SSE Renewables has unveiled plans to convert its 152.5 MW Sloy Power Station, the largest conventional hydro power plant in Britain, into a pumped storage hydro facility.
SSE Renewables said this plan is intended to bolster energy security and help provide the large-scale and flexible renewable energy back-up needed in a future UK net zero power system.
As Britain transitions to a net zero power system, the development of additional pumped storage projects will be crucial for energy security back-up and for balancing a renewables-led energy system during periods when the wind doesn’t blow and the sun doesn’t shine, SSE Renewables said.
The converted Sloy scheme will be capable of delivering up to 25 GWh of long-duration electricity storage capacity. It could provide firm, flexible renewable energy for up to 160 hours non-stop, enough to power around 90,000 homes for up to one week.
SSE’s announcement comes as the company awaits the UK Government’s decision on how it intends to support the deployment of long-duration electricity storage, as set out in last year’s ‘British Energy Security Strategy.’
“In converting our existing Sloy conventional hydro power plant to a pumped hydro storage facility, we can provide the additional large-scale, long-duration electricity storage we need as part of the country’s future energy mix,” said Finlay McCutcheon, Director of Onshore Europe, SSE Renewables. “The development of pumping capability at Sloy also complements our development plans for our other pumped hydro storage project at Coire Glas. Taken together and if approved for delivery, Coire Glas and Sloy can treble Britain’s current flexible electricity storage capacity. That’s why it’s crucial the UK Government urgently confirms its intention on exactly how they will help facilitate the deployment of pumped hydro storage projects as part of our future energy mix.”
“Scotland has vast natural resources which have helped us to become world leaders in renewable energy,” said Humza Yousaf, Scotland First Minister. “Facilities like the Sloy Power Station continue to play a significant role in energy supply, providing flexible services to the grid and help to ensure a continued, resilient and secure electricity supply, by helping to balance our intermittent renewable electricity generation. We continue to call for the UK Government to provide an appropriate market mechanism for hydro power and other long duration energy storage technologies, to ensure this potential is fully realized.”
Over the coming months, SSE Renewables will refine its project design, ahead of a period of public consultation later this year. Subject to the scoping opinion, it’s expected a planning application could be submitted to the Scottish Government by late 2023 or early 2024. SSE hopes to make a final investment decision on Sloy in late 2025 and to fully adapt and commission the new pumped storage scheme by 2028.
Pumped hydro storage would benefit from certainty as to how they would derive revenues, which is expected to be addressed in the UK Government’s upcoming decision on supports for long-duration electricity storage. This could include the introduction by the UK Government of a ‘revenue stabilization mechanism’ in the form of an adapted ‘cap and floor’ scheme to support investment in long-duration storage, effectively without subsidy. This would also be alongside broader consideration of how the electricity market, including the Capacity Market and Flexibility Markets, value the contribution of low-carbon, flexible assets such as pumped storage, SSE said.
SSE owns and operates almost 1.5 GW of flexible hydropower and pumped storage capacity at sites across Scotland that produces over 3 TWh of renewable energy annually.
