Electrical switchgear sits in the background in settings as familiar as offices, shops, and hospitals, yet some of it contains SF6, one of the world’s most potent greenhouse gasses. New regulation means this is set to change, however, as Phil Kane explains.
Electricians and electrical engineers rely on switchgear every day: it is the umbrella term for devices that control, protect and isolate power systems, and there are millions of them in operation.
Switchgear provides overcurrent and short circuit protection to downstream assets, but in recent years a concern that is unconnected with operational effectiveness has come to the fore. At the root of the problem is Sulphur Hexafluoride, more commonly known as SF6, which has been used as an insulator and arc extinguisher in some medium- and high-voltage switchgear for the past 50 years.
Comprising a sulphur atom and six fluorine atoms, each SF6 molecule is devastatingly dangerous to the climate. Of all the greenhouse gases, it is by far the most powerful. Just 1 kg of SF6 is equivalent to 23,500 Kg of CO2 in global warming potential, and each unit of switchgear is estimated to use 2.5 kg of SF6 gas. The scale of the problem is evident.
Why has industry used SF6 for so long?
Scientists first discovered how to make SF6 in industrial quantities during the 1960s – only a small amount occurs naturally. Stable, odourless, and colourless, it was used in applications as varied as insulating windows and providing the ‘bounce’ in tennis balls and vehicle tyres.
As the environmental dangers of fluorine gasses became apparent, however, governments started phasing them out. The EU’s legislative response to ‘F-Gasses’ included its 2015 ban on the use of SF6 in every application except switchgear, which was exempt because of its role as a critical safety feature.
This exemption has had unfortunate consequences. Far from fading away, the use of SF6 in electrical switchgear has increased because it is undoubtedly a good insulator which is widely and readily available. Counterproductively, it has even found its way into applications such as wind farms which are intended to reduce global warming.
Now the tide is turning, and the EU is set to announce an end to the exemption which is likely to come into effect across Europe during the mid-to-late 2020s. On 5 April 2022, the European Commission announced its proposal for a revision of the F-Gas Regulation.
The proposal that relates to switchgear currently includes a transition period which would effectively place a deadline of 1 January 2026 beyond which the use of SF6 would be prohibited in primary and secondary switchgear up to 24 kV, but this is far too late in our opinion.
With the fast-growing market for medium voltage switchgear likely to accelerate as Europe speeds up its transition to renewables, we believe the deadline for prohibiting the use of SF6 in primary and secondary switchgear up to 24 kV should be advanced to start as soon as the revised F-Gas Regulation comes into effect.
What a ban could mean for switchgear users
Well-proven alternatives are already available for switchgear rated up to 24kV. Eaton pioneered the use of SF6-free insulation methods many years ago, at much the same time as SF6 was discovered, back in the 1960s, and it seems we were ahead of the game.
Our vacuum switching technology is supported by more than 200 patents and in 2020 we shipped our one millionth SF6-free medium-voltage switchgear panel for applications up to, and including, 24 kV. We have 3,000 reference sites in 60 countries worldwide.
Gratifying as this is, we know that many electricians and engineers still need encouragement to choose SF6-free switchgear. Some worry about the expense of switching, others are wary of specifying an option that is unfamiliar to them, and some believe the misconception that SF6 doesn’t much vent to atmosphere because it is heavier than air.
Often, it’s a combination of all three factors that makes them reluctant to switch, but as soon as the anticipated removal of the exemption becomes law, they will have no choice but to consider alternatives, and may find their worries were largely unfounded.
Convenience and lifecycle savings
Costs may be of less concern to reluctant switchers when viewed over the average lifespan of switchgear, which runs into decades. Over that time, an SF6 option, which may look cheaper at the start, will be burdened by administration, and gas refills.
Handling SF6-filled switchgear requires specialised training and certification, but an air-insulated SF6-free alternative in a hermetically sealed enclosure is maintenance-free for at least 25 years.
Although many believe the weight of SF6 molecules could prevent dispersion, this is a fallacy. It is difficult to keep the molecules together. If handled incorrectly, at various points during the manufacture of switchgear, and certainly during end-of-life decommissioning, the molecules could diffuse and escape to atmosphere where they persist for thousands of years.
Renewables could make the difference
Renewable generation is driving growth in the new switchgear market and this ups the ante in more ways than one. Firstly, it means that much more switchgear will be installed and without the prompt enforcement of the ban that we believe is critical, there will be no barrier to the use of SF6.
Secondly, technologies such as wind turbines and solar panels require more frequent switching because of the way they work, which makes more frequent replacement likely. If SF6 is used – even during a transition period – its potential to leak during decommissioning could cause unnecessary additional damage to the environment.
Failing to mandate SF6-free switchgear across the EU as early as possible would be a missed opportunity. The switch to renewables is a real chance for the industry to ensconce SF6-free as the technology of choice for electrical switchgear up to, and including, 24 kV.
Much remains to be decided, but as the power industry is responsible for 80% of total annual SF6 emissions, electrical industry professionals clearly can do much to prevent further SF6 emissions from adding to what is already a worrisome burden on the environment.
If there is a good time to go SF6-free, and pre-empt likely new EU regulations, that time is right now.
Phil Kane is the Country Manager for Eaton in Ireland, the intelligent power management company that pioneered SF6-free switchgear.