Wave Energy Devices
Wave Energy Devices convert the substantial amounts of energy stored in sea waves into useful energy. The technologies which have been developed for this purpose can be generalised by eight different types of device [1]:
- Attenuator
- Point Absorber
- Oscillating Wave Surge Converter (OWSC)
- Oscillating Water Column (OWC)
- Overtopping
- Submerged Pressure Differential
- Bulge Wave
- Rotating Mass
Attenuator
An Attenuator is a segmented device which lies parallel to the wave direction, effectively “riding” the wave. The joints separating segments generate power by compressing hydraulic oil by means of two pistons, driving a hydraulic motor and eventually an electric generator. The most well known attenuating device is Pelamis manufactured by Pelamis Wave Power.
Point Absorber
A Point Absorber wave energy converter consists of a floating buoy which is connected to a number of subsurface components. Energy is derived from the relative motion of the buoy to the subsurface components.
Oscillating Wave Surge Converter (OWSC)
An Oscillating Wave Surge Converter is essentially a paddle, which rotates around a fixed seabed, mounting. The surge motion of the waves cause the paddle to rotate which compresses water, driving an onshore hydro power turbine, similar to that of a hydro power scheme. The most commercially available Oscillating Wave Surge Converter is the Oyster device, manufactured by Aquamarine Power.
Oscillating Water Column (OWC)
An Oscillating Water Column is a hollow concrete structure which houses a column of air, sealed at one end by the sea. As waves approach the device, the air column is compressed and forced through a bi-directional turbine. When the wave recedes, the air is drawn back through the turbine. Voith Hydro, have installed the World’s first commercial OWC (LIMPET) on Islay in Scotland.
Overtopping
Overtopping devices work on a similar principle to hydro power. Waves are funneled into a raised reservoir. Seawater is then returned to the sea through a hydro power turbine, generating electricity. An example of an overtopping device is the Wave Dragon by Wave Dragon.
Submerged Pressure Differential
Submerged Pressure Differential devices work on the basis of a pressure differential being created due to the movement of the waves. In the Archimedes Wave Swing device, this is done through the compression of air inside flexible membranes. An example of this is the Archimedes Wave Swing, developed by AWS Ocean Energy.
Bulge Wave
Bulge Wave devices consist of a rubber tube filled with water, lying parallel to the wave direction. As the wave front passes, the tube flexes, compressing the water within. The compressed water can be used to drive a turbine. The Anaconda wave device, developed by Bulge Wave Power is an example of a Bulge Wave device.
Rotating Mass
Rotating Mass Wave Energy Converters use the motion of the Waves to spin a rotating mass, creating mechanical energy. The rotating mass creates power through a electrical generator. An example of this device is the Penguin by Wello.
[1] European Marine Energy Centre. Wave Devices. 2013.
Photo Credits (from top):
Pelamis Wave Power via EMEC, 2012. The first generation Pelamis P1 [online]. Pelamis Wave Power. Available from:
http://www.emec.org.uk/about-us/media-centre/gallery/ [Accessed 6th March 2013].
Coastal Energy and Environment, 2012. Ocean Power Technology [online]. Coastal Energy and Environment. Available from: http://coastalenergyandenvironment.web.unc.edu/2012/07/21/opt-australia/ [Accessed 6th March 2013]
Aquamarine Power via EMEC, 2010. Oyster 1 Wave Energy device before installation [online]. Aquamarine Power. Available from: http://www.emec.org.uk/about-us/media-centre/gallery/ [Accessed 6th March]
Voith, n.d. LIMPET. Voith.
Maritime Journal, 2003. Wavedragon [online]. Maritime Journal. Available from: http://www.maritimejournal.com/news101/industry-news/denmarks_wave_dragon_delivers_power_to_the_grid [Accessed 6th March 2013]
Mendo Coast Current, 2010. AWS Ocean Energy [online]. Mendo Coast Current. Available from:
http://mendocoastcurrent.wordpress.com/2010/07/26/aws-ocean-energy-receives-more-wave-energy-funding/ [Accessed 6th March 2013]
Atkins Global, n.d. Anaconda Project [online]. Atkins Global. Available from: http://www.atkinsglobal.com/projects/anaconda-wave-energy-device [Accessed 6th March 2013]
Wello, 2013. Penguin [online]. Wello. Available from: http://www.wello.eu/penguin.php [Accessed 6th March 2013]
Photo Credits (from top):
Pelamis Wave Power via EMEC, 2012. The first generation Pelamis P1 [online]. Pelamis Wave Power. Available from:
http://www.emec.org.uk/about-us/media-centre/gallery/ [Accessed 6th March 2013].
Coastal Energy and Environment, 2012. Ocean Power Technology [online]. Coastal Energy and Environment. Available from: http://coastalenergyandenvironment.web.unc.edu/2012/07/21/opt-australia/ [Accessed 6th March 2013]
Aquamarine Power via EMEC, 2010. Oyster 1 Wave Energy device before installation [online]. Aquamarine Power. Available from: http://www.emec.org.uk/about-us/media-centre/gallery/ [Accessed 6th March]
Voith, n.d. LIMPET. Voith.
Maritime Journal, 2003. Wavedragon [online]. Maritime Journal. Available from: http://www.maritimejournal.com/news101/industry-news/denmarks_wave_dragon_delivers_power_to_the_grid [Accessed 6th March 2013]
Mendo Coast Current, 2010. AWS Ocean Energy [online]. Mendo Coast Current. Available from:
http://mendocoastcurrent.wordpress.com/2010/07/26/aws-ocean-energy-receives-more-wave-energy-funding/ [Accessed 6th March 2013]
Atkins Global, n.d. Anaconda Project [online]. Atkins Global. Available from: http://www.atkinsglobal.com/projects/anaconda-wave-energy-device [Accessed 6th March 2013]
Wello, 2013. Penguin [online]. Wello. Available from: http://www.wello.eu/penguin.php [Accessed 6th March 2013]