EnBW and Heerema Marine Contractors have demonstrated noise reduction during pile driving at the 960MW He Dreiht offshore wind project in the German Bight.
The noise mitigation system T-NMS-10000, constructed in collaboration with IQIP, in combination with a double big bubble curtain and IQIP’s PULSE system reduces underwater noise up to 24 decibels (dB).
The T-NMS-10000 functions as a “giant subsea noise barrier” for monopiles, effectively containing internal noise emissions.
In response to stringent environmental regulations that are applicable in the German Bight, a maximum of 160 dB at 750 metres from the source, EnBW committed very early in the He Dreiht project design to the development of this latest generation NMS, essentially an upscaling of previous systems complemented with the truss frame template structure, enabling its deployment with floating installation vessels.
Heerema accelerated and completed its development by additional research and engineering efforts.
The T-NMS-10000’s steel structure comprises an inner tube (approximately 12 metres in diameter, so suitable for a 10 metre diameter monopile) and an outer tube (roughly 13 metres in diameter), separated by rubber blocks.
Air compressors expel the water column between these tubes, creating an air barrier across the entire water depth.
The T-NMS-10000 contributes a big part in the noise mitigation spread by reducing noise already up to 15 dB as measured by ITAP.
The need to reduce underwater noise pollution aligns with Germany’s commitment to marine conservation.
EnBW project manager Stefanie Hoper said: “By pioneering the T-NMS-10000, Heerema, IQIP and EnBW not only meet regulatory requirements but also contribute to a sustainable future and set an example for sustainable marine construction.”
After Heerema had been contracted for the installation, the T-NMS-10000 was further developed and built by Heerema and IQIP.
Heerema senior project manager Erik Bogels said: “Having been involved in the development of the T-NMS-10000 for the past two years, we are thrilled to see it in action at the He Dreiht offshore wind farm installation.
“We have estimated the reduction performance of this tool extensively, so it’s great to see that the T-NMS-10000 lives up to its expectations.
“This new tool not only significantly reduces the noise levels generated during pile driving, but also sets a new standard for sustainable marine construction practices.”