Turbine manufacturer Nordex says it has 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 117-m rotor diameter and a 10,715 m2 rotor sweep, the N117/2400 is the most efficient IEC-3 turbine in its class, according to the manufacturer.
The primary new feature is the rotor blade, which is 8.5-m longer than the previous onshore model. In typical IEC-3 locations, the N117 turbine achieves a capacity of over 3,500 full-load hours, exceeding other turbines in this category by 20%. This translates into a capacity factor of 40%. As a result, N117/2400 owners can have high and steady electricity production in regions characterised by lighter winds. With a length of 58.5m, this is Nordex’s first blade to be made from carbon fibre, a material 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 the 2011 EWEA in Brussels. Installation of the first turbine was completed on schedule. Consequently, Nordex completed static testing of the N117/2400 rotor blade at its own blade production plant at its Rostock facility. Static testing involved pulling the 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 static and dynamic testing. This entails fatigue testing during which the blade is vibrated for about six months to simulate exposure to such forces over the entire life cycle of the rotor blade. Dynamic testing follows. Both tests are key prerequisites for the award of the type certificate and commencement of series production by Nordex from mid-2012.
The estimated calculated annual energy yield of the N117 at the 91-m hub height is about 9.9 GWh for 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 project produces a total annual output of 27 GWh.