The Scottish Pumped Storage Gold Rush

There's currently something of a "gold rush" of Scottish pumped storage schemes. This post collects information about this potential growth area for UK renewables and provides a space for discussion.

First off, I've put together a list of the four current UK pumped storage sites and twelve schemes in active development. If you have corrections or additions, let me know (though be aware sources seem to disagree about the storage capacity of existing sites).

Project Area MW MWh Upper reservoir Lower reservoir Operator Planning stage

Dinorwig Gwynedd 1,728 9,100 Marchlyn Mawr  Llyn Peris First Hydro/Engie Open 1984

Foyers Highland 300 6,300 Loch Mhòr Loch Ness SSE Renewables Open 1975

Cruachan Argyll and Bute 440 7,000 Cruachan Reservoir Loch Awe Drax Open 1965

Ffestiniog Gwynedd 360 1,400 Llyn Stwlan Tanygrisiau Reservoir First Hydro/Engie Open 1963

Coire Glas Highland 1,500 30,000 New Loch Lochy SSE Renewables Consent

Cruachan 2 Argyll and Bute 600 0 Cruachan Reservoir Loch Awe Drax Consent

Loch na Cathrach Highland 450 2,800 New Loch Ness Statkraft Consent

Glenmuckloch Dumfries and Galloway 210 1,600 New Glenmuchloch Foresight EIP Consent

Glyn Rhonwy Gwynedd 100 700 Upper quarry Lower quarry Quarry Battery Company Consent

Loch Kemp Highland 600 9,000 Loch Kemp Loch Ness Statera Applied 11/23

Earba Highland 1,800 40,000 Loch Leamhain Loch Earba Gilkes Applied 03/24

Glen Earrach Highland 2,000 30,000 Loch Breac Dearga Loch Ness Glen Earrach Energy Early

Fearna Highland 1,800 37,000 Loch Fearna and Coire Dubh Loch Quoich Gilkes Early

Balliemeanoch Argyll and Bute 1,500 45,000 New Loch Awe Intelligent Land Investment Early

Corrievarkie Perth and Kinross 600 14,500 New Loch Ericht Intelligent Land Investment Early

Sloy Argyll and Bute 152.5 25,000 Loch Sloy Loch Lomond SSE Renewables Early

A few comments:

• No new schemes are under construction yet, though the exploratory tunnel at Coire Glas is now 1km long, and three other schemes in Scotland and one in Gwynedd, Wales have planning consent.
• As has been much hyped, Coire Glas alone would double UK pumped storage capacity. But it's notable that four pipeline schemes (Earba, Glen Earrach, Fearna, Balliemeanoch) are actually slightly larger than Coire Glas by MW or MWh or both. These are all quite big by international standards, though still far from the 2,200 MW/350,000 MWh Snowy 2.0 in Australia.
• If all twelve schemes were completed, UK pumped storage MW would quadruple and MWh would increase by a factor of ten.
• Two schemes are modifications of existing hydro infrastructure, and curiously are near-exact opposites of each other. The consented Cruachan 2 adds a second, larger power station but uses the existing upper reservoir, therefore adding 600MW but zero MWh. Sloy converts a conventional 152.5 MW hydro site into pumped hydro by adding pumps to take water from Loch Lomond to Loch Sloy, thereby creating some 25,000 MWh of storage capacity but zero MW (i.e., there is no addition to the existing turbines).
• Only Sloy (164 hours) and Balliemeanoch (30 hours) can deliver full power for more than 24 hours (which is derived simply by dividing MWh by MW). Only Sloy is anywhere near Snowy 2's 159 hours of full power, and four of the five consented schemes (including the upgraded Cruachan) deliver 8 hours or less, perhaps suggesting that many schemes are not well optimized for reducing wind power curtailment.
• A few schemes have publicized cost estimates, from which a crude MW/£bn can be calculated: Cruachan 2 £0.5bn, 1200 MW/£bn; Glenmuckloch £0.2bn, 840 MW/£bn; Coire Glas £1.5bn, 1000 MW/£bn; Glyn Rhonwy £0.2bn, 500 MW/£bn; Glen Earrach, £2.5bn, 800 MW/£bn.
• A significant barrier to pumped storage deployment is that it does not currently receive UK government subsidies as other renewables do. This is expected to change this year, however, hence the glut of forthcoming schemes.
• There are some local environmental concerns, especially around Loch Ness, which would serve as the lower reservoir for multiple proposed schemes.

PS: Apologies for the formatting – it showed as a proper table until I hit 'post'. Still, I think there's some useful info in there.