GOLD Aerodyn SCD Nezzy 8.0MW
Floating wind turbines are attracting growing attention for their potential to drive down the cost of energy. Aerodyn's Nezzy 8.0MW buoyancy-stabilised floating turbine concept appears to be a groundbreaking innovation in this arena.
The two-bladed 8MW downwind super compact drive (SCD) turbine with a 168-metre rotor diameter and fixed yaw angle is mounted atop a guyed tubular steel tower that tilts 10 degrees backward in wind-flow direction. A guyed design virtually eliminates tower bending moments, offering significant mass and cost savings. The droplet shaped tower with its rounded part facing the wind drastically reduces wind resistance (drag) to enhance overall stability.
The tower is attached to a hollow concrete Y-shaped support structure, and the longest 60-metre leg incorporates a rotating mechanism and chains for structure anchoring and turbine-wind alignment. Each leg is pre-tensioned by marine-proof steel cables to a central interface, also accommodating tower bottom-flange mounting. Three coning plastics-composite floaters provide the necessary buoyancy.
The SCD 8.0 is a further development of the SCD 6.0, but the floating structure has no helicopter-landing platform. The drivetrain is mechanically adapted to acceleration forces caused by floating structure movements. An unrelated modification is the switch from a synchronous permanent magnet generator (PMG) to a synchronous generator with brushless electrical field excitation. This was done to avoid difficulties in handling and assembly of magnets, to benefit from improved ability to warm up from stationary, and for cost reasons.
The Aerodyn-designed blades incorporate carbon fibres in the load-carrying spar caps, and their maximum width is about 6 metres. The bottom structure settles at about 18 metres below the water surface. Minimum required water depth is 40 metres, which qualifies Nezzy for IEC class IB North Sea sites.