Shetland HVDC Connection is a

high-voltage direct current A high-voltage direct current (HVDC) electric power transmission system uses direct current (DC) for electric power transmission, in contrast with the more common alternating current (AC) transmission systems. Most HVDC links use voltages betwe ...

submarine power cable A submarine power cable is a transmission cable for carrying electric power below the surface of the water.Shetland Shetland (until 1975 spelled Zetland), also called the Shetland Islands, is an archipelago in Scotland lying between Orkney, the Faroe Islands, and Norway, marking the northernmost region of the United Kingdom. The islands lie about to the ...

to the British mainland.

History

The project was proposed in 2007. In January 2008, the report published by the

Crown Estate The Crown Estate is a collection of lands and holdings in the United Kingdom belonging to the British monarch as a corporation sole, making it "the sovereign's public estate", which is neither government property nor part of the monarch's priva ...

found the project would be "economically and technically possible". At the same year, Scottish Hydro Electric Transmission filed planning application and started public consultations. Originally, the cable was planned to run from Shetland to to Portgordon on the Scottish mainland, and then on to

Blackhillock substation Blackhillock Substation is an electrical substation located in the north east of Scotland, near the town of Keith in Moray. It is owned and operated by Scottish Southern Electricity Network (SSEN). Covering an area the size of 24 football pit ...

, near

Keith, Moray Keith (Scottish Gaelic: ''Baile Chèith'', or ''Cèith Mhaol Rubha'' (archaic)) is a small town in the Moray council area in north east Scotland. It has a population of 4,734. Keith is historically in Banffshire, a name which persists in c ...

via underground cable. However, the end point was moved to Caithness, and the remaining part of the connection was constructed separately as the Caithness - Moray Link. In 2019,

Ofgem The Office of Gas and Electricity Markets (Ofgem) is the government regulator for the electricity and downstream natural gas markets in Great Britain. It was formed by the merger of the Office of Electricity Regulation (OFFER) and Office of G ...

announced that it was minded to authorise construction, subject to the Viking windfarm winning a CfD contract in the government auction held in September 2019. Viking Energy was unsuccessful in this auction, putting the future of the interconnector in doubt. SSEN submitted a revised proposal in January 2020. Ofgem carried out a final consultation on this revised proposal, and concluded in April 2020 that it would grant conditional approval for the link, conditional on Ofgem receiving sufficient evidence by the end of 2020 that the 457MW Viking Wind Farm project is likely to go ahead. In April 2020, Ofgem approved revised proposals for the project, subject to "evidence that the Shetland Viking Wind Farm project will go ahead". On 17 June 2020, the Viking Wind Farm sponsor, SSE Renewables, made a final investment decision to proceed with the wind farm investment, conditional on certain indu stry code modifications, and "the outcome of the consultation on Ofgem’s minded-to position to approve the transmission link, expected in July 2020". According to ''Shetland News'', this meant that both the Windfarm and the HVDC Connection were "likely to go ahead". On 16 July 2020, Ofgem gave final approval for the connection. Contracts for construction were awarded in August 2020 to Hitachi and BAM Nuttall. In February 2022, Hitachi Energy started the process of installing HVDC equipment at Kergord. Installation of the subsea cable started in July 2022. In April 2022, the project was described as "on track to be completed by 2024". The subsea cable installation is ongoing, and expected to continue until 2023. The first transmission of energy happened in June 2024, and the connection was commissioned in August of the same year.

Route

The interconnector starts at the Upper Kergord Valley converter station in Shetland. From the converter station an underground cable runs to a landing area in Weisdale Voe. From there, a subsea cable runs to landfall at Noss Head in Caithness, with onward connection to an HVDC switching station north of the village of Staxigoe in Caithness. The route of the cable crosses

TAT-10 TAT-10 was AT&T Corporation's 10th transatlantic telephone cable, in operation from 1992 to 2003, initially carrying 2 x 565 Mbit/s between United States and Norden in Germany. The A-segment was the part on the US continental shelf, the B- ...

TAT-14 TAT-14 was the 14th consortium transatlantic telecommunications cable system. In operation from 2001 to 2020, it used wavelength division multiplexing. The cable system was built from multiple pairs of fibres—one fibre in each pair was used fo ...

and

Atlantic Crossing 1 Atlantic Crossing 1 (AC-1) is an optical submarine telecommunications cable system linking the United States and three European countries. It transports speech and data traffic between the U.S., the U.K., the Netherlands and Germany. It is one ...

telecommunication cables and the

Piper A piper is a musician, a player of the bagpipe. As a noun proper, Piper may also refer to: People * Piper (given name) * Piper (surname) Arts and entertainment Fictional characters Comics * Piper (Morlock), in the Marvel Universe * P ...

–

Flotta Flotta () is a small island in Orkney, Scotland, lying in Scapa Flow. The island is known for its large oil terminal and is linked by Orkney Ferries to Houton on the Orkney Mainland, Lyness on Hoy and Longhope on South Walls. The island ha ...

oil pipeline.

Technical description

The interconnector will connect to the existing 320kV Caithness - Moray Link to form a three terminal HVDC network, with converter stations at Spittal in Caithness;

Blackhillock Substation Blackhillock Substation is an electrical substation located in the north east of Scotland, near the town of Keith in Moray. It is owned and operated by Scottish Southern Electricity Network (SSEN). Covering an area the size of 24 football pit ...

in Moray; and Upper Kergord on Shetland. The Shetland leg will have a power rating of 600MW; the Spittal and Blackhillock converters are rated at 800MW and 1,200MW respectively. This will be the first multi-terminal HVDC interconnection in Europe.

Project developer

The project is being developed by Scottish Hydro Electric Transmission, a subsidiary of

SSE plc SSE plc (formerly Scottish and Southern Energy plc) is a multinational energy company headquartered in Perth, Scotland. It is listed on the London Stock Exchange, and is a constituent of the FTSE 100 Index. SSE operates in the United Kingdom a ...

Project economics

It is estimated that it will cost more than £600million. Another source stated cost of £660million. The project is needed for development of Shetland's renewable energy potential and it is necessary for the projects such as the Viking Wind Farm. It also contributes to the security of Shetland's electricity supply, especially as

Lerwick Power Station The main power supply for Shetland is provided by Lerwick Power Station, located in Gremista, northwest of Lerwick town centre. This is the principal source of electrical energy for Shetland. However, as of 2015, about 20 MWe is provided by the ...

is nearing the end of its operational life.

References

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