As governmental bodies are trying to protect the marine life, companies are facing more regulations and restrictions on the offshore installations.
During the foundation installation, hydraulic impact hammers create a lot of noise harmful to marine mammals as well as to other sea life.
Hamburg-based engineering and services company, Bilfinger Marine & Offshore Systems, developed an innovative Hydro Sound Damper (HSD) system which helps reduce the noise pollution in ways previously not achieved.
As part of Bilfinger Group, the company deals with fabrication, installation and services.
We wanted to find out more about this system and about Bilfinger’s plans, so we met with Tim Klatt, head of sales and development at Bilfinger Marine & Offshore Systems GmbH, at the WindEnergy Hamburg.
The story behind HSD began three years ago when “the contact was made between my boss Moritz Horn and noise mitigation expert Dr. Karl-Heinz Elmer with his company Offnoise Solutions, which cooperated at that time also with University of Braunschweig,” explained Mr. Klatt.
Bilfinger then teamed up with Dr. Elmer, Offnoise Solutions, who invented a system which keeps air enclosed in small balloons or bladders connected to the fishing net, in developing Hydro Sound Damper (HSD).
Mr. Klatt explained that the system is more cost effective than other solutions and that it doesn’t take space on the deck thus not harming the logistic process. “The bubble curtain needs an extra spread so it’s also not harming the installation process itself because it’s located somewhere else but it is very cost intensive because you have to hire additional vessels.”
“Our HSD is attached as curtains below the pile gripper which hold the monopile and you just let the curtain down and hammer the pile.”
Besides attaching it to the pile griper, the HSD can also be attached to the hammer and used as a stand-alone system where it is placed on the ground and then the floating elements are released covering the whole monopole.
First system tests were made on London Array, followed by Amrumbank West by Menk.
This week, Bilfinger started work on Wikinger Pile Testing Campaign where it will test Iberdrola’s anchor piles for the jackets in a 40 meter water depth. Bubble curtain will be used for the initial piling as the piling template is too big, while the HSD will be used for the restrikes.
“The system will be used for restrikes. Meaning that ten weeks after the initial piling we will come back and do restrikes to test the bearing capacity of the piles.”
Earlier this year the company signed a €100 million Sandbank foundation transportation and installation contract. The installation is planned to commence in mid summer and is expected to be completed by the end of 2015.”
For this job, the company has charted the wind farm installation vessel of Swire Blue Ocean, the Pacific Orca, which will transport and install 72 foundations at the project site. This will be the first large-scale project where Bilfinger will use the HSD system.Furthermore, Mr. Klatt explained that marine mammal protection regulations vary from country to country.
For example, in Germany, the Federal Maritime and Hydrographic Agency (BSH) has set the standard sound exposure level of 160 dB and the peak level of 190 dB at 750-meter distance from the offshore pile driving location as part of the building permission of offshore wind farm.
“This is a specific German requirement, and if you go to UK they exclude certain periods in the year, for example when sea mammal babies are regularly born, from any installation which produces noise. Even for the time allowed to work the limitations are project-specific.”
He added that USA might set up even different regulations regarding the marine mammal protection.
“Everywhere the regulations are different and that is very difficult for the industry. We need standardization in Europe,” concluded Mr. Klatt.
Currently, the company is focusing on North Europe, particularly on UK, Germany, Benelux, Denmark, Sweden and Poland, as they all have offshore wind energy plans.