Coire Glas: Hydro scheme which would double the UK's ability to store energy gets £100m boost

A proposed 92m-high dam and two reservoirs in the Scottish Highlands that would double the UK's ability to store energy for long periods of time has been given a £100 million boost.

SSE is providing the funding to help develop what would be the UK’s biggest pumped hydro storage scheme in 40 years.

The giant 1.5GW hydro scheme at Coire Glas, north of Fort William, was approved by Scottish ministers in 2020 and will more than double the UK’s storage capacity.

Perth-based SSE says the £1.5 billion scheme would help tackle climate change and improve UK energy security, but want assurances from the UK Government before finally signing it off.

The reservoir at Coire Glas would contain 26 billion litres of water

Located on the shores of Loch Lochy, the Coire Glas project is expected to require a capital investment of over £1.5bn 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 would also provide vital back up to an increasingly renewables-led system and bolstering energy security.

Once complete, Coire Glas would be capable of delivering 30GWh of long duration storage and would provide full time construction roles for up to 500 people.

The scheme would take excess energy from the grid and use it to pump water 500m 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.

When required, Coire Glas could generate enough renewable energy to be able to power three million homes in just under five minutes and could provide this level of firm, flexible power for up to 24 hours non-stop.

A flow chart showing how energy would be generated

The project would also allow for transition away from oil and gas by storing electricity generated in windy or sunny weather for use on cold, still or dark days.

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.

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.

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.

Net zero and energy secretary Michael Matheson said: “If built, Coire Glas will more than double Britain’s long duration electricity storage capacity, allowing the grid to more flexibly deploy renewable electricity.

"The Scottish Government has long been supportive of pumped hydro storage capacity, which we believe will play a key role in the energy transition and is a vital component of a more flexible, resilient and secure electricity supply.

“However, it is critical that the UK Government puts in place the appropriate market and regulatory arrangements to support the industry’s development as a matter of urgency. Only with a supportive policy environment can this sector realise its full potential.”

SSE finance director Gregor Alexander said: “Coire Glas will be one of the most ambitious energy infrastructure projects the UK has ever seen and is a key component of SSE’s commitment to helping lead Scotland and the UKs’ energy transition.

“The £100m investment we have announced today will help play a crucial role in further advancing the Coire Glas project towards a final investment decision in 2024, which will enable the project to move towards construction. If delivered around the turn of the decade, Coire Glas could play a crucial role in getting the UK to net zero.

“Our investment commitment today also signals a significant down-payment by SSE to keep this critical project moving forwards. And our ability to reach a positive final investment decision will clearly depend on the prevailing policy environment for long duration electricity storage and long-term infrastructure projects more broadly.

“Whilst Coire Glas doesn’t need subsidy, it does require more certainty around its revenues and it is critically important the UK Government urgently confirms its intention on exactly how they will help facilitate the deployment of such projects.”

The next phase of detailed project design and refinement, construction planning and procurement will progress through 2023 and into early 2024. Around half of the £100m development investment will now be allocated to the pre-construction refinement phase of the Coire Glas project, including a comprehensive package of site investigation works, which have now commenced and will be completed later this year.

These include the construction of a major exploratory tunnel to enable the project team to fully assess the geological conditions that will be encountered in constructing the scheme.