Tidal Energy

What is Tidal?

Tides are the long period waves that occur in the ocean. These are caused by the combined gravitational effects of the sun, the moon and by the rotation of the earth. The two forces that give rise to tides are gravitational and centrifugal force.

Tidal Energy Definition

Tidal energy is a form of hydro power which converts the energy obtained from tides into other useful energies (electricity). The tidal energy is the result of the sun and moon's influence over the ocean. The height difference between low and high tides gives rise to tidal currents in coastal areas, which drives the turbines.

Tidal energy is also called tidal power. Tidal power utilizes the energy contained in tides to produce electricity.

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Characteristics of Tide

Here are some of the characteristics of tides:

  • When sea level rises in the ocean, it covers the intertidal zone, this is the floor d tide.

  • The water level rises to the highest position and creates a high tide.

  • The sea level gradually falls and reveals the intertidal zone. This is the ebb tide.

  • The water stops falling and reaches low tide.

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Tides are normally semi-diurnal (i.e two high tides and two low tides occur each day), or diurnal (i.e one tidal cycle occurs per day). The two high waters that occur per day are not of the same height (this is called the daily inequality); these are known as the higher ‘high water’ and the ‘lower high water’ in tide tables.

Similarly, the two low waters that occur each day are called the ‘higher low water’ and the ‘lower low water’. The daily inequality for high and low water is not consistent and is usually small when the Moon is exactly over the Equator.

Uses of Tidal Energy

Tidal Energy is a renewable source of energy like Solar, Geothermal and Wind energy. Here are some of the uses of Tidal Energy.

  • Tidal Electricity

The most important use of tidal energy is the generation of Electricity, called Tidal Electricity. The electric power generated from the tides is reliable as tides are predictable and uniform in nature.

  • Grain Mills

Tidal Energy has been in use for hundreds of years. Just like the Wind Mills, Tidal Energy was used for mechanical crushing of grains in grain mills. To crush grains. Here, the movement of the turbines powered by tidal energy was used.

  • Energy Storage

Tidal Energy is also used to store energy in hydroelectric dams, which acts as a large energy storage. Tidal Barrages and the reservoirs can be modified to store energy.

  • Provide Protection to Coast During High Storms

Tidal Barrages are capable to prevent damage to the coast during high storms. They also serve to create an easy transport between the two arms of an estuary or a bay.


Tidal Energy Advantages and Disadvantages

Advantages of Tidal Energy

  • Renewable

Tidal energy is a renewable source of energy. It is generated by the combined effects of the gravitational force of the moon and the sun and the rotation of the earth.

The power generation in tidal energy is possible due to the difference of the potential energies of the tides. Different kinds of power generators like stream generators, tidal barrages and dynamic tidal power (DTP) use this.

  • Green

Tidal power is an environmentally friendly source of energy. It does not produce any harmful gas. One of the major benefits of tidal energy is that it utilizes a very small space for energy production.

  • Predictable

Tidal currents or waves are highly predictable. High and low tide develop with the ocean as per some renowned cycles. This makes it easier to develop a system with exact dimensions to produce energy, as we already have knowledge of what kind of waves the equipment will be exposed to.

This is the reason that the tidal stream generators are similar to that of wind turbines.

  • Effective at Low Speeds

It is possible to generate electric power at very low speeds, because the density of water is much more than that of air. Power can also be generated at a water speed of about 1 m/s.

Disadvantages of Tidal Energy

  • Environmental Effects

The tidal power plants generate green electricity, but its effect on the environment is not completely known.

  • Close to Land

Tidal power plants are only to be constructed in an area close to land due to the limitations. Hopefully, very soon we will be able to construct power plants in an area to harness energy from weaker currents.

  • Expensive

The methods which are involved in generating energy from tidal plants require new technology, which is very expensive. Tidal power plants are estimated to be commercially beneficial by 2020 for large-scale use.

FAQ (Frequently Asked Questions)

1. What is wave energy?

Wave energy is the energy which is harnessed from oceanic waves. When the wind blows across the surface of the ocean, it creates waves in the sea. These waves created by wind are known as wind waves. Due to absence of any land mass, the wind waves form most effectively over the water surface.

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These waves are commonly seen on the surface of the ocean. They also occur in lakes, canals and rivers and are called capillary waves, ripples, seas or swells. No two wind waves are of the same height and width as waves differ from each other as far as their crests and troughs are known.

2. Difference between tidal energy and wave energy

Tides and waves are formed due to different conditions. Few points to distinguish between tidal and wave energy is discussed here below:

  • Tides are caused due to the rise and fall of the oceanic water caused by the gravitational pull of the sun and the moon on the earth, while waves are formed due to the moving wind across the ocean surface.

  • Tides are less noticeable, due to their smaller size, as compared to waves. Tides are normally seen in the shorelines, thus affecting the visibility of water and sand.

  • Waves are seen on the ocean surface, gradually rising and falling. Tidal power fluctuates on a daily basis, and wave power can be considered as a more sustained source of energy. The wave power is not widely used, because it has only fewer number of test sites in the world.