Hydroelectric Power

What is Hydroelectric Power?

Hydroelectric power is the technology of converting the kinetic energy of flowing or falling water into electrical energy.

How does it work?

A dam is constructed where there is a big river or a natural lake in a valley. Water is reserved in the reservoir of the dam. There is the water intake near the bottom of the dam. Dam creates pressure so that water can produce more electrical power. Gravitational potential energy stored in the water and this energy is utilized to rotate turbines of generators in order to generate power. These turbines are constructed within tunnels in the dam wall.

With great pressure, water flows inside these tunnels and helps to rotate these turbines. Water can provide huge pressure due to the great height at which is kept in the dam. If the difference of height between the water levels and the water where it flows is very large, then there is the possibility to gain more power out of the water for its greater potential energy. This difference in height of the water is called the head. 


Basically, a generator is a device which can convert mechanical energy into electrical energy. Generators work on the principal of electromagnetic induction discovered by Michael Faraday in 19th century. Faraday discovered that flow of electric charges could be induced by rotating an electrical conductor like a wire which holds electric charges in a magnetic field. This rotation creates a voltage difference between two ends of electrical conductor. It causes the electric charges to flow and as a result electric current is generated.

There are two main parts exist in the generator. They are the rotor and the stator. The rotor is the part which can rotate. It contains magnetic field. On the other hand, the stator is the stationary part. Coils or insulated windings are located in slots near an air gap in the stator core. When the rotor is rotated, alternating current (AC) is induced in the stator. Alternating characteristics of the current is produced by changing the polarity of rotor. The generated voltage is proportional to the strength of magnetic field, number of coils, number of windings in each coil and rotating speed of rotor. 


Comparison with other power generation methods

Hydroelectricity removes emissions of the fuel gas from combustion of fossil fuel. It significantly contributes to eliminate harmful pollutant like carbon monoxide, nitric oxide, sulphur dioxide, dust and mercury in the coal. In comparison to nuclear power, hydroelectric power does not generate any nuclear waste. Here,no danger of uranium mining or nuclear leaks. Hydroelectricity also avoids coal mining hazards. Hydroelectric power stations have more predictable load factor than wind farms.


Advantages of hydroelectric power
  • There is no carbon emission or air pollution during power production by hydroelectric power plant. 
  • It is a renewable energy source and environmentally friendly technology.
  • Dams can contribute to generate power for many years. 
  • After constructing dams, energy is virtually free indeed.
  • It is cost effective.
  • Maintenance of dams are not very expensive.
  • The sluice gates can be shut when electricity is not necessarily required. It will stop electricity generation. This water can be saved for use another time when there is a peak demand of electricity.
  • Stored water can be utilized during peak demands.
  • Water of the lake can be utilized for irrigation purposes.
  • Lake which is created behind dams can be utilized for recreational or entertainment activities like water sports and leisure. Sometimes, tourists can observe the natural beauty of large dams.


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