Hydroelectric Energy: Definition, Advantages & Disadvantages

Electricity generated by generators operated by turbines that convert the potential energy of falling or fast-flowing water into mechanical energy is known as Hydroelectric Energy. In ancient times, as the need for energy sources began to rise, scientists worldwide voiced their concerns over the use of traditional sources of energy like coal, petroleum, and other fossil fuels. 

Technology was developed to harness the energy from the most abundant resources – wind and water! Hydroelectric energy, also called hydroelectric power or hydroelectricity, is a form of energy that harnesses the power of water in motion—such as water flowing over a waterfall—to generate electricity.

What is Hydroelectricity?

Hydroelectricity is a conventional energy source that is a renewable and sustainable energy source, unlike coal or petroleum. The generation of electrical power or electricity by harnessing the potential of the water in motion or hydropower is known as hydroelectricity. Hydropower refers to the power developed by the gravitational force of falling water.

A power plant that utilizes the power of the falling water to rotate the turbines connected to a generator that produces electricity is called a Hydropower plant. Thus, a hydropower plant converts the kinetic energy of the flowing water into electrical energy.

What is a Hydropower Plant?

As we learn more about hydroelectricity, the first question that comes to mind is how do we get electricity from water? Energy from coal and water both fall under conventional sources and in fact, the hydroelectric and coal-fired power plants employ similar methods to produce electricity. In a hydro or coal-powered plant, a power source is used to rotate a propeller-like piece called a turbine, turning a metal shaft. This metal shaft is a part of an electric generator, which is the motor that produces electricity. In a coal-fired power, plant steam is used to turn the turbine blades, whereas a hydroelectric plant employs the energy of falling water to turn the turbine. The results are the same.

How is Hydroelectricity Produced?

On a small scale, with just a basic ‘run-of-river’ type of installation, we can produce hydroelectric energy. Natural waterfalls are often used for this purpose. The water with sufficient potential energy falls at the turbines, which rotate to produce the electric energy. But there are only a limited number of waterfalls, and out of these, very few can be employed to produce hydroelectric energy.
In the last century, a large number of dams were built all over the world. To learn hydroelectricity production, we need to understand how a hydroelectric power plant works. A hydroelectric power plant converts the energy of the moving water or the kinetic energy possessed by the flowing or falling water into electrical energy that is required to power homes and businesses.

Step 1: Convert Kinetic energy to Potential energy: Hydroelectric plant is generally constructed along the path of a river falling from a certain height. A hydroelectric dam provides a blockade to the course of a river, thereby straddling the motion of water downstream. An artificial lake known as a reservoir is formed as the water gets collected on the dam’s upstream side. The water level rises, and in this process, the kinetic energy of flowing water gets transformed into potential energy. Just as the battery acts as a source of electric potential,  the reservoir, in a similar way, acts as a store of water possessing specific potential energy that can be released a little at a time. These days along with being a source of energy or a source of drinking water, some reservoirs are being developed as major tourist spots and offer activities like boating lakes.

Step 2: Convert Potential energy to Kinetic energy: To produce hydroelectricity, the sluice gates or the sliding gates of the reservoir are opened. When the gate opens, an immense weight of the reservoir acts on the stored water. Water is pushed through a channel called the penstock towards the turbine located at the end of the pipe. Since the waterfalls are from a great height and exerts immense pressure on the turbines, the turbines rotate rapidly. Thus, the reservoir’s potential energy is converted back into kinetic energy by opening underwater gates, or intakes, in the dam.

Step 3: Convert Kinetic energy to Mechanical energy: The water from the high level in the dam is carried through pipes, to the turbine, at the bottom of the dam and this rushing water then hits the turbine,  striking its blades and forcing it to spin rapidly. Thus, a part of the kinetic energy of the water is converted into mechanical energy.

Step 4: Convert Mechanical energy to Electrical energy: The water then finally flows out of the dam and continues its journey downstream. The generator is connected to the turbine by a shaft, and as the turbines rotate, it rotates the shaft, which causes the generator to start functioning. Based on electromagnetic induction, the generator converts mechanical energy into electrical energy by producing an electromagnetic field.

Step 5: Electrical energy to EMF: A transformer is present along with the turbine and generator in the dam’s powerhouse. The transformer converts the electrical energy from the generator to a high voltage. This high voltage is sent into the national grid to transmit electricity efficiently through the power lines to the homes and businesses that need it. Step up and step down transformers ensure that the voltage is being transferred at optimum levels.

1. Since the water in the reservoir would be refilled each time it rains. Also, the water liberated from the generator can be reused multiple times again to generate electricity (hydropower is a renewable energy source); we would not have to worry about hydroelectricity sources getting used up the way fossil fuels would get finished one day.
2. A hydroelectric dam can quickly function according to the demand for electricity as long as there is plenty of water in the reservoir. The amount of electricity being generated by a dam can be controlled directly by the opening and closing of the sliding gates. This directly controls the amount of water flowing through the penstock.

