The three most common types of hydropower plants are Impoundment Hydro Power Plant, Diversion Hydro Power Plant, and Pumped Storage Hydro Power Plant. In 2020, installed hydropower capacity reached 1,330 gigawatts (GW), with generation reaching a new high of 4,370 terawatt-hours (TWh). By installed capacity, China, Brazil, the United States, Canada, and India are the top hydropower producers. This article will explain to you the types of hydropower plants which will be helpful in preparing the Environment syllabus for the UPSC Civil Service exam.

How Do Hydropower Plants Work?

• Three things are required to generate hydroelectricity: moving water, a turbine, and a generator.
• Hydropower plants use the kinetic energy of moving water to generate electricity.
• They are, in theory, factories that turn the energy of falling water into a flow of electrons, or electricity.
• In most cases, a dam is built across a river to raise the water level and provide the necessary fall to produce a driving force.
• The falling water is then directed to a lower-level turbine wheel.
• A turbine wheel attached to a generator is turned by the flowing water.
• A rotor is attached to the generator, which is rotated by the turbine. The rotor of the generator produces electricity as it rotates.
• The generated electricity is then stepped up in voltage and delivered across transmission lines via the hydroelectric power station transformers.
• After serving its purpose, the used water is diverted out of the power plant and into the river's main channel, continuing the power generation cycle.

Types of Hydro Power Plant

• Today, there are numerous hydropower plants. The net volume and flow of water are used to classify them.
• The categories are also based on the amount of capital invested in the project and the availability of land to build the power plant.
• However, Impoundment facilities, river diversion, and pumped storage hydro plants are the three main types of hydroelectric plants.

Impoundment Hydro Power Plant

• An impoundment facility is the most prevalent type of hydroelectric power plant.
• A dam is used to store river water in a reservoir at an impoundment plant, which is usually a big hydroelectric system.
• Water released from the reservoir spins a turbine, which then activates a generator, which generates power.
• The water might be released to satisfy fluctuating electrical needs, as well as other purposes including flood control, recreation, fish passage, and other environmental and water quality concerns.

Disadvantages

• Impoundment and pumped storage facilities have the potential to affect the ecosystem in the surrounding area.
• They can affect plant life as well as aquatic and land-based animal species by changing the volume and quality (e.g., oxygen level) of water flowing downstream.
• Turbines kill fish in the river, however, this can be alleviated by using fish ladders and other similar structures. Dams obstruct migratory paths, especially for anadromous species like salmon, which live in the ocean but spawn in rivers.
• The construction of new dams has the potential to disrupt species' habitats, particularly forests. Forest devastation releases methane, a powerful greenhouse gas.
• Dams also lower downstream silt and nutrient discharge, as well as the temperature of the water.
• Impoundment facilities can also impair the aesthetic value of streams, particularly wild rivers, in addition to these environmental consequences.
• Run-of-river facilities, on the other hand, have a lower environmental impact and cause less alteration in the stream channel and flow.

Diversion Hydro Power Plant

• This type of hydroelectric plant is also known as a run-of-river plant.
• Diversion is the process of generating energy by diverting a large percentage (about 90%) of a river's flow into a pipeline or tunnel to drive turbines before returning the water to the river's main channel.
• Turbines are not installed in the river in this variant.

Infrastructure Required

The size of river diversion projects varies. Each project, however, necessitates significant infrastructure, such as:

• A dam to create a small reservoir known as a head pond.
• A penstock, a tunnel or pipeline to transport water from the headpond to the turbines over a distance of several kilometers.
• Generator storage in a guarded powerhouse structure.
• A tributary of the tailrace via which the power plant's used water flows.
• Access roads to the powerhouse and headpond are well-built.
• Transmission lines running from the power plant to the BC Hydro transmission line next door and
• An electrical substation in rare situations.

