In the last six years, Scottish Hydro Electric Transmission (SHE Transmission) has seen a £1 billion investment in the infrastructure across the north of Scotland.
The network itself is made up of more than 5,000km of high voltage overhead lines, underground and subsea cables and serves around 70% of the land mass of Scotland. The money invested in projects since 2010 has built the resilience of the supply to SHE Transmission’s 750,000 customers in the area while providing the network needed to allow renewable energy generators to connect in to the grid, and it’s an investment spread across five separate projects.
The £26 million build at Foyers-Knocknagael was the first of its kind for SHE Transmission, involving the installation of twin conductors across existing 40-year-old 275kV steel towers. The 85 towers and 24km overhead line run between Knocknagael substation, south of Inverness, and the Foyers pumped storage hydro station on the southern shore of Loch Ness, where teams tackled extreme environmental challenges, using specialised equipment and techniques to safeguard the renewed overhead line and the sensitive environment that it traverses.
A further £53 million was invested in completing the circuit running from Beauly to the substation near Mossford. Overhead line, underground cables and works on Beauly substation to introduce new, higher capacity conductors enabled greater export of generation in the Strathconon area and a more resilient supply to customers. The visual impact was reduced as 188 old towers were replaced with 97 new ones and 3km of undergrounded cable, and the project was completed on time despite the workforce twice downing tools; initially to respect the environment and breeding habits of local wildlife, and again to allow archaeologists to document several round house settlements that had been revealed, providing information on those who inhabited the area centuries before.
The past made itself present again on the £94m project to refurbish the 55-year-old overhead line running 157km on the transmission route from Beauly via Blackhillock to Kintore, when the remains of a medieval farm building at Leylodge were uncovered, allowing archaeologists to explore and record the heritage that may otherwise have lain undiscovered. Spanning the three local authority areas of Highland, Moray and Aberdeenshire, the refurbishment provided an 85% increase in the capacity of the overhead line route.
SHE Transmission’s most recently completed project was to reinforce the electricity network on the Kintyre peninsula in Argyll to Hunterston; working with SP Energy Networks, the different aspects of this £197 million project - involving power lines that travel overhead, underground and beneath the sea bed - raised some very interesting challenges. The storms and snow that left thousands of customers in the area without power three years ago reinforced the company’s determination to upgrade this network, making it stronger for the many householders and businesses that rely on it, and giving renewable developers the capacity to build further generation.
The largest of these works has been the £680 million Beauly-Denny project; to date it has enabled the connection of 80 additional wind, hydro and solar generation developments in the north of Scotland. Working again with SP Energy Networks, the build employed over 2,000 workers and holds two records - it’s the longest UK transmission line to be built in recent times, and also crosses the highest and most inaccessible terrain on the Great Britain transmission system at the 2526ft summit of the Corrieyairack Pass.
Director of SHE Transmission, Dave Gardner said: “It all adds up to some sizeable figures; £1 billion of investment to build a stronger supply for communities, 3,700MW of additional renewable generation able to connect to the grid and a workforce of hundreds of highly skilled operatives.
“All of these projects, in one way or another, have given us an insight into the history of the production and transmission of electricity across the north of Scotland and that allows us to give a respectful nod to the past while keeping an eye firmly on the future, and part of that future is the Caithness-Moray High Voltage Direct Current transmission link.
“As our flagship project and its largest capital investment project to date at £1.1 billion, it will enable the connection of up to 1,200MW of additional generation capacity in the north of Scotland and the islands. It’s a considerable investment and one which our predecessors who built the first towers and lines decades ago couldn’t begin to comprehend, but like them, we know we’re building the strong foundations of the future and the developments that are yet to come."