Renewable Energy

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Wave Device Principles

Waves are created by the interaction of wind with the surface of the sea, sometimes over very long distances.  The size of the waves is influenced by wind, the local seabed bathymetry (which can focus or disperse the energy of the waves) and currents.  Waves offer a large source of energy which can be converted into electricity by a wave energy converter (WEC).  Some wave energy converters have been developed to extract energy from the shoreline, others from waters offshore, some with a hydraulic power take-off system and some with an electrical power take-off system.  EMEC has identified six main types of wave energy converter that are outlined below. 

 

Example 1 Example 2
Wave_principles_1 Wave_principles_2

The motion of waves causes the elements of the device to move relative to each other.  This oscillating movement is used to generate electricity.

The motion of waves causes the floating element to move relative to the anchor point.  This linear oscillating movement is used to generate electricity.

 

Example 3 Example 4
Wave_principles_3 Wave_principles_4
A water column is formed using a partically submerged, hollow structure.  The motion of the waves causes the water level to rise and fall and this movement is used to compress and force air through a turbine.  The rotation of the turbine is used to generate electricity. By positioning of guides interacting with waves, water is forced upwards and into a reservoir before returning back down to the sea via a low head turbine.  The rotation of the turbine is used to generate electricity.

  

Example 5 Example 6
Wave_principles_5 Wave_principles_6
The motion of wave surges causes the device to move with a pendulum-like motion.  This oscillating movement is used to generate electricity. The motion of the waves causes the sea level to rise and fall above the device, inducing a pressure differential.  The alternating pressure is used to pump fluid to turn a hydraulic motor.  The rotation of the motor is used to generate electricity.