2. WHAT IS IT?  It is a type of energy that takes advantage of the energy of the tides. There uses the difference of height between the tide and the low tide.

3.  It is a renewable energy, that is to say, a type of energy that takes advantage of resources that do not end, in this case, the water

4. Tides The tides are periodic changes of the level of the sea that are different depending on the zones.

5. The tides are produced by the attractive force of the Moon and, in minor measure, of the Sun. When in a place there is high tide, in other one there is low tide

6. When the Sun and the moon attract in the same direction the alive tides are produced. If they attract in opposite directions, dead tides are produced

7.  In order that this energy works out profitable it is necessary that the difference between tides is major of 5 meters. Therefore only it is possible to install plants in a few places.

8.  The tidal power stations must place in zones closed as the estuary of a river. Estuary of the river Adige (Italy) The Guadalquivir

9.  A plant consists of: Turbine Pelton Francis A turbine "bulb" with arms or blades A bun - a camera of entry of the water - a pipe of aspiration

10. 11. When the tide rises, the hatches of the plant are opened to allow the step.

11. 22. The deposit is closed creating a prey with the water dammed in its interior.

12.  3. When the tide is in its point more low the hatches are opened to allow the step of the water along the turbines.

13.  4. The turbines move the blades that, together with the alternator, produce alternating current.

14. Tidal power station of the river The Rance  It is the only tidal power station with energetic purposes of the world. Others only are used by scientific purposes.

15. IIt is in the river mouth of the river The Rance, in the north of France. It is formed by 24 generators. It has a power of 240 MW

16.  The dike has 700 m of length and 15 of height. It produces 600 millions of kwh annual, the sufficient ones as to supply 330000 persons.

17.  Other tidal power stations are: Annapolis Royal in Canada Murmansk in Russia

18.  It neither emits any pollutant nor emits any dangerous residue  It is a renewable energy.  The cost of maintenance is low.

19.  Its cost is very high.  The production of energy lasts only a few hours.  It produces a great environmental impact.

20. TThe wave energy is a clean energy, which takes advantage of the difference between tides and which does not produce pollutants but which is very expensive its construction, only one can in a few zones of the planet and that generates a great environmental impact.