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Tidal Power

Power From The Oceans

The ocean has currents and tides that circulate round the world. This vast amount water with high potential movement produces immense amounts of energy. Tidal is a form of hydropower that converts the energy of tides into electricity or other useful forms of power. Tidal energy is produced using tidal energy generators. Some of the oldest ocean energy technologies make use of tidal power.

All coastal areas experience two high and two low tides. These tidal differences can be harnessed into electricity, but the difference between high and low tides must be at least five meters or more.

submarine turbines at work

Large underwater turbines are placed in regions with high tidal movements, and are designed to capture the kinetic motion of the ebbing and surging of ocean tides in order to produce electricity. Tidal power has potential for future power and electricity generation because of the massive size of the oceans. Tides are more predictable as compare to wind energy and solar power.

Electricity Generation

how tidal energy is harvested

The tides of the sea can be harnessed to generate electrical power. The tides are often extremely powerful. When the tide approaches the land, the amount of water rushing forward released an immense amount of energy that can be transformed into electricity.

A barrage or the huge dam is built across a bay. This barrage has gates which allow the water to flow into the barrage with the incoming tide. These gates get closed when the tide begins to go back from outgoing tide. This water which is now placed inside the barrage is called a ‘hydrostatic head’. The greater the head helps to generate more power from the out flowing water. There are other gates within the barrage which are opened and these gates contain hydro-electric generators, which is very similar to the ones used in Hydropower. These generators are turned by the out flowing water and power is generated.

The range of tidal has to be sufficient in order to generate power. This range should be in excess of 5 meters otherwise there is insufficient power generated. The main problem with tidal power generation is that the capital required to construct the barrages is extremely high and the effect on the environment by the change in the water levels. But once the barrages have been constructed then there is a very low maintenance cost. The generators need to be changed every 30 or 50 years.

The main problem with tidal power is the difficulty in harnessing it and investment of large amounts of money. Also, sophisticated engineering and technology are required to convert sea power to electrical power.

Advantages

Tidal power is truly renewable which is freely available and is a non-polluting source of energy. The startup cost to construct is very large, comparatively maintenance is very low. Barrages or small dams helps to protect nearby cities or ship ports from dangerous tides during a storm, or at least reduce the damage done, produce electricity city very reliable. Tidal turbines are up to 80% efficient in converting tidal energy to usable electricity. This is much higher than solar or wind energy generators.

Disadvantages

Tidal power station is very expensive to construct, and affects a very wide area – leading to environment alterations for many miles upstream and downstream. Many birds depend on the tide uncovering the mud flats for food. This type of energy can only provide power for around 10 hours each day, when the tide is actually moving in or out. Only some of the sites are suitable for building the barrage. Tidal power cannot be generated inland and can be used where there is appropriate wave motion or tidal flow. It can only generate electricity when there is a tidal surge, not every time.

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