The document provides an overview of hydroelectric power plants, detailing their history, construction methods, and significance in energy production. It discusses the advantages and disadvantages of hydropower, its applications, and the status of hydroelectric power both globally and in India. The conclusion highlights the ongoing challenges associated with hydropower development, particularly in relation to social and environmental impacts.

1. Hydro Electric Power Plant
A comprehensive note, prepared by:
Ankit Kumar
Roll No.: 016
EE - A [2014-18]
TICT, Rajarhat.

2. Contents:
1. A Short Introduction
2. History and Vision of using hydropower
3. Construction and working methods
4. Properties
5. Generation of power and application
6. Hydro-electric power production in India and world
7. Conclusion

3. 1. A Short Introduction:
As we know a power plant is defined as the place where the power is generated from a given
source. There are various methods to generate electricity from a given source. A generating
station which utilizes the potential energy (in general) of water (or hydro) at high level for the
generation of electricity is called Hydro-Electric Power Station, also known as Hydro Electric
Power Plant.
In Hydro Power Plant we use gravitational force of fluid water to run the turbine which is
coupled with electric generator to produce electricity. This power plant plays an important role to
protect our fossil fuel which is limited, because the generated electricity in hydro power station
does the use of water which is renewable source of energy and available in lots of amount
without any cost.
The big advantage of hydro power is the water which is the main stuff to produce electricity in
hydro power plant is free, it not contain any type of pollution and after generated electricity the
price of electricity is average, i.e. not too much high.
Hydro energy is available in many forms, which are potential energy from high heads of water
retained in dams, kinetic energy from current flow in rivers and tidal barrages, and kinetic energy
also from the movement of waves on relatively static water masses. Many ingenious ways have
been developed for harnessing this energy but most involve directing the water flow through a
turbine to generate electricity. Those ways which don’t usually involve using the movement of
the water to drive some other form of hydraulic or pneumatic mechanism to perform the same
task.
The figure shown below shows the basic block diagram for Hydro Electric Power Generation

4. 2. History and Vision of using Hydropower
 History:
First hydro power was used by the Greeks to spin water wheels for crushing wheat into flour
before more than 2000 years ago. French engineer Bernard Forest de Bélidor published
Architecture Hydraulique which described vertical- and horizontal-axis hydraulic machines.
In the 1700's, hydropower was generally used for pumping irrigation (non-natural use of
water on the way to the land) water.
By the late 19th century, the electrical generator was developed and could now be coupled
with hydraulics. The growing demand for the Industrial Revolution would drive development
as well. We started to generate electricity from hydro power in 1882 when United States
(US) establishes a first Hydro Power Station which generate 12.5 kilowatts (KW) of power.
The rapid growth of hydro power comes in 1900’s when hydraulic reaction turbine comes in
picture as a result in 1900’s hydro power plants fulfill the requirement of 40% of total United
States' electricity. In between 1905-1911 largest hydro power station (Roosevelt Dam) is
built by the united state and its generated capacity is increased from 4500 kW to 36,000 kW.
In 1914 S.J. Zowski developed the high specific speed reaction (Francis) turbine runner for
low head applications. 1922 the first time a hydroelectric plant was built specifically for crest
power. In 1933 Hoover Dam, Arizona generated electricity first time. In 1940 over 1500
hydro power plants generate about one third of the United States electrical energy.
Hydroelectric power stations continued to become larger throughout the 20th century.
Hydropower was referred to as white coal for its power and plenty. Hoover Dam's initial
1,345 MW power station was the world's largest hydroelectric power station in 1936; it was
eclipsed by the 6809 MW Grand Coulee Dam in 1942. The Itapúa Dam opened in 1984 in
South America as the largest, producing 14,000 MW but was surpassed in 2008 by the Three
Gorges Dam in China at 22,500 MW. Hydroelectricity would eventually supply some
countries, including Norway, Democratic Republic of the Congo, Paraguay and Brazil, with
over 85% of their electricity. The United States currently has over 2,000 hydroelectric power
stations that supply 6.4% of its total electrical production output, which is 49% of its
renewable electricity.
In Asia, first hydro power station, capacity of 130kW was established at mounts of
Darjeeling in 1898, and after that in 1902 Shimsh (Shivanasamudra) was established and
both the power stations were located in India.

