Innovative noise reduction technology protects animals

Weinheim. August 22, 2013. Porpoises off the North and Baltic coast – they have a good-natured face, a somewhat plump body and above all a very delicate sense of hearing. Sadly, these marine mammals are in decline and it is therefore more important than ever to ensure their protection. In particular noise-intensive underwater construction work at offshore wind farms stresses the animals and drives them away from their preferred habitats near the coastline. Freudenberg has developed a process which successfully reduces the noise level of underwater ramming work.

Anyone going on holiday to the North or Baltic Sea has probably planned a walk or two over the mud flats and is looking forward to relaxing in a deck chair breathing in the fresh sea air. But very few people know that whales also live in German waters. Porpoises are the smallest of the species and count as endangered. Sea pollution and over-fishing have substantially reduced the population over the years, although porpoises are a protected species. Furthermore, these marine mammals suffer considerably from the noise of underwater construction work. They have an acute sense of hearing which enables them to communicate with their fellow species over great distances. But this sensitivity and their preference for water near the coast place an immense strain on the animals.

Foundation work, in particular at offshore wind farms whereby piles are driven up to 40 meters into the sea bed, are especially noise intensive. This causes the shy marine mammals to lose their sense of direction and leads them to withdraw to other habitats. In an effort to change this, the German Federal Agency for the Environment as well as the Federal Agency for Nature Conservation commissioned studies years ago to develop techniques to reduce noise. The so-called cushion air process proved itself as the most cost-effective and efficient sound proofing system. This new method was brought into production through the development of a special sealing system from Freudenberg Sealing Technologies Merkel in Hamburg. “It’s wonderful to be able to do something so positive for the environment,” explains Jens Kuhnert, Project Manager in Hamburg. The sound proofing process lowers the noise from ramming work by up to ten decibels.

The idea behind it is simple and effective at the same time: In this process, columns that are to be driven are enclosed in a hollow pipe. Inside the pipe, an air cushion is generated, which at first is filled with water and replaced at a later stage with air. The specially-developed seals are used at the upper end of the hollow pipe to close the opening, pressing air into the space and pushing water out.

The resulting reduction in noise is less stressful for the porpoises and there is hope they will return to their original habitat. Maybe then we will see more of these beautiful creatures - how they serenely come to the surface, snatching at air before gently swimming away.