Siemens Power Generation installed the largest wind turbine in the Netherlands last month at the national wind turbine test centre at Wiiringeermeer, operated by Dutch energy research centre, ECN. The 3.6 MW machine is an upgraded version of the 3.6 MW prototype installed by Bonus at Denmark's Hovesøre test site in northern Jutland. Bonus was taken over by Siemens in late 2004. Hovesøre is operated by the Danish national laboratory at Risø. The Dutch prototype has a rotor diameter of 107 metres and hub height of 80 metres. The main components were docked at De Oude Zeug harbour on December 1, which is close to the Windturbines, Materialen en Constructies research centre, a partnership between ECN and Dutch university TU Delft. Although the wind turbine is the country's largest in terms of installed capacity, the tallest, with a hub height of 100 metres, is one of the two GE 2.5 MW prototypes also being tested at Wieringermeer. The test site opened in 2003 with five Nordex 2.5 MW turbines owned by ECN. The turbines have been used for several research and development projects, including the current testing of a bird collision detection system. The site also houses a Vestas NM 2.75 MW machine. The addition of the Siemens 3.6 MW turbine completes the test facility, says ECN's site director Wim Stam. But there is potential for expansion if height restrictions will allow it. The turbines are tested by their manufacturers, while ECN carries out measurements of wind speed, wind direction, production and noise levels.