Underground natural gas storage (depleted fields & salt caverns)

One of the largest energy infrastructure companies in North America; holds natural gas and NGL storage assets including salt cavern storage. Kinder Morgan's Products Pipelines segment operates refined products and NGL pipelines with associated storage. Also a leading operator of liquefied natural gas (LNG) facilities and CO2 pipelines for enhanced oil recovery. Less dominant in LPG salt cavern storage specifically vs. Enterprise/Energy Transfer/ONEOK, but holds meaningful storage capacity.

NiSource Inc. (Westfield, IN; NYSE: NI) operates regulated gas distribution utilities across seven states through its Columbia Gas subsidiary brands: Columbia Gas of Ohio, Columbia Gas of Pennsylvania, Columbia Gas of Virginia, Columbia Gas of Kentucky, Columbia Gas of Maryland, and Bay State Gas (Massachusetts). NiSource's distribution utilities operate approximately 60 underground gas storage fields with a combined working gas capacity of approximately 630 Bcf — making NiSource one of the top three US underground storage operators by working gas capacity, though primarily as a regulated utility operator (not a merchant storage provider). NiSource's Ohio storage fields (Columbia Gas of Ohio) are critical to winter gas supply for the entire Great Lakes and Ohio Valley region. NiSource also controls the largest number of UGS fields of any single corporate entity in the US. In September 2018, Columbia Gas of Massachusetts caused fatal gas explosions in the Merrimack Valley (Lawrence, Andover, North Andover) due to over-pressurization of gas distribution mains, which ultimately led to the sale of Bay State Gas.

TC Energy Corporation (Calgary, Alberta; TSX/NYSE: TRP) is one of the largest operators of underground natural gas storage in the northeastern US through its Columbia Gas Transmission subsidiary. Columbia Gas Transmission operates approximately 30 underground storage fields in West Virginia, Ohio, Pennsylvania, Virginia, and Kentucky — the largest concentration of UGS fields by count in the US. These fields have combined working gas capacity of approximately 600 Bcf, serving the Northeast and Mid-Atlantic markets. TC Energy's storage is primarily in depleted gas reservoir fields in the Appalachian Basin. The Columbia storage system plays a critical role in winter peak supply for the most densely populated region of the US. In addition, TC Energy's Canadian Mainline pipeline system includes storage fields in Ontario (Dawn Hub — the most liquid natural gas trading hub in Canada).

Southern California Gas Company (SoCalGas; San Diego, CA; subsidiary of Sempra Energy, NYSE: SRE) is the largest US natural gas distribution utility and the operator of the Aliso Canyon underground gas storage facility in Los Angeles County — the largest underground gas storage site in the United States by working gas capacity (~86.6 Bcf). SoCalGas operates four underground storage fields in Southern California: Aliso Canyon (Porter Ranch), Playa del Rey (Los Angeles), Honor Rancho (Santa Clarita), and the Goleta field. These four fields together hold the entire gas buffer for the Southern California and San Diego markets. In October 2015, a blowout at Aliso Canyon's SS-25 injection well released approximately 96,000 metric tonnes of methane over 112 days in the largest methane leak in US history. SoCalGas serves approximately 21 million customers across Southern California and San Diego.

EQT Corporation (Pittsburgh, PA; NYSE: EQT) is the largest US natural gas producer by volume and operates significant underground gas storage assets in West Virginia and Pennsylvania. EQT's storage is integrated with its Appalachian Basin production — depleted reservoir fields that serve as both production infrastructure and seasonal storage. EQT's storage fields in West Virginia (including storage along the Equitrans Midstream system, now an EQT subsidiary after the 2024 Equitrans acquisition for ~$5.5 billion) give EQT direct control over Appalachian gathering, compression, and storage. Equitrans Midstream operated the Mountain Valley Pipeline (MVP, ~303 miles from West Virginia to Virginia, completed June 2024) and associated gathering systems that include storage infrastructure. EQT's storage capacity is approximately 45 Bcf of working gas across its storage fields.