Waved away

The Pelamis wave machine is a clever idea but on my AAA ranking for renewable energy projects it comes as no surprise that it now appears to be practically and financially unviable (your report, 22 November).

On achievability, it should be noted that 10,000 of these devices off the western coast could provide just 1 per cent of UK 
energy needs.

On affordability, these are obviously very expensive devices. More than 3.5 million tons of steel alone would be required for the above number; how long would it take to make them and in a hostile marine environment just how long would they last?