The offshore wind energy

Offshore wind energy brings a new momentum to the wind energy industry by opening up new perspectives. Setting up wind farms away offshore considerably reduces visual and noise nuisance while exposing the turbines to winds stronger and more constant than onshore.

The technology currently in use to operate the offshore wind energy resource is based on fixed foundations. However this technology rapidly reaches its limits since, for technical and financial reasons, it cannot be set up on more than 50 m depth.

The development of the offshore wind energy sector is therefore strongly restricted and many high potential sites remain untapped. It is amongst others the case for deep seas such as the Mediterranean or the Japanese shores. For those deep seas, the only sites that can be contemplated with current technology are sites very close to the shores, where visual and noise nuisance is the more acute.


Offshore wind energy comes with the perfect setting for wind farms development since at sea, the very strong wind resource makes up for the sporadic character of electric production while curbing space use conflicts.

Nevertheless fixed base wind energy’s growth is restricted by the difficulty to find sites fulfilling all geotechnical and environmental criteria with satisfactory wind resource. Worldwide, only the North Sea offers a vast space with good wind resource and depths compatible with fixed foundations (less than 50m depth). Moreover, and despite regular and powerful winds, the large marine wind farms’ production remain limited for most turbines (after the first row), because of the wake effect. 

A new technology is developing to overcome offshore wind energy limits, namely the floating wind turbines. They are fixed on a floater moored in the marine ground and can therefore be set in deep waters, with more than 50 m depth. It is therefore possible to set them up there where usage conflicts are limited and the wind resource at its strongest.

However this new technology has to take up many challenges. The turbine is placed on a floating structure, therefore it tips with the wind thrust. In the case of usual horizontal axis wind turbines the aerodynamic output then rapidly decreases. You therefore have to build a very stable, ie.very heavy and expensive floater to reduce the tilt, which makes the wind turbines unprofitable.

With its unique and innovative approach, Nénuphar bypasses those difficulties to come to a competitive solution that fits floating conditions.


 

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