Comhairle Leader, Cllr Roddie Mackay, today met with senior representatives from Scottish & Southern Electricity Networks (SSEN) regarding the recent failure of the subsea electricity cable between Skye and Harris.
The 33kV cable, currently rated at 22MW, is part of a line that carries power from the National Grid at Fort Augustus to the island network node at Stornoway. The entire link comprises an overland cable from Fort Augustus to Ardmore in Skye, the subsea section between Skye and Harris and a further overland section from Stockinish to Stornoway.
Peak demand in Lewis and Harris is currently around 23MW so the on-island diesel stations at Battery Point and Arnish are regularly called into service in order to supplement the imported supply. Now that the imported supply to Lewis and Harris has failed, diesel stations at Battery Point and Arnish will work full time to keep the islands on supply.
At the meeting, SSEN confirmed that the cable fault was located 15km from land and at a water depth of 130m. An on-site repair is not possible in these water depths and SSEN intend to replace the entire subsea cable, end-to-end – a length of some 32km. A 33kV cable of larger diameter is being considered which could upgrade the rating of the link from 22MW to 30MW, possibly providing community generators in Lewis and Harris with a higher capacity for export.
SSEN are currently sourcing generator back-up sets at the Battery Point station to guarantee security of supply for island consumers and there is no question of island blackouts while the on-island diesel stations are providing power.
Early indications are that replacement of the subsea link could take up to 12 months due to procurement challenges with a cable of this length. SSEN continue to explore all avenues in the procurement process to shorten this timescale.
Cllr Mackay stressed the considerable impact this failure will have on community electricity generators through protracted inability to export power. Commenting afterwards, Cllr Mackay said, “Our two priorities here are ensuring a robust electricity supply for homes, businesses and the health sector in the islands and the protection of our community generators who have invested so much on the basis that their product can be exported to Grid without restriction.
“The business case for many of our community generators relies on export of generated electricity and many of these community groups have purchased land, taken on staff and supported vital projects in the community. Across the sector, hundreds of thousands of pounds of revenue from exported electricity could be lost every month due to this failure. Insurance policies will help but, in most cases, a month of no export has to elapse before insurance payments become available and, even then, payments will be based on an insurer’s monthly average taken across the entire year.
This average will be well below the income expected by community generators over the winter months when wind speeds are high and consistent. Some policies also cap insurance reimbursement at six months. We will continue to press SSEN and others to ensure that this vital community income is safeguarded and, if necessary, compensated for”.
Dialogue will continue on a weekly basis between Cllr Mackay and senior representatives of SSEN and it is hoped that a firmer timescale for cable replacement will emerge over the next two weeks.