Advantages of Hydroelectric Energy

1. It is a renewable energy source: Hydroelectricity uses the energy of running water to produce electricity, and this water can be reused multiple times for electricity generation.

2. It is efficient: The flexibility of Hydroelectric power plants and storage capacity of the reservoir makes hydroelectricity generation quite efficient. Also, the supply of electricity can be controlled by controlling the supply of water through the pipes.

3. It is low-cost energy: River water is a domestic resource that is not subject to market fluctuations contrary to fuel or natural gas. In addition to this, its cost-benefit ratio, efficiency, flexibility and reliability assist in optimizing the use of thermal power plants.

4. It generates employment: The construction and maintenance of a hydropower plant provide an opportunity for skilled and unskilled workers and bring industrial growth around the area it is established around.

5. It contributes to the storage of drinking water: The reservoirs built along a hydropower station collect rainwater, which can then be used for consumption or for the irrigation of crops. This stored water helps maintain the water tables against depletion and reduce our vulnerability to floods and droughts.

6. It is a stable and reliable energy source: The electricity production in a hydroelectric power plant can be ramped up or scaled down as per the requirement. In fact, the energy generated in a hydropower plant can be injected directly into the electric grid network. This makes it a much more reliable and stable source of energy.

7. Hydroelectricity helps fight climate changes: All energy production methods cause some pollution, but establishing a hydroelectric power plant leads to \(33\%\) less pollution than any other fossil fuel-based plant. Its functioning is much more carbon-efficient than any other conventional source.

8. Environmentally sound: There are no pollutants released into the environment by the working of these hydroelectric power plants, and that’s why they are a perfect substitute for fossil fuel-based plants.

9. Ensures development: The installation of a hydroelectric power plant ensures electricity, and this serves as a basis for the development of industries and infrastructure.

10. Futuristic and sustainable: Hydroelectric energy is the energy for the future. A hydroelectric plant has an average lifetime of \(50 – 100\) years. In fact, with only a small investment, these can easily be upgraded and maintained. The development of such hydroelectric enterprise is economically sensible, and it ensures reduced pollution and a sustainable and eco-friendly source of energy.

Disadvantages of Hydroelectric Energy

1. For the construction of a hydroelectric power plant, massive agricultural land is cleared off its vegetation. A lot of people are displaced from their homes, and many villages are destroyed. A huge part of the flora and fauna of the region gets submerged under the reservoir water. Many animals, plants and trees get killed or chopped off to clear the space for a reservoir.
2. The construction of a dam can be a considerable blow to the ecological balance of a region. Vast animal and plant life is lost. There are changes in the rainfall pattern of the region. Due to the construction of a dam, the annual overflooding of a river becomes impossible. Thus, the downstream river eventually loses its fertility due to a lack of silt and other nutrients, which destroys the region’s agricultural prospects downstream.
3. The fish in the downstream area do not get their nutrition because of dam construction; hence, the fisheries suffer losses due to a decrease in the quantity of fish.
4. The vegetation that rots under the reservoir water gets decomposed anaerobically. A large amount of methane is produced, which poses a major threat to people working in or around the dam area and is a significant pollutant.
5. If not cleaned regularly, the dams can lead to major flooding during the rainy season and cause massive devastation to life and property.

Summary

In this article, we discussed Hydroelectric Energy and hydroelectricity. How is hydroelectricity generated? The advantages and disadvantages of hydroelectricity power.

FAQs

Q.1. What is Hydroelectricity?
Ans: The generation of electrical power or electricity by harnessing the potential of the water in motion or hydropower is known as hydroelectricity.

Q.2. What is a hydroelectric plant?
Ans: A power plant that utilizes the power of the falling water to rotate the turbines connected to a generator that produces electricity is called a Hydropower plant. Thus, a hydropower plant converts the kinetic energy of the flowing water into electrical energy.

Q.3. Explain, in short, the working of a hydropower plant.
Ans: Dams are built over the river to control the flow of river water and thus, collect the water in large reservoirs. As the water level in the reservoir increases, the kinetic energy of the flowing river water gets converted into its potential energy. With the help of pipes, the water is carried down at great speeds at the bottom of the dam. At the bottom, turbines are placed, and this water, coming down at great speed, rotates the turbines. The turbines are connected to a generator, which then produces electricity. This electricity is transferred into electric lines by a transformer.

Q.4. Give a few advantages of hydroelectric energy.
Ans: 1. It is renewable
2. It is environment friendly
3. It is sustainable
4. It generates employment opportunities

Q.5. Write a few disadvantages of hydroelectric energy.
Ans:
1. It leads to the loss of flora and fauna.
2. It leads to the displacement of people.
3. It leads to the loss of agricultural land.
4. It disturbs the ecological balance of the region.

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