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Swedish 'underwater kite' looks to make clean energy waves

Geoff Mortimore · 26 Apr 2011, 10:26

Published: 26 Apr 2011 10:26 GMT+02:00

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With the hunt for new ways of producing electricity growing ever more intense, and the recent tragedy in Japan raising doubts about nuclear power, the world's oceans may provide a viable clean-energy alternative.

And a Swedish company has been attracting plenty of attention with its award-winning “underwater kite” solution for generating power from beneath the ocean waves.

Minesto, based in Frölunda outside Gothenburg, has developed a form of underwater kite, which harnesses energy from ocean tides and currents at a far more efficient rate than wind turbines above the surface.

The technology, called Deep Green, looks like a child’s small kite with a turbine on its back.

It is tethered to the seabed and “flies” in a circular motion converting tidal currents into energy. As seawater is 800 times denser than air, the turbine can generate 800 times more energy than if it were in the sky.

The kite can travel 10 times faster than the flow of water it operates in, and because of the relationship between speed and energy, the faster the kite travels, the more efficiently it creates energy.

For example, if the kite moves as 10 times its normal speed, the increase in energy production will be 1,000-fold.

As sea currents and the flow of energy from this source are so stable and predictable, the company claims that it can generate 500 kilowatts of power even in calm conditions.

“We are confident once successful trials have been carried out for it to be commercially operative by 2013,” Minesto CEO Anders Jansson explains.

Minesto has already won several plaudits for its prototype model, not least from Time Magazine, which included it in its 50 Best Inventions of 2010.

It was also the only non-American company to make the 2011 Top 15 Utility Solutions listed by The Clean Technology and Sustainable Industries Organization (CTSI).

Each year a panel honours those companies with the best business plans and most compelling solutions to real-world customers.

Minesto raised €2 million ($2.9 million) last year to develop the technology further and build a scale model, which will be unveiled after this summer off the coast of Northern Ireland, giving the company a chance to test it out in real conditions.

Comparisons with wind power in particular are favourable. There is also likely to be less opposition as it does not blight the landscape as many believes the huge turbines do.

There is, however, an environmental impact beneath the sea surface though and extensive studies have been carried out to see how marine wildlife would be affected, says Jansson.

“One of the major obstacles has been the threat of things getting caught up by the tethers. We will place the kites far enough apart so they cannot get intertwined, but there is a danger of floating devices and fishing nets for example,” he explains.

“We have a special security system to counteract this and a fail safe mechanism if something does go wrong, but it is a major factor.”

Jansson adds that in one way the kites can actually have a positive environmental effect.

“The kites actually pump air back into the ocean which will help clean up the water. Also, where the kites are tethered there is no possibility of trawling the seabed.”

Story continues below…

The pumping of air back into the ocean water will minimise any adverse effects on sealife.

“The fish and mammals are used to having objects moving past them so the kites do not pose a threat to them,” he adds.

'Underwater kite' technology has been under development for several years, with Swedish Saab Group working on the underwater kite technology as far back as 2003.

Minesto was eventually formed as a Saab spin-off in 2007 to further develop the Deep Green concept.

Jansson is convinced that once successfully trialled in real life conditions, the underwater kite technology will prove to be a low cost way of harnessing tidal energy.

It is he says a low cost highly efficient concept, where each small kite device will be capable of generating enough energy to power 300 households.

Geoff Mortimore (mortimore.geoff@gmail.com)

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Your comments about this article

14:25 April 26, 2011 by Federico at bfred.it
My mind is spoiled, I totally read it "underwear kite"... that sounded interesting.
17:14 April 26, 2011 by Gregory Allen Leeds
The state of Delaware is slated to be among the first linked to an offshore wind power grid that has just been given the go-ahead. This concept of underwater "kites" that generate renewable energy cleanly, has many potential paradigm shifts for the entire nation if investigated,implemented and given proper oversite to make this nation master of it's own energy needs.
18:06 April 26, 2011 by Swedesmith
Call me a simpleton but I believe that all of the answers are already here. All we have to do is look for them in nature...work with nature and not against it.

This idea looks promising to me.
19:55 April 26, 2011 by here for the summer
This is good.
00:33 April 27, 2011 by DamnImmigrant
The only thing that scares me with this stuff is when they talk about putting it in the "Gulf Stream". But I am not seeing that here so COOL. I am into anything that flies.
05:01 April 27, 2011 by BarCode
Good luck getting machinery to last under salt water.
16:09 April 27, 2011 by babychuma
Wow this is cool, wind turbines are unreliable and can wreak havoc on migratory birds.
16:20 April 27, 2011 by Rick Methven
@ Barcode

If they trial it in the Baltic there is no slat problem as it is only 6% saline
17:43 April 27, 2011 by jmclewis
I hope no one is fishing with a net in that area, if this type of energy generation can be supported without excessive subsidies....... why not.
21:59 April 27, 2011 by HYBRED
I guess if there was a short circuit with one of these things you could catch a fish that was already poached.
11:44 April 28, 2011 by Nemesis
This is a brilliant advance.

I hope it works out.
18:38 April 29, 2011 by tadchem
The wind turbines used to generate electrical power have earned the nickname "Cuisinarts of the Air" for their proficiency at indiscriminantly slaughtering many flying animals - bats, migratory fowl, and birds of prey.

This could do the same thing for sea life.

Any sailor can tell you that sea water is one of the most corrosive substances around, and it has a special fondness for things with moving parts.

Things in the ocean can do 3 things: they rust, they rot, or they become encrusted with mussels.
04:31 May 2, 2011 by TX4ever
Some people have complained that: "The kites will rust, rot or become encrusted with mussels." So what? That's life in this world!

Besides there is always someone who will be quite glad and grateful for a job that asks for them to clean up rust, rot or mussel invasion. Just look at the mini industry that surrounds our offshore oil platforms in the TX Gulf coast. These structures are easily as tall as any skyscraper on land.

Consider the need to perform maintenance anywhere where there are large ocean going or river going vessels.

Its a JOB for someone, therefore it is good for the economy.
08:44 May 5, 2011 by karex
Brilliant. I'm sure that the small details will be worked out (corrosion, fishing nets, etc...)
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