5.  Vision of using Hydropower:
The goal of the Hydropower Vision is to operate, optimize and develop hydropower in a
manner that maximizes opportunities for low-cost, low-carbon renewable energy production,
economic stimulation, and environmental stewardship to provide long-term benefits for the
nation.
Vision of using Hydropower includes a Roadmap that defines a range of actions needed to
realize the economic and social benefits of increased hydropower in the future. It is based on
three foundational “pillars”, that are critical to ensuring the integrity of the research,
modeling, and analysis in the Hydropower Vision:
Optimization: Optimize the value and power generation contribution of the existing
hydropower fleet within the nation’s energy mix to benefit national and regional economies,
maintain critical national infrastructure, and improve energy security.
Growth: Explore the feasibility of credible long-term deployment scenarios for responsible
growth of hydropower capacity and energy production.
Sustainability: Ensure that hydropower’s contributions toward meeting the nation’s energy
needs are consistent with the objectives of environmental stewardship and water use
management.

6. 3. Construction and working methods
Hydropower uses water to power machinery or make electricity. Water constantly moves
through a vast global cycle, evaporating from lakes and oceans, forming clouds, precipitating as
rain or snow, and then flowing back down to the ocean. The energy of this water cycle, which is
driven by the sun, can be tapped to produce electricity or for mechanical tasks like grinding
grain. Hydropower uses a fuel—water—that is not reduced or used up in the process. Because
the water cycle is an endless, constantly recharging system, hydropower is considered as a
renewable energy.
Fundamental parts of hydro power plant are:
 Area
 Dam
 Reservoir
 Control gate
 Penstock
 Surge tank
 Turbines and generators
 Switchgear and protection
For construction of hydro power plant first we choose the area where the water is sufficient to
reserve and there is no crisis of water and are suitable to build a dam.
Dam and Reservoir: The dam is constructed on a large river in hilly areas to ensure sufficient
water storage at height. The dam forms a large reservoir behind it. The height of water level
(called as water head) in the reservoir determines how much of potential energy is stored in it.
Control Gate: Water from the reservoir is allowed to flow through the penstock to the turbine.
The amount of water which is to be released in the penstock can be controlled by a control gate.
When the control gate is fully opened, maximum amount of water is released through the
penstock.
Penstock: A penstock is a huge steel pipe which carries water from the reservoir to the turbine.
Potential energy of the water is converted into kinetic energy as it flows down through the
penstock due to gravity.
Water Turbine: Water from the penstock is taken into the water turbine. The turbine is
mechanically coupled to an electric generator. Kinetic energy of the water drives the turbine and
consequently the generator gets driven. There are two main types of water turbine; (i) Impulse
turbine and (ii) Reaction turbine. Impulse turbines are used for large heads and reaction turbines
are used for low and medium heads.

7. Generator: A generator is mounted in the power house and it is mechanically coupled to the
turbine shaft. When the turbine blades are rotated, it drives the generator and electricity is
generated which is then stepped up with the help of a transformer for the transmission purpose.
Surge Tank: Surge tank comes in picture when due to some reason the pressure of water in
reservoir is decreased, then we use storage tank, which is directly connected to penstock and is
used only in emergency condition.
Switchgear and protections: In hydro electric power plant we also add switchgears and
protections which control and protect the whole process inside the plant. The control equipments
consist of control circuits, control devices, warning, instrumentation etc. and is connected to
main control board.
After generating electricity at low voltage, we use step up transformer to enlarge the level of
voltage (generally 132 KV, 220 KV, 400 KV and above) as per our requirement. After that we
transmit the electric power to the load center, and then we step down the voltage for industrial
and large consumer and then again we step down the voltage to distribute electricity at domestic
level which we use at home.
This is the whole process of generating electricity by the means of hydro (hydro power plant)
and then transmitting and distributing electricity.
The below image shows the typical layout of a hydro electric power plant and its basic
components:

