Wind turbine (Vind turbin):
Rotor blades (Rotorblad), Strut (Stag)

Submersible floating foundation (Undervattensdel):
Keel (köl), Floating element (Flytelement)

Technical principle

SeaTwirl developes a new type of floating wind turbine that is customized for the sea. SeaTwirl use a vertical axis wind turbine with a tower that is placed on an underwater structure that reaches deep down under the water surface. The underwater structure consist of a buoyancy element and at its lowest point a keel. The wind turbine, tower and underwater structure is fixed together and rotates as a unit. The water carries the full weight of the structure and when the wind turbine captures wind energy the structure is stabilized by the keel like the function on a sailing boat.

To transform the wind turbines kinetic energy into electrical energy a generator is placed in a generator housing surrounding the rotating tower. The generator housing have a low placement underneath the wind turbine, but above the water surface. The ability to place generators and other equipment in the generator housing underneath the wind turbine make SeaTwirl obtain a low center of gravity and a stable structure. At the same time the placement eases the accessibility for maintenance and the boats needed for this kind of work may be small. SeaTwirls floating wind turbine is anchored between the generator housing and the bottom of the sea. Since Sea Twirl is floating it can be placed in deeper waters, where traditional bottom fixed wind turbines can´t be installed.

By placing the wind turbine on the floating underwater structure the bearings don’t need to carry the weight of the wind turbine. This is unique for SeaTwirl and implies that the bearings will be exposed to lower loads than other wind turbines.

SeaTwirl use a vertical wind turbine which can absorb wind energy independent of wind direction. There is no need for any yaw system for the turbine to face the wind as it is in the traditional horizontal axis wind turbines. A pitching mechanism to turn the rotor blades is not needed either. Therefore a vertical wind turbine contains fewer moving parts which imply lower maintenance costs and more available operating hours.


SeaTwirls advantages

• SeaTwirl has a simple and robust design with few moving parts that can break which leads to less downtime and more operative hours
• SeaTwirl has easy access to parts that needs maintenance
• SeaTwirl easily obtains a stable structure due to the low center of gravity
• The water carry the weight of the wind turbine which implies lower loads on the bearings
• Scientific reports show that vertical axis wind turbines have a high structural limit and can be built larger than horizontal axis wind turbines.


Why offshore wind?

• There is much more energy available offshore than onshore. This is due to that offshore the wind is stronger, the wind blows more hours and is more even
• Floating structures may be placed where the best wind conditions prevail
• Offshore floating wind is a new market with great potential

Watch the movie of one of few installed floating wind turbines in the world.
Watch the movie below to see how it works.