This special interest group is where you can bring thoughts and ideas on renewable energy. 

40,813 Members

WARNING: SIGN-IN

You need to be a member of Energy Central to access some features and content. Please or register to continue.

Post

Prevention Measures for Piling Operations used on Offshore Wind Farms

Photo by author Jochem Tacx

Offshore Piling causes strong impulse underwater noise that’s potentially harmful to the marine environment, in particular to marine mammals. The blow rates of a hammer are usually between 15 to 60 per minute and the total of blows may vary from 500 to more than 5000, with frequencies between 100 Hz and 400 Hz depending on the soil properties and on the required penetration dept of the pile.

Underwater sound behaves very differently compared to sound in the air, as sound travels faster in water than in air (~1500 m/s vs. ~340 m/s). Noise is perceived more intensely underwater and can propagate over greater distances. To protect the marine fauna, various prevention methods are employed which are launched prior piling operations.

The FaunaGuard The FaunaGuard is an acoustic deterrent device which creates a noise that positively deters the animals from the work location. The philosophy of the FaunaGuard, which is developed by Van Oord and SEAMARCO, is to make optimal use of the behavioral effects induced by specific sounds with different species or species groups. This causes the area in and around the work location to be (temporarily) unattractive to marine fauna, and so prevents more serious effects related to high peak energy events. As such, the FaunaGuard aims to utilize mild behavioral effects (moving from an area) just before piling, to prevent more serious physiological effects on marine fauna during the piling.

FaunaGuard Van Oord

Source: https://www.vanoord.com/sites/default/files/leaflet_faunaguard_1.pdf

Bubble Curtain A bubble curtain can be described as a screen of bubbles around the working area. Underwater bubbles can inhibit sound transmission through water due to density mismatch and concomitant reflection and absorption of sound waves. A bubble curtain is produced by heavily perforated hoses which are positioned around the construction site as a ring prior to piling operations. An excessive amount bar of oil-free compressed air is pumped into the hoses, which escapes through the holes in the hoses according to a well-defined pattern. The result is a curtain of millions of small bubbles that rise to the water surface, forming a kind of whirlpool around the construction site. The air bubbles change the density of the water and thus break down the sound waves, thereby protecting marine life from piling noise.

Bubble Curtain Underwater View

Arkona Offshore Wind Farm, Bibble Curtain Top View

Find out more on how offshore wind farms are build from the Building an Offshore Wind Farm: Operational Master Guide:

https://www.amazon.com/Building-Offshore-Wind-Farm-Operational/dp/1078162816/ref=sr_1_4?keywords=offshore+wind&qid=1565265794&s=gateway&sr=8-4

Jochem Tacx's picture

Thank Jochem for the Post!

Energy Central contributors share their experience and insights for the benefit of other Members (like you). Please show them your appreciation by leaving a comment, 'liking' this post, or following this Member.

Discussions

No discussions yet. Start a discussion below.

Get Published - Build a Following

The Energy Central Power Industry Network is based on one core idea - power industry professionals helping each other and advancing the industry by sharing and learning from each other.

If you have an experience or insight to share or have learned something from a conference or seminar, your peers and colleagues on Energy Central want to hear about it. It's also easy to share a link to an article you've liked or an industry resource that you think would be helpful.

                 Learn more about posting on Energy Central »