8. 4. Properties
 Types of Hydro Power Plants:
 Conventional Plants:
Conventional plants use potential energy from dammed water. The energy extracted
depends on the volume and head of the water. The difference between height of water
level in the reservoir and the water outflow level is called as water head.
 Pumped Storage Plant:
In pumped storage plant, a second reservoir is constructed near the water outflow from
the turbine. When the demand of electricity is low, the water from lower reservoir is
pumped into the upper (main) reservoir. This is to ensure sufficient amount of water
available in the main reservoir to fulfill the peak loads.
 Run-Of-River Plant:
In this type of facility, no dam is constructed and, hence, reservoir is absent. A portion
of river is diverted through a penstock or canal to the turbine. Thus, only the water
flowing from the river is available for the generation. And due to absence of reservoir,
any oversupply of water is passed unused.
 Advantages and Disadvantages:
 Advantages:
o Once a dam is constructed, electricity can be produced at a constant rate.
o If electricity is not needed, the sluice gates can be shut, stopping electricity
generation. The water can be saved for use another time when electricity demand is
high.
o Dams are designed to last many decades and so can contribute to the generation of
electricity for many years / decades.
o The lake that forms behind the dam can be used for water sports and leisure /
pleasure activities. Often large dams become tourist attractions in their own right.
o The lake's water can be used for irrigation purposes.
o The buildup of water in the lake means that energy can be stored until needed,
when the water is released to produce electricity.

9.  Disadvantages:
o Dams are extremely expensive to build and must be built to a very high standard.
o The high cost of dam construction means that they must operate for many decades
to become profitable.
o The flooding of large areas of land means that the natural environment is
destroyed.
o People living in villages and towns that are in the valley to be flooded, must move
out. This means that they lose their farms and businesses. In some countries,
people are forcibly removed so that hydro-power schemes can go ahead.
o The building of large dams can cause serious geological damage. For example, the
building of the Hoover Dam in the USA triggered a number of earth quakes and
has depressed the earth’s surface at its location.
o Although modern planning and design of dams is good, in the past old dams have
been known to be breached (the dam gives under the weight of water in the lake).
This has led to deaths and flooding.
o Dams built blocking the progress of a river in one country usually means that the
water supply from the same river in the following country is out of their control.
This can lead to serious problems between neighboring countries.
o Building a large dam alters the natural water table level. For example, the building
of the Aswan Dam in Egypt has altered the level of the water table. This is slowly
leading to damage of many of its ancient monuments as salts and destructive
minerals are deposited in the stone work from ‘rising damp’ caused by the
changing water table level.

10. 5. Generation of power and application
The power of a hydropower plant is generally dependent upon the water flow rate and the drop
height of the system, and on the efficiency of the water turbine, gear mechanism, generator and
transformer. A distinction is made between large hydropower plants and small hydropower
plants depending on the power category.
As per the requirement, the size of a hydro electric power plant is categorized into mainly three
parts:
 Large Hydro Power Plant:
Although definitions vary from country to country, in an average, power plants that
have a capacity of more than 30 megawatts (MW) comes under large facilities.
 Small Hydro Power Plant:
Although definitions vary from country to country, in an average, power plants that have
a capacity of more than 10 megawatts (MW) comes under small facilities.
 Micro Hydro Power Plant:
A micro hydro power plant has a capacity of up to 100 kilowatts (KW). A small or micro-
hydroelectric power system can produce enough electricity for a home, farm, ranch, or
village.
 Calculating available power:
A simple formula for approximating electric power production at a hydroelectric station is:
, where
 is Power in watts,
 is the density of water (~1000 kg/m3
),
 is height in meters,
 is flow rate in cubic meters per second,
 is acceleration due to gravity of 9.8 m/s2
,
 is a coefficient of efficiency ranging from 0 to 1.
Efficiency is often higher (that is, closer to 1) with larger and more modern turbines.
Annual electric energy production depends on the available water supply. In some installations,
the water flow rate can vary by a factor of 10:1 over the course of a year.

