Renewable energy can be used to decrease global dependence on natural resources, and tidal power can be the primary form of renewable power utilized. Built upon steam turbine knowledge, tidal turbines draw on innovative technology and design to operate on both the inflow and outflow of water through them. Two case studies, Annapolis Royal and La Rance, prove that tidal power plants are capable of producing reliable and efficient power. Problems, such as initial cost and power transportation hinder future implementation of tidal power plants. This paper emphasizes the possibilities of utilizing the power of the oceans by pollution free, tidal Power generation. Tidal power utilizes twice the daily variation in sea level caused primarily by the gravitational effect of the Moon and, to a lesser extent by the Sun on the world's oceans. The Earth's rotation is also a factor in the production of tides
Tides, the daily rise and fall of ocean levels relative to coastlines, are a result of the gravitational force of the moon and sun as well as the revolution of the earth. The moon and the sun both exert a gravitational force of attraction on the earth. The magnitude of the gravitational attraction of an object is dependent upon the mass of an object and its distance. The moon exerts a larger gravitational force on the earth because, although it is much smaller in mass, it is a great deal closer than the sun. This force of attraction causes the oceans, which make up 71% of the earth's surface, to bulge along an axis pointing towards the moon. Tides are produced by the rotation of the earth beneath this bulge in its watery coating, resulting in the rhythmic rise and fall of coastal ocean levels.
The gravitational attraction of the sun also affects the tides in a similar manner as the moon, but to a lesser degree. As well as bulging towards the moon, the oceans also bulge slightly towards the sun. When the earth, moon and sun are positioned in a straight line (a full or new moon), the gravitational attractions are combined, resulting in very large "spring" tides. At half moon, the sun and moon are at right angles, resulting in lower tides called "neap" tides. Coastal areas experience two high and two low tides over a period of slightly greater than 24 hours. The friction of the bulging oceans acting on the spinning earth results in a very gradual slowing down of the earth's rotation. This will not have any significant effect for billions of years. Therefore, for human purposes, tidal energy can be considered a sustainable and renewable source of energy.
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