Dating back to 1901, a French chemist Henri Moissan, who is well known for discovering a number of fluorine compounds, first formulated Sulphur hexafluoride (SF6). Nowadays, more than 70% of global SF6 usage is in some or other way connected to the (electric) power industry.
During the early stage of development of the switchgear industry, oil was being used as the arc-quenching medium, but owing to its drawbacks including fire risk and higher maintenance intensity, gradually SF6 was adopted as a better alternative.
Intensive research works on SF6 began in the 1930s, and it was first used as a switching dielectric in 1953. As per some sources, the first research into industrial applications of SF6 was conducted by General Electric in 1937, and the first high-voltage SF6 circuit breaker was produced by Westinghouse in 1959. At that time, it was used only in high-voltage load switches (15 to 161 kV) with a breaking capacity of 600 A. Later, with the development of puffer technology that uses a blast of SF6 under pressure to extinguish the arc generated when a circuit opens, SF6 started creating its own space in the switchgear industry.
Afterwards, it was realized that – although SF6 is a highly effective dielectric, and in spite of its superior arc quenching property, its high Global Warming Potential (GWP) may cause tremendous amount of damage to the environment. To be very specific, SF6 gas has a GWP of ~23,500 over a 100-year time horizon. In a simpler version, it traps 22,800 times more heat than an equivalent amount of carbon dioxide (CO2) over 100 years. SF6 is the most potent greenhouse gas known, and its atmospheric lifetime is extremely long, exceeding 1,000 years (approximately 3,200 years).
Protest against the use of SF6
Today SF6 is one of the major components of Gas Insulated Switchgears (GISs). In the latest applications, the entire switchgear is sealed in a tank filled with SF6, offering advantages like compact size and protection from the environment. However, the environmentally aware societies across the globe have been repeatedly demanding phase-out of the gas.
Although it is difficult to pinpoint any single mass-scale organised global protest against use of SF6 in the power industry, there are many instances of (isolated) protests across the globe. For example: in January 2017, a protest against SF6 in Bhangar, West Bengal, India, led to extreme violence. While the residents of Bhangar were protesting against a proposed power grid, their opposition escalated, resulting in injuries and fatalities.
The latest trend
According to the latest report of Research And Markets, “An emerging trend is the shift to SF6-free or low-GWP insulation for medium-voltage switchgear, as governments restrict SF6 usage (due to its high greenhouse potential). This transition fosters innovation in alternative gas compositions, vacuum technology, and solid insulation, with advanced sensor-equipped designs enabling real-time condition monitoring.”
Their report also states that high upfront costs and legacy infrastructure compatibility remain as barriers to the path of transition. Smart switchgear or digitally enhanced transformers, especially SF6-free designs, can be more expensive. Additionally, older distribution networks might require significant retrofits or replacements, complicating or delaying modernization.
A few examples of transition
In the next few paragraphs, I’ll try to draw a picture of transition in the switchgear industry highlighting a few (arbitrarily chosen) developments in the market that have happened within the last one decade.
Hitachi Energy
Just a few days (May 2025) back, the company has declared that it will deliver the world’s first SF6-free 550 kV Gas-Insulated Switchgear (GIS) to the Central China Branch of the State Grid Corporation of China (SGCC). SGCC is the world’s largest utility company, serving over 1.1 billion people across 88% of China’s national territory.
The SF6-free 550 kV GIS is part of EconiQ, Hitachi Energy’s eco-efficient portfolio for sustainability, where products, services, and solutions are scientifically proven to deliver exceptional environmental performance. This technology strengthens critical infrastructure while significantly reducing the environmental impact of the power system.
By replacing SF6 with a sustainable gas mixture, this GIS eliminates the greenhouse gas emissions caused by SF6 while maintaining the same reliable performance and compact design as the conventional solutions. Replacing SF6 is crucial for protecting the environment because it has a global warming potential 24,300 times higher than CO2 and remains in the atmosphere for over 1,000 years if it leaks from the equipment.
An official from the Central China Branch of SGCC said, “In recent years, SGCC has been comprehensively promoting the emission reduction of power grid equipment and its clean and low-carbon development. Using an alternative gas to replace SF6 can effectively reduce the consumption and emission of greenhouse gases. This project is the world’s first pilot application of 550 kV SF6-free GIS, which is of great significance to the Central China Branch of SGCC and will contribute to the clean transformation of the electrical industry to achieve the dual carbon goals.
Source: Hitachi Energy
Schneider Electric
Last year (October 2024), this company launched Ringmaster AirSeT in the UK. Ringmaster AirSeT is a next-generation SF6-free digital Medium Voltage (MV) switchgear, which is critical to the development of smarter, more sustainable electricity grids.
The product is targeted to help grid operators decarbonise and modernise their infrastructure and enable electric distribution utilities to improve operational performance and reliability.
Ringmaster AirSeT has a pure air design which replaces SF6, the greenhouse gas that is traditionally used in electrical equipment for insulation, with pure air. The use of pure air, which has a GWP of 0, removes the need for complex and costly gas recycling at end of life, minimising the Total Cost of Ownership (TCO) of the equipment.
The rollout of Ringmaster AirSeT in the UK was a key element of Schneider Electric’s ‘Grids of the Future’ programme and a milestone in its progress towards producing a complete portfolio of SF6-free switchgear by 2025. By eliminating use of SF6 in switchgear through an innovative and unique combination of pure air and Shunt Vacuum Interruption (SVI), the environmental footprint of electrical networks can be reduced.
Schneider Electric had invested £7.2million at its site in Leeds, expanding the facility so that it could produce the Ringmaster AirSeT in response to the increasing demand for Schneider Electric’s portfolio of green and digital switchgear products.
Source: Schneider Electric
Siemens
In 2019 Hannover Messe trade fair, Siemens showcased its 8DJH 12, an additional medium voltage switchgear that uses clean air as the insulating medium. Clean air is an insulating gas consisting only of the natural constituents of ambient air. The gas-insulated load-break switchgear (ring main unit) thus combines the sustainability of the ‘blue GIS’ portfolio with the benefits of the proven 8DJH product family. The switchgear was earlier used in public and industrial power grids on the secondary distribution level.
Epilogue
Although in the small expanse of this article, I have just included three developments in the industry, there are plenty of other examples. Companies like Eaton, Emerson Electric (GE Vernova Division), Mitsubishi Electric Corporation, and others are actively working in this field and delivering innovative SF6-free switchgears.
Most importantly, several countries and regions have already declared steps to restrict use of SF6 in switchgears. For example: the European Union has set a staggered phase-out of SF6-containing switchgears starting in 2026, with a complete ban on new medium-voltage equipment by 2030 and high-voltage switchgear by 2032. States like California and Massachusetts in the United States, have also implemented rules to limit or end SF6 use.
Not only harnessing renewable energy, but also a complete ban on use of SF6-containing switchgears in (electrical) power industry will have a substantial effect on global warming.
By P. K. Chatterjee (PK)
