Marine Renewable Energy

Increasingly, governments and energy companies are looking at ways of harvesting wave and tidal energy. But what about the environmental impacts of marine-based renewable energy...
12 September 2010

Interview with 

Ben Wilson, Scottish Association for Marine Science


Richard -   Waves lapping the beach, wind bending the trees, and the tides pulling the pebbles along the shore.  Increasingly, governments and energy companies are looking at ways of harvesting this energy.  Well, it makes sense.  But what about the environmental impacts of marine-based renewable energy technologies?  Well, I'm on the beach at Oban in Western Scotland with Ben Wilson from the Scottish Association for Marine Science.  Now, you're looking at the impact of these devices.  What sorts of things harvest the power of the waves or the tides?  

Seaflow tidal stream generator

Ben -   Some of them, at their most basic, do look just like wind turbines put underwater.  There are other ones that are more complicated with lots of different blades put on the rotors, other ones that are like wind turbines in tubes and so on.  There are lots of ideas that people have had but it's very much a new thing.

Richard -   Now we've heard about problems with wind turbines on land and birds.  Are you imagining the same sorts of things are going to go on with these turbines underwater and fish or seals or whales?

Ben -   What we want to make sure is that those devices that go into the sea are the right ones and that organisms that are already moving around in the sea are not going to become a cropper by bumping into these devices.  What we're looking at in particular is, they're probably going to hear these devices upstream somehow.  How are they going to hear it?  What are they going to hear?  And are they going to hear it far enough in advance to be able to take the right manoeuvring actions to actually get out of the way?

Richard -   But before Ben could find out what sorts of noises renewables ought to make, he realised he needed to know what life beneath the waves already sounds like.  Back in the lab, Ben played me some of his recordings.  

Ben -   This is a recording I made when I was working on Killer Whales and so I was listening away to some Killer Whales swimming around probably about half a kilometre away from the boat.  And somebody way in the distance started a little out-board motor on a little skip and went driving away and completely drowned out all the recording I was trying to make.

[Plays whale noises]

Mother and calf, Type C Killer WhalesRichard -   That sound we're hearing of the boat in the distance, would that be similar to the sorts of noises a turbine underwater might make?

Ben -   Well that's what we don't know - this is a new industry, these devices are being built at this very moment, so we don't know what they're going to sound like.  Particularly of interest is what they're going to sound like after they've been in the sea for a couple of years.  You know, the day they go in they're going to be nice and well-lubricated and so on but after they've been in a couple of years they might become a lot more noisy later on.

Richard -   So you've got another sound here.  What is this one?  That's a bit different.

Ben -   This is two noises that are all-pervasive, particularly in this area.  First one is a sort of a "snap, crackle and pop" sound.  What's commonly called "snapping shrimps".  It's not quite clear what's making that sound - it's probably a crustacean.  If you go anywhere in coastal waters anywhere in the world, you'll hear this sound.  And then the other sound on top of that is the noise of a seal scarer.  It's quite high frequency, it's quite common around this part of the coast.

Richard -   That's extraordinary that these sounds are recorded underwater!  These are sounds of things that are happening under the sea that we wouldn't hear!  

Ben -   Absolutely.  And the other point to this is that it's different in different environments.  If you imagine walking through a wood, you hear different noises as you're near a road or as you're near some trees with the wind blowing through them.  As you move around underwater, you get this soundscape of different sounds in different areas.  

Richard -   So how will you use the results of this?  Once you've gathered your sounds, how will you use that?  

Ben -   I think the first thing is an appreciation of what it sounds like underwater.  We need to get an idea of what the variation is and how it varies between different environments where these things are going to go.  And then the second one is that we need to make sure that the noises that devices are making will be audible to animals moving through and if not, do we need to think about adding a bit of noise?

Richard -   So can we just end with one more sound?  What's this one?

Ben -   Okay this is an unusual sound that we discovered a couple of years ago and kind of shot us to fame.  It's a sound made by herring.  We don't know what they use it for - probably communication.  They basically blow bubbles out of their rear-end and in it comes a sound.  


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