Pumped Storage Hydro

Seismic surveys under way for ‘Hollow Mountain’ pumped storage

Seismic surveys under way for ‘Hollow Mountain’ pumped storage
(photo courtesy Drax)

As it progresses plans to build a new 600 MW underground pumped storage hydro plant adjacent to its Cruachan facility, Drax is performing seismic surveys to provide crucial geological data about the rock in which the new plant would be housed.

The process involves drilling holes into the rock and laying small explosive charges that are detonated to produce a powerful sound wave within the rock mass. The sound wave is expected to penetrate up to 60 m below the ground surface before its reflected signal fades away. Geophones mounted on the ground measure the progress of the sound waves to provide information about fractures, fissures or potential weak spots in the rock.

Drax is expanding the existing Cruachan pumped storage hydroelectric generation station located beneath the Ben Cruachan mountain in Argyll, Scotland, which was officially opened on Oct. 15, 1965. Cruachan can reach full load of 440 MW in 30 seconds and can maintain its maximum power production for more than 16 hours if necessary.

The expansion, known as Cruachan 2, will offer long-term and large-scale energy storage, thereby solving intermittency issues for the UK’s electricity system. Cruachan 2 will be built within a new, hollowed-out cavern to the east of Drax’s existing pumped storage hydro station. The project, expected to be operational in 2030, will bring an additional 600 MW of power.

“The expansion of Cruachan will be one of the most significant engineering projects in Scotland for many decades,” said Steve Marshall, development manager. “The start of these seismic surveys of the mountain is a real milestone moment for the project and everyone at Drax is excited to see the development take another step forward. These surveys will further complement borehole drilling works undertaken in 2022 and 2023 at the site.

“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.”

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