, VERTIGRO ALGAE TECHNOLOGIES
LLC, a Texas limited liability company, and VALCENT PRODUCTS EU LIMITED, a
corporation organized under the laws of the United Kingdom, each with an address
Valcent Products Inc., Suite 1010 - 789 West Pender Street, Vancouver, British
Columbia, Canada V6C 1112 (jointly and severally, the "Borrower"), for the
benefit of  PLATINUM
LONG TERM GROWTH VI,
LLC, having a place of business at 152 West 57th Street, 54th Floor,
New York, New York 10019 and the other Purchasers identified in the Purchase
Agreement identified and defined below (collectively, the
"Lenders").
 
 RECITALS
 
 WHEREAS,Valcent and the
Lenders are parties to a certain Note and Warrant Purchase Agreement dated, as
of July 16, 2008 (as the same may be amended, modified, restated or consolidated
from time to time, the "Purchase Agreement"), which provides for the issuance by
Valcent of the Securities defined therein, including the Notes (as defined in
the Purchase Agreement);
 
 WHEREAS,the Notes will be
secured by, among other things, (i) one or more deeds of trust and collateral
assignments of the Borrower's interest in the real property described on Exhibit
A hereto (all such real property is collectively referred to as the "Property");
and (ii) a Security Agreement evidenced by UCC-1 Financing Statements covering
all assets of Borrower ((i) and (ii) together, the "Security
Documents");
 
 WHEREAS,the Lenders have
required, as a condition to purchasing the Notes, that Borrower indemnify and
hold the Lenders harmless against and from certain obligations for which Lenders
may incur liability, whether as beneficiary ofany leasehold mortgage, or
mortgagee in possession, or successor-in-interest to Borrower by foreclosure or
deed in lieu offoreclosure, by reason of the threat or presence of any Hazardous
Substance (as defined below) at or near the Property; and
 
 WHEREAS,Borrower is willing
to indemnify Lenders with respect to certain events involving Hazardous
Substances at or near the Property.
 
 NOW, THEREFORE,in
consideration of the foregoing premises, the loan evidenced by the Purchase
Agreement, and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Borrower and Lenders, intending to
be legally bound, hereby agrees as follows:
 
 1.            Recitals. The
foregoing recitals are incorporated into this Agreement by this
reference.
 
 2.            Covenants.
 
 (a)
Borrower covenants and agrees with Lenders that it shall not cause, permit to
occur or permit to exist any deposit, storage, disposal, burial, discharge,
spillage, uncontrolled loss, seepage or filtration of oil, petroleum or any
hazardous wastes, hazardous substances, infectious wastes or asbestos
(collectively, "Hazardous Substances"), as those terms are used in the
Comprehensive Environmental Response, Compensation and Liability Act of 1980, 42
U.S.C. § 9061 et seq., Hazardous
Materials Transportation Act, 49 U.S.C § 1802, or The Resource Conservation and
Recovery Act, 42 U.S.C. § 6901 et seq., or in any other
federal, state or local law governing hazardous substances or infectious wastes,
as such laws may be amended from time to time (collectively, the "Hazardous
Waste Laws"), at, upon, under or within the Property, except for the storage or
use, in compliance with Hazardous Waste Laws, of Hazardous Substances (i)
commonly used in the customary and normal maintenance and operation of
commercial buildings, (ii) used in the ordinary course of the Borrower's
manufacturing operations at the Property or (iii) as disclosed in writing to the
Lenders prior to the date hereof.
  (b)  Borrower
further covenants and agrees with Lenders that: (i) neither Borrower nor any
other person will be involved in operations at the Property, which operations
will create (A) the imposition of liability under the Hazardous Waste Laws on
Borrower, or on any subsequent owner of the Property, or (B) the creation of a
lien on the Property under the Hazardous Waste Laws or under any similar laws or
regulations; and (ii) Borrower will not permit any tenant or occupant of the
Property to engage in any activity that is likely to impose liability under the
Hazardous Waste Laws on such tenant or occupant, on Borrower or on any other
subsequent owner of any of the Property.
 
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  (c) Borrower
shall comply with the requirements of the Hazardous Waste Laws and related
regulations and shall notify Lenders immediately upon becoming aware of any
discharge or discovery of any Hazardous Substance at, upon, under or within the
Property. Borrower shall promptly forward to Lenders copies of all orders,
notices, permits, applications or other communications and reports received by
Borrower in connection with any discharge or the presence of any Hazardous
Substance or any other matters relating to the Hazardous Waste Laws or any
similar laws or regulations, as they may affect the Property.
 
