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Navy denies causing power failure on isles after military exercise

By Mike Merritt

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Exercise Joint Warrior took place earlier in October.
Exercise Joint Warrior took place earlier in October.

The Royal Navy has denied it is responsible for damaging the major 20-mile-long subsea power cable in the Minch that takes electricity to the Outer Hebrides.

It will have to replaced at a cost of "tens of millions of pounds".

Europe's largest war games have just been held in and around the Minch and ended on October 15. The next day a major fault between the isles of Skye and Harris blacked out almost 18,000 homes on Lewis and Harris.

Now it has been announced that the 33,000-volt link will need to be replaced at a huge cost and may take a year.

The fault is in deep water and could have been caused by a third party, according to Scottish and Southern Electricity Networks (SSEN).

But the MoD says it was not them.

Exercise Joint Warrior saw 11 nations taking part, bringing 28 warships, two submarines, 81 aircraft and over 6000 military personnel – including 130 ground troops – to military ranges across the country and to maritime exercise areas off the east, west and north coasts of Scotland.

A Royal Navy spokesperson said: “There have been no reports of any incidents in the Little Minch. Undersea power cables are well charted and actively avoided by submarines for their own safety and the protection of critical infrastructure.”

SSEN is investigating how the underwater cable was cut suddenly.

It believes the breach happened at a depth of over 100 metres about nine miles offshore from Skye and is investigating whether it was cut by a trawler or another vessel.

SSEN has asked for local shipping records so it can pinpoint which vessels were in the area when the cable failed.

Properties on the two outer islands are now being powered by the diesel-fired turbines at Battery Point power station at Stornoway – and this will continue for the foreseeable future.

The undersea cable break means that the only power link between the whole mainland transmission network and the northern half of the Western Isles has been severed, although power continues to flow to the southern isles through a separate spur of undersea cable from Skye.

SSEN said a repair has now been ruled out and a full replacement is required.

While it is too early to determine specific timescales, SSEN expects the replacement project to take between six and 12 months given factors including cable procurement and manufacture, securing necessary permissions from statutory authorities and suitable weather conditions for cable installation.

"An end-to-end subsea survey of the Skye to Harris cable was undertaken in August 2020 which did not identify any material concerns requiring attention. Further investigations are ongoing to determine the root cause of the fault, including to rule out any instance of third-party damage," said SSEN.

Western Isles MP Angus MacNeil has written to Ofgem, which regulates power supplies, to look at the options with greater resilience.

He said the cost of replacement will be "tens of millions of pounds".

“The concern here is that the backup is now a long-term backup – there is no backup left," he said.

Communities across Lewis and Harris have also been dealt a major blow by the failure of the subsea cable between the islands and the mainland grid, losing their ability to export renewable electricity from local wind turbine production and the vital income it brings.

Winter wind speeds are critical to the profitability of locally-owned turbines.

Wind farm operating company Galson Energy has been able to distribute nearly £400,000 to the Galson Estate community during its first six years in operation.

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