Plan to tap Cornwall's 'hot rocks' for power

The granite bedrock of Cornwall could become Britain's greatest source of power, under an ambitious project planned by a former Armed Services boxing champion.

Nelson "Ned" Rawlins, once a Royal Navy stoker, claims that the natural heat of the earth trapped in the granite rocks under Cornwall could produce more electricity than conventional power stations.

His proposals, which have won support from experts at Imperial College London, use geothermal energy: the very high temperatures found deep beneath the earth's surface. Geologists have calculated that boring six miles down would reach temperatures of 400C.

That energy could flash-heat pressurised water into steam, powering steam turbines and generating electricity. If successful, the plant would be highly efficient ­ but there are formidable obstacles.

Much smaller geothermal power stations are in use around the world but mining at that depth is at present just a theoretical possibility.

The rock waste from cutting deep shafts and huge underground chambers for the turbines and pumps would be huge. The rock is also mildly radioactive, and the costs immense. The most modest version of Mr Rawlins's scheme would cost £80bn, and take 25 to 30 years to realise.

Yet Mr Rawlins has persuaded engineers at Imperial College and geothermal-power experts involved in Britain's first experimental geothermal scheme, also based in Cornwall, to endorse or join his project.