The above-water part of the wind turbine consists of a static generator body and a rotating “tower” attached to the spacers and vertical rotor blades, while the underwater part consists of an oblong “float” having a jacket with a fixed-ballast at the tip. The generator housing and the wind turbine will be secured to the seabed during operation with several mooring ropes – this will ensure stability of the structure at great depths and in strong winds.
The SeaTwirl development has several advantages over the conventional horizontal turbines used for offshore wind generation. Due to the floating underwater structure, the bearings inside the generator do not bear the turbine weight and are subjected to comparatively low loads. The generator vertical axis makes possible not only withstanding of strong winds but also avoiding any dependence on its direction at power generation. Finally, a successful location of the generator – under the blades, but over the water – provides a low gravity center, which also adds to the wind turbine stability.
The design simplicity will minimise the operating costs. SeaTwirl estimates that the levelised cost of electricity (LCOE) will be 21% lower than for horizontal offshore wind turbines whose high LCOE is one of their weaknesses. By comparison, the levelised cost of the EU offshore wind turbines in 2020 was $75 per megawatt-hour (MWh), while it was $50 per MWh for the onshore wind turbines and $55 per MWh for the solar panels according to the data of the International Energy Agency. The SeaTwirl innovation could spur introduction of offshore wind turbines, which remain less widespread than the onshore turbines. According to the data of the International Renewable Energy Agency (IRENA), the global installed capacity of the offshore wind turbines was 34.4 gigawatts (GW) in 2020, the onshore turbines had 698.9 GW capacity. Over half of the global capacity of the above-water wind generators came from the Great Britain (10.4 GW), China (9 GW) and Germany (7.9 GW).
