The use of wave powered fog-horns on buoys at sea has been common for over a
century. As the buoy moves up and down in the waves, a column of water, or oscillating
water column (OWC), in the centre pipe of the buoy's hull acts like a piston, pushing air out
the top of the pipe or, alternately, drawing it in, thereby sounding the fog-horn.
This pneumatic power can also be converted, indirectly, by turning a turbine-generator to
electricity. This is the principle on which current wave-powered generators operate. Seawater
enters and leaves the shoreline compression chamber naturally through the motion of the
waves. As it enters, the air in the chamber is compressed andforced through a hole into a
turbine, turning it. As the water recedes, the air is sucked back, keeping the turbine moving
and driving a generator which converts the energy into electricity.
The UK based company Ocean Power Technologies (OPT) have developed a Power
Buoy wave generation system which uses a "smart," ocean-going buoy to capture and convert
wave energy into electricity.
In 2011 a 150 KW versionwas installed for testing in the waters off Invergordon,
Scotland; OPT are currently developing a 500 KW PB500 ‘PowerTower’ model, with the US
Department of Energy (DOE) and UK government providing funding for several stages of the
development program.