National Grid’s London Power Tunnels (LPT) project has reached a major landmark, with developers completing all 32.5km of the project’s underground route.
The £1 billion LPT project aims to rewire south London via deep underground tunnels to provide “safe and reliable” electricity supplies. The tunnels are three metres in diameter tunnels and are being constructed deep below the road network between Wimbledon and Crayford. These tunnels will carry high voltage electricity cables.
National Grid stated that with the completion of 32.5km of tunnelling, 200km worth of high voltage cable is now being installed between substations at Wimbledon and Crayford. An image of the underground tunnelling route can be found below:
The LPT project’s newly installed transmission infrastructure is due to be fully operational by 2026, with the aim of reinforcing and future-proofing London’s electricity network – and supporting Britain’s transition to net zero – as demand in the capital grows.
Construction of the tunnels began in March 2020 with the tunnelling works undertaken by National Grid’s delivery partner HOCHTIEF-Murphy Joint Venture (HMJV).
Alice Delahunty, president of National Grid Electricity Transmission, said: “Our London Power Tunnels project has achieved a lot since it kicked off in 2020, but the final tunnelling breakthrough at Eltham is a particularly remarkable moment.
“This complex engineering endeavour is now really taking shape, with completion of tunnelling now physically linking our sites across south London for the first time and meaning we can move on to the next chapter to progress our vital cabling work.
“The outstanding effort by our project teams and suppliers is strengthening London’s electricity network and making sure it safely, reliably and efficiently powers homes and businesses in the capital for years to come.”
Efforts to reduce SF6 from the LPT project
At the start of 2023, National Grid confirmed it would be using green technology to reduce the use of sulphur hexafluoride (SF6) across the LPT project.
SF6 has a global warming potential that is 25,200 times greater than carbon dioxide, but is a highly efficient electrical insulator. It can be utilised within various applications such as medium and high voltage switchgear and circuit breakers. As such, reducing its usage could be of huge benefit to the overall decarbonisation of the grid.
It is worth noting SF6 had been instrumental in the creation of the UK power network, however National Grid has made a commitment to reduce SF6 emissions by 50% by 2030, and remove such emissions entirely by 2050.
For the LPT project, it was confirmed that Hitachi Energy would deliver EconiQ 400kV gas-insulated switchgear and gas-insulated lines containing no SF6 to reduce the emissions of the Bengeworth Road substation.