## Wave power : Archimedes Wave Swing Machines

written by: Raunekkโขedited by: Lamar Stonecypherโขupdated: 6/29/2009

Extracting large amounts of energy from oceans requires large engineering structures, which might disturb the marine ecological balance. The solution to the problem can be found in an Archimedes wave swing machine, which is a simple, effective mechanism for harnessing a large amount of wave energy.

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### Introduction

The demand for renewable resources increased due to the emergence of oil crises and issues related to global warming. Some serious work on harnessing twave energy started in the late 1990's when the real demand for renewable energy increased. Since then, all the devices that have been generated are just the variations of the basic arrangement which involved a relative motion between the parts or in relation to a fixed reference, which was converted into useful energy by a hydraulic or air turbine. These basic implements were known as "First generation" machines.

A climb to the "next generation" of machines not only require transformational steps, but also a healthy blend of quondam, or old-school, technology and modern science. The Archimedes wave swing is believed to carry these peculiar traits to be called one of the best "First generation" devices in terms of reliability, safety, and power density.

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### Archimedes Principle

According to Archimedes principle, when an object is emerged in a fluid, a force acts on the object which forces it upwards. This force is known as the buoyant force and is equal to the weight of the fluid displaced by the object. The weight of the displaced fluid can be found by the formula W = mg, where 'm' is the mass and the 'g' the gravitational force.

It is to note that the buoyant force does not depend on the weight or shape of the object, but on the mass of the fluid displaced.Also, when the density of the object is equal to the density of the fluid, the object will neither float or sink.

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### Archimedes Wave swing

The Archimedes wave swing is a remarkably simple and elegant solution to tidal power generation. This wave energy converter is a cylindrical shaped buoy which is submerged and tethered to the ocean floor. Moored to the seabed, this generation unit has got only one moving part, the floater unit. The floater unit is an air-filled device which is connected to a lower fixed cylinder. In the fixed cylinder, a uniquely designed linear generator converts the up and down motion into energy.

The system comprises of only one moving part, the floater and uses hydraulic unit or a motor generator set in order to generate electricity.

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### Working

An Archimedes wave swing has the simplest working procedure. The wave action powers the floater which moves up and down, generating a reciprocating movement. When the wave crest approaches, pressure on the top of the floater increases, which pushes mechanism inside the cylinder downwards, compressing the gas within the cylinder to balance the pressure.

When the wave trough passes over the floater, the reverse process takes place , moving the floater upwards and decompressing the gas inside the cylinder. This reciprocating motion generated by the floater is converted into electricity by means of a hydraulic system or a motor-generator set.

Having only one moving part makes the sytem more reliable with less need for maintenance.

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Following are the advantages of Archimedes Wave Swing (AWS)

• Reliable - AWS is reliable due to its simple arrangement and less moving parts. It is submerged atleast 6 meter below the sea surface and is thus not affected by high stroms. This reduces the mooring cost and risk of damage.
• Power Density -The power density offered by AWS is 10 times greater than any other means of renewable energy.
• Environmental Friendly - AWS is a no-noise device without any high speed rotational equipments. Also, there is no pollution problems related with the generation unit.
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### References

Accociated Content website - Energy options

AWS ocean website

Thinkquest website- Archimedes principle

Image reference

http://www.hydrovolts.com/images/Waves.2.jpg

http://www.rise.org.au/info/Tech/wave/image022.jpg

http://www.powermag.com/Assets/Image/Imports/2008-05/48-02.jpg