 (d)  If
at any time Lenders reasonably believe in good faith that a discharge of
Hazardous Substances may have occurred, or that Hazardous Substances may be
present in breach of Section 2(a) hereof, promptly upon the request of Lenders,
the Borrower shall provide Lenders, at Borrower's expense, with an environmental
site assessment or environmental audit report prepared by an environmental
engineering firm reasonably acceptable to Lenders and the Borrower, to assess
with a reasonable degree of certainty the presence or absence of any Hazardous
Substances and the potential costs in connection with abatement, cleanup or
removal of any Hazardous Substances found on, under, at or within the
Property.
 
 3.            Indemnity.
 
 (a)
Borrower shall at all times indemnify and hold harmless Lenders against and from
any and all claims, suits, actions, debts, damages, costs, losses, obligations,
judgments, charges, and expenses, of any nature whatsoever suffered or incurred
by Lenders, whether as assignee of a leasehold estate, as mortgagee in
possession, or as successor-in-interest to Borrower by foreclosure deed or deed
in lieu of foreclosure, under or on account of the Hazardous Waste Laws,
including the assertion of any lien thereunder, with respect to the Property
which involve any one or more of the following events or
circumstances:
 
 (i)              any
discharge of Hazardous Substances, the threat of a discharge of any Hazardous
Substances, or the presence of any Hazardous Substances affecting the Property
in breach of Borrower's covenants in Section 2 hereof, including any loss of
value of the Property as a result of any of the foregoing.
  (ii)           any
costs of removal or remedial action incurred by the United States Government or
any state or local governmental authority, any response costs incurred by any
other person or damages from injury to, destruction of, or loss of natural
resources, including reasonable costs of assessing such injury, destruction or
loss, incurred pursuant to any Hazardous Waste Laws.
 
 (iii)           liability
for personal injury or property damage arising under any statutory or common law
tort theory, including, without limitation, damages assessed for the maintenance
of a public or private nuisance or for the carrying on of an abnormally
dangerous activity at the Property.
 
 (iv)           any
other event or circumstance involving Hazardous Substance affecting the Property
within the jurisdiction of the Environmental Protection Agency or any state or
local environmental agency.
 
 Borrower's
obligations under this Agreement shall arise upon the discovery of the presence
of any Hazardous Substance, whether or not the Environmental Protection Agency,
or any other federal agency or any state or local environmental agency has taken
or threatened any action in connection with the presence of any Hazardous
Substances; provided, however, that Borrower's obligations under this Agreement
shall not arise with respect to Hazardous Substances released on or under the
Property subsequent to a foreclosure or acceptance of a deed in lieu of
foreclosure by Lenders.
 
 (b) In
the event of any discharge of Hazardous Substances in violation of Hazardous
Waste Laws, the threat of a discharge of any Hazardous Substances, or the
presence of any Hazardous Substance affecting the Property in violation of
Hazardous Waste Laws, in breach of Borrowers covenants in Section 2 hereof,
and/or if any indemnitor shall fail to comply with any of the requirements of
the Hazardous Waste Laws or related regulations or any other environmental law
or regulation, Lenders may at their election, but without the obligation so to
do, give such notices and, after the expiration of thirty (30) days' notice to
Borrower thereof (unless Borrower commences to cure such condition within thirty
(30) days after such notice is sent to it or within such additional time (not
exceeding sixty (60) days) as shall be reasonably necessary to cure such
conditions, provided Borrower continues to diligently pursue such cure during
such additional time period), cause such work to be performed at the Property
and/or take any and all other actions as Lenders shall reasonably deem necessary
or advisable in order to abate the discharge of any Hazardous Substance and to
bring the Property into compliance with the Hazardous Waste Laws.
  
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  (c) Borrower
acknowledges that Lenders have agreed to make the loan evidenced by the Purchase
Agreement in reliance upon Borrower's covenants in this Agreement. For this
reason, it is the intention of Borrower and Lenders that the provisions of this
Agreement shall supersede any provisions in the Transaction Documents as defined
in the Purchase Agreement, which in any way limits the liability of Borrower and
that Borrower shall be liable for any obligations arising under this Agreement.
All of the covenants and indemnities of this Agreement shall survive the
repayment of the Notes issued in connection with the loan and the release of the
lien of the Security Documents and shall survive the transfer of any or all
right, title and interest in and to the Property by the Borrower to any party,
whether or not affiliated with the Borrower, except that such covenants and
indemnities shall not apply to events or circumstances which are to be
indemnified against hereunder and which first arise after the transfer of the
Property by the Borrower (or an affiliate) to a party unaffiliated with the
Borrower, if such transfer was permitted by the Security Documents and the
Transaction Documents. For example, Borrower shall remain responsible under this
Agreement with respect to the discharge of Hazardous Substances, or the
introduction onto the Property of Hazardous Substances (in breach of the
covenants of Section 2), if the discharge or introduction occurred during the
period of the Borrower's (or an affiliate's) ownership of the Property but a
claim is asserted after the period of such ownership.
  (d)
Borrower's obligations hereunder and indemnities herein shall not apply to any
Hazardous Substance released or installed in, at, below or near the Property by
Lenders or any other party seeking the benefit of indemnifications herein
contained.
 
