Pumped storage |
“If consented, the scheme will provide an economic and employment boost to the local area and help provide balance to our increasingly renewables-led grid, during times of peak demand. This latest proposal, alongside our other investments in the technology, are a further example of the importance of hydro as a key part of a homegrown UK energy system.”
Above: The Cruachan Dam and reservoir, part of the pumped storage project nestled in a valley on the mountain Ben Cruachan in the Highlands of Scotland. Expansion plans are underway
Sloy Power Station is currently the UK’s largest conventional hydroelectric plant, producing approximately 130 million kilowatt hours of electricity per year in average rainfall conditions. The plant uses water carried from Loch Sloy through a tunnel and steel pipelines to power four Francis turbines. The environmental impact of the project is
addressed in a report covering areas such as ecology, water, noise, heritage, and transport, which is available on the SSE Renewables website.
Digging deep at Coire Glas Located on the banks of Loch Lochy, near Inverness
in Scotland, Coire Glas will be the first hydro storage project of its size to be constructed in the UK since Dinorwig Power Station in the 1980s. Conwy-based provider of borehole geophysical and petrophysical logging technologies and services Robertson Geo was contracted by Strabag UK Ltd to collect a comprehensive set of geotechnical statistics for the development. Driven by energy firm SSE Renewables, the site will have a potential capacity of up to 1300MW, generating enough power for up to three million homes in a matter of minutes.
Robertson GEO Managing Director Simon Garantini said the business – which also has locations in the US and Hong Kong – deployed a suite of geophysical probes in an exploratory tunnel more than one kilometre long and 700m below ground level. A “challenging” task, he revealed the operation
required equipment and new techniques they had never used before, including a 2000m winch enclosed in a safety cage “The exploratory work being undertaken for
Coire Glas is among the most extensive ground investigations of its time, collecting and analysing a huge volume of geotechnical data before construction begins,” said Garantini. “The comprehensive scope of the ground investigation is not least required due to the site’s proximity to the Great Glen fault line, which is visible from outer space. “The geotechnical data will observe ground conditions to inform on the potential risks and challenges posed to a successful delivery of the project, so this was a hugely important task, pivotal to them moving forward.” The tunnel included three “galleries” from which a series of long, near horizontal and angled boreholes were drilled, and a series of short “televiewer” boreholes for imaging, deformability and stress testing. Work continued 24/7 with two teams of two engineers alternating on back-to-back 12-hour shifts. “Logistics underground could be difficult with equipment needing to be moved around underground whilst many other tasks were occurring simultaneously,” said Garantini. “The most challenging aspect of the logging operation was the development
Project roundup
The BHA recently gave a roundup of the UK’s pumped storage projects in the pipeline. Across Scotland these include: The 1.5GW, 45GWh Balliemeanoch in Argyll & Bute which is being developed by the ILI Group & AECOM. When fully operational it will have 30 hours of storage, feature a 110m high dam and a 2.8km, 9m wide headrace tunnel, a large catchment area and an upper reservoir storing 58Mm3 of water at a hydraulic head of 385m. The tail race will be into Loch Awe which is also used for the Cruachan project. Cruachan Expansion in Argyll and Bute will have a capacity of 0.6GW and 8.6GWh. Under development by Drax, the expansion encompasses the development of a new powerhouse, transformer cavern and tailrace tunnel adjacent to the existing power station to provide a further 600MW of generating capacity.
Glenmuckloch in Kirkconnel, Dumfries & Galloway will have a capacity of 0.2GW and 1.6GWh, and is being developed by the Foresight Group. The site is on a partially restored open cast coal mine which forms the lower reservoir with 200m of head. As the scheme is near several operational wind turbines with more in development, it makes an ideal site to provide grid balancing and energy storage. Loch Kemp Storage in Whitebridge has a capacity of 0.6GW and 9GWh. Near Fort Augustus in the Scottish Highlands it is being developed by Statera Energy and is one of three proposed projects to use Loch Ness as the lower reservoir. The project plan is to generate for 15 hours at 600MW, with a total storage capacity of approximately 9GWh. The scheme involves four new
saddle dams and four minor cut-off dams of 16-34m high around Loch Kemp to raise the current water level, enabling an upper reservoir of 21Mm3
.
Loch na Cathrach in Dores will have a capacity of 0.45GW and 4GWh and is under development by Statkraft. Formerly known as Red John, the scheme was approved by the Scottish Government in June 2021, and utilises Loch Ness as the lower reservoir and a newly constructed upper reservoir at 250m of head near Loch Duntelchaig. The system will employ three reversible pump turbines housed in an underground powerhouse, facilitating energy storage and generation. And then over in Wales there’s the Moel Tryfan project in Gwynedd where Caernarvonshire Crown Slate Quarries is developing this 0.1GW, 0.6GWh scheme from twin quarries. The site would use Alexandra Quarry as the upper reservoir with a capacity of 1.2 million m3
, with a hydraulic head of 250m and a headrace tunnel of
around 1.3km. The scheme is rated at 100MW for ease of planning but could be marginally increased to better meet regional energy storage needs
Plus in Llanberis there’s the 0.1GW, 0.8GWh Glyn Rhonwy scheme
which is under development by the Quarry Battery Company. Also known as Snowdonia Pumped Hydro, this 100MW project plans to form a new 1.3Mm3
reservoir in a former slate quarry. Planning
consent, grid connection and an abstraction licence were achieved in 2017. A main investor has been secured but the project awaits the progression of the government’s cap and floor mechanism. For more details see:
https://british-hydro.org/pumped-storage- hydropower/
24 | July 2025 |
www.waterpowermagazine.com
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