AMENDMENT NO. 6
                            TO AGREEMENT AND PLAN OF
                            REORGANIZATION AND MERGER
                     BY AND AMONG U.S. ENERGY SYSTEMS, INC.,
                            USE ACQUISITION CORP. AND
                      ZAHREN ALTERNATIVE POWER CORPORATION


                  This Amendment No. 6 to Agreement and Plan of Reorganization
and Merger (the "Amendment") is made as of the 1st day of November, 2002 by and
between U.S. Energy Systems, Inc. ("Parent") and), and Zahren Alternative Power
Corporation (the "Surviving Corporation"), as the surviving corporation of the
merger with USE Acquisition Corp.("Merger Sub"). Unless indicated otherwise,
capitalized terms shall have the same meanings herein as they have in the Merger
Agreement (as defined below).

                               W I T N E S S E T H
                  WHEREAS, Parent, Merger Sub and the Surviving Corporation
previously entered into that certain Agreement and Plan of Reorganization and
Merger dated as of November 28, 2000 as amended by Amendment No. 1, Amendment
No. 2, Amendment No. 3, Amendment No. 4 and Amendment No. 5 (collectively the
"Merger Agreement"); and

                  WHEREAS, the Parent and the Surviving Corporation now wish to
amend the Agreement.

                  NOW, THEREFORE, in consideration of $10.00 and other
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereto agree as follows:

          1. Clause (B) of Section 2.01(a) of the Merger Agreement is
         hereby amended by deleting the existing clause in its entirety and
         inserting in its place the following clause:

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                  (B) a contingent obligation of Merger Sub to pay $800,000 in
         cash on the date which is twenty one months after the Effective Date
         (the "Contingent Merger Payment") (of which Contingent Merger Payment
         62.5% of the payment is guaranteed severally but not jointly by USE and
         37.5% of the payment is guaranteed severally but not jointly by CSHC
         pursuant to guarantees of USE and CSHC, respectively (the
         "Guarantees"), substantially in the form of Exhibits 2.01(a-2) and
         2.01(a-3)),

                  2. Parent and Surviving Corporation hereby waive until
         February 11, 2003 compliance with section 2.05(a)(ii) of the Merger
         Agreement to the extent of the submission of the response and objection
         to the Draft Effective Date Balance Sheet.

                  3. Except as amended hereby, the Merger Agreement is as hereby
         ratified and confirmed and, as so amended, remains in full force and
         effect on the date hereof.

                   IN WITNESS WHEREOF, Parent and the Surviving Corporation have
caused this Agreement to be executed as of the date first written above.

                                       U.S. ENERGY SYSTEMS, INC.


                                       By: /s/   Goran Mornhed
                                               ------------------
                                           Name: Goran Mornhed
                                           Title:Chief Executive Officer

                                        U.S. ENERGY BIOGAS CORPORATION


                                        By: /s/ Frank Fitzgerald
                                                ----------------
                                            Name:Frank Fitzgerald
                                            Title: Treasurer