Scottish Hydro Electric Transmission, owned by the utility SSE, says the 450MW interconnector is now likely to cost at least £700m ($1.12bn), up from its previous estimate of £400m, meaning the likely transmission charges for renewable-energy generators would be unfeasibly high.

SSE is under intense pressure from the Scottish government to build the Western Isles interconnector, which would enable renewables projects on the sparsely populated Isle of Lewis to sell power onto the UK grid, while also boosting the island’s own energy security.

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