The provisions of Sections 6-6-11, 6-6-13 through 6-6-18 and 13-4-1 through 13-4- 24 NMSA 1978 and of the Public Purchases Act shall not apply to the acquisition, construction, disposal and operation by a municipality of any generating facility and any undivided or other interest in a jointly owned generating facility, or to any contract, indebtedness or agreement for the operation, maintenance and management of such facility or the sale or other disposal of power or energy therefrom.