SSE Renewables has submitted a Section 36 planning application to the Scottish Government to convert the existing Sloy Power Station near Loch Lomond into a pumped storage hydro scheme.
The proposal would see the station, which has operated since 1950, adapted to include a pumping capacity of up to 100MW, allowing it to deliver up to 16GWh of long-duration electricity storage.
If approved, SSE plans to reach a final investment decision by late 2027, with the conversion completed and operational by the end of 2030.
The project would involve installing new pumps at the Inveruglas site, enabling water to be pumped from Loch Lomond to Loch Sloy during low electricity demand periods. This stored water would then be released to generate electricity when demand is higher.
The application also includes a proposal to upgrade the station’s existing 32.5MW G4 turbine, which would raise the plant’s total generating capacity from 152.5MW to 160MW.
According to SSE, the development phase could support up to 70 full-time equivalent jobs and contribute to the local economy. A dedicated community benefit fund would also be created, adding to the recently launched £10 million Hydro Community Fund.
Robert Bryce, Director of Hydro at SSE Renewables, said: “The proposed pumped storage hydro scheme will play an important role in the UK Government’s Clean Power by 2030 ambitions, providing firm, flexible renewable energy for up to 100 hours non-stop at the flick of a switch.
“The existing Sloy Power Station has been operational since 1950 and over the past seven decades has played a significant role in our energy system. The new proposals will ensure this remains an important asset for decades to come.
“If consented, the scheme will provide an economic and employment boost to the local area and help provide balance to our increasingly renewables-led grid, during times of peak demand. This latest proposal, alongside our other investments in the technology, are a further example of the importance of hydro as a key part of a homegrown UK energy system.”
Sloy Power Station is currently the UK’s largest conventional hydroelectric plant, producing approximately 130 million kilowatt hours of electricity per year in average rainfall conditions. The plant uses water carried from Loch Sloy through a tunnel and steel pipelines to power four Francis turbines.
The environmental impact of the project is addressed in a report covering areas such as ecology, water, noise, heritage, and transport, which is available on the SSE Renewables website.
