Landmark Coire Glas in the Scottish Highlands could power 3 million homes and more than double GB electricity storage.

SSE is providing a £100 million investment boost into what can be Britain’s biggest pumped hydro storage scheme in 40 years. The announcement is being made today as part of a visit by Scotland’s Cabinet Secretary for Net Zero, Michael Matheson, to SSE’s Pitlochry Dam and Hydro Station where he will welcome the investment news being made by executives from SSE.

More than doubling GB’s electricity storage capacity

Located on the shores of Loch Lochy, between Fort William and Inverness, the Coire Glas project is expected to require a capital investment of over £1.5 billion to construct and, if approved for final delivery, would be the first pumped hydro storage scheme to be built in the UK in 40 years.

The project, which received planning consent from the Scottish Government in 2020, would also more than double Britain’s total current electricity storage capacity – providing vital back up to an increasingly renewables-led system and bolstering energy security. SSE hopes to make a final investment decision on Coire Glas in 2024, subject to positive development progress and the prevailing policy environment, and to fully construct and commission the pumped storage scheme by 2031.

Powering 3 million homes

Once complete, Coire Glas would be capable of delivering 30GWh of long duration storage. The scheme would take excess energy from the grid and use it to pump water 500 meters up a hill from Loch Lochy to a vast upper reservoir equivalent to nearly 11,000 Olympic-sized swimming pools where it would be stored before being released to power the grid when wind output is low and customer demand is high.

At the flick of a switch, Coire Glas would begin generating enough renewable energy to be able to power three million homes in just under five minutes. Critically, the Coire Glas project could provide this level of firm, flexible power for up to 24 hours non-stop.

SSE’s £100m commitment to further developing Coire Glas comes as the leading low carbon energy infrastructure company awaits the UK Government’s decision on how it intends to financially support the deployment of long-duration electricity storage, as set out in last year’s British Energy Security Strategy.

This could include the introduction by the UK Government of a ‘revenue stabilisation mechanism’ in the form of an adapted Cap and Floor scheme to support investment in long-duration storage. This would also be alongside broader consideration of how the electricity market, including the Capacity Mechanism and the Flexibility Markets, value the contribution of low carbon flexible assets such as pumped storage.

One of the biggest engineering projects in the Scottish Highlands and the UK

Coire Glas is expected to be one of the biggest engineering projects in the Scottish Highlands since the 1943 Hydro Electric Development (Scotland) Act kickstarted the construction of major hydro-electric schemes across Scotland 80 years ago. At peak delivery, the project would create up to 500 full time construction roles.