RENTECH, INC. WARRANT To Purchase 5,000,000 Shares of Common Stock

THIS WARRANT (the “ Warrant ”) CERTIFIES THAT, for value received, ClearFuels Technology Inc., or permitted registered assigns (the “ Holder ”), is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth, at any time during the applicable Exercise Period (defined below), to subscribe for and purchase at the applicable Exercise Price (defined below) from Rentech, Inc., a Colorado corporation (the “ Company ”), up to 5,000,000 shares (the “ Shares ”) of the common stock of the Company, par value $0.01 per share (the “ Common Stock ”).

1.   DEFINITIONS - As used herein, the following terms shall have the following respective meanings:

(A)  “ Bloomberg ” shall mean Bloomberg Financial Markets (or a comparable reporting service of national reputation selected by the Company and reasonably acceptable to the Holder if Bloomberg Financial Markets is not then reporting sales prices of the Common Stock).

(B)  “ Business Day ” shall mean any day other than a Saturday, Sunday, or a day on which banks in New York City are authorized or required by law to close.

(C)  “ Construction Financing ” shall mean the debt and/or equity financing for the first commercial-scale facility (i.e. with an output of 1,000 or more barrels per day of synthetic fuels) using the combined ClearFuels-Rentech process, pursuant to one or more loan agreements and equity purchase agreements between the applicable project entity and third-party lenders and investors approved by the Company, which financing results in aggregate net proceeds reasonably sufficient to the project entity for the construction of such facility, provided such financing occurs on or prior to December 31, 2013.

(D)  “ Exercise Period ” shall mean, as applicable, the First Exercise Period, the Second Exercise Period or the Third Exercise Period, each as defined in Section 2 .

(E)  “ Exercise Price ” shall mean (i) with respect to each of the Closing Shares, $.60 per share, (ii) with respect to each of the Qualified Financing Shares, the average of the daily Volume-Weighted Average Prices of the Common Stock for the ten (10) consecutive Trading Days immediately preceding (but not including) the closing date of a Qualified Financing or a Construction Financing, as applicable, and (iii) with respect to each of the Construction Financing Shares, the average of the daily Volume-Weighted Average Prices of the Common Stock for the ten (10) consecutive Trading Days immediately preceding (but not including) the closing date of a Construction Financing, in each case, subject to adjustment pursuant to Section 5 below.

(F)  “ Financing Deadline ” shall mean March 24, 2010, provided that, in the event that the board of directors of ClearFuels Technology Inc. delivers written notice to the Company prior to such date that it has determined in good faith that the closing of a Qualified Financing is reasonably likely to occur with the ninety (90) days following such date and such closing actually occurs within such ninety-day period, then the “Financing Deadline” shall be extended to such closing of the Qualified Financing.

(G)  “ Qualified Financing ” shall mean one or more closings of a capital raise or raises by ClearFuels Technology Inc. for aggregate gross proceeds of at least $25,000,000 on terms acceptable to ClearFuels Technology Inc.’s Board of Directors, provided such closings occur on or prior to the Financing Deadline.

(H)  “ Securities Act ” shall mean the Securities Act of 1933, as amended.

(I)  “ Trading Day ” shall mean (i) any day on which the Common Stock is listed or quoted and traded on any eligible Trading Market, (ii) if the Common Stock is not then listed or quoted and traded on any eligible Trading Market, then a day on which trading occurs on the OTC Bulletin Board (or any successor thereto), or (iii) if trading does not occur on the OTC Bulletin Board (or any successor thereto), any Business Day.

(J)  “ Trading Market ” shall mean the NYSE Alternext US, New York Stock Exchange, NASDAQ Capital Market, NASDAQ Global Market, NASDAQ Global Select Market or other market or exchange on which the Common Stock is listed or traded.

(K)  “ Volume-Weighted Average Price ” shall mean, with respect to any Trading Day, the volume-weighted average sales price for the Common Stock for such Trading Day on the NYSE Alternext US or other Trading Market where such security is listed or traded as reported by Bloomberg.

(L)   “Warrant Shares ” shall mean, collectively, the Closing Shares, the Qualified Financing Shares and Construction Financing Shares, each as defined in Section 2 , in each case as adjusted in accordance with the terms hereof.

2.1   CLOSING SHARES - Subject to the terms and conditions hereof, this Warrant may be exercised for 2,000,000 Shares (as such number of Shares may be adjusted pursuant to Section 5, the “ Closing Shares ”), at any time during the period (the “ First Exercise Period ”) commencing on the Date of Issuance and ending on the close of business on the fifth anniversary of the Date of Issuance.

