What are bubble curtains used for?

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This noise mitigation system helped to protect porpoises, a small cetacean in danger of extinction, during the construction works of the Wikinger marine wind farm.

Porpoises are small cetaceans very similar to dolphins that live near the coasts of the northern hemisphere. Despite measuring only a meter and a half, much less than other marine mammals that populate the oceans, they play a key role in the balance of coastal ecosystems. However, due to them being accidentally caught in fishing nets, only 600 have been counted in the Baltic.

To prevent these cetaceans from being affected by the noise of the work during the construction of the Wikinger offshore wind farm to power 350,000 German homes, Iberdrola deployed an acoustic impact mitigation system.

The most critical phase of the work in noise generation was fixing the jackets to the sea floor, the foundations that allow wind turbines to rise above the sea. This installation required the use of a hydraulic hammer, which could produce an intense uproar that spread to long distances under the waters and can harm the orientation of cetaceans.

In order to prevent this, as part of its commitment to biodiversity conservation and ecosystem protection, Iberdrola deployed a compressor-driven bubble curtain to attenuate noise around the foundations.

Wikinger offshore wind farm.Wikinger offshore wind farm.

The system consisted of two circles of pipes with microperforations connected to a ship full of compressors that pumped air inside them. Through the holes, the emitted air exited towards the surface creating the bubble curtain.

The protection of these small cetaceans was one of the great challenges of the construction of the offshore wind park.