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♪ [Soothing music] ♪

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The use of water[br]to produce electrical energy

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is an extraordinary invention

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made possible by[br]gravity power plants.

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A hydroelectric plant[br]on the water

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produces renewable energy[br]from a river current.

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The hydroelectric plant[br]includes a dam,

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which allows water to accumulate[br]into a quasi-reservoir.

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♪ [Soothing music] ♪

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The more the distance between[br]retained and open water is raised,

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the greater the potential energy.

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Retained water flows through[br]underground pipes,

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to be deposited on[br]the other side of the dam.

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A turbine,

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for instance a Kaplan turbine,[br]is integrated into the pipeline.

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It is fitted with a propeller wheel,[br]similar to a ship's propeller.

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The steering wheel has[br]orientating blades,

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which direct the water flow[br]towards the moving wheel blades,

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in an effective manner.

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The electric motor [br]changes the blades' direction.

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Once set in motion,

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the turbine drives an electric[br]generator, which produces electricity.

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The change of the blades'[br]direction

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strives to achieve[br]a high degree of efficiency,

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avoiding the inconvenience[br]of fluctuating river water levels.

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The spiral cover accelerates[br]the water...

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then, the steering wheel blades[br]direct it toward the moving blades.

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As the water hits the blades,[br]the moving wheel drives the generator

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which transforms mechanical energy[br]into electrical energy.

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Here are the components of[br]a hydroelectric power plant

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to better explain[br]the operation.

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Several installations, and the generator,[br]are in the machine building.

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With some exceptions,

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a transformer raises the voltage[br]of the current produced,

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so it can be transported easier[br]through high voltage lines.

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In 1913, engineer Victor Kaplan[br]invented the Kaplan turbine

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which perfected the concept[br]of the Francis turbine.

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The efficiency of a Kaplan turbine[br]varies generally between 90 and 95 %.

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The cavitation phenomenon has been[br]a major problem, persisting to this day.

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However, today there are several solutions[br]against cavitation,

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to protect the blades[br]of the Kaplan turbines.