Project summary

A novel technology is helping us fix leaks of greenhouse gas SF6 – a significant contributor to our company’s climate footprint – all while keeping our substations safely in service.

We worked with engineering technology company Rawwater to deploy innovative technology that can be used to seal flowing leaks – a fix that has previously required a planned outage.

Following successful development and trials, we’ve used the technology to fix leaks at some of our substations, preventing thousands of tonnes of emissions into the atmosphere.

Background

Sulphur hexafluoride (SF6) is an insulating gas commonly used in high voltage electricity equipment to prevent short circuits and to keep networks safe and reliable. However, it’s a potent greenhouse gas with a global warming potential many thousands of times greater than CO2.

While SF6 filled equipment is designed to be effectively sealed, small leaks do occur as equipment ages – and it often requires an outage for the gas to be removed, the repairs carried out, and the gas refilled again.

We have a programme of work underway to reduce our dependency on SF6 technology in England and Wales. We’re also working hard to find innovative ways to reduce its impact in the meantime.

One of these solutions is Rawwater’s novel ‘M3CollarCast’, which involves easy application of a mould to leaking pipework. A low-melting point liquid alloy is then injected into the mould. The seal requires no curing time once solidified, so it can be applied to equipment that’s in service.

Collaboration

In addition to Rawwater, we worked with other teams and organisations to bring this innovative solution to fruition in our network. National Grid’s Deeside Centre for Innovation hosted crucial trials, and Cardiff University provided invaluable support with further studies.

We were then able to initially deploy Rawwater’s technology in the field at Dinorwig and Sizewell substations – meaning that while leak repairs took place, power could continue flowing to the grid from two of the country’s largest hydroelectric and nuclear plants

Benefits for energy consumers

Since 2022, we’ve saved the equivalent of some 9,000 tonnes CO2 from direct SF6 emissions to the atmosphere. That’s involved applying 42 Rawwater seals at eight substations to date. 

And it’s all been done without the need for an outage. That’s because as well as reducing SF6 leaks, we can deploy this clever and cutting-edge new technology while keeping our critical infrastructure in service. That’s a double benefit for consumers, as we reduce environmental impact and keep electricity flowing around the country.

Gordon Wilson, Lead Innovation Engineer:

Rawwater’s technology is helping us reduce emissions of SF6 through outage-free leak repairs, for which there have traditionally been few or no options. So, it’s having a direct impact on our transition to a low carbon network.