The hydroelectric power plant utilizes the potential energy of water to convert electrical energy.
In a hydropower plant, the gravitational force of water is used to run the turbine which is coupled with an electric generator to produce electricity. Hydroelectric power stations are generally located in hilly areas because in this area the dam can build conveniently with the head as well as produce a high amount of potential energy. From the dam, water is fed to a water turbine in form of potential energy and then is converted into mechanical energy than by using a generator electricity is produced.
Advantages of Hydro Power Plant:
(i) It requires no fuel as water is used for the generation of electrical energy.
(ii) It is neat and clean as no smoke or ash is produced.
(iii) It requires a very small running cost because water is available at free of cost.
(iv) It is comparatively simple in construction and requires less maintenance.
(v) It does not require a long starting.
(vi) It has a longer life.
(vii) The dam also helps in irrigation and controlling floods.
Disadvantages of Hydro Power Plant:
(i) It required much capital cost for the construction of the dam.
(ii) The availability of water depends on weather conditions.
(iii) It requires a high cost of transmission lines as the plant is located in hilly areas which are away from the consumers.
Schematic Arrangement of Hydro-electric Power Station:
In a hydropower plant, hydraulic energy is converted into electrical energy by the different arrangements of the component. The schematic arrangement of a modern hydroelectric plant is shown in Fig below.
Some of the major components in hydroelectric power plants are following
- Reservoirs,
- Dam,
- Surge Tank,
- Penstock,
- Spillway,
- Generator etc
Reservoir:
- The main function of the reservoir is to store the water during the rainy season and supply this stored water during the dry season. This is in a simple, water storage area.
Dam:
- The main function of the dam has increased the head of the power plant to increase the potential energy behind it which increases the reservoir capacity. Building a dam also plays a great role in agriculture's purpose through irrigation.
Surge Tank:
- The main function of a surge tank is to reduce the water hammering effect.
Penstock:
- The penstock is a pipe between the surge tank and the prime mover. The structural design of the penstock is the same as for any other pipe except it has to bear high pressure on the inside surface during the sudden decrease in the load and increase in the load. Penstocks are made of steel through reinforced concrete.
Spillway:
- The function of the spillway is to provide safety for the dam.
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Hydroelectric Power Plant: Frequently Asked Questions (FAQ)
What is a hydroelectric power plant?
A hydroelectric power plant converts the potential energy of stored water into mechanical energy using a turbine, which is then converted into electrical energy by a generator.
How does a hydro power plant work step by step?
Water stored in the reservoir flows through the penstock → hits the turbine runner → turbine rotates the generator → generator produces electricity → power is stepped up by transformers and transmitted to the grid.
Why are hydro power stations located in hilly areas?
Hilly regions provide a natural head (height difference) for water, allowing higher potential energy and efficient turbine operation. They also offer suitable dam sites and reservoirs.
What are the main components of a hydroelectric power plant?
Reservoir, Dam, Spillway, Intake, Trash Rack, Surge Tank, Penstock, Turbine, Generator, Draft Tube, Powerhouse, and Switchyard/Transformer.
What is the function of a surge tank?
A surge tank mitigates water hammer by absorbing pressure fluctuations in the penstock during sudden load changes.
What are the advantages of hydro power?
No fuel cost, clean and renewable, low running cost, quick start/stop, long plant life, and additional benefits like irrigation, flood control, and recreation.
What are the disadvantages of hydro power?
High initial cost, site limitations, environmental and resettlement issues, dependency on rainfall, and long gestation period.
What types of turbines are used in hydro plants?
Pelton (high head), Francis (medium head), and Kaplan/Propeller (low head). Selection depends on head and discharge.
What is the typical efficiency of a hydroelectric plant?
Overall plant efficiency can be 80–90% (with turbine and generator efficiencies individually even higher under optimal conditions).
What is the role of the spillway?
A spillway safely releases excess water from the reservoir to protect the dam structure during high inflow conditions.
How is power calculated in a hydro plant?
Theoretical hydraulic power: P = ρ g Q H, where ρ = water density, g = acceleration due to gravity, Q = discharge (m³/s), and H = effective head (m). Actual output equals this multiplied by overall efficiency.
What is head in hydropower?
Head is the vertical height difference between the water surface at the reservoir and the turbine runner level; it represents available potential energy per unit weight of water.