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

The proposed conversion aims to enhance energy security and balance the increasing reliance on renewable energy sources.

The existing power station, located on the banks of Loch Lomond, would be adapted to incorporate a pumped storage hydro scheme with a proposed pumping capacity of up to 100MW. This conversion would enable the facility to provide up to 16GWh of long-duration electricity storage, ensuring a reliable energy supply during periods of low wind and solar generation.

Subject to planning approval, SSE Renewables anticipates making a final investment decision in late 2027, with the adapted pumped storage scheme fully operational by the end of 2030.

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


The project is expected to create up to 70 full-time equivalent (FTE) jobs during its design, development, and construction phases, providing a significant boost to the local economy. A dedicated community benefit fund, in addition to the recently launched £10 million Hydro Community Fund, will also be established.

Robert Bryce, Director of Hydro – SSE Renewables, highlighted the project's importance: "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."

He also emphasised the continued significance of the Sloy Power Station, which has been operational since 1950: "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."

The conversion of Sloy into a pumped storage scheme involves introducing new pumps near the existing power station at Inveruglas on the shore of Loch Lomond. These pumps would facilitate the transfer of water from Loch Lomond to Loch Sloy during periods of low energy demand or oversupply, using the existing pipelines and tunnels. This stored water can then be released to generate electricity during peak demand.

The project aims to minimise the curtailment of renewable energy from other sources during periods of low demand, enhancing grid stability and efficiency.

The Environmental Impact Assessment Report, available on SSE Renewables' website, provides a comprehensive assessment of the project's potential environmental impacts, covering aspects such as aquatic and terrestrial ecology, ornithology, geology, landscape, traffic, noise, cultural heritage, and recreation.