Offshore construction work, such as the anchoring of foundations for wind turbines, creates an enormous amount of underwater noise. Therefore, in order to protect noise-sensitive porpoises and other marine creatures, a maximum noise level of 160 decibels applies in German waters at a distance of 750 meters from any construction site.
Devices known as big bubble curtains are used to comply with this threshold set by the Bundesministerium fuer Umwelt, Naturschutz und nukleare Sicherheit (BMU – Federal Ministry of the Environment, Nature Conservation and Nuclear Safety). This involves a perforated hose laid around the construction site that creates a curtain of air bubbles generated by compressed air. As a result, the density of the water is changed, sound waves are broken up and construction noise is therefore reduced. To ensure that the structure stays on the sea floor without any additional weights or steel chains, we have now developed an innovative system that protects nature and makes installation work easier.
- Our innovative solution works without any additional anchoring to the sea floor and therefore leaves no trace.
- It makes installation work and handling easier and saves time.
- Our technology is reusable.
- Our technology reduces noise during the construction phase by up to 18 dB, which equates to a reduction in volume of 95%.
- It is characterized by high abrasion resistance and high resistance to saltwater.
- A meter-long hose with an inside diameter of 100 millimeters weighs 20 kilograms.
A Heavyweight for Easy Handling
Previously, installation companies fitted the hoses with additional weights to anchor them to the sea floor or positioned them on piping systems. However, these structures create complications when the bubble curtain is to be transported back to the surface of the water following completion of the work or when it is to be installed on the sea floor. What makes Continental’s development special is that an additional wire is wrapped around the hose. The result is a real heavyweight that lends the hose the right degree of balance at the required depth and without the need for compressed air to keep it buoyant.
“As with all construction projects, it’s all about doing the work as quickly and with as little effort as possible. That’s why we have developed a solution involving a hose that is flexible and that works without any complicated anchoring using additional weights, such as steel chains,” explains David Hoffmann, who is responsible for industrial hose solutions in the EMEA and APAC regions at the Continental Corporation. “We are therefore facilitating handling for installation companies. At the same time, we are contributing to the expansion of regenerative energy sources, thereby protecting marine life from construction noise,” adds Hoffmann.
The big bubble curtain hose for sound insulation is suitable for many other applications, such as mine clearance, offshore oil drilling, seismic surveys, port and coastal development, bridge-building and the construction of artificial islands.
Note: An increase in sound level of 6 dB is perceived as a doubling of the volume. Likewise, a measure that reduces the volume by 6 decibels halves the perceived noise, which is why a noise reduction of 18 dB can be quantified as a 95% decrease.