World-leading Transmission project energised – first in Europe

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  • Shetland connected to GB grid – powering c.500k homes

For the first time ever, hundreds of thousands of homes and businesses can now be powered by homegrown clean energy from Shetland, in a landmark project delivered by SSEN Transmission and partners.

This follows completion of two major clean energy projects on the islands – the energisation of SSEN Transmission’s 260km (160 mile) subsea link to transport electricity between Shetland and the GB mainland, and construction of SSE Renewables’ Viking Wind Farm.

Shetland is the windiest area of the UK, according to the Met Office, with an average annual wind speed of 14.6 knots. The Shetland projects alone will produce enough clean energy to power the equivalent of some half-a-million homes*. As a result, Viking is expected to be the UK’s most productive onshore wind farm in terms of annual electricity output**.

The 260km High-Voltage Direct Current (HVDC) subsea link will help secure Shetland’s security of clean, low carbon power and enable 600MW of renewable generation to support UK and Scottish net zero and energy security targets.

The HVDC cable runs from a new converter station at Kergord in Shetland to a new switching station at Noss Head on the Scottish mainland, near Wick in Caithness.

  • The project is world-leading as a multi-terminal HVDC link – the first in Europe and only the second in the world (the other being in China). This enables the flow of energy to be split in different directions, in this instance being sent from the switching station to both the HVDC converter stations at Spittal in Caithness and Blackhillock in Moray.
  • The subsea cable was installed in three campaigns, using specialist cable-laying vessel NKT Victoria throughout 2022 and 2023, with the final section installed on the seabed last autumn.
  • Final energisation was completed in August 2024, connecting Shetland to the GB electricity transmission system.
  • Work is continuing to connect Shetland’s existing electricity distribution network to the transmission network, connecting Shetland’s homes and businesses to the GB grid for the first time via the new Grid Supply Point being constructed at Gremista. The Kergord-Gremista 132kV overhead lines and underground cable circuits currently being installed, which are scheduled for completion by the end of 2025, will then connect the HVDC link to the new Gremista Grid Supply Point.

SSEN Transmission’s delivery partners for the Shetland HVDC Link project are:

  • BAM Nuttall, the main civil engineering contractor, which constructed the converter and switching station buildings, access roads and major groundworks. And the Siemens & BAM Joint Venture, who constructed the AC substation and switchgear.
  • Hitachi Energy provided the innovative electrical HVDC technology, and main circuit apparatus and systems used in the project.
  • NKT provided the HVDC cable system used in the 260km cable system laid between Kergord in Shetland and Noss Head in Caithness, including utilising their specialist cable laying vessel NKT Victoria to install the cable on the seabed.

Rob McDonald, Managing Director of SSEN Transmission, said:
“The Shetland HVDC Link project is a hugely important investment in the journey of Shetland, Scotland and the UK as a whole towards a clean energy future – linking Shetland to the GB electricity grid for the first time.

“We can all take huge pride in the fact that it has been delivered ahead of time, on budget, and above all safely. It is a truly world-leading project here in the north of Scotland, as the very first multi-terminal HVDC link in Europe, and only the second on the planet.

“Delivering a project of this size and scale sets a new standard for what we can achieve. It has required innovation, collaboration, and resilience - qualities that will be crucial as we press forward with our Pathway to 2030 investment programme.

“This has been a big team effort, and I want to express a special thank you to the Shetland community and to our delivery partners: BAM Nuttall, Hitachi Energy and NKT.”

Huw Jones, Executive Director, BAM Nuttall, said:

“We often talk in civil engineering about how proud we are to work in an industry where we can leave a legacy. This team’s work in Shetland is an incredible example of that.

“Not only have we contributed to a project which connects Shetland to the National Grid for the first time, we’ve also taken another step towards securing a greener, fossil fuel free future for the United Kingdom. We’re still at the early stages of that journey, but the entire team who have contributed towards delivering our work in Kergord can be incredibly proud of their achievements. They’ve achieved something that once seemed like a far-off ambition and turned it into reality - I’d like to thank them for their exceptional levels of commitment to make that happen.”

Niklas Persson, Managing Director of Hitachi Energy's Business Unit Grid Integration, said:

“We’re proud of this landmark achievement for the UK and to collaborate once again with SSEN Transmission. As we collaborate to advance a sustainable energy future for all, we continue to set the benchmark for deploying innovative solutions at scale. Multi-terminal solutions are important building blocks for realizing the climate-neutral grid. HVDC Light, part of the Grid-enSure™️ portfolio of fully integrated power electronic solutions, is the breakthrough technology behind the successful energization of Caithness Moray-Shetland in Scotland, the first European multi-terminal HVDC system integrating wind energy generation from remote islands.”

Executive Vice President Darren Fennell, head of NKT’s high-voltage business in Karlskrona, Sweden, said:
“We are very satisfied with this milestone of our continuous contribution to the development of the power grid in Scotland and Great Britain. With the Shetland HVDC Link, we continue the close collaboration with SSEN Transmission by leveraging our extensive experience within HVDC technology to enable low-carbon power supply.”

* 475,099 homes powered per annum based on annual GB average domestic household consumption base of 3.781MWh published by the Department of Business, Energy and Industrial Strategy (BEIS) as of November 2018, and projected total generation output by Viking Wind Farm of 1,796.35 GWh per annum.

** Most productive UK onshore wind farm claim based on projected total average generation output by Viking Wind Farm of ~1.8TWh per annum and a comparison with the leading UK operational and in construction wind farms.