TAKING THE STRAIN

Under testing a British manufactured wood composite blade withstood a maximum load of 9.9 tonnes -- the weight of 13 Ford Escorts. This means the blade should survive a wind speed of 87 m/s, 60% above its maximum design load, according to its manufacturer, the Wind Energy Group. The firm has already signed contracts for the new blade for projects in India and the Netherlands.

A blade manufactured by the UK Wind Energy Group (WEG) survived a load equivalent to extreme hurricane force winds in a test by City University of London, reports the wind company. The 14.5 metre wood composite blade, designed and manufactured by WEG, withstood a maximum load of 9.9 tonnes -- the weight of 13 Ford Escorts. This means the blade should survive a wind speed of 87 m/s, 60% above its maximum design load.

In the test-to-failure, City University mounted the blade at the root at an angle of six degrees to the ground, giving a tip clearance of over three metres in height. It applied loading in steps of 25% up to the 100% design load, before continuing in steps of 10% until the blade failed. The maximum load held for 15 minutes and comfortably exceeded the maximum design criteria for both a Class I and II wind site, says WEG.

So far this year WEG has signed two contracts for its blades worth a total £900,000. The first is with Elecon Engineering Ltd in India for 81, 14.5 m blades. These are destined for the State of Gujarat where WEG has already supplied blades to seven WindMaster turbines. The second contract, with WindMaster Netherlands, is for three sets of 21 m blades for its 750 kW machine at sites in Holland.