Nordex has now passed a major milestone towards the series production of the N117/2400 onshore turbine: On 16 December 2011, it installed the first version of this model at the “Stadum” citizens’ wind farm in Schleswig-Holstein. With a rotor diameter of 117 metres and a rotor sweep of 10,715 square metres, the N117/2400 is the most efficient IEC-3 turbine in its class.
The primary new feature is the rotor blade, which is 8.5 metres longer than that of the previous onshore model. In typical IEC-3 locations, the N117 turbine achieves a capacity of over 3,500 full-load hours, thus exceeding other turbines in this category by 20 percent. This translates into a capacity factor of 40 percent. As a result, Nordex customers using the N117/2400 are able to achieve high and steady electricity production in regions characterised by lighter winds. With a length of 58.5 metres, this is Nordex’s first blade to be made from carbon fibre, a material which is lighter yet more rigid than glass fibre hybrids. Despite its greater length, the NR58.5 blade weighs less than 11 tons and is thus somewhat lighter than its predecessor.
Nordex unveiled the N117/2400 at EWEA in Brussels nine months ago. Installation of the first turbine was completed in full accordance with the schedule. Consequently, Nordex completed static testing of the new N117/2400 rotor blade at its own blade production plant at its Rostock facility two weeks ago. Static testing involved pulling the rotor blade consecutively in four different directions; the forces applied exceeded those arising in the field by many multiples. The successful test was a prerequisite for the award of the TÜV Nord design certificate. Full certification of the new rotor blade requires not only static but also dynamic testing. This entails fatigue testing during which the blade is caused to vibrate in two consecutive directions over a period of around six months to simulate exposure to such forces over the entire life cycle of the rotor blade. Dynamic testing is to commence in the near future. Both tests are key prerequisites for the award of the type certificate and commencement of series production by Nordex from mid-2012.
The expected calculated annual energy yield of the N117 turbine with its hub height of 91 metres stands at around 9.9 GWh at the “Stadum” site, which has a mean annual wind speed of 7.4 m/s. Together with two N100/2500 plants at the same site, the wind farm produces a total annual output of 27 GWh of electricity, sufficient to supply roughly 6,700 four-person households with clean wind-produced electricity.