Environment

SeaTwirl puts a new spin on offshore wind turbines

SeaTwirl puts a new spin on of...
The SeaTwirl's vertical wind turbine (1), torus ring (2), float assembly (3) and generator (4)
The SeaTwirl's vertical wind turbine (1), torus ring (2), float assembly (3) and generator (4)
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The SeaTwirl's vertical wind turbine (1), torus ring (2), float assembly (3) and generator (4)
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The SeaTwirl's vertical wind turbine (1), torus ring (2), float assembly (3) and generator (4)
The SeaTwirl is a proposed offshore wind power-harvesting system, that stores kinetic energy using a flywheel-like principle
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The SeaTwirl is a proposed offshore wind power-harvesting system, that stores kinetic energy using a flywheel-like principle
The small-scale SeaTwirl prototype, in production
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The small-scale SeaTwirl prototype, in production
The small-scale SeaTwirl prototype off the Swedish coast
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The small-scale SeaTwirl prototype off the Swedish coast
The small-scale SeaTwirl prototype being deployed in the ocean
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The small-scale SeaTwirl prototype being deployed in the ocean
The small-scale SeaTwirl prototype off the Swedish coast
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The small-scale SeaTwirl prototype off the Swedish coast
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View gallery - 7 images

One of the main drawbacks of wind turbines is the fact that for maximum efficiency, the power that they generate must be fed into the grid right as the wind is blowing and their blades are spinning. While that power can be stored in batteries for later use, some of it will always be lost in the process. Sweden's experimental new SeaTwirl system, however, is designed to kinetically store wind energy until it's required - it's basically a seagoing flywheel.

The top of a SeaTwirl system consists of a vertical wind turbine, with a hollow torus ring attached to the bottom. This is the only part of the system that is located above the surface of the water.

An axle runs vertically through the center of the turbine and proceeds into the water. Mounted on that axle, just below the surface, is a hollow cylindrical float body. At the bottom of the axle is a generator. The whole system is held in place by anchoring lines attached to the bottom of the generator.

The wind causes the turbine to spin, regardless of the direction from which that wind is blowing. Because it's attached to the turbine, the axle also spins. The water itself acts as a sort of ultra-low-friction roller bearing, allowing the turbine and shaft to keep spinning even once the wind has lessened. Electricity is generated where the rotating axle meets the non-rotating generator axis. That electricity is fed to the shore via seabed cables.

The SeaTwirl is a proposed offshore wind power-harvesting system, that stores kinetic energy using a flywheel-like principle
The SeaTwirl is a proposed offshore wind power-harvesting system, that stores kinetic energy using a flywheel-like principle

When the wind is high, the turbine's vigorous spinning action causes water to be drawn up from the float, and into the torus ring. This added weight around the outside of the circular turbine adds to the centrifugal force, keeping it spinning longer. As the turbine slows, it folds down, and the water runs back down into the float. This drawing-in of mass is said to also help keep the turbine moving, in the same way that figure skaters start to spin faster when they draw in their arms and legs.

A one-fiftieth-scale prototype SeaTwirl was tested off the coast of Sweden in August, and it reportedly performed well. The designers claim that in its proposed 430-meter (1,411-foot)-long full-scale incarnation, a commercial SeaTwirl should be able to generate 4.5 megawatts of mean power, or 39,000 megawatt-hours per year. It could reportedly store 25,000 kilowatt-hours worth of power, which they say would be enough to support 8,000 homes for one hour.

Because much of the SeaTwirl system's weight would be supported by the water, it is also claimed that production costs would be lower than those of present offshore wind turbines, as heavier, less expensive materials could be used.

The video below contains some animation that illustrates how the technology would work.

View gallery - 7 images
26 comments
windykites
As the contribution of wind power is such a small percentage, surely there is no need to store electricity? Also the wind blows stronger at the normal height of regular 3 blade turbines, so why is this device so close to the surface?
Anumakonda Jagadeesh
Very good innovation in Wind Energy Harvesting.
byzehr.111
http://contest.techbriefs.com/sustainable-technologies-2011/1283-the-combined-aero-hydro-turbine-and-propeller
under this link can be loked the project of thr best combined turbine.
or on web-site:
http://technogeo.ucoz.com
Stewart Mitchell
energy storage is not needed. Controlled consumption is better. I control mine. Most of my consumption is off-peak
bgstrong
Great Idea...Vertical Axis Wind Turbines are also an improvement over the horizontal..
Burnerjack
Stewart, you have quite a bit to learn about how utilities operate and match output to load. My question, should anyone care to answer...: Besides the manufacturers, has anyone made a profit utilizing wind or solar? It\'s great to \"be green\" but the world goes \'round according to the folding kind. Allow be to qualify my question further, :Has anyone made a profit utilizing wind or solar WITHOUT government subsidies?
cm
Of course the grid needs storage. It is stupid, at least to me, that all power is of the instantaneous \"use it or loose it\". If we had grid storage we wouldn\'t need peaking stations, we wouldn\'t need the above \"local storage\". All the renewable s could simply just work intermittently as they do, but say at times of excess production, in relation to consumption, make say, hydrogen. If we had our entire grid making full power with the excess power making hydrogen then we would soon build up excess hydrogen supplies which could then power say our new hydrogen cars.
and if our base load is met by nuclear (which realistacally is the only technology that can make a dent in our consumption requirements) then a by product of nuclear is, you guessed it hydrogn
kellory
Interesting concept. the the \"electric storage \" is in the form of a flywheel system. The same concept would work at home, floated in a rain water tank. hardest part would be the colapsing mechinism and the water proofing of the generator. Though the home versoin could use something like the flex-shaft of a drimel or a speedometer cable and waterproof housing, run through the tank wall, and a dry conventional DC motor as an elrctrical sorce.
Richardf
Wind genration in the uk made no real dint in the power the goverment claimed it woudl and could provide,Not to mention the eye sores they are the noise to neighbours and the animals they kill.Just what effect will this have on the sea life and birds.We have have as one gentlemen said hydrogen witch now seems to be in compation with more competative electrical cars witch will bring down there charging times puting the worlds so called future enery source in direct compation in terms of cars wise with electrical.Nuclear as one fellow said is the only real sure way to meet our demands.Green is great and yes we are al head for some far out star trek world of the future thats perfect and logical were no life forms die or feel pain.I can see wind turbines being replaced way of in 2070 by turbines in space or solar collectors or 4x more energy.
dsiple
Windikites, I don\'t know how close to the surface of the ocean is - there\'s nothing relative, like a boat to compare its size. As for downtime - use the power to make hydrogen for the fuel cells we\'re eventually be using.