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Tidal energy (or Tidal power) is the energy contained in the oceanic tides. Tidal energy is a form of hydro power. This hydro power can be converted into mechanical energy which can further be converted into electrical energy.
Tides are generated in the ocean due to gravitational force exerted on earth by the moon. This force attracts sea water, which creates a bulge on sea surface. This bulge moves according to moon’s gravitational effect. When this bulge strikes the sea shore it has very high potential energy which can be converted into mechanical energy (and electricity).
Tidal energy is considered as a form of renewable energy. Historically tidal power was used to mill grains. Incoming tide water was stored in large water ponds which is later used to rotate water wheel. Mechanical energy of the rotating water wheel is used to mill grains.
Tidal Power Station at Sihwa Lake
Methods of harnessing tidal energy
Currently there are three ways of harnessing tidal power.
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Tidal streams
In this method turbines are placed directly in the tidal streams. Turbines converts kinetic energy of tidal stream into electrical energy.
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Barrages
In this method tidal water is stored in large barrages when tides are high. This water is released into turbines when tides are low. Hence converting potential energy of water into electrical energy.
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Tidal lagoons
Tidal lagoons are almost same like barrages but the difference is that it can provide continuous power supply. It can produce power from the kinetic energy of tide when it is filling the lagoon and it can also produce power from the potential energy of water when lagoon is emptying.
Advantages of tidal energy
- It is a source of renewable energy.
- Tidal energy can even be generated at very low speeds of water compared to that of air, in case of wind turbine. The high density of water compared to air is responsible for this.
- Its availability is more predictable and stable compared to solar energy and wind energy.
- Energy density of tides is high compared to solar or wind energy.
Disadvantages of tidal energy
- Electromagnetic field generated by the turbines destroys ability of navigation and to detect odor of some sea species.
- It has high construction cost.
- Rotating Turbine blades can kill marine life.
- Constant noise making turbines can force some marine life to leave that area.
- Sea water will cause rapid corrosion of turbine parts.
- Biological fouling will occur on the turbine structure.
Featured Image source: By 핑크로즈 – http://blog.naver.com/pfmusic/10122410431, CC BY 2.0 kr, https://commons.wikimedia.org/w/index.php?curid=41208311