REVISTA DYNA ENERGÍA

With it, unit powers of more than 15 MW are being achieved when installed in offshore locations. This entails major foundation and support work, especially when offshore in shallow coastal areas, complex flotation and anchoring in deep water, as well as high transport and installation costs.
Until now there seemed to be no variants or innovations available in this field, but the Norwegian company World Wide Wind (WWW) has proposed and designed a new floating wind turbine for offshore situations that it calls "counter-rotating", which it claims represents a considerable advance over existing turbines, both in terms of size, cost and the possibility of achieving higher power outputs. Together with the Norwegian AF Gruppen (AFG), it will install a 30 kW floating prototype that will allow it to test real operating conditions.
The prototype turbine has a total length of 19 metres and has two levels of fixed blades (rotors) at 45 degrees to the vertical axis, rotating in opposite directions, with the submerged generator located at the bottom of the structure which, with a simple anchoring, allows the turbine to oscillate in the wind like a sailboat. Whatever the wind direction, the floating assembly is passively tilted to an optimum angle, and the two turbines begin to rotate in opposite directions, effectively doubling the speed at which the rotor rotates relative to the stator. This doubles the power generation and reduces the cost. In addition, maintenance work is carried out at the base rather than at considerable heights.
The torque that the wind exerts on the structure is compensated by the two opposing rotations and, as the rotors are inclined, they produce less mutual affection and allow them to be installed closer to each other, generating more energy from a given surface area and reducing the connection wiring. The next step after the prototype will be a 1.2 or 1.5 MW pilot wind turbine to be tested during 2025, with the idea of having a 24 MW commercial turbine by 2030. They claim that this design would allow 40 MW to be reached, although in this case the total length of the tower would be around 400m.