National Grid has teamed with Hitachi Energy to deploy gas-insulated switchgear and gas-insulated lines at its Bengeworth Road substation as part of its London Power Tunnels project, in a UK first. The London Power Tunnels 2 project is a seven-year, £1bn project to rewire South London to meet future energy demands and replace technology that has reached the end of its life. It has already completed part one in 2018, which saw 32km of tunnels created across the capital. The tunnelling for London Power Tunnels 2 is being carried out by a Hochtief-Murphy JV, with Aecom as lead designer, and involves construction of 32.5km of 3m-diameter tunnels from Wimbledon in the west to Crayford in the east. The tunnels will be 30m to 50m below ground level and will have minimum design life of 120 years. The construction of the Bengeworth Road substation, in Lambeth, is being constructed by Linxon and is where the UK-first green grid technology is being deployed. Currently, electricity industry substations require the use of the gas sulphur hexafluoride (SF6) to prevent short circuits and keep the network safe and reliable – but it has high global warming potential. National Grid has a target of reducing its SF6 use by 50% by 2030 and eradicating it entirely from electrical assets by 2050. Bengeworth Road will be an SF6-free substation thanks to Hitachi Energy’s EconiQ 400kV gas-insulated switchgear (GIS) and gas-insulated lines (GIL), which contain no SF6 but enable the transmission of energy over long distances. Installation of the GIS and GIL is expected to begin in 2023, subject to prior approval of the substation by Lambeth Council. The EconiQ tech has been piloted as a retrofit solution at National Grid’s Richborough 400kv substation in Kent. On this project, SF6 was replaced in gas-insulated busbars without changing the equipment, avoiding the environmental impact and cost of replacing equipment in existing substations.

Bengeworth Road will Be the UK’s First Substation Purposely Built to Be SF6 Free.

London Power Tunnels 2 is expected to be completed by October 2026. London Power Tunnels project director Onur Aydemir said: “We’re delighted that Bengeworth Road substation, at the heart of London Power Tunnels, will be SF6 -free. This key power project will deliver a secure energy supply to the capital, and by using sustainable technology we are minimising the environmental impact of our operations and using transformational engineering to support the transition to net zero.” Hitachi Energy high voltage products business managing director Markus Heimbach said: “Following the successful collaboration with National Grid on the world’s first replacement of SF6 in existing high-voltage equipment and award-winning project in Richborough, UK, we are proud to be supporting National Grid again in its transition to SF6-free solutions. The EconiQ GIS is based on our breakthrough SF6-free 420 kV circuit-breaker that demonstrates the reliability and scalability of the technology for the lowest carbon footprint.” Linxon chief executive Stefan Reisacher added: “Linxon is building the infrastructure to power the world with carbon free energy. Thanks to strong collaboration with Hitachi Energy, Linxon is able to provide the pioneering EconiQ SF6-free solution from Hitachi Energy for the Bengeworth substation, supporting our client to meet their sustainability targets.”