Renewables’ cost

The interview with Sir Donald Miller (your report, 4 August) was principally about the costs of electricity following independence, yet the response from Scottish Renewables did not mention cost.

May I correct this shortcoming using data from my own studies, since all costs will have to be paid by customers?

Wind generation adds a number of extra costs for customers because of its geographical location in the north of Great Britain, and its intermittency.

The extra costs comprise additional transmission circuits, extra losses, costs of flexing and standby of thermal or hydro plant to accommodate intermittency, and capital costs of back-up gas turbines to contain the risk to security of supply.

Compared with an optimum plant mix of gas turbines and nuclear, the proposed 28GW of wind generation will cost the 25 million Great Britain households about £16 billion per annum extra, which will amount to £725 per annum per household.

If only two-thirds, say, of GB wind was connected to a Scottish system, and that part of the £16bn had to be shared between 2.5 million Scottish households the costs would be unbearable, and English and Welsh customers would be under no obligation to continue paying these large subsidies.

The suggestion of Scottish Renewables to add further to these costs by providing more pumped storage and interconnection capacity does not seem reasonable unless, of course, the wind companies are prepared to pick up the costs.

The turn-round efficiency of pumped storage (including transmission) would only be about 70 per cent; and interconnection would incur significant transmission and conversion losses.

The country needs to see the results of properly structured and supervised Total Power System Cost studies to provide transparency on these issues. It would appear that Sir Donald has good reason to express his concerns.

Colin Gibson

National Grid Group

Cormiston

Biggar