2.2   QUALIFIED FINANCING SHARES .  In addition to the Closing Shares and subject to the terms and conditions hereof, this Warrant may be exercised for an additional 1,500,000 Shares (as such number of Shares may be adjusted pursuant to Section 5 , the “ Qualified Financing Shares ”), at any time during the period (the “ Second Exercise Period ”) commencing on the closing date of a Qualified Financing and ending on the close of business on the fifth anniversary of the Date of Issuance; provided that if the closing date of a Qualified Financing does not occur on or prior to the Financing Deadline, then the Second Exercise Period shall not commence and the Holder shall have no right hereunder to exercise the Warrant for the Qualified Financing Shares, except as provided for in Section 2.3 .

2.3   CONSTRUCTION FINANCING SHARES .  In addition to the Closing Shares and, if the Second Exercise Period has commenced pursuant to Section 2.2 above, the Qualified Financing Shares, and subject to the terms and conditions hereof, this Warrant may be exercised for the remaining 1,500,000 Shares (as such number of Shares may be adjusted pursuant to Section 5 , the “ Construction Financing Shares ”), and, if the Second Exercise Period has not commenced pursuant to Section 2.2 above, for the Qualified Financing Shares at any time during the period (the “ Third Exercise Period ”) commencing on the closing date of the Construction Financing and ending on the close of business on the fifth anniversary of the Date of Issuance; provided that if the closing date of the Construction Financing does not occur on or prior to December 31, 2013, then the Third Exercise Period shall not commence and the Holder shall have no right hereunder to exercise the Warrant for the Construction Financing Shares (or for the Qualified Financing Shares if the Second Exercise Period has not previously commenced pursuant to Section 2.2 above).

Upon expiration of any Exercise Period, the right to exercise this Warrant for the applicable Warrant Shares shall terminate and shall be of no further force or effect (except with respect to the Second Exercise Period as provided above in this Section 2.3 ).  Upon expiration of all of the Exercise Periods, this Warrant shall terminate in its entirety and shall be of no further force or effect.

3.1   EXERCISE .  The rights represented by this Warrant may be exercised in whole or in part at any time during the applicable Exercise Period, by delivery of the following to the Company at its address set forth below (or at such other address as the Company may designate by notice in writing to the Holder):

(A)  An executed and duly completed Notice of Exercise in the form attached hereto;

(B)  Payment of the applicable Exercise Price in cash or pursuant to a cashless exercise as provided for in Section 3.2 ; and

(C)  This Warrant.

Each exercise of this Warrant shall be irrevocable.  Execution and delivery of the Notice of Exercise shall have the same effect as cancellation of the original Warrant and issuance of a new Warrant evidencing the right to purchase the remaining number of Warrant Shares, if any, in accordance with the terms and conditions of this Warrant.

Upon issuance for cash in accordance with this Section 3.1 , it is anticipated that the Warrant Shares would be “restricted securities” under Rule 144(a) under the Securities Act or any successor provision and all Warrant Shares delivered to Holder shall be in certificated form and bear restrictive legends in compliance with the Securities Act.

In lieu of a cash payment for the Exercise Price in Section 3.1 above, the Holder may provide written notice for a cashless election, in which event the Company shall issue to the Holder a number of Warrant Shares computed using the following formula:

For purposes of the above calculation, the “fair market value” of one share of Common Stock shall mean (i) the average of the Volume-Weighted Average Prices for the Shares for the ten (10) consecutive Trading Days immediately preceding (but not including) the applicable Exercise Date, or (ii) if the foregoing does not apply, the volume-weighted average sales price of the Shares during the same period in the over-the-counter market on the pink sheets or bulletin board for such security as reported by Bloomberg, or if no sales price is so reported for the Shares, the last bid price of the Shares as reported by Bloomberg or (iii) if none of the foregoing applies, the fair market value shall be as determined by the Board of Directors of the Company in the exercise of its good faith judgment.

The Company shall provide to the Holder prompt written notice if the Company is unable to issue the Warrant Shares via Deposit Withdrawal Agent Commission (“DWAC”) transfer (or otherwise without restrictive legend), in which case the Warrant Shares would be “restricted securities” under Rule 144(a) under the Securities Act or any successor provision.

For purposes of Rule 144(d) promulgated under the Securities Act, as in effect on the date hereof, it is intended that the Warrant Shares issued in a Cashless Exercise shall be deemed to have been acquired by the Holder, and the holding period for the Warrant Shares shall be deemed to have commenced, on the date this Warrant was originally issued.