On 23 July the Scottish government granted Section 36 consent for upgrades to SSE Renewables' Sloy Hydro-electric Power Station. The decision provides the company with regulatory clearance to pursue conversion of the 152.5 MW plant into a pumped storage hydro scheme capable of delivering up to 16 GWh of long-duration electricity storage.
The proposals also permit a potential rise in installed generation capacity to 160 MW through later asset improvements. Such flexibility matters. It allows SSE to weigh the economics of pumped storage against continued operation as a conventional hydro plant with higher output, all within the discipline of its capital return thresholds.
SSE submitted the Section 36 application in April 2025. Officials have now cleared modification of the existing 1950s-era facility at Inveruglas on Loch Lomond rather than requiring an entirely new build. The station already generates around 130,000 MWh of hydro-powered electricity each year and can reach full output in under five minutes, a response time that has made it a cornerstone of rapid flexible generation for decades.
Robert Bryce, director of hydro for SSE Renewables, said the consent delivers important optionality for an iconic plant. "We’re delighted our upgrade proposals for Sloy have received planning consent from the Scottish Government. This provides SSE with important optionality for our iconic Sloy Power Station plant, whether as a new pumped storage hydro facility or as a conventional hydro-electric plant with increased generation capacity, and will help ensure Sloy continues to play a vital role in Scotland’s energy future."
The consent stands in contrast to earlier pumped storage proposals at Sloy that secured approval in 2010 but lapsed unused in 2018. This time the regulatory milestone arrives with a clearer focus on engineering practicality and long-term investment signals. Any final investment decision will still depend on meeting SSE’s strict financial criteria. Subject to a positive outcome the company had previously targeted late 2027 for that decision and end-2030 for commissioning.
Bryce also acknowledged the contribution of those living nearby. "We would also like to take this opportunity to thank key stakeholders, local residents and community groups who have engaged with us so positively throughout the development of these proposals. We greatly value the time, feedback and insights shared during the planning process, which have helped shape our approach. Maintaining open and constructive relationships with the communities around Sloy remains extremely important to us."
