TIDAL WAVE ENERGY GENERATION MECHANISM
By-- Siddhant Mishra(second year undergraduate)
Tidal wave & difference between Tidal wave and Tsunami
Although both are sea waves, a tsunami and a tidal wave are two different and unrelated phenomena. A tidal wave is a shallow water wave caused by the gravitational interactions between the Sun, Moon, and Earth. A tsunami is an ocean wave triggered by large earthquakes that occur near or under the ocean, volcanic eruptions, submarine landslides, or by onshore landslides in which large volumes of debris fall into the water.
How are energy extracted from Tidal wave
Energy can be extracted from tides by creating a reservoir or basin behind a barrage and then passing tidal waters through turbines in the barrage to generate electricity.It is produced by the surge of ocean waters during the rise and fall of tides. Tidal energy is a renewable source of energy.The basic concept of tidal energy is the conversion of the kinetic or potential energy derived from tides into electricity.
Types of Tidal Energy
Tidal energy is one of the most reliable sources of renewable electricity. Unlike sunlight or wind, two high tides and two low tides are guaranteed every day.
Energy from tides can be tapped in two forms.
1. Kinetic energy drawn in from the sea currents:
Kinetic energy is harnessed by employing a setup that is similar to a wind turbine. The density of water is much higher that of air, so the kinetic energy that it can impart is also higher. Thus, the blades of a tidal turbine are smaller than that of wind turbine, as they can operate at lower velocities.
2. Potential energy due to changes in water levels : When the tide changes from high to low and vice-versa, potential energy is generated. In order to tap this potential energy of tides, dams need to be constructed. These dams are called barrages. They capitalize on the differences in water level between high tide and low tide.
Tidal wave generator types:
Tidal Barrages: A tidal barrage is a dam that taps the potential energy generated by the difference in the height of the high tide and the low tide. The gates of the barrages are kept closed when it is high tide. This results in the water accumulating on one side of the dam. As the tide starts falling, the level of the water on the ocean side of the dam falls. When the difference in height is more than 5 meters, the dam is opened.
Tidal Lagoons: These are similar to barrages, except that lagoons are highly localized and specific to a particular stretch of water. Barrages span the entire width of a river or estuary. In the case of lagoons, the structure is confined to the parts with a high tidal range. Basically, lagoons are miniature barrages, the only difference being that a barrage blocks an entire estuary, whereas lagoons block only a certain part of the river.
Tidal Stream Systems: These can be regarded as the windmills of the sea since, instead of air, they rely on water currents. The underwater turbines are anchored to the sea bed. These systems exploit the kinetic energy from the water to drive the blades of the rotor.
