Exploratory ground investigations are now underway at its existing Cruachan facility in Scotland, where the company plans to build a new 600 MW underground plant. A 70m deep borehole is being drilled to recover rock core which will be analysed in a lab to determine structural and geological stability for elements of the new plant.

The preliminary works are being carried out whilst the project awaits consent from the Scottish Government alongside an updated policy and market support mechanism from the UK Government.

Increasing the UK’s pumped storage hydro capacity is critical to enabling more renewable power to come online, strengthening the country’s energy security whilst helping Britain decarbonise.

Ian Kinnaird, Drax’s Scottish assets director, said: “This is a significant moment in the expansion of Cruachan. The project team has been working extremely hard to move the development forward, and the start of ground investigation works is the next phase in delivering this vitally important new plant.

“The scale of the proposed development matches Drax’s ambitions when it comes to tackling the climate crisis. More than 2 million tonnes of rock will be excavated to create a new cavern inside the mountain which will be big enough to house Big Ben on its side.

“Expanding Cruachan will strengthen the UK’s energy security by enabling more homegrown renewable electricity to come online to power homes and businesses across the country. This major infrastructure project will support hundreds of jobs and provide a real boost to the Scottish economy.”

The new underground 600 MW plant would be one of the largest infrastructure projects carried out in Scotland for many years, with Drax expecting the plant to come online in 2030 following a six-year period of construction and an investment of around £500 million.

Pumped storage hydro plants act like giant water batteries, using reversible turbines to pump water from a lower reservoir to an upper reservoir which stores excess power from wind farms and other low carbon technologies when supply outstrips demand. These same turbines are then reversed to bring the stored water back through the plant to generate power when it is needed.

In order to deploy this critical technology, Drax must secure consent from the Scottish Government alongside an updated policy and market support mechanism from the UK Government.

The existing lack of an appropriate framework for new long-duration, large-scale electricity storage technologies means that private investment cannot currently be secured in new pumped storage hydro projects, with no new plants built anywhere in the UK since 1984 despite their critical role in decarbonisation.