Pumped Storage Hydro Power Plant

• Pumped-storage hydroelectricity (PSH), or pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage utilized by electric power systems for load balancing.
• Water pumped from a lower elevation reservoir to a higher elevation is used to store energy in the form of gravitational potential energy.
• Pumps are often powered by low-cost surplus off-peak electric power.
• During times of high demand for electricity, the stored water is released through turbines to generate electricity.
• Despite the fact that the plant is a net consumer of energy due to pumping losses, the system boosts revenue by selling more electricity during peak demand periods, when electricity prices are greatest.
• If the upper lake receives sufficient rainfall or is fed by a river, the plant, like a regular hydroelectric plant, might be a net energy producer.

*To know more about the topic, click this link Pumped Storage Hydro Power Plant

Advantages of Hydropower Plants

• Year Around Availability of Water: Water is a renewable natural resource that is available at all times of the year.
• Its quality and quantity may be diminished as a result of seasonal changes or other man-made factors, but it can be regenerated over time. Anyone installing hydropower plants will make certain that water is readily available in the areas where the plants are being installed.
• Lower Operational and maintenance cost: The cost of operation and maintenance is lower than that of other power plants. Hydropower plants require a lot of infrastructures to build embankments. Therefore the money or financing required is also a lot at first, although it's not as much as other plants.
• Nil Fuel Cost: Hydropower facilities do not require fuel because they rely on the flow of water to create electricity. Plants do not use water to generate electricity in the same way that other plants use fuel.
• Multi-purpose Use: Hydropower facilities are utilized for a variety of reasons, including irrigation, flood control, recreational activities, and so on. As a result, hydropower plants indirectly contribute to the development of a nation's economy.
• Reduced Working Hours: The number of people required to monitor the plant's operation is reduced. This also lowers the cost of operating hydroelectric facilities, making them more cost-effective for a country.

Disadvantages of Hydropower Plants

• Higher Embankment Construction Cost: Hydropower necessitates a large initial capital investment, whereas other electricity-generating plants necessitate the construction of plants and the installation of devices that are less costly.
• Large Land Space Requirement: Because an embankment or dam is built over a river, a vast amount of land is necessary to build up the massive infrastructure.
• Need of Abundant Water: Water is required in hydropower facilities, but the quantity can be reduced owing to drought conditions or natural causes, and with less water, electricity generation might be disrupted.
• Impact on Aquatic Life: Embankment makes it more difficult for fish to reach their spawning grounds, which has a negative impact on other creatures that rely on fish for food. The neighboring habitat of rivers is limited as the flow of water ceases, and they are unable to reach the water.
• Necessitates Evacuation: A hydroelectric plant, wherever it is built, has a huge impact on the surrounding community and area since residents must evacuate to meet the plant's needs. When a dam collapses owing to high wind and heavy rainfall, it might harm a significant number of people living nearby.

Conclusion

Hydropower is a very old form of energy, dating back to the watermills that have been a part of human civilization since the dawn of time. It is now the world's largest source of renewable energy. Some researchers, however, have questioned the future of hydropower, fearing that it may have a greater climate impact than is often accepted. According to studies, some hydropower plants produce emissions that are comparable to those produced by fossil fuel plants, adding to a lengthy list of other issues associated with the technology, ranging from consequences on river flow and ecosystems to the eviction of local residents.

FAQs

Q1: What are the different types of hydro power plants?

Q2: What is a run-of-river hydro power plant?

Q3: How does a pumped storage hydro power plant work?

Q4: What is the advantage of reservoir-based hydro power plants?

Q5: What are the environmental impacts of hydro power plants?

MCQs

1. Which of the following is a key feature of a run-of-river hydro power plant?

a) Large reservoir for water storage

b) Minimal storage capacity

c) Continuous pumping of water

d) High capacity for seasonal regulation

2. What distinguishes a pumped storage hydro power plant from other types of hydro plants?

a) It operates only during rainy seasons.

b) It uses excess electricity to pump water to an upper reservoir.

c) It does not generate electricity directly.

d) It has no environmental impact.

