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                                                                     EXHIBIT 4.6

THIS WARRANT AND THE SECURITIES PURCHASED ON EXERCISE HEREOF HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"),
OR ANY STATE SECURITIES LAW, AND MAY NOT BE SOLD, TRANSFERRED, PLEDGED,
HYPOTHECATED OR OTHERWISE DISPOSED OF UNTIL EITHER (i) A REGISTRATION STATEMENT
UNDER THE SECURITIES ACT AND APPLICABLE STATE SECURITIES LAWS SHALL HAVE BECOME
EFFECTIVE WITH REGARD THERETO, OR (ii) THE CORPORATION SHALL HAVE RECEIVED AN
OPINION OF COUNSEL ACCEPTABLE TO THE CORPORATION AND ITS COUNSEL THAT AN
EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OR APPLICABLE STATE
SECURITIES LAWS IS AVAILABLE IN CONNECTION THEREWITH.

Warrant to Purchase
112,994 shares

                        WARRANT TO PURCHASE COMMON STOCK
                                       OF
                           AER ENERGY RESOURCES, INC.


         THIS CERTIFIES that FW AER II, L.P., a Delaware limited partnership
("Holder") or any subsequent holder hereof, has the right to purchase from AER
Energy Resources, Inc., a Georgia corporation (the "Company"), up to 112,994
fully paid and nonassessable shares of the Company?s Common Stock, no par value
("Common Stock"), at a price of $1.77 per share subject to adjustment as
provided below (the "Exercise Price"), at any time on or before 5:00 p.m.,
Atlanta, Georgia time, on March 30, 2005.

         This Warrant is issued and all rights hereunder shall be held subject
to all of the conditions, limitations and provisions set forth herein.

         1.       Exercise.

         This Warrant may be exercised as to all or any lesser number of full
shares of Common Stock covered hereby upon surrender of this Warrant, with the
Subscription Form attached hereto duly executed, together with the full Exercise
Price in cash, or by certified or official bank check payable in New York
Clearing House Funds for each share of Common Stock as to which this Warrant is
exercised, at the office of the Company, AER Energy Resources, Inc., 4600
Highlands Parkway, Suite G, Smyrna, GA 30082, or at such other office or agency
as the Company may designate in writing (such surrender and payment hereinafter
called the "Exercise of this Warrant"). The "Date of Exercise" of the Warrant
shall be defined as the date that the original Warrant and Subscription Form are
received by the Company. This Warrant shall be canceled upon its Exercise, and,
as soon as practicable thereafter, the Holder hereof shall be entitled to
receive a certificate or certificates for the number of shares of Common Stock
purchased upon such Exercise and a new

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Warrant or Warrants (containing terms identical to this Warrant) representing
any unexercised portion of this Warrant. Each person in whose name any
certificate for shares of Common Stock is issued shall, for all purposes, be
deemed to have become the Holder of record of such shares on the Date of
Exercise of this Warrant, irrespective of the date of delivery of such
certificate. Nothing in this Warrant shall be construed as conferring upon the
Holder hereof any rights as a shareholder of the Company.

         2.       Payment of Warrant Exercise Price.

         Payment of the Exercise Price may be made by any of the following, or a
combination thereof, at the election of Holder:

         (i)      cash, certified check or cashiers check or wire transfer; or

         (ii)     surrender of this Warrant at the principal office of the
Company together with notice of election, in which event the Company shall issue
Holder a number of shares of Common Stock computed using the following formula:

                                    X = Y (A-B)/A

where:            X = the number of shares of Common Stock to be issued to
                  Holder (not to exceed the number of shares set forth on the
                  cover page of this Warrant, as adjusted pursuant to the
                  provisions of Section 4 of this Warrant).

                  Y = the number of shares of Common Stock for which this
                  Warrant is being exercised.

