Exploratory tunneling for SSE Renewables’ Coire Glas project, the first large-scale pumped water storage system (PHES) in Britain in 40 years, has been completed.
The proposed Coire Glas storage development would have an installed capacity of 1,300 MW and be capable of providing 30 GWh of long-term electricity storage. It is being developed by the sustainable energy branch of the British energy producer SSE.
Exploration work at Coire Glas began in December 2022 and is being completed by Strabag UK, a construction company specializing in mining and tunneling. The completion of the 1.2km tunnel is progress for the project, based in the Scottish Highlands near Loch Lochy.
In early 2023, SSE announced a £100 million investment boost for Coire Glas, including the construction of a major exploration tunnel as part of an extensive package of site investigation works.
The work includes the construction of a 5 by 4.5 meter tunnel, cutting through the hillside where the underground power station complex would be located. SSE’s technical partners, environmental engineers Stantec and COWI, a British consultancy, designed and oversaw the soil investigation program.
Exploratory drilling and testing will take place over the next three months. SSE Renewables hopes to make a final investment decision on the project in late 2025 or early 2026, with construction commencing in the second half of 2026, pending success in the administrative allocation of an investable cap-and-floor mechanism.
Mike Seaton, SSE Renewables development director for Coire Glas, said: “Works proceeded as planned and samples of the materials excavated from the hills are currently being analyzed.
“This phase of the project is in itself a technical challenge and we are learning a huge amount as we progress with the works. The findings from the tunnel works, in addition to our wider ground investigation work completed by Fugro in December 2023, will be used as a basis for the final design, including the detailed design of underground structures, and will be an important consideration in any final decisions regarding the project.”
SSE Renewables develops PHES
SSE Renewables is also developing a 1.8 GW pumped hydro storage project in Loch Fearna, Scotland. The project has already delivered a network connection offering totaling 1,795 GW and is expected to become commercially operational in the mid-2030s.
Ross Turbet, head of hydropower investment management at SSE Renewables, stressed that PHES projects “will be critical to energy security and balancing the increasingly renewables-led energy system”.
“The proposed Fearna project is a welcome addition to our development pipeline of pumped storage hydro projects, which also includes our proposal to develop one of Britain’s largest pumped storage systems at Coire Glas in 40 years and our intention to expand our existing Sloy Power Station converted into a PHES facility” Turbet added.
In March this year, former Australian Prime Minister and current President of the International Hydropower Association (IHA), Malcolm Turnbull, wrote a open letter to Rishi Sunak stating that Britain has “almost 7GW of shovel-ready”. hydropower projects with pumped storage with more than 135 GWh storage capacity”.
If these projects were all built, they would increase the UK’s energy storage capacity fivefold.
