Utility Week

UTILITY WEEK | OCTOBER 2022 | 35 Innes tells Utility Week Innovate that the lack of policy framework to facilitate the deployment of exible long-duration elec- tricity storage technologies has made it dif- cult to press ahead with capital-intensive large-scale pumped storage schemes such as Coire Glas due to high upfront costs and a lack of forecastable revenue streams. However, hollowing out peaks in the Scot- tish highlands to house enormous energy projects appears to be making something of a comeback amid e• orts to hit ambitious net- zero targets. In May, for example, it was announced that generator Drax had applied for plan- ning consent to more than double the capac- ity of its Cruachan hydro power station from 2030. A prospective plant of up to 600MW, Cruachan Two would be located inside Ben Cruachan – Argyll's highest mountain – and require the excavation of around two million tonnes of rock to create a hollowed-out cav- ern large enough to t Big Ben on its side. Large amounts of long-duration energy storage will be needed to support accelerated renewable energy plans set out in the Energy Security Strategy, in which the government increased its o• shore wind target to 50GW by 2030 and committed to onshore wind and solar rollouts that could see 95% of power coming from low-carbon sources by 2030. What's more, a government document published in August discussing the deploy- ment of large-scale and long-duration electricity storage concluded that it has an important role to play in achieving net zero, integrating and maximising the use of renewables, contributing to security of sup- ply, and shaking up Britain's technology mix. "The importance of hydro power has been reasserted in light of climate change, both as a source of low-carbon electricity, and through pumped storage as an enabler for other renewable energy sources," explains Liam Knapp, chief commercial o— cer at Peacock Engineering – SSE Renewables' enterprise asset management solutions pro- vider. "This is re ected in schemes such as CoirešGlas." Innes says several recent studies have highlighted the bene ts of deploying long- duration storage technologies such as pumped storage. For example, Aurora Energy Research, a group founded by University of Oxford professors and economists, found that 24GW of such storage – eight times the current installed capacity – would be needed to meet the government's commitment to decarbonise the power sector by 2035. "Such levels of long-duration energy stor- age would not only reduce overall system costs by 2.5% to £1.13 billion per annum, bene ting bill payers, but also drastically cut our reliance on imported gas," he says. "Local communities are also set to bene t through local community investment funds, while the construction of the project would create at least 500 jobs, further supporting the UK government's 'levelling-up' agenda." New tools and targets Featuring large-scale hydro power station Glendoe, SSE Renewables' hydro portfo- lio currently totals 1,459MW. It includes 300MW of pumped storage and 750MW of exiblešhydro. However, to make the required progress at Coire Glas and grow this further, Innes emphasises the need for the supply chain to ensure modern technologies and construc- tion techniques are adopted where possible. Construction can't and won't be a matter of picking up the same tools and techniques asšbefore. "This includes maximising the perfor- mance of the scheme using the latest pump turbine designs and technologies to provide ancillary services to support operation of the transmission network and modern sustain- able construction methods," he says. Already partnering with Stantec and COWI – respective experts in hydro pump storage design and underground engineer- ing works – at Coire Glas, SSE Renewables selected mining and tunnelling rm Strabag to undertake further exploratory work. However, it goes without saying that hollowing out a mountain and installing the means to more than double Britain's total electricity storage capacity comes with its share of environmental and logistical challenges. "Before any construction can begin at Coire Glas the geological conditions at the site need to be fully investigated and under- stood," Innes explains. "This means tunnelling into the heart of the hill underneath the proposed dam site to the proposed location for the underground power cavern and sampling and surveying the rock structures to inform the design of the underground works. "The exploratory works to do this will take between 12-18 months, so represent a considerable engineering project in their own right." Once this is complete, project teams will then excavate underground works and begin moving – and reusing where possible – mil- lions of tonnes of material. But how are teams ensuring that no undue damage is caused to the Great Glen – a huge ri¦ valley housing four lochs and a de ning feature of the north of Scotland – amid unprecedented focus on environmental impact? "A full environment impact assessment was undertaken as part of the planning con- sent for the project," Innes explains. "Once constructed, a large part of the scheme's infrastructure will be underground and out of view. Also, by using the natural features of Coire to create the upper reservoir, this makes the scheme's location environmen- tally ideal as there are no signi cant works required to create the reservoir behind theššdam." Stuart Stone, editor, Utility Week Innovate

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