Wind turbines are 25 per cent less effective than the renewable energy industry claims, according to research.  The John Muir Trust (JMT), one of Scotland's leading conservation bodies, has challenged the assertion that wind farms run at an average of 30 per cent capacity over a year. a study carried out for the trust into the energy generated by dozens of wind farms, the majority of which are in Scotland, between November 2009 and last month, found they ran at 22 per cent of capacity.  Niall Stuart, the chief executive of Scottish Renewables, which represents the industry, said the winter of 2009-10 was one of the calmest on record and that it was "no surprise" figures for the year were below average.