<
https://www.bbc.com/future/article/20231106-the-big-bubble-curtains-protecting-porpoises-from-wind-farm-noise>
'Over the past decade, a curious invention has spread across Europe's northern
seas. It's called a big bubble curtain, it works a bit like a giant jacuzzi,
and it helps protect porpoises from the massive underwater noise caused by wind
farm construction.
A very large, perforated hose is laid on the seabed, encircling the wind
turbine site. Air is pumped through, and bubbles rise from the holes to the
surface of the water, forming a noise-buffering veil.
The quirky gadget, also known as a big bubble veil, was pioneered in Germany to
help protect the endangered harbour porpoise, the only cetacean species living
in its North Sea and Baltic Sea. The bubble curtain was designed around the
porpoise's specific needs and traits, lowering wind farm construction noise to
a threshold deemed safe for the species, based on scientific research. Its
proven muffling effect may also benefit other marine mammals that are
vulnerable to noise, such as seals.
The bubble curtain is now widely used by northern European countries racing to
build more offshore wind farms as part of their efforts to curb CO2 emissions
and fight global warming. Countries including the Netherlands, Germany, Denmark
and Belgium have pledged to turn the North Sea into "the world's largest green
power plant", aiming to jointly increase their offshore wind capacity there to
300GW by 2050. At the same time, they are under pressure to reduce the
potential impact of wind farm construction noise on marine creatures, for whom
sound is everything.
"Pretty much every creature in the sea relies on underwater sound. On land,
most animals tend to use vision as their main sense, but in the underwater
world, it's hearing," says Carina Juretzek, a specialist in underwater noise at
Germany's Federal Maritime and Hydrographic Agency, which regulates and
approves offshore wind farms.
The small, round harbour porpoise is very sensitive to sound. It uses
echolocation to navigate, communicate, hunt and avoid obstacles in often dark
or murky waters, emitting ultrasonic clicks that bounce off fish or objects.
Loud, human-made underwater noise – including from shipping and offshore wind
farm construction – can disturb and disorient the porpoise.
Bubble curtains are based on a simple principle: sound travels faster through
water than through air, because water and air have different densities. When
sound waves hit the bubble curtain, they slow down, break up, and bounce
against the bubbles, resulting in a loss of energy. The remaining sound that
emerges on the other side of the curtain is therefore quieter.'
Via
What Could Go Right? November 9, 2023:
https://theprogressnetwork.org/work-life-balance-gen-z/
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