11. 6. Hydro-electric power production in India and world
 Hydro Power In World:
The ranking of hydro-electric capacity is either by actual annual energy production or by
installed capacity power rating. In 2015 hydropower generated 16.6% of the world’s total
electricity and 70% of all renewable electricity. Hydropower is produced in 150
countries, with the Asia-Pacific region generated 32 percent of global hydropower in
2010. China is the largest hydroelectricity producer, with 721 terawatt-hours of
production in 2010, representing around 17 percent of domestic electricity
use. Brazil, Canada, New Zealand, Norway, Paraguay, Austria, Switzerland,
and Venezuela have a majority of the internal electric energy production from
hydroelectric power. Paraguay produces 100% of its electricity from hydroelectric dams,
and exports 90% of its production to Brazil and to Argentina. Norway produces 98–99%
of its electricity from hydroelectric sources.
A hydro-electric station rarely operates at its full power rating over a full year; the ratio
between annual average power and installed capacity rating is the capacity factor. The
installed capacity is the sum of all generator nameplate power ratings.
The below image shows some of major Hydro Electric Power Projects under construction
in the world:

12.  Hydro Power In India:
With the liberalization of the economy, the Government of India has been encouraging
and invited private sector for investment in the power sector. A conducive policy
environment has been created by modifying the Electricity Act. The new Electricity Act-
2003 deals with the laws relating to generation, transmission, distribution, trading and use
of electricity. The Act has specific provisions for the promotion of renewable energy
including hydropower and co-generation. It has been made mandatory that every state
regulatory commission would specify a percentage of electricity to be purchased from
renewable source by a distribution license.
Indian power supply system has a peculiar limitation of huge variation between peak and
off peak requirements. Management of peak load in an effective manner could be
conveniently handled through availability of hydroelectric support. The system at present
does suffer from large frequency variations. Better hydro support could address this
problem better. Locations of Hydroelectric projects in India are also in areas which need
substantial support for their economic development. In an integrated hydroelectric project
– there are many such projects – the schemes involve not only supply of electricity but
also provision of drinking water and irrigation. Hydroelectric projects, in many cases, do
have the ability to mitigate these problems. Flood control is also an issue and quite often
a challenge. Integrated hydroelectric projects could adequately address this concern.
Now a day in India, the leading hydro power plant is Naptha Jhakri hydro project of 1500
MW in Himachal Pradesh. In India main boost came in the field of hydro power in august
of 1998 when the Government of India publicized a plan on ‘Hydro Power
Development’, after that in November 2008 once again Indian government announced
this plan and as a result India become leading country in the list to produce Hydro Power.
The below image shows the Hydro Electric Power generation by countries in 2016:

13. 7. Conclusion
Though, Hydro Power is one of the most famous and easily available renewable natural resource,
but still it has some challenges associated with it while harnessing it.
Relocating people from the reservoir area is the most challenging social aspect of hydropower,
leading to significant concerns regarding local culture, religious beliefs, and effects associated
with inundating burial sites. While there can never be a 100 percent satisfactory solution to
involuntary resettlement, enormous progress has been made in the way the problem is handled.
There is always a complexity in development of Hydroelectric projects, particularly large ones,
emanating from dam height, submergence, ramification of submergence, dam safety, drinking
water schemes, irrigation, infrastructure etc.
There are also some technical challenges, which are faced while harnessing the Hydro Power.
Such as:
 Variability of the sea conditions
 Matching the generating equipment the wave characteristics
 Equipment construction
 Housing and mooring the equipment
 Energy transmission
 Resistance to storm damage
Despite of having some major drawbacks, Hydropower stands as the most significant renewable
energy source. It uses the single but very powerful energy force of moving water. By some
comparison, it competes with the energy produced by fossil fuels and nuclear power, but is
considered much cleaner and more simplistic. Hydropower remains popular even in third-world
countries, which do not have the resources to build expensive nuclear generating stations.
Hydropower does not pollute the atmosphere or environment.
