Where could you find tidal power?

Answer 1

Origin

The daily rise and fall in the level of ocean water relative to the coastline is referred to as tide. Tides originate from the motions of the earth, moon and sun. The gravitational pull of the Moon and Sun along with the revolution of the Earth result in tides. (The magnitude of the gravitational attraction of an object is dependant upon the mass of an object and its distance.) The moon exerts a larger gravitational force on the earth, though it is much smaller in mass, because it is a lot closer than the sun. This force of attraction causes the oceans, which make up 71 percent 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 similarly, 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 i.e on the occasion of a full or new moon, the gravitational attractions are combined, resulting in very large spring tides. At half moon, the sun and moon are positioned at right angles, resulting in lower neap tides. Coastal areas experience two high and two low tides over a period of 24 hours and slightly above.

The presence of geographical features such as bays and inlets result in higher tides. To produce enough amounts of power (electricity) that can be put to practical use, a difference of at least five meters between high and low tides is a must. There are about 40 suitable sites around the world with this kind of tidal range. The higher the tides, the greater is the amount of electricity that can be generated from a given site. It is inversely proportional to the cost of electricity produced, making such sites also more economical. Approximately 3000 GW (1 Giga Watt = 1 GW = 1 billion watts) of energy are available from the tides, worldwide. However considering the limitations as mentioned above, only about 2% (= 60 GW) can potentially be exploited for electricity generation.

Generating tidal energy

The technology required to convert tidal energy into electricity is comparable to technology used in traditional hydroelectric power plants. The first requirement is a dam across a tidal bay or estuary. However building a dam is expensive and the best sites are those where a bay has a narrow opening, thus reducing the length of dam required. Gates and turbines are installed. When there is adequate difference in the levels of the water on the different sides of the dam, the gates are opened. This causes water to flow through the turbines, turning the generator to produce electricity.

Electricity is generated by water flowing both inwards and out of a bay. There are periods of maximum generation every twelve hours, with no electricity generation at the six-hour mark in between. The turbines may also be used as pumps to pump extra water into the basin behind the dam at times when the demand on electricity is low. This water can later be released when the demand on the system is very high, thus allowing the tidal plant to function like a "pumped storage" hydroelectric facility.

Uses and economy

The friction of the bulging oceans acting on the spinning earth results in a very gradual slowing down of the earth's rotation but this is not expected to impact us for billions of years. Therefore, for practical purposes, tidal energy can be considered a sustainable and renewable source of energy. It can prove to be a valuable source of renewable energy to an electrical system. The demand of electricity from a grid varies with the time of the day. Tidal power, although variable, is reliable and predictable and can make a valuable contribution to an electrical system, which has a variety of sources. Tidal electricity provides a good alternative to conventional methods of generating electricity, which would otherwise be generated by fossil fuel (coal, oil, natural gas) etc, thus reducing emissions of greenhouse and acid gases.

Answer 2

For the most part, coastal cities. Unless the USA and other countries devise a long term system in which they can transport energy inland (Which, as of February 2012 has still not been invented).

Answer 3

it is a poo!

Answer 4

it can help the envirmant bye bye