 4.           Attorneys' Fees. If
Lenders, or someone on Lenders' behalf, retains the services of an attorney in
connection with the subject of indemnity herein, Borrower shall pay Lenders'
reasonable costs and reasonable attorneys' fees thereby incurred. Lenders may
employ one or more attorneys of Lenders' own choice.
 
 5.           Interest. In the
event that Lenders incurs any obligations, costs or expenses under this
Agreement, Borrower shall pay same to Lenders immediately on demand, and if such
payment is not received within ten (10) days after written demand from Lenders
to Borrower, interest on such amount shall, after the expiration of the ten (10)
day period, accrue at the rate of eighteen percent (18%) per annum until such
amount, plus interest, is paid in full.
 
 6.           Consent to
Jurisdiction. This Agreement shall be governed by, and construed in
accordance with, the laws of the State of New York without reference to its
conflicts of laws provisions. Each Borrower agrees that any suit for the
enforcement of this Agreement may be brought in the courts of the State of New
York or any federal court sitting therein and consents to the non-exclusive
jurisdiction of such court and to service of process in any such suit being made
upon the Borrower by mail at the address specified above. Each Borrower hereby
waives any objection that it may now or hereafter have to the venue of any such
suit or any such court or that such suit was brought in an inconvenient
court.
 
 7.           Notice. All notices,
demands, requests and other communications required hereunder shall be in
writing and shall be given in accordance with the terms and provisions of the
Purchase Agreement.
  8.           Waivers. BORROWER AND
LENDERS WAIVE TRIAL BY JURY IN ANY ACTION BROUGHT ON, UNDER, OR BY VIRTUE OF
THIS AGREEMENT. BORROWER WAIVES ANY RIGHT TO REQUIRE LENDERS AT ANY TIME TO
PURSUE ANY REMEDY IN LENDERS `POWER WHATSOEVER. The failure of Lenders to insist
upon strict compliance with any of the terms hereof shall not be considered to
be a waiver of any of such terms, nor shall it prevent Lenders from insisting uponstrict
compliance with this Agreement or any other Transaction Documents at any time
thereafter.
 
 9.           Severability. If any
clause or provision herein contained operates or would prospectively operate to
invalidate this Agreement in whole or in part, then such clause or provision
shall be held for naught as though not contained herein and shall not affect any
other provisions or the remaining part of any effective provisions of this
Agreement, and the remainder of this Agreement shall remain operative and in
full force and effect.
 
 10.          Inconsistencies Among the
Transaction Documents. Nothing contained herein is intended to limit in
any way the obligations of Borrower under the Notes, the Security Documents or
any of the other Transaction Documents. Any inconsistencies among such documents
shall be construed, interpreted and resolved so as to benefit Lenders, and
Lenders' election of which interpretation or construction is for Lenders'
benefit shall govern.
  11.          Successors and
Assigns.This Agreement shall be binding upon Borrower's successors and
assigns, and shall inure to the benefit of Lenders and their successors and
assigns.
  12.          Controlling Law.This
Agreement shall be governed by and construed in accordance with, the laws of the
State of New York.
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  13. Review of Instrument.
Borrower represents and warrants to Lenders that it (i) has read each and every
provision of this instrument, (ii) has consulted, or has been given the
opportunity to have this instrument reviewed by competent legal counsel of its
choosing, and (iii) understands, to and accepts the provisions
hereof.
 
 IN WITNESS WHEREOF, the
parties have executed this Hazardous Substances Indemnity Agreement under seal
as of the date first above written.
 
 BORROWER:
 
 VALCENT
      PRODUCTS INCBy: /s/ F. George
      Orr
                Name:
      F. George Orr
                Title:
      Director / CFOVALCENT
      USA INC.By:
      /s/ Perry
      Martin
                Name:
      Perry A. Martin
                Title:
      PresidentVALCENT
      MANUFACTURING, LTD.
                
                ITS:
      General PartnerBy:
      /s/ Perry
      Martin
                Name:
      Perry A. Martin
                Title:
      PresidentVALCENT
      MANAGEMENT LLCBy:
      /s/ Perry
      Martin
                Name:
      Perry A. Martin
                Title:
      PresidentVERTIGRO
      ALGAE TECHNOLOGIES, LLCBy:/s/ F. George Orr  /s/ M. Elden
      Shorn
                Name:
      F. George Orr & M. Elden Schorn
                Title:
      Director / CFO & DirectorVALCENT
      PRODUCTS EU LIMITEDBy:
      /s/ M. Glen
      Kertz
                Name:
      M. Glen Kertz
                Title:
      Director
  Exhibit
A
 
 The Company owns the
following parcel(s) of real property:
 
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