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  • Inaya Abdul-Haqq

Overlooked but Impactful: the Implications of Sulfur Hexafluoride

The progression of technology is often anything but a disadvantage when it comes to the human footprint – the more we learn how to undo the harm advancements have caused to the environment, the more we can salvage. One important technological development is the use of electric power systems: they power homes, jobs, schools and hospitals. However, the environment faces a serious problem due to the insulation aids frequently used for power systems. The culprit? One of the most destructive greenhouse gases: sulfur hexafluoride.

Sulfur hexafluoride (SF₆) is an inorganic and fluorinated gas composed of six fluoride atoms bonded to one sulfur atom, creating a very stable molecular structure. Because of its unique structure, SF₆ is also a dielectric, meaning the gas can transmit electric force without any aid of conduction – in other words, it is an insulator. The property of dielectrism for SF₆ is what makes this gas a perfect use in electric power systems for voltage electrical insulation, as well as current interruption. In transmission systems, gas-insulated stations not only use this fluorinated gas primarily for insulation, but also to isolate specific portions of the system where the current flow has been interrupted.

The structure of sulfur hexafluoride.

Essentially, sulfur hexafluoride is an excellent resource for these transmission systems, and significantly improves voltage management in order to help networks run safer and without major issues. However, this resource does not come without major risk – SF₆ has been identified by the Kyoto protocol as one of the six main greenhouse gasses. Not only is sulfur hexafluoride a major greenhouse gas, it is the most potent and harmful greenhouse gas to date.

Take carbon dioxide (CO₂), for instance. Most recognize this as a very prominent greenhouse gas, whether that information was relayed to them through schooling, mass media, or even just in conversation. CO₂ is a greenhouse gas emitted into the atmosphere through the combustion of fossil fuels, often used for transportation and electricity. In this case, CO₂ seems a lot more prevalent than SF₆, which is only really utilized in the electricity industry – although the environmental impacts of sulfur hexafluoride have been identified, there are substantial challenges in replacing technology that contains it. Nonetheless, when comparing CO₂ and SF₆ in terms of its lingering effect in the atmosphere, it has been found that SF₆ is around 22,000 times more effective at trapping infrared radiation than an equal amount of CO₂. Furthermore, sulfur hexafluoride has an atmospheric lifetime of around 3,200 years due to its chemical stability, whereas carbon dioxide has an atmospheric lifetime between 300 to 1,000 years.

From this information, it is clear that although SF₆ is not nearly as commonly emitted as other major greenhouse gasses, its effect is even more disastrous. In the electricity industry, it has the biggest impact – even though we are now beginning to see the harmful effects of this gas on the environment and are trying to lessen its impact, developing countries are still catching up on technological advancements and so their electrical switchgear still contains SF₆.

Due to more research on sulfur hexafluoride, more countries and political powers across the world are beginning to focus on how to lessen its footprint in our environment. The first big step was the United Nations’ Kyoto Protocol in 1997 highlighting SF₆ as a major greenhouse gas and limiting participating countries’ emissions. However, the most effective way to take action and regulate SF₆ emissions across the board is improving practices of management when it comes to technology containing the gas. By accurately recording the amount of SF₆ gas used in one setting as well as checking for and fixing leaks, accidental emission into the atmosphere can be avoided altogether.

Major organizations involved with the betterment of the environment have also been looking into reducing the footprint of SF₆ in both the electrical sector and the environment. The United States Environmental Protection Agency (EPA) has shared practices on how to reduce SF₆ emissions, including leak detection and repair, employee training for those that do come across this gas in their work, and the use of recycling equipment when handling. The EPA also suggests that by reducing SF₆ emissions and finding an alternative for this gas, electric power systems will ultimately save money and make their equipment more reliable.

Companies are also searching for their own alternatives to sulfur hexafluoride and phasing out of their technology, replacing gasses and improving their equipment. General Electric has phased out SF₆ for g³ (a gas mixture based on fluronitrile and CO₂), which the company developed specifically for high-voltage (HV) electrical transmission equipment. Their alternative offers products with the same reliability of those with sulfur hexafluoride – however, the g³ alternative has more than 99% less gas global warming potential. The UK-based utilities company National Grid has partnered with Hitachi Energy to develop and make accessible a replacement product for SF₆ gas-insulated switchgear. The Kyoto Protocol was the first step in identifying sulfur hexafluoride as a threat to the atmosphere; there is still a long way to go to make sure this gas is eliminated from our technology, but companies like General Electric and National Grid are paving the way.

This incredibly impactful gas deserves more attention, especially as those in power try to find a way to reduce humanity's footprint in the environment. The United Nations Climate Change conferences have begun this important work, but it is now up to to those engineering power systems to find a way to both reduce emissions and replace SF₆ with an environment-friendly alternative.

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