Bubble curtain (technical noise protection)
Bubble curtains are a measure of technical environmental protection in the marine area for the insulation of noise , such as occurs, for example, when building offshore plants or when detonating old ammunition. Bubble veils are intended to protect hearing-sensitive marine mammals such as porpoises and seals from hearing damage. Bubble curtains are created with air bubble systems .
environmental Protection
In the construction of offshore facilities, such as offshore wind turbines , oil drilling platforms, research platforms and the like. a., foundations are rammed into the seabed, drillings are made or foundations are poured with great noise. Harbor porpoises in particular, which have a hearing range of approx. 1–150 kHz and use ultrasound to orient themselves, can be damaged by the sound waves under water. This can lead to TTS (Temporary Threshold Shift), i.e. temporary hearing loss due to exposure to noise, or PTS (Permanent Threshold Shift), permanent hearing loss in animals.
Technical implementation
In order to create a bubble curtain, compressed air hoses are laid around the underwater construction site. Compressors , such as those used in road construction, pump compressed air into the hoses on the seabed. This compressed air rises in the form of a curtain of air bubbles and thus forms an acoustic-damping element surrounding the sound source for the propagation of the sound.
During the establishment of the foundation for the FINO 3 research platform , about 80 km west of the island of Sylt , the Institute for Statics and Dynamics at the University of Hanover accompanied the large-scale testing of a so-called " large bubble veil " scientifically as part of the BMU-funded research project Schall FINO 3 . The bubble curtain was created with the help of a 440 m long plastic pipe with nozzle openings, which was laid on the seabed in a radius of 70 m around the construction site and supplied with compressed air during the pile-driving work. In this way, a noise reduction of 12 dB (broadband level, SEL ) or 14 dB (peak level, L peak ) could be achieved at a distance of 910 m .
In a further research project, the effectiveness and practical feasibility of a so-called “small bubble curtain” for the construction of a wind turbine in the offshore wind farm “ alpha ventus ” was examined. This project was also funded by the BMU under the title Schall alpha ventus . The test also demonstrated a noise reduction of 12 dB (broadband level, SEL) or 14 dB (peak level, L peak ) in the direction of flow . Against the direction of flow, however, the effectiveness was drastically reduced due to the drifting of the bubbles. The use of the bubble curtain was later discarded there due to ineffectiveness due to currents.
According to more recent information, sound attenuation of up to 18 dB can be achieved.
Individual evidence
- ↑ Tanja Grießmann: Research platform FINO³ - Use of the large bubble curtain. (PDF; 1.3 MB) (No longer available online.) Federal Maritime and Hydrographic Agency, 2009, archived from the original on October 10, 2015 ; Retrieved June 1, 2013 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Tanja Grießmann et al .: Final report on the BMU project: Research and application of noise minimization measures when ramming the FINO3 monopile ("Schall FINO3"). (PDF; 4.3 MB) Retrieved June 1, 2013 .
- ↑ Effects of the construction of offshore wind farms on harbor porpoise populations - Federal Government's response to the minor question from MPs Undine Kurth (Quedlinburg) (...) and the Alliance 90 / THE GREENS parliamentary group - printed matter 17/2390 - . Bundestag printed paper 17/2642 of July 20, 2010.
- ↑ Jochen Vennemann: Soundproofing for sea creatures . In: Noise Control , Volume 13, No. 5, September 2018, ISSN 1863-4672, p. 183
