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The Three R's: Reducing the Environmental Impact of SF6

By Billy J Lao

Sulfur Hexafluoride (SF6) Gas is used as an electrical insulator and arc suppressant in high and medium voltage electrical equipment in the electrical power utility and industrial power industries. SF6 is also used in medical devices, metal production and other manufacturing applications. The same properties that make SF6 useful as a dielectric create environmental problems. SF6 is a major greenhouse gas with a GWP of 23,900; however, with proper training and equipment, SF6 can be used in a closed loop cycle where it is not emitted into the atmosphere. Utilizing the three Rs: Recover, Recycle, and Re-use, along with best gas handling practices the T&D industry can enjoy the benefits that SF6 provides while minimizing environmental impacts.

History:

Discovered in 1901 by French Chemists Henri Moissan and Paul Lebeau, Sulfur Hexafluoride is a man-made gas that has a greater dielectric strength and density than air. When in pure form, SF6 is inert, non-flammable, non-toxic, thermally stable, and has unmatched arc quenching capabilities. Most interesting is the molecule’s self-healing abilities. The gas begins to break down at a temperature of 380 degrees Fahrenheit and once the heat source is removed, the atoms will regenerate like new. The chemical properties of SF6 make it ideal for use within circuit breakers and switchgear.

Environmental Impact:

Unfortunately, the same properties that make SF6 such a great insulating gas also make SF6 the most potent of all greenhouse gases. One molecule of SF6 can trap 23,900 times more heat than carbon dioxide over a 100-year period and remains in the atmosphere for thousands
of years. About 80% of manufactured SF6 is used in
high voltage equipment like switchgear and circuit breakers (GIE).

Read full article in the Overhead and Underground T&D Special Edition 2021

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