London Power Tunnels substation to be SF6-free

A new substation at Lambeth in south London is set to be the first in Britain with Hitachi Energy’s SF6-free gas insulated switchgear technology.

The new substation, which will be built for National Grid, is at the heart of the London Power Tunnels project and will form a new connection between the electricity transmission network and UK Power Network’s distribution network.

London Power Tunnels is a major initiative to rewire the capital, replacing ageing high voltage cables typically laid close to street level with new cables buried deep underground.

In phase one running from 2011 to 2018, some 32km of tunnels varying in depth from 20m to 60m were constructed across north London between Willesden in the west and Hackney in the east and from Kensal Green south to Wimbledon.

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Phase two, which was launched in Spring 2020, is a similar seven-year £1 billion (US$1.2 billion) initiative to extend the tunnels from Wimbledon through to Crayford in the east.

In total 32.5km of 3m diameter tunnels are planned across south London.

The new substation at Bengeworth Road, Lambeth, on which construction is expected to begin in 2023, will utilise Hitachi Energy’s EconiQ 400kV gas-insulated switchgear and gas-insulated lines containing no SF6.

National Grid, like other companies, is moving away from SF6 in switchgear due to its global warming potential, with ambitions to reduce its SF6 emissions by 50% by 2030 and to remove all SF6 gas from electrical assets by 2050.

“We’re delighted that Bengeworth Road substation, at the heart of London Power Tunnels, will be SF6 -free,” says Onur Aydemir, Project Director for London Power Tunnels.

“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.”

The project follows National Grid’s piloting of the EconiQTM retrofill solution at its Richborough 400kV substation, in which SF6 was replaced in gas-insulated busbars without changing the equipment, thus avoiding not only the environmental impact but also the cost of replacing equipment in existing substations.