SSE submits planning to Scottish Government for Sloy pumped storage hydro scheme

**The plans would see the existing Sloy Power Station on the banks of Loch Lomond converted into a pumped storage hydro scheme with a pumping capacity of up to 100MW**

**If given the green light, the converted Sloy scheme would be capable of delivering up to 16GWh of long-duration electricity storage capacity**

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

The existing power station on the banks of Loch Lomond would be converted into a pumped storage hydro scheme with a proposed pumping capacity of up to 100MW.

If consented, the scheme would be capable of delivering up to 16GWh of long-duration electricity storage capacity, helping to bolster energy security and balance an increasingly renewables-led energy system during periods when the wind doesn’t blow, and the sun doesn’t shine.

Subject to a positive consenting outcome, 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.

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

During the design, development and construction phases, the proposed conversion could support up to 70 full-time equivalent (FTE) jobs, helping to boost the local economy and employment.

A dedicated community benefit fund would also be established, in addition to 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 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”

About Sloy Power Station

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 of 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 152.5MW.

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

About New Proposals

SSE Renewables is proposing to convert the existing hydro-electric scheme at Sloy into a pumped storage scheme by introducing new pumps located in the grounds of the existing asset, immediately north of the power station at Inveruglas on the shore of Loch Lomond. The site has been considered for pumped storage as far back as the 1930s.

The new pumps would enable water to be lifted from Loch Lomond to Loch Sloy using the existing pipelines and tunnels during times of low demand (typically overnight) or times of oversupply (when there is too much renewable energy being generated).

This would enable energy to be stored at Loch Sloy until it is required during periods of higher demand, enabling the scheme to operate for longer periods of time which would minimise the likelihood of renewable energy from other sources being constrained off the grid during times of low demand.

The Environmental Impact Assessment Report, available to read on SSE Renewables’ website incorporates a robust assessment of the following environmental aspects: Aquatic Ecology; Terrestrial Ecology; Ornithology; Soils, Geology and the Water Environment; Landscape and Visual Amenity; Traffic and Transport; Noise and Vibration; Cultural Heritage; and Recreation.