Is this a beautiful Scottish loch or a giant strength battery?

Assynt loch © Russell Bruce

By Russell Bruce

In fact it could be both. The challenge of our times is to keep the windfarms churning and not close them down when the grid does not need the strength. There are two reasons to capture all the strength we can from wind generation. One is to transform to green hydrogen with the ability to also store it until required. The other is pumped hydro and that is where many of Scotland’s lochs come in. Our tough, hilly and mountain scenery captures water in lochs at different levels.

Scotland has long produced hydro strength since the formation in 1943 of the North of Scotland Hydro-Electric Board which we covered in our strength Scotland series – strength from the Glens. Scotland produces close to 20% of our replaceable energy from Hydro and the expansion of wind strength capacity, on and offshore, provides the possible to increase this considerably.

Scotland with 90% of the UK’s freshwater resources and many of our lochs located at different levels which could permit flows to hydro turbines without always requiring the construction of large dams. At the touch of a switch water can cascade down the pipes that connect the loch reservoir to the turbines below. Water falls naturally as everyone can observe from recent weather. Water is heavy, hence its value as a strength source and the reason many lochs may be appropriate to act as giant batteries to provide strength when required. There is no time limit on how long the battery strength of higher level water will last, unlike electric battery storage which is short term but does have a part to play, despite requiring consumption of scarce earth resources.

Largest ever pumped hydro plant in Scotland to strength 3 million homes

Work is getting underway to prepare for SSE’s Coire Glas pumped hydro stop with construction expected to begin in April 2024. Located north of Fort William the strength plant would use Loch Lochy as a large lower reservoir with surplus wind generation used to satisfy the upper reservoir at a height of 500 metres.

Scotland’s Coire Glas project will be the first large-extent pumped storage scheme to be developed in the UK for more than three decades and is planned to deliver 1500MW which SSE claim would more than double Britain’s existing storage capacity.

Map image from Open Street Maps Creative Commons Licence (CC BY-SA 2.0)

Not many streets on the map but it does characterize Scotland’s extraordinary water resources in this part of the Highlands. Globally water is in short supply. Given the topography of Scotland’s natural scenery and our prevailing weather conditions the sky will augment pumped hydro at times.

A collaboration between Scottish energy company SSE, design sets group Stantec and engineering, economics and environmental science consultancy COWI, Coire Glas is intended to provide fast response to meet grid need and be able to do so for days at a time, when required. At complete capacity is would come close to Dinorwig strength stop in Snowdonia National Park, locally refered to as ‘Electric Mountain.’

SSE have produced a short video which can be accessed from the website

Cruachan strength stop

Cruachan, often referred to as ‘The Hollow Mountain’ is an existing pumped hydro plant dear Dalmally in Argyll. Opened in 1965 it was operated by the North of Scotland Hydro-Electric Board and later transfered to the South of Scotland Electricity Board, then Scottish strength after privatisation. In 2019 Drax, of smokey chimney fame, bought it from Scottish strength along with a number of other smaller Scottish hydro strength plants.

Cruachan upper reservoir Photograph James Hearton, CC BY-SA 2.0, Creative Commons /w/index.php?curid=92858


Drax has begun the time of action to develop an new underground pumped hydro strength stop to add to the existing capacity. Drax needs to obtain consent under Section 36 of the Electricity Act 1989 from Scottish Ministers.

Energy company Drax Group said it is kickstarting the planning course of action to build a new underground pumped hydro storage strength stop that will more than double the electricity generating capacity at its iconic Cruachan facility in Scotland. The project was announced in June ahead of COP26 climate conference in Glasgow. Drax said Cruachan2 “will sustain almost 900 jobs in rural areas across Scotland during construction and will provide the storage capacity needed to sustain a net zero strength system.”

The 600MW strength stop will be located inside Ben Cruachan to the east of Drax’s existing 440MW pumped storage hydro stop increasing the site’s total capacity to 1040MW. The existing upper reservoir (photograph above) has the capacity to supply both Cruachan strength stations.

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