Re:Oceans Are Getting Louder, Posing Potential Threats to Ma...
by josefresco on Tuesday January 22, 2019 @10:14AM
(#18968770)
Are the construction of offshore windfarms unique in this regard? What about other construction in the ocean? Piers, waterfront building etc. If not, I find it odd that it's framed as an "offshore wind turbine" issue and not a "ocean construction" issue.
Re:Oceans Are Getting Louder, Posing Potential Threats to Ma...
by abootstrapper on Tuesday January 22, 2019 @01:06PM
(#18970562)
Not only that, but construction is usually once and done, besides maintenance or repairs. Unlike ship paths that are ongoing indefinitely.
And this discussion is disregarding the net benifits of why we’re building wind farms to begin with. It’s a weird dig at wind farms.
Re:Oceans Are Getting Louder, Posing Potential Threats to Ma...
by 7j on Tuesday January 22, 2019 @08:25AM
(#18968058)
Just to plug-in - there are technologies that don't require hammering- suction buckets and floating wind turbines.
Re:Oceans Are Getting Louder, Posing Potential Threats to Ma...
by strainer on Tuesday January 22, 2019 @02:16PM
(#18971372)
So to summarize, a beat per second about as loud as an oil tanker (its engine?) continuing for several hours per foundation - which itself will last decades.
The mention of "broadband and continuous sound from an operational wind farm" seems included for creative effect since it leaves the matter of the intensity of such noise entirely to the readers imagination. I would guess it should be of little interest if audible at all to ocean creatures over the sound of waves, even aside from shipping and sonar.
> A hydraulic or diesel fuelled hammer hits the pile repeatedly to drive it into the seabed. The single acoustic pulse created during impact is between 50 and 100 ms in duration with app. 30 - 60 beats per minute. It usually takes several hours to drive one pile into the bottom. This activity creates high levels of sound pressure and acoustic particle motion that are transferred through the pile into the water and seabed. Noise is radiated from the pile itself, but it could also radiate back from the seabed into the water column. The sound from pile driving is transient and discontinuous, to be compared with the more broadband and continuous sound from an operational wind farm. Several acoustic measurements of sound pressure during piling have been performed, showing source levels of over 180 dB re 1μPa(peak) at 1 m (Madsen et al., 2006; Betke et al., 2004; Betke, 2008; Erbe, 2009).
So 180 dB re 1μPa. While this is well below air guns or sonar (around 240 db for the air guns) [2], this is definitely comparable to the noise created by tankers (around 180 dB as well) [3].
[1]: https://www.diva-portal.org/smash/get/diva2:391860/FULLTEXT0... [2]: https://www.arc.id.au/SoundLevels.html [3]: http://cetus.ucsd.edu/Publications/Publications/PAPERS/McKen...