Drax unveils plan to expand ‘Hollow Mountain’ Cruachan power station



Renewable energy company Drax Group is kickstarting the planning process to build a new underground pumped hydro storage power station – more than doubling the electricity generating capacity at its iconic Cruachan facility in Scotland.

Cruachan Dam holds back enough water to fill 4,440 Olympic-sized swimming pools

The project 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 within a new, hollowed-out cavern which would be large enough to fit Big Ben on its side, 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 cavern and other parts of the power station. The existing upper reservoir, which can hold 2.4 billion gallons of water, has the capacity to serve both power stations.

Like Drax’s existing site, the new station will be able to provide lifeline stability services to the power system alongside acting like a giant water battery. By using reversible turbines to pump water from Loch Awe to the upper reservoir on the mountainside, the station can store power from wind farms when supply outstrips demand. 

The stored water would then be released back through the turbines to generate power quickly and reliably when demand increases. This will help to cut energy costs by reducing the need for wind farms to be paid to turn off when they are generating excess power. The new station would have the capacity to generate enough power for around a million homes.

The new power station will be housed in a vast underground cavern like the current Cruachan power station

Will Gardiner, Drax Group CEO, said: “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.

“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.”

Drax’s decision to pursue planning approval has been welcomed by the Hollow Mountain’s local MP and MSP.

Brendan O’Hara, Argyll & Bute MP, said: “I am delighted that Drax is progressing plans to expand the Ben Cruachan site. This will support 900 rural jobs and create a pumped storage facility that will be able to provide enough renewable energy to power a million homes while helping us reach our 2045 net zero target, it is great news for this area and for Scotland.”

Jenni Minto, Argyll & Bute MSP, said: “Investment in new pumped storage hydro capacity could greatly enhance the flexibility and resilience of the electricity network and help us move towards meeting our ambitious global climate change targets. In the run-up to COP26 in Glasgow, it’s more vital than ever that we come up with innovative solutions to the climate emergency and ensure that future generations to reap the rewards of Scotland’s vast renewable potential.”

A labyrinth of underground tunnels and caverns would be created as part of the major infrastructure project

In order to deploy this critical technology, 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, when people can provide comments on Drax’s proposals for Cruachan via the project website from 1 July. 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.



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