Coire Glas to double UK’s ability to store energy following £100m investment

Coire Glas, a huge hydroelectric scheme in Scotland will double the UK’s ability to store energy following a £100m investment by SSE.

The proposed 92m-high dam and two reservoirs at Coire Glas in the Highlands will be Britain's biggest hydroelectric project for 40 years.

Coire Glas in the Scottish Highlands could power 3 million homes and more than double electricity storage.

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

Balance Out

Developers of the technology say it can help to balance out a growing amount of renewable electricity on the power grid. The system uses the surplus renewable power when demand is low to pump the water and storing it.

Scottish ministers approved the 1.5GW pumped storage facility in 2020.

But power giant SSE wants assurances from the UK government before finally signing it off.

A spokesperson for the Department for Energy Security and Net Zero said it was "committed to supporting the low carbon hydro sector, including hydro storage".

Climate Change

SSE says the £1.5bn scheme would help tackle climate change and improve UK energy security.

The concept of Coire Glas involves two reservoirs at different heights. This is located in the Great Glen, the geological fault which slices through Scotland between Inverness and Fort William.

When power is plentiful and cheap, water would be pumped 500 metres uphill for storage. This would be kept in an upper reservoir with the capacity of 11,000 Olympic-sized swimming pools.

When supply is tight and prices high, it would be released, using gravity to generate electricity. This would be acheived by spinning four turbines way below on the banks of Loch Lochy, before flowing into the lower reservoir.

Powering 3 million homes

According to the SSE website, Coire Glas would begin generating enough renewable energy to be able to power three million homes in just under five minutes. Critically, the project could provide this level of firm, flexible power for up to 24 hours non-stop.

Coire Glas will help smooth the transition from oil, gas and coal to more sustainable but intermittent sources of energy such as wind and solar.

The government announced measures to support energy security in a budget document. Oil and gas producers had called for floor prices to be applied to a windfall tax imposed last year.

"In addition to the measures in the spring budget, the government will set out further action later this month to ensure energy security in the UK and meet our net zero commitments," the government said in a budget document.

"We believe strongly it could play a huge role in enabling a decarbonised energy system," said Finlay McCutcheon, SSE's director of onshore renewables.

Net Zero

This would greatly assist Scotland's target of net zero greenhouse gas emissions by 2045.

Mr McCutcheon insisted there was a clear case for the UK government to support a strategic expansion in hydro capacity.

The firm's existing assets had been "absolutely critical" in keeping the lights on during a "full-blown energy crisis" in the UK and Europe this winter, he said.

Despite mild weather, "our existing pumped storage - Foyers on the shores of Loch Ness - has never been used so intensely," Mr McCutcheon added.

Scotland's only other pumped storage scheme, operated by Drax Group, is housed within a giant artificial cavern inside Ben Cruachan on the shores of Loch Awe in Argyll.

The North Yorkshire-based company plans to more than double the generating capacity of its facility, to more than 1GW, with the construction of a new underground power station.

But both Drax and SSE have been reluctant to press ahead without assurances from Whitehall.

"SSE needs clarity around how the UK government is going to support projects like Coire Glas," Mr McCutcheon explained.

"It was a key element of their energy security strategy last year, but we need to see how that's going to work in practice."

He added: "It doesn't require subsidy but they are enormous investments."

Greater Energy Security

The Department for Energy Security and Net Zero spokesperson accepted that hydro would be "critical to delivering greater energy security and independence, economic growth, and our net zero ambitions".

"We are supporting up to 480,000 well-paid green jobs. This is as well as leveraging up to £100bn of private investment in low-carbon technologies including storage by 2030. This will bolster our energy security and help ensure we bring down wholesale electricity prices to among the lowest in Europe," they added.

SSE says it hopes to make a final investment decision next year. If it goes ahead, completion is expected in 2031.

The £100m outlay announced by the FTSE 100 company will be used for exploratory work, which includes boring a tunnel four metres wide for about 1km into the hillside to assess the geology of the site.

The investment in Coire Glas comes on the 80th anniversary of the Hydro Electric Development (Scotland) Act 1943, which nationalised the industry and kick-started the creation of more than 50 dams.

The visionary Labour politician Tom Johnston was the driving force behind the expansion, dramatically improving life in rural Scotland in the years after the war. 

Finlay McCutcheon, SSE's director of onshore renewables, said:

“We believe strongly it could play a huge role in enabling a decarbonised energy system "

“SSE needs clarity around how the UK government is going to support projects like Coire Glas," Mr McCutcheon explained.

"It was a key element of their energy security strategy last year, but we need to see how that's going to work in practice. It doesn't require subsidy but they are enormous investments.”