The city may enter into a contract so that the city may provide its customers with an adequate, reliable, and economical supply of electric power and energy, and join with other members of the Municipal Power Agency for the purpose of the Agency providing the planning, financing, locating, and building of needed new facilities for generation and transmission, and for other purposes contemplated in the contract. The electric utility of the city electric power and energy from the Agency under and pursuant to the terms of the contract. The Agency shall have full responsibility for planning and obtaining an adequate supply of power and energy for the city pursuant to the contract. The President of the City Council is hereby authorized and directed to execute and deliver, and the Clerk-Treasurer is hereby authorized to attest and seal, the contract with any modifications therein as they shall approve by their execution thereof.