Pfleiderer, a German maker of wind turbine towers, is testing a hybrid tower for large turbines at a site near its headquarters in Neumarkt. A Pfleiderer 1.5 MW nacelle with a rotor diameter of 77 metres has been installed on a 100 metre hybrid tower -- the lower 35 metres is constructed from external pre-stressed concrete while the upper 65 metres is made of steel. The pre-stressing cables, anchored in the concrete foundation, help to pull the steel part of the tower onto the lower concrete section, says the company's Rolf Werner. "This method is very economic and while the concrete part of the tower will last a very long time, the steel portion of the tower can be replaced after a lifetime of 25 to 30 years," he adds. Pfleiderer has supplied about 1500 concrete towers and 3000 steel towers to the German wind market since 1985. The Pfleiderer Group, which is also active in wind turbine manufacture, has an annual turnover of EUR 1.1 billion and expects to install its first large wind stations in Germany and Spain next year.