What Are Wave & Tidal Energy?
Wave and tidal energy is power generated from the movements of large natural bodies of water. In both systems of energy, the flow of the water is leveraged to move turbines that produce mechanical power that can spin generators, producing electricity. Although not in wide use, tidal and wave generators cause little pollution and have the potential to be implemented as alternatives to fossil-fuel and nuclear-power generators.
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History
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Humans have been drawing power from the tides since the 8th century A.D. Although the early tide mills did not produce electricity, the principles can be adapted for generating electricity. The process is relatively simple: tides fill a pond, and as the water flows in and out, it turns a water wheel to produce mechanical energy. According to the U.K.'s National Engineering Laboratory, the first use of waves for electricity generation occurred in Royan, France, in 1910.
Features
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Both wave and tidal energy operate using the same principle---the motion of water turns turbines to generate electricity. Wave energy uses floating generators placed on the surface of the ocean to draw energy from the motion of waves or from subsurface pressure fluctuations. By contrast, tidal energy turbines are placed below the water to extract power from the movement of water currents (similar to turbines used on rivers).
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Types
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There are a number of different types of wave and tidal systems.
For wave power, terminator devices are usually placed offshore, and face perpendicularly to the direction in which the waves are traveling. Another technology called "point absorbers" use the relative motion of fixed buoys inside floating cylinders to move hydraulic energy converters. Another wave-based technology, "overtopping devices," use reservoirs that fill with water from high waves, and the water is then released through turbines.
Tidal power schemes work in one of two ways---like river dams, in which water moves through barriers, or like standalone wind turbines, in which the the turbines move with the direction of the water flow.
Benefits
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There are a plethora of advantages to wave and energy power. Although initial costs are high to build the systems, such systems cost relatively little to maintain. Neither technology causes significant pollution or emits any greenhouse gases, making them a low-carbon alternative. Unlike some renewable energy sources, tidal and wave generators are very reliable; indeed, the electricity derived from tidal power can be predicted with as much accuracy as the tides themselves.
Potential
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Wave power and tidal power are currently responsible for producing only a small fraction of the world's electricity. However, interest and investment in these technologies are growing as concerns about climate change and energy independence grow. According to the website Energy Resources, tidal power alone could provide up to 20 percent of Britain's energy needs.
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References
- Photo Credit waves image by Melva Vivian from Fotolia.com
