Nuclear reaction

Carolyn Taylor (Letters, 27 January) thinks the 4.5 billion tonnes of uranium in the oceans will only fuel us for 6,500 years. However, her calculation is 100- fold too small.

Current UK reactors use less than 1 per cent of supplied uranium. Fast breeder reactors now being constructed in various parts of the world are more expensive to build, use 99 per cent of the uranium and consequently access 100-fold more energy.

The radioactivity in the remaining waste decays in 100 years. Thorium is three times more abundant than uranium on land, and thorium reactors likewise use 99 per cent of their material with a similar short half-life of waste. I estimate at least 60,000 years of energy available in known thorium resources alone.

The European intention of targeted reduction of fossil fuel use and emissions was to encourage others to follow. Governments of most of 95 per cent of the world population have made it clear by statement or policy that they will continue to use fossil fuels until they have brought their populations to an acceptable standard of living many decades hence and probably longer.

The gesture has failed but its net effect has been to make European economies uncompetitive and mired in recession because of the huge emphasis on expensive and unreliable renewables.

They should be and will be abandoned, and the EU is already sensibly backtracking on emissions targets.

For the foreseeable future, emissions will continue to rise; the answer is, of course, adaptation.

(Prof) Tony Trewavas FRS FRSE

Scientific Alliance Scotland

North St David Street

Edinburgh