SSE has submitted a Section 36 planning application to the Scottish Government to convert the iconic Sloy Power Station into a new pumped storage hydro scheme. u6e4n

Sloy Power Station is Britain’s largest conventional hydro power plant and has been in operation since 1950. Opened by Queen Elizabeth the Queen Mother, it currently generates around 130 million units (kWh) of electricity in a year of average rainfall.

The current scheme makes use of the water from Loch Sloy, which is carried over 3km by a tunnel through Ben Vorlich before travelling down four high-pressure steel pipelines to Sloy Power Station at Inveruglas Bay on Loch Lomond.

Inside the power station, four Francis turbines each drive a vertical shaft generating set with a combined generating capacity of 152.5 MW.

When full, Loch Sloy holds 36 million cubic metres of water, translating to a useful storage capacity of approximately 16 GWh.

The proposed project would see the existing power station converted into a pumped storage hydro scheme with a proposed pumping capacity of up to 100 MW. If approved, the scheme would be capable of providing up to 16 GWh of long-duration energy storage. This storage capacity would help bolster energy security and balance an increasingly renewables-led energy system, especially during times when the wind doesn’t blow, and the sun doesn’t shine.

SSE Renewables hopes to make a final investment decision on Sloy in late 2027 and to fully adapt and commission the new pumped storage scheme by the end of 2030.

Economic impact and community benefits 3a634e

As part of the planning application, SSE Renewables is also proposing to upgrade the existing 32.5 MW G4 turbine to match its sister units, which would increase the station’s generating output by 7.5 MW to 160 MW.

During the design, development, and construction phases, the proposed conversion could up to 70 full-time equivalent (FTE) jobs, helping to boost the local economy and employment. Additionally, a dedicated community benefit fund would be established, complementing the recently launched £10m Hydro Community Fund.

Robert Bryce, Director of Hydro – 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 Sloy Power Station has been operational since 1950 and has played a significant role in our energy system. The new proposals will ensure this remains an important asset for decades to come.

With this latest proposal, SSE Renewables further demonstrates its commitment to hydro power as a key pillar of a sustainable and resilient national energy system.