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New breakers: From climate risk to green technology
Many large circuit breakers are filled with sulphur hexafluoride (SF6) – a greenhouse gas that is 24,300 times more powerful than CO2.
The EU has already required mandatory reporting and phasing out of the greenhouse gas SF6.
The reason is that even small leaks cause large emissions. SF6 gas is already heavily regulated and managed, but circuit breakers have so far been excempt from the ban.
From January 2026, new breakers in medium-voltage systems up to 24 kV must be SF6-free, while the deadline for the highest voltage is 2032.
Norway is expected to introduce similar regulations soon, and the industry wants to be at the forefront of the changes.
Adapting breaker design and function for SF6 alternative
The 11 largest power grids in Norway have already signed a joint agreement to stop buying new grid components that contain SF6 gas.
But intentions alone are not enough. So what will the breakers look like, and how will they function without the use of SF6? And how will we get there?
Researchers are working on this now. SINTEF, NTNU, and the ABB group are collaborating to develop breakers that can replace some of these 'climate bombs' in the power grid.
“Replacing SF6 in circuit breakers is technically demanding and involves a number of compromises,” says Nina Sasaki Støa-Aanensen, a senior researcher at SINTEF Energy.
More on that shortly.
Why do we have breakers in the grid?
Have you ever been vacuuming and simply pulled the plug out of the wall instead of using the vacuum cleaner’s on/off switch?
Did you notice a tiny flash of light inside the socket? What you saw was an electric arc flash.
Circuit breakers are absolutely crucial for controlling the flow of energy in the power grid. The small arc in your home electrical system can just die out on its own, because the voltage is so low.
But every time the power has to be disconnected in the much higher-voltage power grid, arcs are created that can reach temperatures above 10,000 degrees Celsius.
Disconnecting the power is sometimes necessary in situations of extreme weather, falling trees, and power outages – or in the worst case, sabotage.
So breakers need to be able to extinguish these arcs safely.
Breakers are like small fire stations in the grid
These breakers have to simultaneously isolate the high voltages to prevent current from finding unwanted paths, Støa-Aanensen explains.
“Breakers are almost like small fire stations in our electrical grid – they extinguish the flames and prevent the fire from flaring up again,” says the researcher.
The circuit breakers must also be able to withstand extreme climate conditions, from bitter cold to extreme heat, humidity, and salty air, she adds.
“And they have to be reliable for several decades, like 40–50 years. SF6 has been a ‘magic gas’ in meeting all these needs. It has been challenging to find alternatives that are both environmentally friendly and technically on par with SF6,” Støa-Aanensen says.
This requires expertise in electrical, mechanical, and thermal design, as well as extensive calculations and physical testing.
Can air solve the climate problem?
It's crucial that researchers and industry collaborate closely to find suitable solutions.
Research efforts have included testing the use of so-called technical (or dry) air as a switching medium – that is, the gas inside the breakers.
“In this particular project, we’re working on a solution using pressurised air. We use twice as high a pressure as exists in the atmosphere, for both circuit breaking and insulation,” says Støa-Aanensen.
Air has a global warming potential of zero and meets EU requirements while solving the switchgear’s greenhouse gas problem.
“To achieve the same performance using pressurised air instead of SF6, we have to increase the filling pressure in switchgear. At the same time, we need to improve the internal design, ranging from the switchgear itself or 'fire extinguisher' to all the transitions between the different materials,” she says.
The researcher says they have found that it works well over time when exposed to arcs.
So perhaps that solves the problem? It’s not quite that simple.
Forever challenges: PFAS
Even though the researchers have found solutions that allow SF6 to be phased out, challenges remain. And this concerns not only the gas inside the switches, but also the switch housing itself.
“All breakers contain PFAS – so-called forever chemicals,” says Støa-Aanensen.
PFAS come in many variations, but they are characterised by important technical properties: They can withstand high temperatures, they have low surface tension, and provide good electrical insulation, the researcher explains.
But just like SF6, PFAS also have problematic aspects.
PFAS do not easily degrade in nature and can accumulate in the environment and body.
The first prototypes have been tested, with promising results
"So even though we’ve solved a major problem by going SF6-free, we may also have to replace other materials that are used in today’s switches," says Støa-Aanensen.
PFAS are not yet banned in the EU, but environmental agencies from five countries, including the Norwegian Environment Agency, have proposed broad restrictions for PFAS.
“The proposal will come up for political consideration in the EU in the coming years,” says Støa-Aanensen. “In the collaborative project with ABB and NTNU, we are therefore trying to find solutions that are not only SF6-free, but also free of PFAS in the switch chamber itself. The first prototypes have been tested in the lab, with promising results.”
Research and industry hand in hand
FreeSwitch is the project that Støa-Aanensen is referring to.
This project is based on more than 20 years of collaboration on research and industrial development.
“This is a typical example of how research and industry can drive green transition together,” says Martin Kristoffersen, the project leader at ABB’s technology centre.
ABB has had a factory in Skien for over 100 years, has almost 1,000 employees, and is the city's largest workplace. ABB has several divisions across nine locations in Norway, and employs a total of 2,200 people nationally.
"Creates jobs"
The fact that ABB still has a factory in Skien is also linked to its close collaboration with SINTEF and NTNU, says Kristoffersen.
“When research environments are connected directly to us in industry, we gain both technological solutions and competitiveness. This arrangement ensures high quality and reliability when we develop products for the future distribution of electrical energy – and that creates jobs,” he says.
In this way, the research collaboration is not only a climate measure, but simultaneously strengthens Norwegian industry.
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Read the Norwegian version of this article on forskning.no
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