COWI to advise on Scottish pumped hydro expansion project

Engineering consultancy COWI has been awarded a contract by renewable energy company Drax to advise on the expansion of the Cruachan pumped hydro plant in Scotland.

In collaboration with the engineers Studio Pietrangeli, COWI will provide consultancy services to support works in advance of the Front-End Engineering Design (FEED) of the project.

The team will provide technical advice for the geotechnical, jetty and marine structures and tunnelling elements of the project. Furthermore, COWI will provide input for the railway line beneath which the new access and tailrace tunnels will run.

Cruachan expansion

Drax is expanding the existing Cruachan pumped storage hydroelectric generation station located beneath the Ben Cruachan mountain in Argyll, Scotland.

According to Drax, it was officially opened on 15 October 1965 and was the first reversible pumped storage hydro system of this scale to be built in the world.

Cruachan can reach full load of 440MW 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 440MW pumped storage hydro station.

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The project, expected to be operational in 2030, will bring an additional 600MW of power – increasing the site's total capacity to over 1GW.

Steve Marshall, Drax's development manager, said: “Pumped storage hydro plants play a critical role in stabilising the electricity system, helping to balance supply and demand through storing excess power from the national grid.

"When Scotland’s wind turbines are generating more power than we need, Cruachan steps in to store the renewable electricity so it doesn’t go to waste...”

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The UK aims to reach 30GW of energy storage by 2030 to ensure sufficient balancing as more renewables are integrated into the grid.

Andy Sloan, managing director at COWI UK comments: “There’s a profound opportunity for hydroelectric developments in the UK, particularly in Scotland, which will not only address our need for long-term storage in the UK energy market but support our journey to net-zero by 2045.”