National Grid Electricity Transmission (NGET) is trialling two new innovative projects to cut harmful environmental emissions. From reducing sulphur hexafluoride (SF6) from its pipework, to trialling a cement-free concrete, these projects that are currently being piloted at Deeside Centre for Innovation (DCI) are another step forward on the journey to meet net zero targets.

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.

Low-Carbon Concrete

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 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 with a Portland 100% cement binder.

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.

Alexander Yanushkevich, DCI manager at National Grid says: “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.”