Underground natural gas storage capacity in the Lower 48 states has remained relatively flat since 2012. The U.S. Energy Information Administration (EIA) measures working natural gas storage capacity in two ways: design capacity and demonstrated peak capacity. Both measures of capacity were relatively unchanged in 2019; design capacity declined 0.4% and demonstrated peak capacity increased 0.1% compared with 2018. For the sixth year in a row, no new storage fields were completed.
Design capacity is calculated as the total of the working gas capacity for all active facilities in the Lower 48 states as of November 2019. Design capacity is an engineering estimate based on the physical characteristics of the reservoir, installed equipment, and operating procedures on the site, which often must be certified by federal or state regulators.
Design capacity declined by 19 billion cubic feet (Bcf) in the Lower 48 states during 2019. Most of this decline occurred in the Mountain region, where working design capacity fell by 15 Bcf, or slightly more than 3% of the regional total.
Storage operators may reduce design capacity at a storage field following an asset acquisition or reassessment of the operational capabilities. In the Mountain region, Spire Storage West reduced the working design capacity at the Belle Butte (formerly Ryckman Creek) field by 16 Bcf after acquiring the field in 2018.
Increases in design capacity occurred primarily in the Pacific and East regions. In the Pacific region, the Northwest Natural Gas Company completed the North Mist capacity expansion project in Oregon, increasing working natural gas capacity by 2.5 Bcf. The North Mist expansion project was the only new natural gas storage reservoir to come online in 2019, increasing capacity at the Mist Underground Natural Gas Storage Facility. The facility provides flexible natural gas storage to Portland General Electric’s Beaver and Port Westward facilities to balance renewable power generation, such as wind and solar, which varies in response to changing weather conditions.
In the East region, in 2019, the Cranberry Pipeline Corporation brought back online the Heizer A-1/Big Lime field, which had been inactive, increasing working natural gas capacity in the natural gas-producing area of West Virginia by 2.7 Bcf.
Demonstrated peak capacity is calculated as the total of the highest storage levels reached by each storage facility during any month during the most recent five-year period, with the most recent period covering December 2014 to November 2019 (the beginning of each annual heating season). Demonstrated peak reflects how storage facilities were actually used, not just how they were designed.
Demonstrated peak capacity remained nearly flat, increasing 3 Bcf, or 0.1%, for the Lower 48 states in 2019 compared with 2018, marking the first time that this metric posted an annual increase since November 2016.
Storage capacity in a given location may be a function of several factors, including production, consumption, existing infrastructure, geography, and geology. The increase in demonstrated peak capacity was driven by rising storage levels and high natural gas production in 2019. Dozens of natural gas storage fields in the Lower 48 states reported new demonstrated peaks in 2019 as working gas levels rose above the five-year average for the first time since 2017.
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