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Up till now we have been aware of the ways for generating energy from tides, waves , turbines, and dams, but now scientists have come up with a new way of generating energy from the slow moving ocean and river currents without using of any of the methods that have been previously used. Scientists have built a machine that can convert the destructive vibrations in water into a renewable energy source.
Wind and water vibrations have been the cause of many destructive incidents in the past such as the collapse of the Tacoma Narrows Bridge in Washington in 1940 and the Ferrybridge Power Station cooling tower in 1965. Engineers and scientists have been continuously working to invent new ways and methods to suppress these vibrations, but now they have thought of doing something completely opposite: instead of looking for ways to prevent those vibrations they will be utilizing them.
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What are Vortex Induced Vibrations?
The new machine the scientists have come up with works on a system known as VIVACE, for Vortex Induced Vibrations for Aquatic Clean Energy. VIVACE is a hydrokinetic energy system which works by utilizing the vortex induced vibrations of water. Vortex Induced vibrations are generated when a cylindrical or spherical object is placed in water against the flow of the current. Undulation is generated in the current due to the presence of the cylindrical body. This leads to formation of vortices and convolutions around the body that pulls and pushes it in a direction perpendicular to the current. The vibrations thus formed are known as vortex induced vibrations.
The VIVACE system consumes the energy from the slow water currents that are moving with a speed lower that two knots. Turbines and dams utilize the energy of water currents moving at a speed greater than five knots. Also, most of the water bodies on the earth surface have currents that flow at a rate of around two knots. Thus VIVACE can be used to procure the maximum benefit out of this unused energy.
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Why the Name - Fish Technology?
Vortex Induced Vibration is not a new term to scientists. Fish use these vibrations to swim in the most efficient way. If you observe the speed with which fishes swim and compare it with their muscular energy, you would be surprised to find that fish swim faster than their muscular strength suggests. This is because they utilize the vortices that are generated by the fish swimming in front of them and by gliding between them. This not only allows them to use less muscular energy, but also propels them at a much faster rate.
As the new machine utilizes this concept of fishes to generate energy, the technology is known as Fish Technology.
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Construction and Working of the Machine
Though the machine doesn't look like a fish it utilizes the same concept that the fishes use. The apparatus consists of a cylinder that is attached to a spring. The cylinder hangs above a water tank which has water flowing at a rate of 1.5 Knots. The cylinder is then put in water by lowering it. The construction of the machine is very simple.
When the cylinder is in water, vortices are formed around the cylinder which pulls and pushes the cylinder in a perpendicular direction on its spring. This results in the creation of mechanical energy which can then be converted into electrical energy.
It's been speculated that only a few cylinders are necessary to generate power that can propel a ship. The first project utilizing this technology is being made on the Detroit River and should be working within 18 months.
The main advantage is that, as the machines oscillate at a very slow rate, they can cause no possible harm to the marine and coastal life, like other sources do. It is projected that the energy produced can cost as low as 5.5 cents per kilowatt hour.
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VIVACE (Vortex Induced Vibration for Aquatic Clean Energy): A New Concept in Generation of Clean and Renewable Energy from Fluid Flow. Journal of Offshore Mechanics and Arctic Engineering, December 2008 - Michigan University
Fish Technology Draws Renewable energy from slow water currents by Science Daily