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Transcript of Hydroelectric energy
This provides 10% of China's electrical needs
17% of its domestic use
1 million people have had to be relocated as the dam was built (13 cities 140 towns and 1350 villages.)
185meters high 2km wide the reservoir behind is 600km long.
some of china's most fertile farm land has been lost
and the rest below the dam will become less productive as sediment and soil is trapped behind the dam.
also the water needs to be treated due to the sediment in the water.
The dam provides the equivalent of burning 50 million tonnes of coal a year. Hydro Electric Power (HEP) is generated from the potential energy of dammed water forcing the blades of a turbine to spin.
The turbines powers a generator, which transforms the kinetic energy (of water) into electrical energy.
The sheer power of the dammed water has made HEP the most used renewable method of creating energy in the world
However hydroelectric power is still a very small contributor to global energy (16% of global electricity consumption) Advantages
1. Once a dam is constructed, electricity can be produced at a constant rate.
2. 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.
3. Dams are designed to last many decades and so can contribute to the generation of electricity for many years / decades.
4. The lake that forms behind the dam can be used for water sports and leisure / pleasure activities. Often large dams become tourist attractions in their own right.
5. The lake's water can be used for irrigation purposes.
6. The build up of water in the lake means that energy can be stored until needed, when the water is released to produce electricity.
7. When in use, electricity produced by dam systems do not produce green house gases. They do not pollute the atmosphere.
1. Dams are extremely expensive to build and must be built to a very high standard.
2. The high cost of dam construction means that they must operate for many decades to become profitable.
3. The flooding of large areas of land means that the natural environment is destroyed.
4. People living in villages and towns that are in the valley to be flooded, must move out. This means that they lose their farms and businesses. In some countries, people are forcibly removed so that hydro-power schemes can go ahead.
5. The building of large dams can cause serious geological damage. For example, the building of the Hoover Dam in the USA triggered a number of earth quakes and has depressed the earth’s surface at its location.
6. Although modern planning and design of dams is good, in the past old dams have been known to be breached (the dam gives under the weight of water in the lake). This has led to deaths and flooding.
7. Dams built blocking the progress of a river in one country usually means that the water supply from the same river in the following country is out of their control. This can lead to serious problems between neighboring countries.
8. Building a large dam alters the natural water table level. For example, the building of the Aswan Dam in Egypt has altered the level of the water table. This is slowly leading to damage of many of its ancient monuments as salts and destructive minerals are deposited in the stone work from ‘rising damp’ caused by the changing water table level. Generally there are more limitations on the production of HEP around the world than oil. HEP requires suitable source of water and good sized rivers or lakes which are located in more developed countries.
The UK has the technology but few suitable sites. most sites are located in the Scottish highlands with the river seven tidal dam as the only major one in the south. the UK produces only 0.8% of its energy from HEP.
There are only 4 main production countries of HEP USA,Brazil,China and Canada. They account for 47% of the global production. These countries all have the technology and suitable sites.
Where as the poorer countries mainly in Africa lack the technology needed to produce effective energy from the possible sites. Production and influencing factors ... small The Hoover Dam USA Hydroelectric Power How it produces energy Global patterns of production Looking at Gapminder you can see that the 4 main HEP producing countries are China Brazil Canada and USA.
China generates just over 50 million in HEP
Canada is second with close to 33 million
Brazil third with almost 32 million
The USA fourth with just over 22 million.
The graph also shows that there are a lot of middle eastern, African, south east asian and European countries who generate less than 1 million and some generate no HEP. The Aswan Dam Egypt The Itaipu Dam Brazil Located on the Brazilian boarder with Paraguay Other prominent dam projects Guri Dam Venezuela