Coire Glas pumped storage hydro
Doubling Great Britain’s electricity storage capacity
SSE’s 1.4GW Coire Glas is one of the UK’s most advanced pumped storage hydro-electric projects in development.
Located on the shores of Loch Lochy in the Scottish Highlands between Fort William and Inverness, Coire Glas would provide at least 45GWh of long duration electricity storage – making it Great Britain’s largest energy storage project if delivered and doubling the country’s existing electricity storage capacity.
Coire Glas would deploy pumped storage hydro technology to pump water from the lower Loch Lochy to an upper storage reservoir with a capacity of up to 40 billion litres, before then releasing that water to generate homegrown clean power when Great Britain’s electricity demand is higher or renewable generation output is lower.
The project would have a proposed maximum generation capacity of 1,440MW and a maximum pumping capacity of 1,500MW. At full output, its storage capacity would provide over 30 hours of continuous generation, enough to power almost five million homes across Great Britain for the same period*.
Coire Glas could be delivering vital flexibility to Great Britain’s electricity system in the 2030s subject to a final investment decision by SSE.
In June 2026 Ofgem included Coire Glas as one of 16 Long Duration Electricity Storage (LDES) projects named in its ‘Minded-to-Decision’ list for receipt of cap and floor investment support. SSE is now assessing this outcome and will engage fully with Ofgem to work through a significant number of points of detail, which will need to be resolved for the project to progress. Any final decision to progress the project would be taken in line with SSE’s continued focus on capital discipline and with strict adherence to its return thresholds. Click this link to read SSE’s full statement.
One of UK’s most advanced pumped storage hydro projectsDeveloped by SSE Renewables, the project first secured planning consent in 2013, with updated consent approval granted by Scottish Government in 2020 to optimise the scheme for modern system needs. SSE has invested over £100 million so far to progress Coire Glas through development stages including design refinement, construction planning, procurement and site investigation works. These site investigations have included the excavation and completion of a major 1.2km-long exploratory tunnel built into the hillside above Loch Lochy. The exploratory works gathered important geological data to inform the main design of the scheme with over 90,000 tonnes of rock and earth excavated. Gold Certification for hydropower sustainabilityCoire Glas is the first pumped storage hydro project in the world to achieve Gold Certification under the Hydropower Sustainability Standard in recognition of its strong performance in labour and safety standards, governance, and stakeholder consultation. The project was recognised for its careful planning of environmental and cultural heritage impacts, with detailed strategies for water and sediment management, biodiversity and local community engagement. In September 2025 Coire Glas was awarded the prestigious International Hydropower Association (IHA) Blue Planet Prize 2025, recognising its excellence in sustainable hydropower development. * Quoted 4.86 million homes powered for 30 hours based on 45GWh long duration electricity storage capacity (based on latest Typical Domestic Consumption Values (TDCV) at medium consumption, 2,700kWh per household per annum (Ofgem, May 2023) equivalent to 9.25 kWh for 30 hours of operation). |
Visit the dedicated Coire Glas website
Visit coireglas.com for more informationContact us
If you would like to contact us in relation to the Coire Glas project, please email coireglas@sse.com .