December 12, 1997

Alabama Synfuel #1, Ltd.
c/o Covol Technologies, Inc.
3280 North Frontage Road
Lehi, Utah 84043

Covol Technologies, Inc.
3280 North Frontage Road
Lehi, Utah 84043

         Re:      Letter Amendment

Gentlemen:

         Reference is made to the Alabama Project Purchase  Agreement,  dated as
of March 20,  1997,  as amended by the  letter  agreements  dated as of June 27,
1997, July 7, 1997 and August 28, 1997 (the "Project  Purchase  Agreement"),  by
and among Alabama Synfuel #1, Ltd. and Covol Technologies, Inc., as sellers, and
Birmingham Syn Fuel, LLC, as buyer.

         The parties to the Project Purchase  Agreement hereby amend the Project
Purchase Agreement as follows:

         (i) Section  5.3(c) of the  Project  Purchase  Agreement  is amended by
         deleting the language  "November  30, 1997" and  inserting in its place
         the language "February 27, 1998";

         (ii)  Section  7.3(c) of the Project  Purchase  Agreement is amended by
         deleting the language  "December  31, 1997" and  inserting in its place
         the language "February 27, 1998";

         (iii) Section  7.3(d) of the Project  Purchase  Agreement is amended by
         deleting the language  "December  31, 1997" and  inserting in its place
         the language "February 27, 1998";

         (iv)  Section  7.3(f) of the Project  Purchase  Agreement is amended by
         deleting the language  "December  31, 1997" and  inserting in its place
         the language "February 27, 1998"; and

         (v)  Section  8.1 of the  Project  Purchase  Agreement  is amended  and
         restated in its entirety as follows:  "The  closing of the  transaction
         contemplated by this Agreement (the  "Closing")  shall be at 9:00 a.m.,
         Mountain  Time, on such date as the parties shall mutually  agree,  not
         later than the  earlier of (i) ten (10)  business  days  following  the
         "Date  of  Substantial  Completion"  as  defined  in  the  Construction
         Contract or (ii)
<PAGE>

         February 27, 1998 (the "Closing  Date"),  at the offices of Stoel Rives
         LLP, 201 South Main Street,  Suite 11, Salt Lake City, Utah 84111-2215,
         or at such other time or place as the parties shall mutually agree."

         (vi) A new  Section  8.2(k)  is  inserted  into  the  Project  Purchase
         Agreement as follows:

                  (k) Sellers shall execute and deliver to Buyer an  unqualified
                  warranty  with  respect  to the  binder  facility  in form and
                  substance acceptable to the Buyer.

         (vii) Schedule 2.1 to the Project Purchase Agreement is supplemented by
         the addition of the attached Schedule 2.1 of "Binder Assets."

         This letter agreement may be executed in one or more counterparts,  all
of which shall be considered one and the same letter agreement.

                                                     Very truly yours,

                            BIRMINGHAM SYN FUEL, LLC

                                                       By:   /s/ Reynold Roeder
                                                          ---------------------
                                                     Name: Reynold Roeder
                                                    Title: Vice President


ACCEPTED AND AGREED TO
AS OF THE DATE FIRST SET
FORTH ABOVE:

ALABAMA SYNFUEL #1, LTD.

By:  /s/ Brent M. Cook
   ------------------------------------------
Name:  Brent M. Cook
Title: President, Covol Technologies, G.P.

COVOL TECHNOLOGIES, INC.

By: /s/ Brent M. Cook
   ---------------------
Name:  Brent M. Cook
Title: President