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How Buoys Harness Ocean Energy

With the flowing of the tides and the ceaseless formation and movement of waves, the world's oceans offer mankind the opportunity to convert vast amounts of kinetic energy into electrical power. According to the Ocean Energy Council, a typical 4-foot wave striking 1 mile of coastline produces approximately 35,000 horsepower. Buoy or float systems of varying designs, constitute one form of ocean-wave technology that may one day provide substantial amounts of clean energy in a sustainable manner.

Vertical Buoys
- Vertical buoys, which float on the ocean surface or are located just below it, are designed with partially buoyant piston-like mechanisms that are pushed upward and downward as the devices are tossed around by waves. Every piston drives a crankshaft connected to a gearbox and a generator. Other types use pistons equipped with permanent magnets surrounded by a coil. Each magnet's constant back-and-forth movement through the coil creates an electrical current that is sent to shore via a cable located on the ocean floor.
Horizontal Buoys
- Buoys of the horizontal variety employ a series of semisubmerged cylinders that are linked together by hinged joints. Each cylinder contains a hydraulic ram that pumps pressurized oil through a series of hydraulic motors, which in turn, drive electrical generators. The electrical energy is then fed down to the underground sea cable.
Oscillating Water Columns
- Oscillating water columns utilize the up-and-down motion of water contained within a vertical column that extends beneath the surface. Waves on the surface induce water movement inside the column, which in turn, causes air or fluid to spin an electrical generator located at the top of the buoy.
Underwater Buoys
- This type of power-generating buoy is capable of utilizing wave energy from 50 meters below the ocean's surface. These devices are hollow except for a compressible gas, which allows the top half of the instrument to move up and down. Waves on the surface create an increase in water pressure on the top of the buoy, thereby forcing it down. Between waves the compressed gas pushes the top up again. The resulting pneumatic power is then converted to electricity by turbine generators.
Advantages and Disadvantages
- The California Energy Commission estimates that ocean-based energy, including that derived by harnessing wave power, is potentially capable of providing 20 percent of that one state's electrical needs alone. Buoys, which are durable and have lifespans of approximately 40 years, do not cause visual distractions and can provide energy without the use of polluting fossil fuels. Since energy-harnessing buoys would be situated offshore, however, the initial laying of cable and its continual maintenance might add significantly to total energy costs.

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