Pumped storage |
Underground energy revolution ahead
As the UK gears up for a renaissance in pumped storage hydro, Angus MacGregor emphasizes the importance of sustainable practices and community impact in achieving net-zero goals by 2030
Acknowledgment
An earlier version of this article appeared in IOM3 Materials Works October 2024.
Angus MacGregor is a Registered Ground Engineering Professional at BAM Ground Engineering
IN THE UNITED KINGDOM there are exciting times ahead for those with an interest in all things that lie beneath the ground, as we look for ways to provide long term energy storage in the form of pumped storage hydro. On the journey to net zero, and Clean Power by 2030 with closing date for Ofgem’s Cap and Floor mechanism just passed (9 June 2025) the prospects seem even more real. The cap and floor regime provides a minimum revenue floor for LDES operators to manage high capital costs and long build times, while the revenue cap lowers costs for consumers. The UK Government introduced the scheme to encourage LDES investment and appointed Ofgem as the regulator based on our interconnector cap and floor experience. With career-long exposure (arguably life-long) I
examine specifically in terms of what we will – and should – leave behind. Our positive lasting legacy : in engineering excellence, reduced emissions, and some very social and human considerations. Underground mining and construction continues
Above and below: Glendoe project, 2013
to be active throughout the United Kingdom with exciting things happening across the nation. North of the Highland Boundary Fault, in the strong rocks of the Highlands of Scotland, the last major boom in underground construction arguably spanned 100 years from 1870. Principally for Scotland’s hydro generation schemes for domestic power and aluminium production, these construction activities all-but ceased by 1976. In more recent times, activities that continued these skill sets included Connonish Gold Mine (Stirlingshire, Scotland), Lochaline Silicia Mine (Lochaber, Inverness-shire) and the Duntallich
Mine (Aberfeldy, Perthshire) with construction activities limited to Glensanda’s various supporting projects (Highlander etc.) (Morvern, Argyll) and Glendoe (by Fort Augustus, Inverness-shire) – this last being the only modern day hydro project with significant underground construction. Otherwise, these skills were lost to other national or international projects, as workers sought opportunities suited to/ which matched their specialisms, with many never to return to the area. The last pumped storage hydro project with significant underground construction in these areas was Foyers Pumped Storage, completed in 1976. The scheme converted the 1876 conventional hydro scheme (associated with aluminium smelting) to pumped storage hydro, with this, the most major recent example, now falling well outside the lifetimes of many current professionals in the field.
Renaissance in pumped storage? In 2025, plans to meet our net zero commitments, and
the ambitions for Clean Power by 2030: we approach a potential renaissance in pumped storage hydro, and as a result in vast underground construction in several locations. Firstly, developments are planned that will be similar in scale to the existing Cruachan Power Station (AKA Hollow Mountain, located at Dalmally, Oban, Argyll, Scotland) and Foyers Power Station (Foyers, Inverness, Scotland). Moreover, the largest generating capacity schemes being explored are Coire Glas and Fearna (both Invergarry, Inverness, Scotland), Glen Earrach (Invermoriston, Inverness-shire, Scotland), Earba (by Laggan, Inverness-shire, Scotland), and Bailliemeanoch (by Dalmally, Oban, Argyll). Additionally, the recent report by Biggar Economics (2023) identifies various other schemes which total 6GW potential generating capacity. These include the expansion of the existing Cruachan Scheme, adding a further 600MW of generating potential there. ESO Futures Scenarios 2023 report identifies 15GW of energy storage projects in pipeline which will again inevitably involve aspects of underground construction and tunnelling in the form of pumped storage hydro for long term energy storage. At the British Hydropower Association Pumped Storage Hydro event (July 2024, London), a future scenario of requiring long duration storage of 12GW by 2035 and 20GW by 2050 the majority from pumped storage hydro, as a proven and stable technology, was tabled. Excited and experienced as we are about this
sector and its somewhat resurgence, in looking ahead to these projects, I think it is important that we look to the past for information on solutions we
18 | July 2025 |
www.waterpowermagazine.com
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