school energy&environment

Sea current and tide energy

Tidal power is one of the most interesting and unexplored sources of renewable energy. It must be noted that in Europe alone, the availability of this type of energy is equal to approximately 75 gigawatt (75 million kilowatt). As it is known, besides the power, what is important is the estimate of the energy that can be exploited: in Europe this amounts to approximately 50 terawatt (terawatt hour equivalent to 50 billion kilowatt hour).
In 2003, for the first time a project was realized for the exploitation of this energy in Hammerfest, a town   on the northern coast of Norway. The inhabitants of this remote town, who do not see the sun for long periods of the year, and whose  geographic position is not so suited for connections to the traditional sources of energy, seem to have solved the problem. The blades of the turbine are 10 metres long and turn when the tide rises in the Kvalsund strait, and stop when the seawater reaches its maximum level. They then start moving in the opposite direction when  the tide begins to fall. According to estimates, approximately 700,000 kilowatt hour of non-polluted power should be generated per year (even though production costs are higher), which is enough to guarantee light and heating to about thirty homes.
The turbines to exploit the sea currents can be (as in the case of wind technologies) either horizontal-axis or vertical-axis turbines. Horizontal axis turbines are more suited in the case of constant sea currents, as in  the Mediterranean, while vertical axis turbines are more suited for sea currents, because they can change direction by approximately 180 degrees a number of times in a day.