In Siemens' case, it has created a 154-metre rotor for the 6MW turbine that was launched earlier this year. Currently the machine is in testing with a 120-metre rotor, which will be available for sites with height restrictions. The new 154-version will have a 18,600-square metre swept area.
Areva meanwhile has chosen to revamp the blades and nacelle of its M5000 turbine, seven years after its launch. The new version has a 135-metre rotor (compared with the old 116-metre version). According to chief technology officer Rene Balle, the turbine offers an additional 8% annual yield at nine metres per second average speed sites.
Besides longer and slender rotor blades, other features include a new nacelle, which has been designed for easier assembly, serviceability and access. Balle said the gearbox will remain unchanged.
Elsewhere, GE announced it was installing its 4.1-113 turbine in Gothenburg harbour. Technically, it is the first time GE has installed an offshore turbine since 2003 when it built the 25MW Arklow wind farm in the Irish Sea. Following on from GE's acquisition of ScanWind in 2008, the 4.1 113 is a scaled-up version of the latter's 3.5MW direct-drive turbine.
In terms of trials, it was bad news for Norwegian company Sway, which is developing a floating wind-turbine platform. Exceptionally high seas caused its 1:6 test model to sink off the Norwegian coast. The model was launched in March as a means of raising investment and verifying the design.
According to Sway, the model was only designed to withstand a maximum wave height of four metres whereas data collected by the US government's National Renewable Energy Laboratory showed wave heights of 6.3-metres. Sway said a full-size version of the model would be able to withstand wave heights of up to 26 metres.