                  A = the Market Price of one share of Common Stock (for
                  purposes of this Section 2(ii), the "Market Price" shall be
                  defined as the average closing bid price of the Common Stock
                  for the five trading days prior to the Date of Exercise of
                  this Warrant (the "Average Closing Bid Price"), as reported on
                  the Nasdaq National Market, or if the Common Stock is not
                  traded on the Nasdaq National Market, the Average Closing Bid
                  Price in the over-the-counter market; provided, however, that
                  if the Common Stock is listed on a stock exchange, the Market
                  Price shall be the Average Closing Bid Price on such
                  exchange).

                  B = the Exercise Price.

It is intended that the Common stock issuable upon exercise of this Warrant in a
cashless exercise transaction shall be deemed to have been acquired at the time
this Warrant was issued, for purposes of Rule 144(d)(3)(ii).

         3.       Transfer and Registration.

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         Subject to the provisions of Section 7 of this Warrant, this Warrant
may be transferred on the books of the Company, wholly or in part, in person or
by attorney, upon surrender of this Warrant properly endorsed, with signature
guaranteed. This Warrant shall be canceled upon such surrender and, as soon as
practicable thereafter, the person to whom such transfer is made shall be
entitled to receive a new Warrant or Warrants as to the portion of this Warrant
transferred, and the Holder of this Warrant shall be entitled to receive a new
Warrant or Warrants as to the portion hereof retained.

         4.       Anti-Dilution Adjustments.

         (a)      If the Company shall at any time declare a dividend payable
in shares of Common Stock, then the Holder hereof, upon Exercise of this Warrant
after the record date for the determination of Holders of Common Stock entitled
to receive such dividend, shall be entitled to receive upon Exercise of this
Warrant, in addition to the number of shares of Common Stock as to which this
Warrant is Exercised, such additional shares of Common stock as such Holder
would have received had this Warrant been Exercised immediately prior to such
record date.

         (b)      If the Company shall at any time effect a recapitalization or
reclassification of such character that the shares of Common stock shall be
changed into or become exchangeable for a larger or smaller number of shares,
then upon the effective date thereof, the number of shares of Common Stock which
the Holder hereof shall be entitled to purchase upon Exercise of this Warrant
shall be increased or decreased, as the case may be, in direct proportion to the
increase or decrease in the number of shares of Common Stock by reason of such
recapitalization or reclassification, and the Exercise Price shall be, in the
case of an increase in the number of shares, proportionately decreased and, in
the case of a decrease in the number of shares, proportionally increased.

         (c)      If the Company shall at any time distribute to Holders of
Common Stock cash, evidences of indebtedness or other securities or assets
(other than cash dividends or distributions payable out of earned surplus or net
profits for the current or preceding year) then, in any such case, the Holder of
this Warrant shall be entitled to receive, upon Exercise of this Warrant, with
respect to each share of Common Stock issuable upon such Exercise, the amount of
cash or evidences of indebtedness or other securities or assets which such
Holder would have been entitled to receive with respect to each such share of
Common stock as a result of the happening of such event had this Warrant been
Exercised immediately prior to the record date or other date fixing shareholders
to be affected by such event (the "Determination Date") or, in lieu thereof, if
the Board of Directors of the Company should so determine at the time of such
distribution, a reduced Exercise Price determined by multiplying the Exercise
Price on the Determination Date by a fraction, the numerator of which is the
result of such Exercise Price reduced by the value of such distribution
applicable to one share of Common stock (such value to be determined by the
Board in its discretion) and the denominator of which is such Exercise Price.

         (d)      If the Company shall at any time consolidate or merge with any
other corporation or transfer all or substantially all of its assets or
dissolve, then the Company shall deliver written notice to the Holder of such
merger, consolidation or sale of assets or dissolution at least thirty (30) days
prior to the closing of such merger, consolidation or sale of assets or
dissolution, and this Warrant

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shall terminate and expire immediately prior to the closing of such merger,
consolidation or sale of assets or dissolution.

         (e)      As used in this Warrant, the term "Exercise Price" shall mean
the purchase price per share specified in this Warrant until the occurrence of
an event stated in Section 4 (b) or (c) and thereafter shall mean said price as
adjusted from time to time in accordance with the provisions of said sections.
No such adjustment shall be made unless such adjustment would change the
Exercise Price at the time by $.01 or more; provided, however, that all
adjustments not so made shall be deferred and made when the aggregate thereof
would change the Exercise Price at the time by $.01 or more. No adjustment made
pursuant to any provision of this Section 4 shall have the effect of increasing
the total consideration payable upon Exercise of this Warrant in respect of all
the Common Stock as to which this Warrant may be exercised.

