SSEN submits Needs Case to Ofgem for Western Isles transmission link

Scottish and Southern Electricity Networks (SSEN), operating as Scottish Hydro Electric Transmission under licence, has today submitted to the energy regulator, Ofgem, a Strategic Wider Works (SWW) ‘Final Needs Case’ for a subsea cable transmission link from Western Isles to the Scottish mainland. 

The network reinforcement is required to enable renewable generation seeking to connect on Western Isles access to the GB market.

The Western Isles is home to some of Scotland’s greatest wind resource and following the growth in small-scale renewable electricity generation over recent years, the existing Western Isles electricity network is at full capacity meaning no further generation can connect without significant network reinforcements.

Following confirmation from the UK Government to allow remote island onshore wind to compete in the next Contracts for Difference (CfD) auction in May 2019, there is now an opportunity to progress with the transmission reinforcement, subject to the success of Western Isles renewable developers in the CfD auction and regulatory approval.

SSEN’s proposed solution would deliver a deliver a single 600MW subsea circuit from Arnish on Lewis to Dundonnell on the Scottish mainland.  This would then connect to SSEN’s Beauly substation near Inverness via underground cables.

In the Needs Case, SSEN presents a comprehensive analysis of the investment options available to meet a range of credible future generation scenarios on the Western Isles. This analysis concludes that a 600MW HVDC connection is the optimal solution, predicated on the two largest transmission contracted generation schemes securing a CfD in the forthcoming 2019 auction. SSEN’s analysis has been assessed by both National Grid, as the System Operator, and independent economic consultants. 

SSEN is therefore requesting a conditional approval of the Needs Case from Ofgem subject to demonstration that sufficient volume of generation has been committed to by developers following the 2019 CfD auction.

Throughout the development of the Needs Case, SSEN has engaged with a broad range of stakeholders, from local elected representatives and community groups to its contracted customers and wider industry.  This engagement has identified broad support for SSEN’s proposed solution due to its favourable impact on project economics, the significant socio-economic benefits the link would provide the Western Isles community and the opportunity for additional generation to connect in the future, particularly the many community renewable schemes planned.

Dave Gardner, SSEN’s Director of Transmission, said:

“Today marks a significant milestone in providing a transmission connection to the Western Isles.  We believe our proposal represents a robust, economic case for reinforcement and provides the best possible opportunity to unlock the renewable potential of the Western Isles. 

“There are still many hurdles to overcome, not least the requirement for sufficient volumes of renewable generation capacity securing a CfD contract to underpin the investment case. 

“We would like to thank our generation customers and wider stakeholders who have helped inform the development of the Needs Case and we now look forward to working constructively with Ofgem as they review our submission.”

More information on the Western Isles project can be found here https://www.ssen-transmission.co.uk/projects/western-isles/