SCOTS energy firm SSE is to invest £100m in the creation of one of the UK's largest batteries.

The Perth-based firm's Coire Glas pumped hydro storage project, near Fort William, would be the biggest scheme of its type for 40 years.

It would cost around £1.5bn to build and would boost the UK's ability to store energy for long periods.

A final investment decision is expected in 2024 and the project could be up and running by 2031 but the Perth-based company has said it needed clarity from the government on its policies around energy storage.

SSE said the final investment decision will be subject to "positive development progress and the prevailing policy environment"

As of 2020, the UK had a total hydropower installed capacity of over 4,700MW, including over 2,800 MW of pumped storage. The vast majority of installed capacity is located in the wet and mountainous regions of Wales and northwest Scotland.

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At that point the UK was home to four pumped storage projects in Scotland and Wales. The largest such project, Dinorwig in north Wales, was commissioned in 1983 with a capacity of 1,728MW.

The Scots scheme would work by moving water upwards between two reservoirs using excess energy, to later be released to spin a turbine when demand is higher.

The site has the potential capacity to store up to 1500MW of excess renewable energy when it is not needed energy, enough to power 3m homes.

Experts believed that hydro storage schemes could play a key role in decarbonising the UK’s electricity as they act as a battery energy, capable of providing electricity to the grid when needed, and for long periods of time.

SSE was cleared to build a 600MW scheme at Loch Lochy nearly a decade ago.

A nine-year-old SSE overview of the Coire Glas pumped storage scheme

SSE later submitted revised plans to the Scottish Government in April 2018 for a scheme of up to 1,500MW, which was approved in late 2020 – a change SSE says will enable it to maximise the potential of the site.

Coire Glas is expected to be one of the biggest engineering projects in the Scottish Highlands since the 1943 Hydro Electric Development (Scotland) Act.  The legislation kickstarted the construction of major hydro-electric schemes across Scotland 80 years ago.

The £100m invested now will be spent on design and advancing the project towards an investment decision and site investigation works.

At peak delivery, the project would create up to 500 full time construction roles.

SSE's funding will now go towards the design of the project, which could come online by 2031.

The next phase of detailed project design and refinement, construction planning and procurement will progress through 2023 and into early 2024.

Around half of the £100m development investment will now be allocated to the pre-construction refinement phase of the Coire Glas project, including a comprehensive package of site investigation works.

Exploratory works have already started at the site in Loch Lochy in the Great Glen in the Scottish Highlands.

Strabag UK, an expert in mining and tunnelling projects, was drafted in last year by developer SSE Renewables to undertake the work.

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The project involves tunnelling into a hillside at the site of the Coire Glas project, at Loch Lochy in the Great Glen, to assess the geological conditions.

The information will then be used in detailed design of underground structures.

The scheme will operate by transferring water between Loch Lochy – the lower reservoir – and a newer higher one created at Loch a’ Choire Ghlais. This will be done through a tailrace tunnel, underground cavern power station, high pressure tunnel and low pressure headrace tunnel.

The Herald:

Pumped hydro plants work by pumping water uphill to a higher reservoir before releasing it to enable water to flow downhill through turbines to produce electricity when it is needed.

Developers of the technology say it can help to balance out a growing amount of renewable electricity on the power grid, using the surplus renewable power when demand is low to pump the water and storing it so it is ready to be released when demand is high.


“The £100 million investment we have announced today will help play a crucial role in further advancing the Coire Glas project towards a final investment decision in 2024, which will enable the project to move towards construction. If delivered around the turn of the decade, Coire Glas could play a crucial role in getting the UK to net zero," said SSE finance director Gregor Alexander.

"Whilst Coire Glas doesn’t need subsidy, it does require more certainty around its revenues and it is critically important the UK Government urgently confirms its intention on exactly how they will help facilitate the deployment of such projects."