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, and maintain either within or without its corporate limits, a hospital and public utilities, including but not by way of limitation, public utilities for treating and supplying water, and for supplying light, heat, power, gas, sewage treatment, and garbage disposal facilities, or any of them, to the city and its inhabitants, and also to sell and deliver water, light, heat, power, gas and other public utilities and services without its corporate limits to an amount not exceeding the limitations set by or in accordance with law. The power to supply, as herein possessed and reserved, shall include the power to extract and process water, electricity, or gas from natural sources, to manufacture the same, or to purchase the same from others.