SeaTwirl Offshore Wind Turbines: Size matters…

A solution to this problem is provided by floating turbines. Various prototypes and test systems are currently in use worldwide, mostly basing on a common offshore turbine being placed on a floating foundation structure.

Swedish company SeaTwirl has developed a new solution now. Instead of constructing larger and larger turbines, the Swedes are committed to developing smaller turbines with floating technology. In addition to the possibility of placing these turbines in larger water depths, the innovative design also offers the prospect to install them in areas with heavy weather.

SeaTwirl uses a vertical axis rotor with a tower placed on an underwater structure that reaches deep below the water surface. This structure consists of a buoyancy element and has a keel at its lowest point. The wind turbine, the tower and the underwater structure are assembled and move as a unit. In doing so, their weight is carried by the water, resulting in a lower bearings load. As the turbine rotates, the structure is stabilized by the keel, similar to a sailboat.

Just above the water surface and surrounding the tower the generator is located. The generator is the turbine's only static element. At the same time, it ensures that the SeaTwirl system has a very low center of gravity and thus remains stable. There is also access to maintenance and repair, which allows the use of smaller vessels. The entire plant is anchored at the seabed.

The vertical axis rotor ensures that wind power can be absorbed independently of the wind direction. This makes pichting systems for nacelle and rotor blades dispensable and thus the system lighter. Less moving parts lead to lower maintenance times and minimize the risk of failure.

A first small wind prototype of 30 kW has been tested in Swedish waters since 2015. While they are currently working on a 1 MW plant, the company is also expanding its portfolio by various technical possibilities.

Last week, SeaTwirl was granted a US patent allowing the turbine to flatten its rotor blades and thus providing further protection against heavy storms. “This grant strengthens our patent portfolio and opens up new potential markets. In many places around the world, there is risk of typhoons, cyclones or hurricanes. This patent enables the construction of turbines with less material but still withstanding strong winds. In a future with more and more extreme weather we're very happy with being granted this patent”, says Gabriel Strängberg, CEO of SeaTwirl.