Germany: ContiTech Presents Scour-Protection System

The new offshore rubber mats from ContiTech fit the contours of the seabed perfectly, and their elasticity allows them to absorb the energy of waves and vortices to prevent sand from being washed away around the foot of the turbine. These firm foundations for the piles that support them are absolutely vital.

Electric power from offshore wind turbines is to make an important contribution to future energy and climate policy in Germany and the rest of Europe. High wind speeds at sea harbor enormous energy potential.

With the continuing construction of wind energy plants offshore and in the North Sea, attention is increasingly focused on aspects such as the long-term stability of the plants and, in turn, scour development – this means wash-outs of the foundations by wave movements and ocean currents, and protective measures. This is where the ContiTech Conveyor Belt Group comes in with CONTI® SCOUR PROTECT.

The offshore foundations are an obstacle to the natural ocean currents, which gradually undermine the base of the foundations. This leads to “scour”, that is, depressions that can potentially affect the stability of the foundation design.

“The usual method of preventing scour has been to use stone- and sand-filled geotextile containers to protect the turbines against sand scouring by ocean currents,” says Michael Möschen, application engineer in the Engineered Products segment of the ContiTech Conveyor Belt Group.

But both methods suffer from drawbacks because they in turn are an obstacle to the currents and simply displace the scour to the edges of the scour prevention system. In addition, stones or geocontainers need to be replenished regularly. This displacement and the depletion of the stones or sand-filling also interfere with nature – with yet unknown long-term effects.

Protection for the seabed

The ContiTech Conveyor Belt Group has developed a brand-new method: A conveyor belt that offers absolutely failsafe scour prevention.

“Strictly speaking, this solution involves a mat made of fabric belts with a thickness of 12 mm to 15 mm, an outer diameter of 11 m to 52 m, edge weights of 100 kg to 200 kg per meter and a profiled surface to promote the deposition of sand,” explains Michael Möschen.

Advantages of the scour-prevention mat include the fact that it is fully renaturalizable, has the lowest foundation depth and does not need to be repaired every year. Its long-lasting single-element design creates stable conditions around the foundations so that new life-forms can settle close by.

“Our scour-prevention mats have weights on their ends that anchor them onto the seafloor. So no matter how strong the current, the mats remain unaffected,” says Möschen.

In 2009, developers of the ContiTech Conveyer Belt Group at the Deltares Institute in the Netherlands simulated extreme storms and streams. The result: The scour-prevention mat and the seabed under it remained intact.

The scour-protection system from ContiTech remains highly affordable and consequently contributes significantly to the economic viability of wind farms.

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Offshore WIND staff, August 7, 2012; Image: ContiTech