X-Zweiblatt Floating

In the X-Energy sub-project X-Zweiblatt Floating, huge floating two-bladed 20 MW wind turbines are being investigated in order to further expand the potential of offshore wind turbines.  

Around 80 percent of the world's usable offshore wind potential lies in waters deeper than 50 meters. However, this makes them unprofitable for wind turbines that are anchored to the seabed. Large floating wind turbines offer the opportunity to install wind turbines in deeper and windier waters, thereby further increasing the amount of green electricity . Various pilot projects with floating turbines have already been realized, but so far mostly with standard three-bladed turbines from ground-based systems. However, the use of just two rotor blades could offer major advantages for floating turbines in particular:

  1. A low tower head weight, which reduces the inertial forces in fluctuating systems and reduces the amount of material required to stabilize the floating platform thanks to a lower centre of gravity.
  2. The special option for pendulum hubs, which decouples the tower movement and the rotor surface and results in less stress due to swell.
  3. Fewer parts (one less blade including blade bearing and actuator) and therefore lower failure rates and less effort in maintenance, manufacture, erection and dismantling of the turbine.

However, two-blade turbines are typically characterized by their lower running smoothness, i.e. they run more unsteadily than a three-blade turbine due to the poorer distribution of aerodynamic forces and their rotor geometry.

In order to quantify these advantages and disadvantages compared to conventional three-blade turbines, high-resolution servo-aero-hydro-elastic simulations of floating two-blade and three-blade turbines are being carried out in the X-Zweiblatt Floating project and the results compared. These simulations are so precise that they are used in the industry for the certification of wind turbines. At the same time, a better cost estimate is being made to reduce the manufacturing, maintenance, installation and dismantling costs of floating two-blade turbines compared to floating three-blade turbines.

The results from the completed X-Rotor Zweiblatt sub-project will be used and continued for the X-Zweiblatt Floating sub-project.


Project Team:

Fabian Anstock
In cooperation with
Federal Ministry of Education and Research
CC4E - Competence Center for Renewable Energies and Energy Efficiency