All such grants shall reserve to the city the right to purchase or lease all the property of the utility used in or useful for the operation of the utility, at a price either fixed in the ordinance making the grant, or to be fixed in the manner provided by such ordinance, which price shall in no event include any value for the grant. Nothing, in such ordinance, shall prevent the city from acquiring such property by condemnation proceedings or in any other lawful mode, which rights shall be in addition to those reserved in such ordinance. Upon the acquisition of such property by purchase, condemnation or otherwise, all grants shall at once terminate.