Tidal power - Generation of tidal energy Tidal power is the only form of energy which derives directly from the relative motions of the Earth Moon

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Generation of tidal energy Tidal power is the only form of energy which derives directly from the relative motions of the Earth Moon system, and to a lesser extent from the Earth– Sun system. The tidal forces produced by the Moon and Sun, in combination with Earth's rotation , are responsible for the generation of the tides . Other sources of energy originate directly or indirectly from the Sun, including fossil fuels , conventional hydroelectric , wind , biofuels , wave power and solar . Nuclear is derived using radioactive material from the Earth, geothermal power uses the Earth's internal heat which comes from a combination of residual heat from planetary accretion (about 20%) and heat produced through radioactive decay (80%). [3] Variation of tides over a day Tidal energy is generated by the relative motion of the water which interact via gravitational forces . Periodic changes of water levels, and associated tidal currents, are due to the gravitational attraction by the Sun and Moon. The magnitude of the tide at a location is the result of the changing positions of the Moon and Sun relative to the Earth, the effects of Earth rotation , and the local shape of the sea floor and coastlines . Because the Earth's tides are caused by the tidal forces due to gravitational interaction with the Moon and Sun, and the Earth's rotation, tidal power is practically inexhaustible and classified as a renewable energy source. A tidal generator uses this phenomenon to generate electricity. The stronger the tide, either in water level height or tidal current velocities, the greater the potential for tidal electricity generation.
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Tidal movement causes a continual loss of mechanical energy in the Earth–Moon system due to pumping of water through the natural restrictions around coastlines, and due to viscous dissipation at the seabed and in turbulence . This loss of energy has caused the rotation of the Earth to slow in the 4.5 billion years since formation. During the last 620 million years the period of rotation has increased from 21.9 hours to the 24 hours [4] we see now; in this period the Earth has lost 17% of its rotational energy. While tidal power may take additional energy from the system, increasing the rate of slowdown, the effect would be noticeable over millions of years only, thus being negligible. Categories of tidal power Tidal power can be classified into three main types: Tidal stream systems make use of the kinetic energy of moving water to power turbines, in a similar way to windmills that use moving air. This method is gaining in popularity because of the lower cost and lower ecological impact compared to barrages . Barrages make use of the potential energy in the difference in height (or head ) between high and low tides. Barrages are essentially dams across the full width of a tidal estuary, and suffer from very high civil infrastructure costs, a worldwide shortage of viable sites, and environmental issues. Dynamic tidal power
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This note was uploaded on 12/18/2010 for the course ME 22 taught by Professor Rashid during the Spring '10 term at Superior University Lahore.

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Tidal power - Generation of tidal energy Tidal power is the only form of energy which derives directly from the relative motions of the Earth Moon

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