Statnett Reduces Carbon Footprint - Building Four New 420 kV Stations Without The Powerful Greenhouse Gas SF6

Statnett is in the process of constructing four new transformer stations completely free of the powerful greenhouse gas SF6. This is the first time the new technology is being used throughout the entire facility at a voltage level of 420 kilovolts.

Most of Statnett's facilities are air-insulated and located outdoors. Gas-insulated facilities take up less space and are built particularly where space is limited. Statnett has a large inventory of SF6 as gas-insulated facilities use the greenhouse gas as an insulation and extinguishing agent in enclosed facilities and other components. Each year, an estimated leakage of between 200-500 kilos of SF6 gas occurs from our facilities.

Statnett aims for no new facilities to contain SF6 by 2050 and is working purposefully to adopt alternative gases through new technology. The total inventory of SF6 will thus decrease as new facilities are built without SF6 and older facilities containing SF6 are replaced gradually. Statnett is also working on online monitoring to control potential leaks better.

First in Scandinavia
Statnett is in the process of building the new 420kV substations Hyggevatn and Skaidi in Hammerfest municipality, as well as Liåsen and Ulven in Oslo. These four stations are being built with technology that is one hundred percent free of SF6, both in passive and active components, including circuit breakers.

The four new substations will be the first in Scandinavia to use the SF6-free technology at a voltage level of 420 kV.

—This is a major milestone marking the start of complete SF6-free facilities for 420 kV in Statnett. Every kilo of SF6 corresponds to 25,000 kilos of CO₂ equivalents, and the benefit is therefore significant when using alternatives in such facilities. This will contribute to a significant reduction in Statnett's long-term carbon footprint," says Executive Vice President for Technology and Transformation, Ingeborg Øfsthus.

If the four new stations had been built with SF6 gas, it would have resulted in installing 22,5 tons of SF6 gas in the grid. This is now avoided by using alternative gas.

Adoptingnew technology to phase out SF6
It has been a long technology and qualification journey in close collaboration with several high voltage equipment suppliers to find replacements for the greenhouse gas in Statnett's 145 and 420kV substations. We are very proud to be part of this journey at Statnett and install one of the first 420kV GIS 100% SF6 free 63kA –40C in Scandinavia," says Guilhem Blanchet, VP for Technologies development substation at Statnett.

The technology has been commercially available at lower voltage levels, but it is only now, that the technology is available for the 420 kV voltage level.

The construction of Statnett's new Hamang transformer station in Bærum has been a pilot project where only the passive components of the gas-insulated substation were built without SF6 gas, resulting in a 17 percent savings. The station was commissioned in 2024, and based on this experience, the new stations are being built entirely without the greenhouse gas for both passive and active components.

Hitachi Energy have been awarded of the contract for the delivery of Liåsen and Ulven, and the GE Vernova for Hyggevatn and Skaidi 420 kV stations.

When does Statnett build gas-insulated and air-insulated cacilities?
Statnett owns and operates over 200 stations in Norway. Most of our substations are air-insulated facilities located outdoors, also known as AIS facilities (Air Insulated Switchgear). These outdoor facilities contain little SF6.

Statnett will primarily seek to build AIS facilities as these facilities contain little SF6, are cheaper, and easier to operate. An AIS facility takes up more space than a gas-insulated facility (GIS), which is more compact, and GIS facilities are built particularly where space is limited, and it is not possible to build AIS. Around 50 of Statnett's facilities at higher voltage levels are gas-insulated switchgear type. These have so far contained SF6 because the facilities use greenhouse gas as an insulation and extinguishing agent in enclosed facilities and other components. All new 145kV and 420kV GIS substations will be built SF6-free.

Further research path
Statnett participates in the European Commission's research and innovation program "Horizon Europe" through the project MISSION (eMISsion-free HV and transmisSION switchgear for AC and DC). In this project, Statnett is developing, designing, and testing a pilot for the world's first 420 kV air-insulated SF6-free circuit breaker says Guilhem Blanchet, VP for Technologies development substation at Statnett.