Wave Energy Devices – Wave Energy Convertors,Buoys and Generator Systems Types and Designs

Wave Energy is being developed for a long time almost since the 1700s through a variety of devices and convertors.Wave Devices are being used mainly to generate electricity and for water desalination.Wave Energy has a myriad of systems being developed as the technology is still immature.Wave energy generation is still a research field and there are as many designs as companies active in this field.Note as a technology matures,a single technology system gain ascendance as others are discarded along Darwinian lines.For example solar technology which is in the phase before maturity has majority of its energy convertors of the mainstream polycrstalline solar panels.Wind Energy which is further along the learning curve has most of its energy being generated from large vertical axis wind turbines.Wave Energy on the other hand has not come around a single dominant type of device.A number of devices are being developed to harness wave energy efficienty and at low cost.Wave Energy faces problems of being exposed to strong weather elements therefore wave energy designs are progressing along the lines of devices which require low maintainance and which are able to withstand weather better through devices with lower number of moving parts.

A good wave energy device should be able to

a) Face a Wide range of Wave Sizes

b) Be able to withstand the severe storms

c) Guard against  problems such as algae, barnacles and corrosion.

There are Six Main Types of Wave Energy Devices (source EMEC).The two most popular are Buoys and Surface-following Attenuators .A large number of wave power companies which are startups are  trying to make inroads into this fast developing technology.

1)  Surface-following Attenuator – An attenuator is a floating device which works parallel to the wave direction and effectively rides the waves. Movements along its length can be selectively constrained to produce energy. There are number of companies like Pelamis which use this technology to generate wave energy

2) Buoys or Point absorbers A point absorber is a floating structure which absorbs energy in all directions through its movements at/near the water surface. The power take-off system may take a number of forms.Buoys are the most popular and oldest wave energy devices.Some of the major wave energy companies using this technology are AWS,Ocean Power Technologies and Carnegie

3) Oscillating Wave Surge Converter   – This device extracts the energy caused by wave surges and the movement of water particles within them. The arm oscillates as a pendulum mounted on a pivoted joint in response to the movement of water in the waves.Aquamarine Technologies is using this type of wave energy device to construct wave energy farms.

4) Oscillating water column An oscillating water column is a partially submerged, hollow structure. It is open to the sea below the water line, enclosing a column of air on top of a column of water. Waves cause the water column to rise and fall, which in turn compresses and decompresses the air column.

5) Submerged pressure differential  These devices are typically located nearshore and attached to the seabed. The motion of the waves causes the sea level to rise and fall above the device, inducing a pressure differential in the device.

6) Overtopping/Terminator device -It relies on physical capture of water from waves which is held in a reservoir above sea level, before being returned to the sea through conventional low-head turbines which generates power.