In the 1970's, two countries began to realise the potential that wave energy represented. Japan and England began to develop methods for utilising this resource for power generation.Wave energy generation devices fall into two general classifications, Fixed and Floating.
Fixed Generating Devices
Fixed generating devices, which are mounted either to the sea bed or shore havesome significant advantages over floating systems, particularly in the area of maintenance. However, the number of suitable sites available for fixed devices is limited.
Oscillating Water Column
TheOscillating Water Column generates electricity in a two step process. As a wave enters the column, it forces the air in the column up the closed column past a turbine, and increases the pressurewithin the column. As the wave retreats, the air is drawn back past the turbine due to the reduced air pressure on the ocean side of turbine.
Figure 1 Schematic of an Oscillating Water Column(Image courtesy of Fujita Research)
Figure 2 Artists impression of the Oscillating Water Column
(Image courtesy of Fujita Research)
Much research is occurring internationally to developoscillating water columns which require less stringent siting conditions, including the OSPREY and floating columns, such as the Japanese Mighty Whale.
TAPCHAN, or tapered channel systems, consistof a tapered channel (hence the name) which feeds into a reservoir which is constructed on a cliff as shown in figure 3. The narrowing of the channel causes the waves to increase their amplitude (waveheight) as they move towards the cliff face which eventually spills over the walls of the channel and into the reservoir which is positioned several metres above mean sea level. The kinetic energy ofthe moving wave is converted into potential energy as the water is stored in the reservoir. The stored water is then fed through a Kaplan turbine (see hydroelectric power for more information)....