         (f)      In the event that at any time, as a result of an adjustment
made pursuant to this Section 4, the Holder of this Warrant shall, upon Exercise
of this Warrant, become entitled to receive shares and/or other securities or
assets (other than Common Stock) then, wherever appropriate, all references
herein to shares of Common Stock shall be deemed to refer to and include such
shares and/or other securities or assets; and thereafter the number of such
shares and/or other securities or assets shall be subject to adjustment from
time to time in a manner and upon terms as nearly equivalent as practicable to
the provisions of this Section 4.

         5.       Fractional Interests.

                  No fractional shares or scrip representing fractional shares
shall be issuable upon the Exercise of this Warrant, but on Exercise of this
Warrant, the Holder hereof may purchase only a whole number of shares of Common
Stock. The Company shall make a payment in cash in respect of any fractional
shares which might otherwise be issuable upon Exercise of this Warrant,
calculated by multiplying the fractional share amount by the market price of the
Company's Common Stock on the Date of Exercise as reported on the Nasdaq
National Market or such other exchange or system on which the Company's Common
Stock is traded.

         6.       Reservation of Shares.

                  The Company shall at all times reserve for issuance such
number of authorized and unissued shares of Common Stock (or other securities
substituted therefor as herein above provided) as shall be sufficient for
Exercise of this Warrant. The Company covenants and agrees that upon Exercise of
this Warrant, all shares of Common Stock issuable upon such Exercise shall be
duly and validly issued, fully paid, nonassessable and not subject to preemptive
rights of any shareholders.

         7.       Restrictions on Transfer.

                  This Warrant and the Common Stock issuable on Exercise hereof
have been or will be acquired by the Holder hereof for investment for its own
account and not with a view to the distribution thereof, have not been
registered under the Securities Act of 1933, as amended (the

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"Act") or under any state securities laws (the "State Acts"), and may not be
sold, transferred, pledged, hypothecated or otherwise disposed of in the absence
of registration or the availability of an exemption from registration under the
Act and any applicable State Acts and, in the event a Holder believes an
exemption from the registration requirements of the Act and any applicable State
Acts is available, the Holder must deliver a legal opinion satisfactory in form
and substance to the Company and its counsel, stating that such exemption is
available. All shares of Common Stock issued upon Exercise of this Warrant shall
bear an appropriate legend to such effect. Holder has represented to the Company
that it and any transferee of all or any portion of this Warrant is and will
remain at all times while this Warrant is outstanding an "accredited investor"
as defined in Regulation D promulgated under the Act.

         8. Benefits of this Warrant.

                  Nothing in this Warrant shall be construed to confer upon any
person other than the Company and the Holder of this Warrant any legal or
equitable right, remedy or claim under this Warrant and this Warrant shall be
for the sole and exclusive benefit of the Company and the Holder of this
Warrant.

         9.       Applicable Law.

                  This Warrant is issued under and shall for all purposes be
governed by and construed in accordance with the laws of the State of Georgia.
Jurisdiction for any dispute regarding this Warrant lies in Georgia.

         10.      Loss of Warrant.

                  Upon receipt by the Company of evidence of the loss, theft,
destruction or mutilation of this Warrant, and (in the case of loss, theft or
destruction) of indemnity or security reasonably satisfactory to the Company,
and upon surrender and cancellation of this Warrant, if mutilated, the Company
shall execute and deliver a new Warrant of like tenor and date.

