Pros & Cons of Hydroelectric Dams
Hydroelectric dams, large structures usually made out of concrete that block the flow of a river or stream, are used to generate electricity. This causes a large volume of water to collect in the area behind the dam. This water is allowed to flow through several small tunnels at the base of the dam. These tunnels contain turbines connected to electrical generators. As the water flows through the turbines it generates electricity.
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Reliability
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Hydroelectric dams are extremely reliable. They can be turned on and off very quickly, which makes them useful for balancing loads in electricity grids. Because the dam runs off the flow of water of a natural watercourse there is little short of an extended drought or deliberate sabotage that can render the dam unable to produce electricity. Dams generally require little maintenance apart from ensuring that the turbines do not become clogged with debris.
Carbon Footprint
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Hydroelectric dams produce electricity while generating very low levels of carbon dioxide. This does not mean that they emit zero carbon dioxide. Hydroelectric dams are mainly made of concrete. The production of concrete produces high levels of carbon dioxide. However, this initial burst of carbon dioxide is very small compared with the total lifetime carbon dioxide emissions of fossil fuel power plants.
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Geographic Limitations
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Hydroelectric dams require very specific natural geography. This specific natural geography includes large valleys in mountainous areas. There are many areas of the world where hydroelectric dams cannot be built. As such hydroelectric dams are capable of contributing only a small fraction of global electricity needs.
Impact on People
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Hydroelectric dams often require people to leave their homes and uproot whole communities as they live in the area required for the water behind the dam. An example includes the Three Gorges Dam in China. Over a million people were forcibly relocated to make room for the rising water behind the dam. This meant the flooding of more than a thousand towns.
Impact on Natural Environment
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Building hydroelectric dams involves making major changes to the natural environment. Waterways are enlarged and diverted. The movement of marine animals in waterways is inhibited. Substantial civil engineering work is often required to reform the existing landscape around the dam. This can have a substantial negative impact on animal and plant life in the area around the dam.
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References
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