Tidal Power
Tidal Power, often referred to as tidal energy, is achieved through the capture of the energy created as water moves in ocean currents and tides.
Two types of tidal power can be harnessed for energy-efficient power.
The first is called kinetic energy. This is tidal power directly created as the water is moving in rivers and in oceans as tides.
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The tidal power that requires one more step, called potential energy, comes from the difference between low and hide tide height. This height is commonly referred to as head. The kinetic tidal power process uses turbines to produce the renewable energy.
To understand this process think of windmills and visualize them underwater – this is the means for kinetic tidal power. It is becoming increasingly more popular because its impact on our ecology is so much less dramatic than the building of dams, or what some refer to as tidal fences or barrages.
The United States and other countries across the globe are studying their coastal areas with an eye for the suitability of the region for the production of kinetic tidal power. The ideal of these have high speeds of the water that occurs in the local channels as they enter the river or bay. Water currents in rivers that run between islands are especially good for tidal power as the currents there are highly concentrated and often quite powerful.
Tidal power, with solar and wind energy, are one of the most popular and well-touted of the sources of renewable energy. This is because ocean tides especially are caused by the orbit of our solar system. Ocean currents, as part of this process, happen because of the way winds are affected on the earths surface. This tidal power supply is, thus, deemed inexhaustible.
The primary energy source here is the kinetic energy produced by the orbit of the system of earth and moon, and earth and sun.
Tidal power has an excellent potential as a future source of the generation of electricity because the energy generated by these galactic rotations will continue unabated forever - or so scientists believe.
Tidal power is not something new, however. European tidal mills have been a part of grain grinding operations for almost one thousand years.
How efficient tidal ocean dam power is depends on the height of the tidal swells rise and fall. This is commonly referred to as amplitude. This amplitude can be as high as 33 feet 10 meters. This occurs where the tidal waves are funneled into fjords or rivers and water velocity is extreme.
The speed of the water might be as fast as 16 knots. One example of this is Vancouver Island in Canada. Even greater amplitude is experiences in the Bay of Fundy, where the amplitude might reach 56 feet 17 meters. This is because the tides resonance amplifies the ocean waves.
Thus, we see that the selection of the right location for a tidal power generator is crucial to its success as an efficient source of green energy.
By James Copper
Wave Power
One of the Earth's great renewable energy sources is actually the energy that can be found in all the waves of the ocean. Let's look at this further.
If you have ever been to the ocean, you were probably fascinated by the phenomena of the waves crashing against the shorelines as the tides came in. The ocean's tides are the product of gravitational pull of the sun and the moon, as well as, the Earth's rotation. It causes the ocean waters to be raised and lowered from time to time. The tides have cycles of twelve and one half hours, twice per day, and are easily predictable.
The use of tidal power is seen as early as the twelfth century where tidal mills used the force of the tides to grind grain and corn. The eighteenth century brought competition from windmills and waterwheels. Tidal mills pretty much became extinct with the invention of cheap steam engines. In 1967, France became the first to be able to put tidal wave power to work on a large scale to produce electricity.
The generation of electricity from tidal waves is similar to that of hydroelectric power generation. Bigger dams, known as barrages, are built on the bottom of a tidal basin. Gates on the barrage allow the tidal basin to fill during incoming high tides. Likewise, the basin will empty through a turbine during the outgoing tide. This would turn an electric generator for the production of electricity. There are also systems that generate electricity from incoming and outgoing tides. This system can have a negative effect on plants and animals in the area.
Tidal fences are also used to generate electricity. Vertical axis turbines are mounted on fences. Passing water is forced through the turbines. Ideal locations for these are channels between two landmasses. Tidal fences are cheaper than tidal barrages and cause less of an environmental impact on large marine life.
Tidal turbines are a new technology used for tidal energy. They are similar to wind turbines and are arranged underwater in rows. They work best in areas with strong tides. Although they are heavier and costlier to build, they also are capable of capturing more energy. They are also the least environmentally damaging of all the tidal power technologies, since they do not interfere with migration paths.
In order for tidal power to work successfully it requires a tide difference of at least sixteen feet. Unfortunately there are only a few places where this occurs. This means tidal power plants cannot just be constructed anywhere. There are only a handful of sites on Earth with this type of tidal range. At present, France is the only country that has been successful in using tidal power. It is hoped developments in technology, through research, will be made to allow better use of this, what is now, wasted energy. The future of tidal energy seems hopeful. Tidal power has great potential and hopefully we can make better use of it in the future in our quest to find a replacement for fossil fuels.
