The board of supervisors of a county or the governing authorities of a municipality may enter into an agreement with an enterprise operating a project as defined in Section 57-75-5(f)(iv)1, Section 57-75-5(f)(xxi) or 57-75-5 (f)(xxii), providing that the board of supervisors or governing authorities will agree in advance to approve any request for exemption from ad valorem taxes submitted by a supplier of such enterprise in the manner provided by law and that any such exemption shall be for a period of ten (10) years. Such an agreement on the part of the board of supervisors or governing authorities may be for a period not to exceed twenty (20) years.