WATER ENERGY

TIDAL POWERTidal power, also called tidal energy, is a form of hydropower that converts the energy of tides into useful forms of power, mainly electricity. Many recent technological developments and improvements, both in design (e.g. dynamic tidal power, tidal lagoons) and turbine technology (new axial turbines, cross flow turbines), indicate that the total availability of tidal power may be much higher than previously assumed, and that economic and environmental costs may be brought down to competitive levels.

Tidal power is taken from the Earth's oceanic tides; tidal forces are periodic variations in gravitational attraction exerted by celestial bodies. These forces create corresponding motions or currents in the world's oceans. Due to the strong attraction to the oceans, a bulge in the water level is created, causing a temporary increase in sea level. When the sea level is raised, water from the middle of the ocean is forced to move toward the shorelines, creating a tide. This occurrence takes place in an unfailing manner, due to the consistent pattern of the moon’s orbit around the earth. The magnitude and character of this motion reflects the changing positions of the Moon and Sun relative to the Earth, the effects of Earth's rotation, and local geography of the sea floor and coastlines.

Dynamic tidal power is an untried but promising technology that would exploit an interaction between potential and kinetic energies in tidal flows. It proposes that very long dams be built from coasts straight out into the sea or ocean, without enclosing an area. Tidal phase differences are introduced across the dam, leading to a significant water-level differential in shallow coastal seas – featuring strong coast-parallel oscillating tidal currents such as found in the UK, China, and Korea.

Tidal Stream is the flow of water as the tide ebbs and floods, and manifests itself as tidal current. Tidal Stream devices

seek to extract energy from this kinetic movement of water, much as wind turbines extract energy from the movement of

air.

The sea currents created by movement of the tides are often magnified where water is forced to flow through narrow channels or around headlands. There are a number of

locations around the coastline of the UK where the tidal stream resource is high, and it is in these areas where early

technology developments are taking place to explore the prospect of harnessing tidal energy.

TIDAL STREAM

TIDAL RANGETidal Range is the vertical difference in height between the high tide and the succeeding low tide. Artificial tidal barrages or lagoons may be constructed to capture the tide. Turbines in the barrier or lagoon generate electricity as the tide floods into the reservoir; water thus retained can then be released through turbines, again generating electricity once the tide outside the barrier has receded.

TSUNAMIA tsunami also known as a seismic sea wave or as a tidal wave, is a series of waves in a body of water caused by the displacement of a large volume of water, generally in an ocean or a large lake. In being generated by the displacement of water, a tsunami contrasts both with a normal ocean wave generated by wind and with tides, which are generated by the gravitational pull of the Moon and the Sun on bodies of water. Tsunami waves do not resemble normal sea waves, because their wavelength is far longer. Rather than appearing as a breaking wave, a tsunami may instead initially resemble a rapidly rising tide, and for this reason they are often referred to as tidal waves. Tsunamis generally consist of a series of waves with periods ranging from minutes to hours, arriving in a so-called "wave train"

A waterfall is a place where water flows over a vertical drop in the course of a stream or river. Waterfalls also occur where meltwater drops over the edge of a tabular iceberg or ice shelf. Waterfalls are commonly formed in the upper course of the river.Streams become wider and shallower just above waterfalls due to flowing over the rock shelf, and there is usually a deep area just below the waterfall because of the kinetic energy of the water hitting the bottom. Waterfalls normally form in a rocky area due to erosion. After a long period of being fully formed, the water falling off the ledge will retreat, causing a horizontal pit parallel to the waterfall wall. Eventually, as the pit grows deeper, the waterfall collapses to be replaced by a steeply sloping stretch of river bed. In addition to gradual processes such as erosion, earth movement caused by earthquakes or landslides or volcanoes can cause a differential in land heights which interfere with the natural course of a water flow, and result in waterfalls.

WATERFALL

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