Sir, – David Sowby (November 7th) notes the inefficient contribution of wind to our energy needs. The situation will be exacerbated by regional climate change caused by low solar activity which will reduce available wind power in winter. For instance, already in January, February and December 2010 the available wind energy on the west coast was reduced to 28 per cent of normal due to blocking high pressure systems. We need to exploit more reliable sources of renewable energy such as waves and tides and to build pumped storage reservoirs. – Yours, etc,