Currently the largest wind turbine generators being installed will generate at most 5-7 MW, while most installations are of wind turbines rated at only 2-3MW.
According to the calculation of wind power, if the swept area of a wind turbine can be doubled, its potential power output will increase by a factor of eight. Unfortunately, engineering on the sort of scale required for large wind turbines is not easy, particularly when the best place to build wind turbines is offshore in the harsh marine environment.
The rotors of a typical 7MW wind turbine are already over 120 metres in diameter. Increasing the length of each rotor to give more generating capacity means that the rotors need to be thickened which in turn makes them heavier which in turn increases the stresses on the turbine generator which also needs to be strengthened etc. There will soon come a point when this conventional design of wind turbine cannot be scaled up economically any more.
A completely new design of giant offshore wind turbine is currently being developed by engineering firm Arup amogst others which they hope will result in the first 10MW wind turbine in the world, called the Aerogenerator X.
Pictured above is an artists impression of the Aerogenerator X installed offshore. Looking completely different from a conventional wind turbine, it has a set of aerofoil blades mounted on the vertical axis (see our article vertical axis wind turbine). The span of these blades will be around 300 metres and they will typically complete one full revolution about the central axis once every 20 seconds. Engineers hope that this new design will enable more efficient very large scale wind turbines to be built affordably.
It is planned for the first 10MW Aerogenerator to be installed in 2013 or 2014.