Marine Energy

Marine Energy

OK, so what we’re going to do is shut down
the regular simple sea that we’re running just now and we’ll load up a more complex
and realistic sea state. Just tell the paddles to come down and we’ve pre-compiled a sea
state that’s the sort of sea you would find on the West Coast of the UK. We’re now sending
different signals to each paddle and they’ll all be making adjustments as they go to produce
a much more complex and realistic sea state. We’ve been studying the reactions between
moving machinery and water which is something that has been understood for shipping purposes
for not just decades but centuries. But understanding the physics of the interactions between moving
water for both waves and tides and the machinery that is trying to extract the energy has sat
at the core of the research conducted here at Edinburgh. I believe now that we have enhanced
that understanding far beyond where it was even five years ago and this has been very
exciting to me, this relationship between engineering, the ocean and the environmental
implications.There’s no one way of harnessing the power of waves. Some devices respond by
allowing air to be compressed within their structure and driving that air through turbines
to generate power. The device that’s currently being installed off Orkney called Oyster is
effectively a flap which is attached to the seabed and this simply moves back and forwards
and pumps sea water again through a turbine to generate electricity. One device looks
a bit like a child’s seesaw and it swims back and forwards a little bit like two linked
fishes’ tails to generate power. The challenge for the engineer is to make these systems
reliable, and of course cheap, and most important of all easy to install and easy to maintain. This is a scaled down replica of a real three dimensional sea state. It looks quite small, but if you imagine that we are normally working at a scale of maybe one hundredth, then we
would be about that size. And we can take a device, a model and we can test it, then
we can make a very small change to it, one change, put it back, repeat the test, is it
better or is it worse. Now, in real life the weather would have changed, everything would
have changed, but in the tank only one thing changes. It is possible to make estimates
of the ultimate energy capability within a particular tidal area or particular wave area,
but what we’ve been looking at as part of our research is just how much of that energy
can we realistically extract without seriously compromising the resource itself and of course
the environment. What you’re looking at here is a model of a tidal channel. At the
far end from where I’m standing you could imagine that that’s the Atlantic Ocean and
at this end, where I am, this could be the North Sea and the flow’s then flowing between
the two oceans, a bit like it does in the Pentland Firth, with the land, and the islands
on one side, and the Scottish mainland on the other concentrating the flow and accelerating
it. We can use this to look at what the effects of extracting energy from this channel would be on the overall flow and we can use it to understand what the turbulent structures look
like as the flow comes through the channel. At present, marine energy is making a very,
very small contribution to our energy supply where we’re really only talking about demonstration
devices. If we’re thinking about making measurable proportions of the country’s
electricity need we really need to be looking ten, 15 years into the future towards 2020
when we hope and anticipate that we will be seeing something of the order of two gigawatts
installed capacity of marine renewable energy. Two gigawatts would be roughly equivalent
in terms of capability to a large nuclear power station, which is a sizeable contribution.
At the moment the devices are installed individually. It’s a difficult, expensive process, and
we cannot pack them closely together. That’s a challenge that we believe we can overcome.
In addition, the present generation of tidal current systems really do not like highly
energetic wave environments. We need a new generation which can extract power from the
tidal currents whilst being exposed to significant wave forces. Again to achieve that we need
to draw up on present and future research. Many countries around the world look at the
research and development programme in marine energy in the United Kingdom and are desperately
trying to emulate the initiatives and to follow the lead that the UK has been demonstrating
in research and development. We have to maintain that position. There is an opportunity to
create wealth and to create employment that will be able to develop a clean lower carbon
energy source from the sea for the future.

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About the Author: Oren Garnes

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