aLEX SaLMOND was under pressure to overhaul his green energy policies last night after new evidence indicated wind farms produce a quarter less energy than developers claim.  The John Muir Trust (JMT), one of Scotland's leading conservation bodies, published research showing 47 wind farms north and south of the Border run at an average of 22 per cent of capacity.  But the wind farm industry has claimed that over the course of a year, a turbine operates at an average of 30 per cent efficiency, with the precise figure dependent on the weather.  The trust said the figures show that dozens of wind farms in Scotland have been approved on the basis of "inflated" claims of their output and called for SNP ministers to urgently review their policies.  Mr Salmond has refused to approve a new generation of nuclear power stations north of the Border, instead claiming that all of Scotland's energy needs can be met through wind and wave power.  But he faced embarrassment in November when the head of one of the country's largest energy generators branded the blueprint "bonkers" and warned Scotland was in "serious danger" of suffering power shortages.