         11.      Notice to Company and Holder.

                  Notices or demands pursuant to this Warrant to be given or
made by the Holder of this Warrant to or on the Company shall be sufficiently
given or made if sent by certified or registered mail, return receipt requested,
postage prepaid, and addressed, until another address is designated in writing
by the Company, AER Energy Resources, Inc., 4600 Highlands Parkway, Suite G,
Smyrna, GA 30082, Attention: Chief Executive Officer. Notices or demands
pursuant to this Warrant to be given or made by the Company to or on the Holder
of this Warrant shall be sufficiently given or made if sent by certified or
registered mail, return receipt requested, postage prepaid, and addressed to the
Holder as follows: FW AER II, L.P., 201 Main Street, Suite 2600, Ft. Worth,
Texas 76102, Attn:. Vice President and Controller, with a copy to David G.
Brown, c/o Arbor Investors, 2775 Sand Hill Road, Suite 220, Menlo Park,
California 94025 or another person or address designated in writing by Holder.

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                        (signature follows on next page)

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         IN WITNESS WHEREOF, this Warrant is hereby executed effective as of the
date set forth below.


Dated as of April 3, 2000.


                                AER ENERGY RESOURCES, INC.


                       By: /s/ R. Dennis Bentz
                          ------------------------------------------------------
                          Name: R. Dennis Bentz
                          Title: Vice President, Product and Process Development

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                                SUBSCRIPTION FORM

                         TO: AER ENERGY RESOURCES, INC.


         The undersigned hereby irrevocably exercises the right to purchase
_______________ shares of Common Stock of AER Energy Resources, Inc., a Georgia
corporation, evidenced by the attached Warrant, and herewith makes payment of
the Exercise Price with respect to such shares in full, all in accordance with
the conditions and provisions of said Warrant.

         The undersigned represents that it is an "accredited investor" as
defined in Regulation D under the Securities Act of 1933, as amended, agrees not
to offer, sell, transfer or otherwise dispose of any of such Common Stock,
except in accordance with the provisions of Section 7 of the Warrant, and
consents that the following legend may be affixed to the certificates for the
Common Stock hereby subscribed for, if such legend is applicable:

         "The securities represented by this certificate have not been
         registered under the Securities Act of 1933, as amended (the
         "Securities Act"), or any state securities law, and may not be sold,
         transferred, pledged, hypothecated or otherwise disposed of until
         either (i) a registration statement under the Securities Act and
         applicable state securities laws shall have become effective with
         regard thereto, or (ii) the corporation shall have received an opinion
         of counsel acceptable to the corporation and its counsel that an
         exemption from registration under the Securities Act or applicable
         state securities laws is available in connection therewith."

         The undersigned requests that certificates for such shares be issued,
and a warrant representing any unexercised portion thereof be issued, pursuant
to the Warrant in the name of the Registered Holder and delivered to the
undersigned at the address set forth below:


Dated: _______________________

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                         Signature of Registered Holder

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                        Name of Registered Holder (Print)


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                                     Address
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The attached Warrant and the securities issuable on exercise thereof have not
been registered under the Securities Act of 1933, as amended, or any state
securities law and may not be sold, transferred, pledged, hypothecated or
otherwise disposed of in the absence of registration or the availability of an
exemption from registration under said Act or any state securities law.
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                                   ASSIGNMENT

                    (To be executed by the registered Holder
                        desiring to transfer the Warrant)


FOR VALUE RECEIVED, the undersigned Holder of the attached Warrant hereby sells,
assigns and transfers unto the person or persons below named the right to
purchase ____________ shares of the Common Stock of AER ENERGY RESOURCES, INC.
evidence by the attached Warrant and does hereby irrevocably constitute and
appoint _____________________________ attorney to transfer the said Warrant on
the books of the Company, with full power of substitution in the premises.


Dated: _______________________                   -------------------------------
                                                           Signature

Fill in for new Registration of Warrant:         Signature Guarantee:


----------------------------------------         -------------------------------
                  Name                                  Name of Guarantor

                                                 By:
                                                    ----------------------------
 ---------------------------------------         Name:
 ---------------------------------------              --------------------------
                  Address                        Title:
                                                       -------------------------

Please print name and address of assignee
(including zip code)


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NOTICE

The signature to the foregoing Subscription Form or Assignment must correspond
to the name as written upon the face of the attached Warrant in every
particular, without alteration or enlargement or any change whatsoever.
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