27/05/08
Limpet is a shoreline unit to generate electricity in areas exposed to strong wave energy. It is located on the island of Islay, which is off the west coast of Scotland. The wave power generator was designed and built by Wavegen and researchers from Queen's University in Belfast and has financial backing from the European Union. The current Limpet device is called Limpet 500, which means that it can generate 500 kilowatts of electricity into the island of Islay.
How does Limpet work?
Limpet uses the principle of an oscillating water column (OWC). An oscillating water column is a partially-submerged, hollow structure, either vertically or at an angle, either in shallow water or onshore.
The waves continuously build up crests and troughs in front of the rock face of the power generator. Then, wave power forces seawater to enter the shell chamber. The interior of chamber also follows the sequence of the wave outside the chamber.
During crest formation, the level of water in the chamber rises, compressing the entrapped air at the top of the chamber to a value that is slightly above the atmospheric pressure. Thus, the air is forced through a “blowhole” and into “Wells Turbine”, which is designed by Professor Alan Wells of Queen’s University in Belfast.
However, during trough formation, the water inside the chamber recedes, the air is then decompressed to be under atmospheric pressure. This keeps the turbine moving. However, the crest and trough formation of the wave also cause the air to move in two directions. Hence, Wells turbine has been designed to turn successively in only one direction regardless of the direction of the airflow to ensure the efficiency of the harvesting of energy.
The rotation of turbine produced by the constant movement of air is tehn used to drive a generator that converts the energy into electricity.
--yingshi
Edited and reviewed by: seokting on 26/06/08
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