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  1. 1. Hersh Jalil MSC.
  2. 2. Introduction It is a form of energy … a renewable resource. Hydropower provides about 96 per cent of the renewable energy in the United States. Hydroelectric power comes from flowing water … winter and spring runoff from mountain streams and clear lakes. Water, when it is falling by the force of gravity, can be used to turn turbines and generators that produce electricity
  3. 3. HOW HYDROPOWER WORKS 2 11 ∗ In the hydrologic cycle, atmospheric water reaches the earth is surface as precipitation. Water from rain and melting snow eventually reaches ponds, lakes, reservoirs, or oceans where evaporation is constantly occurring.
  4. 4. ∗ Water from the reservoir flows due to gravity to drive the turbine. ∗ Turbine is connected to a generator. ∗ Power generated is transmitted over power lines.
  5. 5. ∗ Hydro power is available by creating dams in stream and river flows. Hydro power generation is an established technology and maybe as much as one fifth of the world's electricity is generated this way, which is slightly more than by nuclear generation.
  6. 6. Hydroelectric dam in cross section
  7. 7. In electricity generation, an electrical generator is a device that converts mechanical energy to electrical energy, generally using electromagnetic induction. The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, compressed air or any other source of mechanical energy.
  8. 8. Pumped Storage ∗ At night when customer demand for energy is lower, water is pumped to storage pool above the dam
  9. 9. At Day ∗ When demand and heavy load is placed on the system is allowed to flow back through the turbine – generator
  10. 10. ADVANTAGES ∗ 1. Once a dam is  constructed, electricity  can be produced at a  constant rate.
  11. 11. 2 - Economics The major advantage of hydroelectricity is elimination of the cost of fuel. The cost of operating a hydroelectric plant is nearly immune to increases in the cost of fossil fuels.
  12. 12. ∗ 3. If electricity is not  needed, the sluice gates  can be shut, stopping  electricity generation. The  water can be saved for  use another time when  electricity demand is high.
  13. 13. 4. When in use, electricity produced by dam systems do not produce green house gases. They do not pollute the atmosphere. 5. The lake's water can be used for irrigation purposes Although dams prevent the natural flushing out of a river during a flood, they also control flooding downstream in times of high rainfall and snowmelt.
  14. 14. Disadvantages . Dams are extremely expensive to build and must be built to a very high standard. ∗ Usually a large area of land  has to be flooded to ensure  a continuous flow of water  to the turbine. In some  cases when a dam is built,  large populations have to be  relocated. In China, the  Three Gorges Dam Project  on the Yangtze River  will displace more than 1  million people.
  15. 15. Disadvantages  Environmental damage ∗ Hydroelectric projects can be disruptive to surrounding  aquatic ecosystems. For instance, studies have shown that  dams along the Atlantic and Pacific coasts of North America  have reduced salmon populations by preventing access to  spawning grounds upstream, even though most dams in  salmon habitat have fish ladders installed. 
  16. 16. Population relocation ∗ Another disadvantage of hydroelectric dams is the need to relocate the people living where the reservoirs are planned. In many cases, no amount of compensation can replace ancestral and cultural attachments to places that have spiritual value to the displaced population. Such problems have arisen at the Three Gorges Dam project in China.
  17. 17. Dam failures ∗ Failures of large dams, while rare, are potentially serious — the Banqiao Dam failure in Southern China resulted in the deaths of 171,000 people and left millions homeless. Dams may be subject to enemy bombardment during wartime, sabotage and terrorism. Smaller dams and micro hydro facilities are less vulnerable to these threats.
  18. 18. The end