As used in this act
(a) "underground storage" shall mean storage in a subsurface stratum or formation of the earth;
(b) "natural gas" shall mean gas either while in its original state or after the same has been processed by removal therefrom of component parts not essential to its use for light and fuel;
(c) "native gas" shall mean gas which has not been previously withdrawn from the earth;
(d) "natural gas public utility" shall mean any person, firm or corporation authorized to do business in this state and engaged in the business of transporting or distributing natural gas by means of pipelines into, within or through this state for ultimate public use;
(e) "commission" shall mean the state corporation commission.