Scotland’s SSEN Transmission to install first 420 kV Green Gas for Grid gas-insulated substation

420 kV gas-insulated line filled with g3 at National Grid’s new Sellindge substation in the U.K. Credit: GE

SSEN Transmission announced this week that it has awarded a contract to GE Renewable Energy’s Grid Solutions business to manufacture, deliver and commission a 420 kilovolt (kV) Green Gas for Grid (g3) gas-insulated substation (GIS) at its new Kintore 400 kV substation in Aberdeenshire, on the north-east coast of Scotland. 

The 420 kV g3 circuit breaker at the core of the substation is being co-funded over a two-year period by the EU’s LIFE Programme dedicated to climate change. SSEN Transmission joined GE’s LifeGRID project earlier this year to contribute to the specification of the circuit breaker’s main performance requirements.

GE’s g3 technology is an alternative to sulphur hexafluoride (SF6), an insulating and switching gas that has been used for decades in high-voltage substation equipment. Identified as the world’s most potent greenhouse gas by the 1997 Kyoto Protocol, SF6 is estimated to contribute 23,500 times more emissions than CO₂, if leaked, and can remain in the atmosphere for up to 3,200 years.

While SSEN Transmission’s most material contribution to action against climate change is enabling the transition to a low carbon economy, the Scottish utility is also determined to tackle its own emissions. SSEN Transmission has set an ambitious goal to cut its greenhouse gas emissions by one third by 2026, making SSEN Transmission the world’s first electricity networks company to receive external accreditation for a Science Based Target in line with a 1.5°C global warming pathway.

”SSEN Transmission’s 420 kV g3 gas insulated substation order is further proof of the market’s acceptance of our technology as a game-changing alternative to SF6,” said Heiner Markhoff, CEO of Grid Solutions. “Because 420 kV is the highest voltage level used in Europe, it will demonstrate the scalability of GE’s g3 for all standard voltage levels,” he added.

GE says that its g3 products have the same performance and reliability as SF6 equipment but have a lower environmental impact over their lifetime. According to life-cycle assessments (LCAs), based on international ISO 14040/14044 standards, their CO2 equivalent impact is reduced by 99%, compared to SF6. At the same time, because g3 products have the same compact dimensions as SF6 products, there is no increase in emissions during the manufacturing process due to additional material, according to GE.

SSEN Transmission is one of 21 utilities in Europe – along with UK’s National Grid, France’s RTE and Germany’s TenneT – that have chosen GE’s g³ equipment to help reduce greenhouse gas emissions.

The 420 kV g3 substation is SSEN Transmission’s fourth g3 order. Last year, SSEN Transmission ordered the construction of a 1-km long g3-gas insulated line at its New Deer substation, as well as a 145 kV g3-gas insulated substation and a 420 kV g3 gas-insulated busbar for its Fort Augustus site.

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