RIGID vs. SOFT OFFSHORE WIND TURBINES
After 25 years of development, the common 'Rigid' upwind turbines on land still need government subsidies and regulations to compete against electricity from coal. The situation is worse offshore! Their installed cost/kW offshore is three times of that on land, due to the high costs of offshore foundations, installations, and undersea power transmission.
Efforts are being made to build larger wind turbines for offshore applications, 5 MW or larger, to lower the costs per kW installed. But, indications are: these efforts will not lower the costs by much!
Fundamentally, it is very difficult to reduce the costs of the 'rigid' upwind turbines for offshore applications! For the upwind turbine, the blades are upwind of the tower, and have to be 'rigid' and strong, and requires more material, such that they will not be bent back to hit the tower. In addition, the tower has to be 'rigid' and strong, such that the rotor can be turned into the wind with a yaw mechanism. Therefore, it takes a lot of material to manufacture the blades and tower of an upwind turbine, and makes it expensive and heavy! In addition, it also requires a very solid foundation, which is very expensive offshore! Furthermore, the offshore installations and repairs & maintenance are also very expensive!
Therefore, the 'rigid' upwind turbines and their extensions are unlikely to be cost-effective for offshore applications!