A new state-of-the-art 400kV substation at Littlebrook near Dartford is now fully energised, National Grid have confirmed.

The facility enables transmission of up to 2GW of low carbon & renewable electricity from international interconnectors and turbines in the Thames Estuary & southern North Sea into a theoretical maximum of 1.5 million homes.

Since June 2019, NG’s power transmission division has worked with contractors Balfour Beatty and GE Vernova’s Grid Solutions to replace an existing substation on the north Kent site.

Innovative new cooling technology has eliminated the new plant’s reliance on sulphur hexafluoride (SF₆), the industry mainstay used by substation builders to stop overheating circuits fritzing out.

Engineers have deployed GE Vernova Grid Solutions’ innovative g3 gas-insulated busbar equipment, pictured, which is SF6-free.

As much as 5.6 tonnes of the atmosphere-scorching gas was saved, in line with NG’s ambition to halve its SF₆ emissions this decade, and clean all SF₆ from its electrical assets by 2050.

Net Zero construction methods were followed throughout the project, saving over 5,000 tonnes of CO₂ emissions against conventional means.  An onsite biodigester to handle waste water, steel manufactured in Britain, solar-powered electrics and EV charging points were among methods deployed.

Twelve miles off the north Kent coast is the 175-turbine London Array, jointly owned by RWE, Greencoat UK Wind, Emirati investors Masdar & a Québecquois bank.   At 630MW, the London Array was the world’s most powerful marine park when opened in 2013.

Four existing super grid transformers were moved from Littlebrook’s old substation to its replacement. A new transformer was delivered in July 2022.

Installation of underground cabling, overhead line connections and GE’s switchgear – the circuit board used to control, protect, and isolate electrical equipment – all featured.

Laura Mulcahy, senior project manager for NG Electricity Transmission, said: “Getting Littlebrook completed is a huge achievement for the team. We’ve had to overcome some difficult engineering and programme challenges. Reach this milestone is a real testament to the commitment and strong relationships of everyone involved.”

 Mark Wilson of GE Vernova’s Grid Solutions paid tribute. “National Grid has been a leader in removing SF6 from its network”.

“They energised our very first g3 product at their Sellindge substation in 2016”, Wilson recalled.

“This project represents the latest vote of confidence in GE Vernova’s SF6-free products which deliver the same performance and product footprint as traditional SF6 equipment, while delivering a 99% reduction in the gas contribution to global warming.”

Tony Wilson, managing director at Balfour Beatty Power Transmission and Distribution, said: “We are proud to have delivered this vital work on behalf of National Grid, using our extensive knowledge and integrated solutions in power transmission, to supply secure power to over 1.5 million homes for generations to come.”


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