The proposed new Lerwick Power Station at Rova Head was, at least, 50 percent bigger than necessary. It had double the capacity (120MW) of the latest 60MW subsea cable proposal which itself exceeds Shetland’s peak winter demand by about a third. The projected cost of the new power station was therefore excessive and it is little wonder Ofgem balked at the idea.
Q1. Why was the new Lerwick Power Station design so excessively over-sized?
Q2. What would be the cost of a ‘no-frills’, 70MW power station at Rova Head, instead of 120MW?
Q3 What would be the cost of a ‘no frills’, 70MW power station sited at Sullom Voe with upgraded (underground) transmission lines to Lerwick?
Subsea cable connections to Orkney and the Western Isles already existed when the former North of Scotland Hydro-Electric Board was privatised in 1991. By the mid 1990s, its successor company, Scottish Hydro-Electric, keen to cut costs, considered connecting Shetland to the Mainland grid by subsea cable and rejected the idea due to excessive cost.
That assessment was based on the power station using heavy diesel fuel, as now, versus importing cheap coal or gas-fired energy via a grid link. However, a new power station would now use very cheap gas – less than a third the cost of diesel fuel – from Total’s Laggan-Tormore gas field, in which SSE holds a 20 per cent stake, via Sullom Gas Plant.
Gas would cost a fraction of imported mainland renewable energy (Scottish coal power stations have all closed). So there would seem less incentive now than in the 1990s to install a subsea grid connection.
Furthermore, local generation would avoid substantial power losses associated with the very long transmission distance and AC-DC conversion in the proposed subsea cable link.
Q4. What will be the capital cost of this proposed Caithness-Shetland subsea grid connection?