Tidal Power As A Source Of Electricity Tidal Power as a Source of Electricity

Tidal energy has been used by humans for hundreds of years. In the modern era, the power is utilized for the production of electricity. The technologies involved are both proven and effective. However, with the exception of a tidal power plant at La Rance, France, the energy resource remains largely undeveloped. This may be in part because of the relatively high cost of the electricity produced. Only in appropriate circumstances will tidal power ever utilize its potential as both a dependable and enduring power source.

Tidal surges are caused by complex interactions between the gravitational fields of the sun and the moon. These phenomena occur in cycles of varying length. For the most part, the earth's oceans bulge along an axis which is approximately in line with the moon. As the earth rotates, its surface moves with respect to this bulge (Sanders, 1991, p. 273). The result is a half-day tidal cycle of 12 hours and 25 minutes between successive high waters. However, other cycles exist as well. One of these is caused by interaction between the gravitational fields of the sun and the moon. It occurs over a 14 day period and results in tidal maximums and minimums known as the spring and the neap tides, respectively (Twidell & Weir, 1986, p. 344). Spring tide ranges tend to be about twice those of neap tide. All tides, however, may be affected by local influences. Such factors as tunnelling, reflection, and resonance can d

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and its hydraulic head. Although such pumping does require energy input, a net energy gain is acquired because the head generated at low tide is greater than that pumped against toward high tide. Pumping can increase the energy gained from ebb generation systems by 5 to 15% (Cavanagh et al., 1993, p. 520). Tidal power plants generally employ axial-flow turbines. The straight flow of water through these turbines increases their hydraulic efficiency. However, their one drawback is that they tend to be rather large: diameters can be as great as 9 meters. Since tidal methods involve continuously changing hydraulic heads, the angles of either the turbine distributor, the turbine blades, or both, must be regulated to achieve maximum efficiency. Moreover, with two-way generation techniques reverse pumping mechanisms and double regulation must be employed (Cavanagh et al., 1993, p. 519). The two most commonly used generators in tidal flow systems are the conventional bulb turbine and the rim-generator turbine. In bulb turbines, the rotor is positioned in a plane perpendicular to the tidal flow, while the generator is located in a pod behind the turbine runner. Rim-generator turbines have a stator which is outside the water flo
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Approximate Word count = 1868
Approximate Pages = 7 (250 words per page)

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