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What is SF6 gas Why is it used?

Author: Marie

Aug. 23, 2022

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Tags: Chemicals

What is SF6 gas?

Sulfur hexafluoride (SF6) is a synthetic fluorinated compound with an extremely stable molecular structure. Because of its unique dielectric properties, electric utilities rely heavily on SF6 in electric power systems for voltage electrical insulation, current interruption, and arc quenching in the transmission and distribution of electricity. Yet, it is also the most potent greenhouse gas known to-date. Over a 100-year period, SF6 is 22,800 times more effective at trapping infrared radiation than an equivalent amount of carbon dioxide (CO2). SF6 is also a very stable chemical, with an atmospheric lifetime of 3,200 years. As the gas is emitted, it accumulates in the atmosphere in an essentially un-degraded state for many centuries. Thus, a relatively small amount of SF6 can have a significant impact on global climate change.


Use in Electric Power Systems

Since the 1950’s, the U.S. electric power industry has used SF6 in circuit breakers, gas-insulated substations and other switchgear used in the transmission system to manage the high voltages carried between generating stations and customer load centers. Disconnectors and ground switches use SF6 primarily for insulation, and individually, they contain only slightly less SF6 than a circuit breaker. These devices are used to isolate portions of the transmission system where current flow has been interrupted (using a circuit breaker). Gas-insulated substations also use a significant amount of SF6, and GIS installations house SF6-insulated circuit breakers, busbars and monitoring equipment. The largest use of SF6 occurs in high-voltage circuit breakers, where, in addition to providing insulation, SF6 Specialty Gas is used to quench the arc formed when an energized circuit breaker is opened.

Several factors affect SF6 emissions from electric power systems, such as the type and age of the SF6-containing equipment (e.g., old circuit breakers can contain up to 2,000 pounds of SF6, while modern breakers usually contain less than 100 pounds) and the handling and maintenance procedures practiced by electric utilities. Because of its long-life span and high global warming potential (GWP), even a relatively small amount of SF6 can impact the climate.

The electric power industry can reduce the nation’s SF6 emissions through cost-effective operational improvements and equipment upgrades. Through improvements in the leak rate of new equipment, refurbishing older equipment, and the use of more efficient operation and maintenance techniques, utilities often find economical solutions to reduce SF6 emissions.

Under the partnership, EPA shares information on best management practices and technical issues to help reduce emissions. Some cost-effective options to reduce SF6 emissions are:

Leak Detection and Repair

Use of Recycling Equipment

Employee Education/Training