No right to construct, maintain, or operate any public utility in the City of Portsmouth and no renewal or extension thereof shall be exclusive. No franchise granted shall be renewed earlier than two years prior to its expiration unless the Council shall by an affirmative vote of at least all of the members elected to Council less two first declared by ordinance its intention of considering a renewal thereof. All extensions of a franchise granted a public utility shall be subject, as far as practicable, to the terms of the original franchise and shall expire therewith.