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Tidal Power See also: Tidal power, sometimes called tidal energy, is a form of hydropower that converts the energy of tides into electricity or other useful forms of power. Although not yet widely used, tidal power has potential for future electricity generation. Tides are more predictable than wind energy and solar power. Historically, tide mills have been used, both in Europe and on the Atlantic coast of the USA, the earliest occurrences dating from the Middle Ages, or even from Roman times.[1][2] Generation of tidal energy
Tidal power is the only form of energy which comes from the tidal forces produced by the relative motions of the Earth-Moon system. Other sources of energy originate directly or indirectly from the Sun, including fossil fuels, conventional hydroelectric, wind, biofuels, and solar. nuclear and geothermal come from radioactive material in the Earth. Tidal energy is generated by the relative motion of the Earth, Sun and the Moon, 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. A tidal energy generator uses this phenomenon to generate energy. The stronger the tide, either in water level height or tidal current velocities, the greater the potential for tidal energy generation. 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 [3] we see now; in this period the Earth has lost 17% of its rotational energy. Tidal power may take additional energy from the system, increasing the rate of slowing.
Categories of Tidal PowerTidal power can be classified into two main types:
Modern advances in turbine technology may eventually see large amounts of power generated from the ocean, especially tidal currents using the tidal stream designs. Tidal stream turbines may be arrayed in high-velocity areas where natural tidal current flows are concentrated such as the west and east coasts of Canada, the Strait of Gibraltar, the Bosporus, and numerous sites in south east Asia and Australia. Such flows occur almost anywhere where there are entrances to bays and rivers, or between land masses where water currents are concentrated. Global environmental impactA tidal power scheme is a long-term source of electricity. A proposal for the Severn Barrage, if built, has been projected to save 18 million tonnes of coal per year of operation. This decreases the output of greenhouse gases into the atmosphere. If fossil fuel resource is likely to decline during the 21st century, as predicted by Hubbert peak theory, tidal power is one of the alternative source of energy that will need to be developed to satisfy the human demand for energy. Energy efficiencyTidal energy has an efficiency of 80% in converting the potential energy of the water into electricity, which is efficient compared to other energy resources such as solar power or fossil fuel power plants. For more information see the following links: Patents
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This article is licensed under the GNU Free Documentation License. It uses material from Wikipedia Encyclopedia article "Tidal Power" |
