Page 136 - Fundamentals of Ocean Renewable Energy Generating Electricity From The Sea

Wave Energy Chapter | 5 127

FIG. 5.11 PowerBuoy: an example of a point absorber. (Copyright and courtesy of Ocean Power
Technologies.)

Oscillating Water Column
Oscillating water column (OWC) devices are partially submerged, hollow
structures, open to the sea below the water surface so that they contain
air trapped above a column of water. Waves cause the column to rise and
fall, acting like a piston, compressing and decompressing the air. The air is
channelled through an air turbine to generate electricity. One example OWC is
the Limpet.

Overtopping Devices
Overtopping devices consist of a wall over which the waves wash, collecting the
water in a storage reservoir. The incoming waves create a head of water, which is
released back to the sea through conventional low-head turbines installed at the
bottom of the reservoir. An overtopping device may use collectors to concentrate
wave energy. An example of an overtopping device is the Wave Dragon.