Impoundment
A dam is built across a river impounding a head of water behind it in a reservoir which can then be released through a turbine to generate electricity.
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A Diversion
Sometimes called run‐of‐river, facility channels a portion of a river through a canal. It may not require the use of a dam and thus has a lower environmental impact.
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Pumped Storage
When the demand for electricity is low, a pumped storage facility stores energy by pum‐ping water from a low‐er reservoir to an upper reservoir. During periods of high elect‐rical demand, the water is released back through a turbine to the lower reservoir to generate electricity.
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Water turbine runners
Various types of water turbine runners. From left to right:
• Pelton Wheel ‐ Specific Speed 5.0 rpm• Francis Turbine ‐ Specific Speed 30 rpm• Francis Turbine ‐ Specific Speed 70 rpm• Kaplan Turbine ‐ Specific Speed 113 rpm
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Why hydroelectric power?
Pros,• Renewably energy source • Fast to adapt to electricity demand• Low operations cost• Long lifetime• Flood control (in combination with a dam) • Improve transport condition on the river
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Why hydroelectric power?
Cons,• High investment costs • Big local environment impact • River flows and natural flooding cycles sedimentation/silting are changed
• Damage fish migration ways • Loss of land under the reservoir
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Hydroelectric today
• Hydroelectricity stands for 20% of the worlds electricity demand
• About 88% of the worlds renewably electricity comes from hydroelectric power plants
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Future potential
Key‐(TWh/year)Technical feasibilityCurrent productionRealistic development
Estimated hydropower development by region
Source: Energy Council, 2007 Survey of Energy Resources World s272. 13
Europe
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0‐50
50‐100
100‐200
200‐2300
Hydropower potential,gross hypotheticalcapability (TWh/year )
Source: European Environment Agency
Economy
• High investment costs • Long operative lifetime • Improves transport abilities on the river • Flood preventing
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Three Gorges Dam
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To recover the investment of the project, it has to generate 1000TWh, which probably occurs between 2015 and 2017.
Source: www.waterpowermagazine.com
Construction cost 8 billion € ( up to2008)
Relocation of people 8 billion € ( up to2008)
Capital cost 2 billion € ( up to2008)
Finishing (estimated) 3 billion € ( after 2008)
Total 21 billion €
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Months of the year
Maximum plant intake whit 32 main generators
Average actualflow rate
Maximum plant intake whit 26 main generators
18Sources: European Energy Exchange
Type Installed Capacity [ MW ] Income [ € ] Standardized incomeNo dam 1 1173 1
Dam 3 1400 1.19
Dam 6 1485 1.27
Energy costs for different generation technologies (Emission taxes and capital cost not included)
19Source: California Energy Commission
Typical capacity factors
• Wind farms 20‐40%• Photovoltaic solar in Arizona 19%• Hydroelectricity 44%• Nuclear 91%• Coal 72%
20Source: U.S: Energy Information Administration
Conclusion As the pressure to reduce greenhouse gases increases, a bigger part of the electricity will come from renewable sources.The problem with many of the existing ones is that the electricity production is hard to foresee the electricity production in the next time period. Therefore, we need a power source that can easily and rapidly adapt to the electricity demand. As a result the role of hydroelectric power will increase.
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List of references
• Wikipedia.org. [Online] [Cited: 06 10, 2010.] http://en.wikipedia.org/wiki/Capacity_factor.
• U.S. Energy Information Administration. [Online] [Cited: 05 25, 2010.] http://www.eia.doe.gov.
• World Energy Council. [Online] [Cited: 06 01, 2010.] http://www.worldenergy.org
• California Energy Commission. COMPARATIVE COSTS OF CALIFORNIA CENTRAL STATION ELECTRICITY GENERATION TECHNOLOGIES. 2007. CEC‐200‐2007‐011‐SD.
• International Water Power. [Online] [Cited: 06 02, 2010.] Beyond Tree Gorges in China. http://www.waterpowermagazine.com/story.asp?storyCode=2041318
• World Energy Council. 2007 Surver of Energy Resources.
• EEA. The pan‐European environment: glimpses into an uncertain future.
• U.S. Department of the Interior Bureau of Reclamation.
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