3. Which of the following is a major benefit of reservoir-based hydro power plants?

a) They are small and mobile.

b) They help in flood control and water supply regulation.

c) They do not affect the surrounding environment.

d) They rely on thermal energy.

4. What environmental challenge is associated with hydro power plants?

a) Increased air pollution

b) Alteration of river ecosystems

c) High levels of radiation

d) Depletion of fossil fuels

5. Which type of hydro power plant is most dependent on seasonal water flow?

a) Run-of-river

b) Reservoir-based

c) Pumped storage

d) Geothermal

GS Mains Questions and Model Answers

Q1: Discuss the various types of hydro power plants and their significance in sustainable energy production.

Answer: There are three main types of hydro power plants: run-of-river, reservoir-based, and pumped storage. Run-of-river plants use the natural flow of rivers, making them less invasive but highly dependent on seasonal water flows. Reservoir-based plants store large amounts of water, providing reliable electricity generation and benefits like flood control, irrigation, and water regulation. Pumped storage plants act as energy storage systems by storing water in an upper reservoir during low demand periods and generating electricity when demand is high. These plants are significant for sustainable energy production because they utilize renewable water resources, have low carbon emissions, and offer reliable power, especially when integrated with other renewable energy systems.

Q2: Evaluate the environmental impacts of hydro power plants and suggest measures to mitigate these impacts.

Answer: Hydro power plants can have significant environmental impacts, including altering river ecosystems, affecting fish migration, displacing communities, and causing deforestation due to the creation of reservoirs. In some cases, reservoirs contribute to greenhouse gas emissions from decaying vegetation. To mitigate these impacts, measures such as fish ladders, careful planning of reservoir locations, and proper management of water flows can be implemented. Additionally, reforestation programs around reservoir areas and the use of small-scale or run-of-river projects can reduce the negative effects on biodiversity and ecosystems.

Q3: How do pumped storage hydro power plants contribute to grid stability and energy storage?

Answer: Pumped storage hydro power plants are crucial for grid stability as they act as large-scale energy storage systems. During periods of low electricity demand, they use excess electricity to pump water from a lower to an upper reservoir. During peak demand, the stored water is released back through turbines to generate electricity. This ability to store and release energy on demand helps balance supply and demand on the grid, reducing the need for fossil fuel-based power plants during peak hours. Pumped storage also complements intermittent renewable energy sources like wind and solar by providing backup power.

Previous Year Questions on  Types of hydro power plant

1. UPSC CSE 2019

Question: What are the advantages and disadvantages of different types of hydro power plants in the context of India’s energy needs? 

Answer: Hydro power plants, such as run-of-river, reservoir-based, and pumped storage, play a vital role in meeting India’s energy needs. Reservoir-based plants offer reliable energy, flood control, and water storage, making them essential for irrigation and urban water supply. However, they involve significant environmental costs, such as deforestation, loss of biodiversity, and displacement of local communities. Run-of-river plants have less environmental impact but are dependent on seasonal water flows, which can lead to inconsistent energy production. Pumped storage plants provide grid stability and act as energy reserves, but they require large infrastructure and have high initial costs. The choice of hydro plant depends on regional water availability, environmental concerns, and energy demand.

2. UPSC CSE 2020

Question: Analyze the role of hydroelectricity in achieving India’s renewable energy goals. What challenges does the sector face? 

Answer: Hydroelectricity is a crucial component of India’s renewable energy goals due to its ability to provide clean, reliable, and flexible power. It complements other renewable sources like wind and solar by offering backup during periods of low production. Reservoir-based plants also serve multiple purposes, including irrigation and flood control. However, the sector faces challenges such as environmental degradation, displacement of local populations, and high initial capital costs. Climate change poses additional risks by affecting water availability. Overcoming these challenges requires careful planning, adoption of run-of-river and pumped storage systems, and minimizing the environmental and social impacts of large-scale hydro projects.