Sulphur hexafluoride (SF₆) keeps our power grid safe, but its impact on the climate means it’s being progressively banned by the EU. With new grid expansion already required to be SF₆-free, scientists are racing to prove that the replacements can do the job.
Switchgear are the safety valves of the power grid. When a fault occurs, they have milliseconds to interrupt dangerous currents and prevent a cascade of failures across the network. To do this reliably, the gas inside the switchgear has to do more than just insulate — it must actively help extinguish the electrical arc that forms when the switchgear contacts open. SF₆ excels at both, which is why it has been the industry standard for decades.
The challenge is that its replacements are less well understood. Alternative gases may behave differently under extreme electrical stress, at varying temperatures, or after years of degradation inside sealed equipment. Before grid operators can install them at scale, researchers need to characterise how these gases perform; not just when they are new, but also how they will behave when they have been in operation for 30 to 40 years.
This is the challenge that a new Norwegian research project, NEMEGIS, is setting out to address. Short for “Next generation of environmentally-friendly gas-insulated switchgear”, the project will investigate whether the alternative insulation gases now entering the market can match SF₆’s reliability over the full lifetime of the equipment. The research includes both experimental and theoretical studies of how the new gases perform when they are fresh, and critically, how they hold up after years of use.
NEMEGIS builds on a completed project, New gases for GIS, which established fundamental knowledge about the discharge behaviour and insulation properties of the most promising SF₆ alternatives. Where that project focused on understanding the basic science, NEMEGIS goes further: it will collect real-world operating experience from SF₆-free switchgear already in service in Norway and across Europe, and combine that field data with accelerated ageing experiments in the laboratory.
The SINTEF-led project kicked off in Trondheim on Monday, and will be running until 2029. It brings together 25 partners from the entire value chain: research institutions, switchgear manufacturers, companies involved in maintaining the switchgear and the distribution and transmission system operators who will ultimately install the new equipment.
