The city shall possess and hereby reserves to itself all the powers granted to cities by law to acquire, construct, own, operate, improve, enlarge, extend, repair, maintain, encumber, convey, dispose of or sell, either within or without its corporate limits, public utilities, including, but not by the way of limitation, aeronautical facilities, cemeteries, hospitals and public utilities for treating and supplying water and for supplying light, heat, power, gas, sewage treatment, garbage disposal, public transportation and facilities for the storage and parking of vehicles; and also to sell and deliver the products or services thereof, both within and without its corporate limits, subject to the limitations herein contained. The power to supply said utility services, as herein possessed and reserved, shall include the power to extract, process, manufacture, transport or purchase the same from others.