Pelamis[1] is the name given to the technology which absorbs the energy generated by ocean waves and converts it into clean, green electricity.

Approximately 70% of Earth’s surface is covered by the oceans and it is natural that man should think of it as a permanent source of power when confronted with the perpetual movement of its waves.

Such were the thoughts of Dr Richard Yemm who in 1998 conceived a sea serpent which could adapt to sea moods, either softly gliding over them as a patient surfer waiting for his wave or shake, jump or throw itself furiously to its belly, as a bodyboarder not wanting to be untimely brought back to shore.

E.ON P2 Pelamis operating in Orkney July 2011Source: http://www.pelamiswave.com

As such, the serpent had to be designed to withstand all weather conditions and the secret was to discover how to best anchor it to the seabed. Satellite data was employed to study the topography and wave type on the sites where it was to be installed and buoys measured its length.

State-of-the-art computer simulations were run to model the serpent in the worst sea environment conditions and projections made within a 100-year period as well as tests in wave tanks to come up with the best design and suitable moorings with a high safety factor.

And so a Pelamis was conceived which generated electricity inside itself, so there is minimal need for onshore infrastructure and consequently environmental impact on the shoreline. Only a small building is necessary to house the electrical cables connection to the switchgear and transformers for the grid connection.

Since there is no need for man to access the serpent itself, maintenance operations can be run from a small quay or marina pontoon with some small storage amount available. Power is fed back from the ocean to the shore by underwater electrical cable and several Pelamis can be linked so as to share only one cable back to dry land.

PelamisSource: http://www.pelamiswave.com

Brightly coloured Pelamis are anchored to the seabed by a slack chain attached to its front facing the direction of the waves and let to meander as a weather-vane around the mooring.

They are manufactured in Scotland and the first commercial wave farm in the world was installed in the north of Portugal capable of generating electricity up to 2,000 homes.

 

By Silvia Pelham

[1] Pelamis plature, a species of sea snake - http://en.wikipedia.org/wiki/Pelamis
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