The purpose of the authority shall be: (1) to acquire or construct, or to acquire and construct, and to operate and maintain, or to cause to be constructed, operated, and maintained, systems, projects, and facilities for the storage, acquisition, exploration, production, distribution, transmission, purchase, sale, exchange, or interchange of gas; and (2) in addition thereto, to take all other necessary or desirable actions in order to provide or make available an adequate, dependable, and economical supply of gas and related services to those political subdivisions of this state identified in Code Section 46-4-100 which may desire the same and, incidentally and so as to take advantage of economies of scale, in the storage, acquisition, exploration, production, distribution, transmission, purchase, sale, exchange, or interchange of gas to other persons and entities.