Scottish and Southern Electricity Networks (SSEN) Transmission has appointed the main contractors for the construction of an interconnector linking Shetland and the Scottish mainland.
The four key contractors to install the high voltage direct current (HVDC) link and all associated infrastructure are Hitachi ABB Power Grids, NKT, Siemens and BAM Nutall.
The contract awards follow the recent decision by the energy regulator, Ofgem, to grant final approval for the transmission link, with everything now in place for the start of main construction in late August 2020.
The link, which will connect Shetland to the mainland transmission system for the first time, is required to facilitate the connection of renewable electricity developments on the island.
The project consists of a substation at Kergord on Shetland, which is required for the connection of renewable electricity generators on Shetland.
These works will be led by Siemens BAM.
The power will then be converted from alternating current to direct current at a HVDC converter station, also at Kergord, before being transported around 270km via underground and subsea cable (257km) to an HVDC switching station at Noss Head, Caithness, in the north of Scotland.
NKT will be responsible for the manufacture and installation of the subsea cable, with BAM Nuttall delivering all civil engineering works, including the construction of all buildings.
HVDC technology provider Hitachi ABB Power Grids will deliver and commission the HVDC system.
The power will then be transported via the Caithness Moray HVDC link before being converted back to alternating current for onward transmission.
All four contractors played were involved in the construction of the Caithness Moray HVDC link, which has been operational since January 2019.
Enabling works are due to begin at Kergord and Noss Head towards the end of August, with full construction of the AC Substation, and HVDC Convertor and Switching Stations, due to commence in early 2021.
The subsea cable installation will take place in 2022 and 2023 following its manufacture.
SSEN Transmission director of offshore delivery Sandy Mactaggart said: “The Shetland HVDC link will deliver substantial socio-economic and environmental benefits to Shetland’s, Scotland’s and the UK’s economy, supporting hundreds of skilled jobs in the process as part of the green recovery from the coronavirus pandemic.
“With all major milestones complete, we now look forward to working closely with the Shetland and Caithness communities and other stakeholders throughout the construction and future operation of these critical national infrastructure assets.”