WASHINGTON — Working natural gas storage capacity increased by about 2 percent in the lower 48 states between November 2011 and November 2012, according to Underground Working Natural Gas Storage Capacity, released recently by the U.S. Energy Information Administration.

The largest year-over-year increases occurred primarily in the salt dome facilities in the producing region. Most of these increments took place at existing sites, with the largest expansions occurring at salt dome facilities in Mississippi and Louisiana.

New facilities

Four new facilities went into operation during the year, with three beginning operations in the West region and one in the producing region.

According to EIA’s compilation of planned storage projects, another 71 billion cubic feet (Bcf) of design capacity could be added in 2013 from projects that are reported to be currently under construction.

This rough estimate includes 34 Bcf in the producing salt, and 37 Bcf in the West region.There have been no reports of capacity that would be added in the East in 2013. This may be partly explained by readily available volumes of Marcellus Shale gas.

Measures. EIA uses two measures of storage capacity and both increased by similar amounts:

1. Demonstrated maximum working gas volume increased 1.8 percent to 4,265 Bcf.
2. Working gas design capacity increased 2.0 percent to 4,575 Bcf.

Demonstrated maximum working gas volume differs from design capacity in that it is an operational measure and not an engineering measure.

Maximum demonstrated working gas volume measures the highest level of working gas reported at each storage facility over the previous five years, and provides a practical measure of full storage.

Natural gas storage provides pipelines, local distribution companies, producers, and pipeline shippers with an inventory management tool, seasonal supply backup, and access to natural gas needed to avoid imbalances between receipts and deliveries on a pipeline network.