Cofferdam can reduce noise from turbine installation

According to legislation from the EU, sound emissions from the installation of offshore wind turbines need to be reduced in order to reduce the threat to marine mammals. Until now, little effort has been made to reduce the waterborne noise created when driving monopiles into the seabed, although techniques such as ‘bubble curtains’ have been used.

Using the innovative solution developed by Lo-Noise it has proved possible to reduce noise by up to 25dB within a radius of 750m. The technology is based on the use of a cofferdam (for which a patent is pending) which complies with the recommended requirements of a maximum of 160dB SEL and 190dB peak for underwater pile driving noise levels. To date, Germany is the only country to have ratified the legislation, but the remaining EU countries are expected to follow Germany’s example.

The cofferdam concept was first tested towards the end of 2011 in the bay of Aarhus, Denmark with very positive results. Lo-Noise claims that the cofferdam is the only technology that can reduce the noise level by 25dB and meet the requirements of the EU legislation. The tests were undertaken by Lo-Noise working closely with Grundfos, Trelleborg, NICON Industries, DBB, Rambøll and OSK-ShipTech.