THE wind-farm industry has been accused of misleading the public after a study showed turbines are 25% less effective than claimed.  The John Muir Trust (JMT), one of Scotland's leading conservation bodies, has challenged the renewable energy industry's assertion that wind farms run at an average of 30% capacity over a year.  a study of energy generated by dozens of wind farms, the majority of which are in Scotland, between November 2009 and last month, found they actually ran at 22% of capacity.  Campaigners insist the figures, drawn from data provided by the National Grid, blow a hole in claims that wind farms are an efficient source of renewable energy. They said hundreds of wind farms had secured planning permission across Scotland based on inaccurate assumptions of their output.  "This analysis shows that over the course of a year, the average load factor fell well short of what the industry claims, yet the 30% figure is peddled at every public inquiry into a proposed wind farm," said Helen McDade, head of policy at the JMT. "This data is needed to counter that hype."  The JMT examined the performance of 47 wind farms capable of producing 2,430 megawatts (MW) of green energy.  They include Whitelee wind farm, near Glasgow, which comprises 322 turbines, and the 164-turbine Crystal Rig 2 development in East Lothian. apart from Burbo Bank, Barrow and Thanet, which are offshore sites south of the border, all of the wind farms are in Scotland.  The research found over 395 days, the wind farms could have produced 17,586,000M