First stage of ESO’s Pennine Voltage Pathfinder goes live

• First three shunt reactors are now live, helping to manage voltages on the national electricity transmission network. 
• These pathfinder reactors allow the ESO to maintain control of system voltages in the Pennines area, following the recent closure of large conventional power stations.
• Two reactors were able to start early in May 2024 and have operated on a near continuous basis since, allowing the ESO to avoid using more expensive and polluting options to maintain necessary voltage levels on the electricity network.
• The final asset from the Pennines Pathfinder is expected to go live in early 2026.

As part of the ESO’s 2025 ambition to deliver a national electricity network capable of operating safely and reliably whilst producing zero carbon, the ESO has been developing new solutions and alternatives to separate the delivery of electricity from the delivery of system services that keep the network in operational balance.

As older conventional coal and gas power stations close, the ESO has sought alternative solutions that can deliver a range of system services to maintain the optimal levels of voltage, inertia and other physical properties that allow Great Britain’s electricity network to be one of the most reliable in the world.

The latest of the ESO’s voltage pathfinders has recently gone live in the Pennines region with three shunt reactors installed by National Grid Electricity Transmission at its Stalybridge, Stocksbridge and Bradford West substations. The capability of these three reactors will maintain voltage on the network in this region, replacing the reactive power services from several power stations which have recently closed.

Since the first two reactors went live in May they have provided near continuous service, providing critical voltage management tools to the ESO’s control room and reducing the need to call upon other options such as fossil fuelled power stations. With the introduction of the third unit, further cost and carbon savings are expected, as they will further reduce the requirement to deliver voltage management from fossil fuelled power stations, reducing costs for consumers as a result.

In 2026, a further asset from Dogger Bank C windfarm will be introduced in the North-East to maintain voltage levels in this area and replace capability provided by current power stations.

Julian Leslie, Director of Strategic Energy Planning and Chief Engineer

“Delivering new services that can produce the reactive power tools such as voltage management that we use on a daily basis to keep the electricity network stable and secure is paramount to delivering our 2025 ambition and to deliver net-zero.”

“The continuous use of these shunt reactors since May demonstrates their incredible value for the electricity network and their importance in keeping bills down for consumers as we decarbonise the electricity system.”

Jon Davies, Director of Network Operations and Intelligence at National Grid Electricity Transmission, said:

“Making sure electricity supplies are stable and reliable is paramount as Britain’s energy system decarbonises. Our installation of these shunt reactors on our network as part of this innovative project is an engineering solution that supports ESO’s safe and secure operation of the system into the future, with significant savings for consumers.”