National Grid test two new carbon cutting approaches at Deeside Centre for Innovation

SF₆ is a gas commonly used in the electricity industry to prevent short circuits and to keep the network safe and reliable. UK-based Rawwater and NGET have started work on delivering a novel method of sealing harmful environmental SF₆ leaks by reducing emissions from small-bore pipework. The process uses Rawwater’s M3 Molten Metal Manipulation technology and is one of a number of approaches being used by NGET to tackle emissions of SF₆, including its collaboration with Hitachi Energy to replace SF₆ in existing high-voltage equipment with a greener alternative.

Rawwater’s M3 process involves the use of either a ‘leak extinguisher’ alloy spray or an easily deployed ‘CollarCast’, where molten alloy is cast into a custom-made, reusable mould. Both application techniques are low temperature and require no curing time, allowing for in-service application against flowing leaks. 

NGET has tested Rawwater’s M3 alloy spray in difficult-to-access areas to demonstrate its deployability in restricted environments. The M3 CollarCast process has been trialled to heavily mitigate flowing nitrogen leaks (used to simulate SF₆) at pressures of up to 7bar, without the need for a system outage. The reversibility of M3 (a simple process involving reheating) has also been demonstrated, to show that equipment can be returned to its original state for access to the pipework for any reason, with any recovered alloy being retained for reuse. As a result of these successful initial trials, National Grid and Rawwater will now test the leak-sealing capabilities of M3 Molten Metal Manipulation against contained SF₆ leaks.

Kat Lennox, Managing Director of Rawwater Applied Technology comments: “We are delighted to be working with National Grid. There are countless SF₆ installations in electricity generation and supply globally. Even though the phase-out of SF₆ is planned around the world and alternative gases exist for gas-insulated switchgear, it will be many years before this highly insulating greenhouse gas is eradicated from electricity supply networks. Until that day, a rapidly deployable solution is required to seal or mitigate SF₆ leaks. This successful trial gives us confidence that Rawwater’s M3 Molten Metal Manipulation is part of the answer.”

Another innovation project currently underway is the testing of a new patented concrete mixture called Cemfree, which potentially has a carbon footprint of 80% less than conventional types.

Cemfree is a cement-free alternative to conventional concrete and a ground-breaking milestone in low-carbon concrete technology.

Typical barriers to adoption of innovative concrete products include how they will behave on site and long-term durability. To address this, NGET is currently testing two large scale slabs (~50m³) to identify the differences in performance between Cemfree and a conventional concrete.

In addition, smaller monitoring strips have been cast with probes to detect any early corrosion of reinforcement. The aim is to obtain real world experience using the product with a view to future use on NGET substations and throughout the wider construction industry.

Using Cemfree for just one slab foundation at Deeside has saved approximately 13 tonnes of CO₂ emissions, when compared to a Portland 100% cement binder. These savings could be magnified by increased adoption in the UK construction industry, which uses circa 20 million m³ of ready mix concrete each year.

DCI will be the first test centre in Europe where innovations can be tested to voltages of up to 600kV at an off-grid substation, bridging the gap between laboratory testing and installation in a connected and operational substation.

Its ambition is to become a globally recognised centre for innovations and collaborations in all green technologies. Deeside’s role in speeding up carbon-free and cost-saving technology is expected to save households and businesses £300m by 2050.

Adam Gittins, Cemfree Commercial Manager, said: “It’s been a fantastic opportunity to partner with National Grid at Deeside. Innovation is challenging, especially in construction, as the benefits of any new technology are constantly at odds with the perceived risks. To be successful, innovators like National Grid must find a way to balance both sides to achieve their goals and this is evident at Deeside. By better understanding the durability performance of Cemfree, it will enable the material to be specified more broadly for appropriate applications on future NGET substations. This collaboration has already saved approximately 13 tonnes of CO₂ on such a small area of work and has the potential to save much more moving forward. We’re excited to support this important journey.”

Alexander Yanushkevich, Deeside Centre for Innovation Manager, at National Grid said: “Projects such as the trial of Rawwater’s M3 leak-sealing capabilities, where we are investigating new techniques to prevent loss of SF₆ to the atmosphere, are just one of the ways innovation can contribute to National Grid’s commitments to reduce emissions and help achieve Net Zero. 

“We are always looking for new ways to innovate and the Cemfree trial is also very exciting with considerable carbon-saving potential. Initial results have been very positive, and we will continue to explore its potential as a sustainable alternative to traditional concrete.”

Learn more about the Deeside for Innovation Centre and find out more about how National Grid is also developing and deploying a new future solution to replace SF6 with a greener alternative.