Tidal Energy Definition, Principle, Methods, Issues, challenges, Advantages and Disadvantages

Tides

Tidal energy belongs to the category of renewable sources. This means it can be used without being replenished. The gravitational forces between the sun, moon, and earth result in rising sea levels, creating tides. At many places, these tides occur twice as large as on a lunar day. Tides are produced daily and have become a regular phenomenon.

Different tidal conditions

1. When the gravitational force between earth and moon combines, the generated tides are huge and strong. As a result, gallons of water travel across the seashore.
2. Alternatively, when the gravitational force between the earth and moon is perpendicular, the generated tides are weak and low.
3. During a full moon or new moon phase, the sun's gravitational force also aligns with the gravitational force of the moon and earth. This results in high tides of much higher heights and low tides of much lower heights.
4. During the quarter moon phase, neap tides occur. They occur due to the canceling effect between the gravitational force of the moon and the sun. These tides have low heights and are weak.

Tidal energy

The energy produced from the tidal currents is known as tidal energy. Since tides occur daily, the strength of their currents is used to make electricity. These current patterns can be studied and predicted long before, months or years to use the natural phenomenon efficiently. In addition, because of the motion of mass water, energy can be created in a non-polluting way.

Structural health monitoring

The high load factors resulting from the fact that water is 800 times denser than air and the predictable and reliable nature of tides compared with the wind make tidal energy particularly attractive for electric power generation. Condition monitoring is the key to exploiting it cost-efficiently.

Principle

Tidal energy is produced from the tides of the oceans and seas. As mentioned above, they occur due to the planetary positions of the sun, moon, and earth, resulting in low, high and normal tides. A tidal generator is placed near the place where the tidal current is high. The generator converts the tidal energy into electricity. The greater the tidal variation, the greater will be the electricity produced. Tidal power is practically inexhaustible because tides occur due to the gravitational forces, which are inexhaustible. Therefore, tidal energy can be one of the leading sources of renewable energy in the future.

Methods to produce tidal energy

1) Tidal stream generators – They use the kinetic energy of moving water to move the turbines and generate power from them. These generators are placed on the bridges or structures to gather maximum current flow to power turbines. These turbines can be horizontal, vertical, ducted, and open.

2) Tidal barrage – They make use of the potential energy of the tides, i.e., the difference in height between low and high tides. Barrages are the most suitable structures to gather the generated potential energy.

3) Dynamic tidal power – This energy-generating technique deals with both kinetic and potential energies. A dam is constructed to capture tidal phase differences across sea coasts. The dam captures maximum energies resulting in producing a great amount of electricity.

4) Tidal lagoon – It is a new design concept that deals with the making of tidal energy. Circular retaining walls are constructed embedded with turbines to capture the maximum amount of potential energy. After the production of energy, electricity is transferred to the desired locations via generators.

Advantages

• Environment-friendly
• A highly predictable energy source
• High energy density
• Operational and maintenance costs are low
• An inexhaustible source of energy

Disadvantages

• High tidal power plant construction costs
• Negative influence on marine life forms
• Location limits
• The variable intensity of sea waves

Issues and challenges

Tidal energy has several issues and may face challenges while producing electricity from the aggressive tides and strong currents. Some of them are-

1) Environmental concerns – Turbines damage sea life along with the species living within the sea. Many marine animals pass through the turbines, resulting in the loss of energy and their life simultaneously.

2) Corrosion – Metal parts of the turbines can easily corrode due to salts present in seawater. Corrosion-resistant materials like stainless steel, copper-nickel alloys, high-nickel alloys, and titanium can reduce corrosion. However, they cannot eliminate corrosion due to the continuous damage caused by seawater. In addition, many lubricants may also leak into the sea, damaging sea life and affecting the turbine's blades.

3) Fouling – Many biological events can take place near the turbines or the place where tidal energy is being produced. This reduces the working efficiency of the machines and workers as they require frequent cleaning or it may alter with the production units.

4) Cost – The initial cost of setting up a tidal energy plant is very high. This is why many countries do not prefer tidal energy to be a contributing factor in their renewable energy sources. However, once installed and completely operating, it may reduce the future costs of electricity in the country. In addition, as tides occur daily, tidal energy can be a major source to contribute towards a safer environment.