SF6-free, gas insulated switchgear is being installed on our network in the UK

In a first for the UK, 400kV SF6-free, gas insulated switchgear is being installed on our network.

While sulphur hexafluoride (SF6) is a fantastic insulating gas for assets like circuit breakers at our substation sites, it can be very harmful to the environment. In fact, it’s around 24,300 times more effective at trapping infrared radiation than the same amount of CO2¹. 

Across our transmission network, our teams have been working to tackle leaky assets and rethinking the way we look at insulating and interrupting gases (IIGs)   when planning new additions or changes to our network. New, SF6-free assets have also started to appear across our network – such as at Littlebrook, where the old substation site was recently replaced with a new substation, which features switchgear containing GE Grid Solutions’ innovative g³ gas in place of SF6.  

Storing and reusing SF6

At the moment, we’re purchasing SF6 for use in our assets while simultaneously decommissioning assets and substations in other areas. Reclaiming and storing SF6 taken from old assets would allow us to recycle it, deploying it where it’s needed on other sites and projects across our network.  

This would save the need to destroy old SF6. While properly destroying the gas is less environmentally destructive than the gas leaking into the atmosphere, this practice still has a significant environmental impact given the high temperatures needed to incinerate it.  

If we’re able to stockpile SF6, this has the potential to reduce our dependence on creating new SF6 in the short term and provide insurance to be able to maintain current assets into the future – a dual benefit, alongside the environmental considerations, as while some SF6 assets are reaching end of life, we have plenty that aren’t.  

What we’ve achieved so far

While the SF6 reuse trial and framework is still in its early stages, we’ve already managed to reclaim 19 tonnes during the decommissioning of the old Littlebrook site.  

Around five tonnes of this gas has already been taken by Siemens Energy for factory acceptance testing. This will determine the gas’s suitability for assets intended for use at Humber Refinery, demonstrating that original equipment manufacturers (OEMs) are happy to use this gas and developing the beginnings of a circular economy in this area.  

¹According to the Intergovernmental Panel on Climate Change’s (IPCC) sixth assessment report.