Hydroelectric energies

1. Hydroelectric energies Rivers energy Sea energy

3. Hydropower plants • Worldwide, hydropower plants produce about 24 percent of the world's electricity and supply more than 1 billion people with power. • Hydropower is the second source of electricity in France. • In France it is 12% of the total electricity production, with an average production capacity of 70 TWh per year

4. How does it work ? Hydropower plants are based on a rather simple concept Hydropower plants harness water's energy and use simple mechanics to convert that energy into electricity. Water flowing through a dam turns a turbine which turns a generator.

6. Here are the basic components of a conventional hydropower plant • Dam - Most hydropower plants rely on a dam that holds back water, creating a large reservoir. Often, this reservoir is used as a recreational lake • Intake - Gates on the dam open and gravity pulls the water through the penstock, a pipeline that leads to the turbine. Water builds up pressure as it flows through this pipe • Turbine - The water strikes and turns the large blades of a turbine, which is attached to a generator above it by way of a shaft. The most common type of turbine for hydropower plants is the Francis Turbine, which looks like a big disc with curved blades. A turbine can weigh as much as 172 tons and turn at a rate of 90 revolutions per minute (rpm) • Generators - As the turbine blades turn, so do a series of magnets inside the generator. Giant magnets rotate past copper coils, producing alternating current (AC) by moving electrons. • Transformer - The transformer inside the powerhouse takes the AC and converts it to higher-voltage current • Power lines - Out of every power plant come four wires: the three phases of power being produced simultaneously plus a neutral or ground common to all three • Outflow - Used water is carried through pipelines, called tailraces, and re-enters the river downstream

7. Here are the basic components of a conventional hydropower plant

8. Pumped-storage hydroelectric plant

9. Pumped-storage hydroelectric plant: • A plant that usually generates electric energy during peak load periods by using water previously pumped into an elevated storage reservoir during off-peak periods when excess generating capacity is available to do so. When additional generating capacity is needed, the water can be released from the reservoir through a conduit to turbine generators located in a power plant at a lower level.

10. Hydroelectric production

12. The Rance tidal power plantThe dam of the plant measures 332.5 meters

13. The Rance tidal power plant, power from the ocean • The Rance site lent itself well to such a project. • First, because the amplitude between low and high tides is one of the highest in the world (it reaches up to 13.5 metres during equinoctial tides) • Second, because the estuary offers a reservoir of 22 km2 capable of impounding 180 million m3. At peak periods, 18,000 m3 of water per second go through the estuary, or a flow that is ten times greater than that of the Rhone River. • To harness such power, the estuary had to be blocked by a 750 metres long and 13 metres high structure. Twenty-five years of studies and six years of construction works were needed to erect the Rance tidal power plant. • Since 1967, this facility, the only full-scale power station of this type in the world, generates 600 million kWh every year, enough to provide energy to 250 000 households.