"The tenfold reduction in the energy efficiencies Professor Stephen Salter seeks to explain (Letters, 19 September) is an automatic result of the renewablists trying to find new and innovative ways to measure "efficiency".  

I have seen them using thermal efficiency, efficiency of input fuel, payback time in terms of CO2 (measuring production in myriad competing methods), cost per construction, cost in continuous optimum wind levels etc, all of them misleading

In the real world, we use cost because money very efficiently correlates all the various inputs required to pay for things.  

In money, the 8,000 offshore windmills the UK government intends to build will cost at least £100 billion, while six off-the-shelf-nuclear reactors would produce the same power and cost under £6 billion – a 17-1 cost ratio. If the renewablists want to pay that much more on what they consider ethical grounds, let them say so."