In this subchapter:
(1) "Intrastate gas pipeline facility" has the meaning assigned by the United States Department of Transportation under 49 U.S.C. Section 60101 et seq. and its subsequent amendments or a succeeding law.
(2) "Natural gas" means any gaseous material composed primarily of methane in either its original or its manufactured state.
(3) "Natural gas underground storage" means the storage of natural gas beneath the surface of the earth in a formation, stratum, or reservoir.
(4) "Storage facility" has the meaning assigned by Section 91.173.