The Cruachan pumped storage plant in Scotland could see it capacity more than doubled as owner Drax Group seeks planning permission to expand the iconic project, often referred to as Hollow Mountain.

The project, announced as the UK prepares to host the COP26 climate conference in Glasgow, will support almost 900 jobs in rural areas across Scotland during construction and will provide critical storage capacity needed to support a net zero power system.

The 600MW power station will be located inside Ben Cruachan – Argyll’s highest mountain – and increase the site’s total capacity to 1.04GW. The new power station would be built to the east of Drax’s existing 440MW pumped storage hydro station. More than a million tonnes of rock would be excavated to create the hydro cavern and other parts of the power station. The existing upper reservoir will serve both power stations.

“This is an exciting and important project which underlines Drax’s commitment to tackling the climate crisis and supporting the energy system as it continues to decarbonise. Our plans to expand Cruachan will unlock more renewable electricity to power homes and businesses across the country, and support hundreds of new jobs in rural Scotland,” Will Gardiner, Drax Group CEO, said. “Last year, the UK’s lack of energy storage capacity meant wind farms had to be paid to turn off and we lost out on enough renewable power to supply a million homes. We need to stop renewable power from going to waste by storing it, and Drax is ready to move mountains to do just that.”

In order to expand the project, Drax must secure consent under Section 36 of the Electricity Act 1989 from Scottish Ministers – a process which takes around one year to complete from the application’s submission.

Alongside a successful Section 36 application, the project will also require an updated policy and market support mechanism from the UK Government. The existing lack of a framework for large-scale, long-duration storage and flexibility 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.

The first phase of the Section 36 application process includes public consultation this summer. Further consultation events are planned for later in the year, and an application is then expected to be submitted to Scottish Ministers in early 2022.

If it gets the go-ahead, building work on the project could start as early as 2024. 

An artist's impression of Cruachan 2 (top) and the existing Cruachan Power Station (bottom)