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Your editorial“The global warming conundrum ”(14 November) says Scotland is “moving from an economy built on coal, oil and gas to one powered mostly by the sun, wind and sea ”. Was theo mission of nuclear, which provides 30-40 percent of Scotland’s electricity, a deliberate or a Freudian slip? When Torness finally closes, Scotland’s electricity will indeed beat the mercy of the weather and nothing else.

There are connectors to England but an intention to make Scotland independent means placing its most fundamental energy supply in the hands of another country which may not, because of the same weather, have any excess itself. Renewables are parasitic on as table electricity supply– when the wind doesn’t blow those companies that provide them are simply in different to the cost consequences; the needs of the country to maintain stability of supply.

That need requires mainte - nance of a complete alternative, stable supply of gas- fired power stations to cover the periods of wind or sun absence and whose costs therefore rise enormously because of insufficient routine use.

That is one reason our electricity bills continue to rise. Economist Diet er Helm, in his requested submission to explain the rising cost of electricity to the UK Government, stated that renewable subsi dies“should be gradually phased out and merged into a unified equivalent firm power capacity auction. The costs of intermittency will then rest with those who cause them, and act as a major incentive for intermittent generators to invest in the demand side, storage and back- up plants”.

Since large - scale storage is decades away, wind and solar will therefore have to subsidise both the development and running of both nuclear and gas- fired power stations. ( PROF) TONY TREWAVAS

FRS FRSE Scientific Alliance Scotland North St David Street, Edinburgh