Scottish and Southern Electricity Networks Transmission (SSEN Transmission) has become the first UK transmission owner to energise sulphur hexafluoride gas (SF₆) free technology, reaffirming its commitment to reducing its own environmental impact.

SSEN is currently preparing for the next transmission price control, RIIO-T2, which covers the period from April 2021 to March 2026. As part of this, the transmission owner has set five ambitious goals, one of which is a science based commitment to deliver a one third reduction in its greenhouse gas emissions, which is consistent with a 1.5 degree pathway, critical to achieve net zero targets. One of the key ways in which it will achieve this goal is to clean up the gases it uses to operate its critical transmission infrastructure.

For decades, SF₆ gas has been used extensively across the electrical industry as an insulating gas for switchgear in substations, with the electricity transmission industry responsible for 80% of the world's usage. SF₆ gas was chosen for its excellent insulating properties making it possible to reduce equipment size and improve reliability and safety.


However, SF₆ is a greenhouse gas that is 23,500 times more harmful to the earth's atmosphere than CO2 which if released, stays in the atmosphere for over 3,000 years. Its lifecycle management requires careful handling, particularly when decommissioning aging substations. Whilst leaks are relatively rare, when they do occur the environmental impact is substantial.

The SF₆ gas free circuit breakers installed at SSEN Transmission's substation in Dunbeath are the first of their kind in the UK. The technology has been developed by Siemens, using a combination of vacuum and clean air technology to provide the same level of performance and reliability, without the need for SF₆ gas and with no Global Warming Potential (GWP).

Commenting on this UK energy industry first, Dave Allan, SSEN's Head of Policy & Standards, said: "As a responsible operator, we are continually working to reduce the environmental impact of our activities and have set a stretching ambitious goal to cut our emissions by one third. While our most material contribution to action against climate change is our role in enabling the transition to a low carbon economy, we are also determined to put our own house in order and tackle our own emissions.

"By using this innovative new technology at Dunbeath, not only are we reducing the environmental impact on our own network, we are hoping that this will also demonstrate to the wider transmission industry that there is a viable alternative to SF6 out there, and one which they may consider using in similar scenarios in the future.

"We are extremely proud to be leading the industry in the drive to reduce greenhouse gas emissions and look forward to working with our partners across the industry to encourage even greater action in the battle against climate change."

As part of SSEN Transmission's commitment to reduce its greenhouse gases, it is working with suppliers to install SF6 alternatives across its network, as well as working with the Energy Networks Association to support industry wide adoption of these technologies.

(MH/JG)