Hydropower is a renewable, non-polluting and
environment friendly source of energy.
Oldest energy technique known to mankind for
conversion of mechanical energy into electrical energy.
Contributes around 22% of the world electricity supply
Maximum benefits in minimum time.
Offers the most fastest economical means to enhance
power supply, improve living standards, stimulate industrial
growth and enhance agriculture with the least
environmental impact and without heavy transmission
Due to less transmission losses there is a reduction in
distribution cost as well
The first hydroelectric power dam in the world was built in
Appleton, Wisconsin in 1882.
In India, Jamshed ji Tata built the first hydroelectric power dam
in the Western Ghats of Maharashtra in the early 1900s to supply
power to Bombay’s Cotton and Textile Mills.
He took the British Government’s permission to build dams,
namely the Andhra, Sirowata, Valvan and Mulshi hydel dams in
the Western Ghats to generate electricity using high rainfalls in
the hills as storage.
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 cogeneration. It has been
made mandatory that every state regulatory commission
would specify a percentage of electricity to be purchased
from renewable by a distribution license
rank country Mw station
1 china 20300 Three Gorges Dam
2 Paraguay 14000 Itaipu dam
3 venenzula 10200 Guri dam
4 brazil 8370 Tucurui dam
5 United states 6809 Grand coulee dam
The dam is made on a river to collect water. Whenever it rains, the water is collected into the dam so it serves
as a water reservoir. The potential energy for further work is generated by the water level difference between
the dams and the turbines because the water level in the dams is very high. Dams also control the water flow
The next step is to convert this kinetic energy of water into mechanical energy. The water flows from a
height throw the penstocks which are the channelled vessels to the turbines which have blades. The falling
water has enough kinetic energy that when they strike hard with the blades of the turbines, they start spinning
which means that the kinetic energy is converted into mechanical energy. The turbines resemble a lot with the
windmills in which wind energy is used instead of water. But the turbines use potential and mechanical energy
of falling water to convert into work.
The shafts of the turbines convert the mechanical energy into electric energy. Basically, the generators work
on the principle of magnets which is that when you pass a magnet near a conductor, electric current flows
Rotor and stator
The rotor having field pole rotates on a specific speed. When it rotates it passes the field poles across the stator
to make sure that it has the same effect of electric field. The water should keep on moving constantly to make
sure that the amount of electricity produced is great. Static water cannot generate electricity.
The electricity via power lines is transferred to substation which provides it to the consumers.
1. Dams are extremely expensive to build and must be built to a
very high standard.
2. The high cost of dam construction means that they must operate
for many decades to become profitable.
3. The flooding of large areas of land means that the natural
environment is destroyed.
4. 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.
5. 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.
6. 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.
Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator. The
power extracted from the water depends on the volume and on the difference in height between the source and the
water's outflow. This height difference is called the head. The amount of potential energy in water is proportional to the
head. A large pipe (the "penstock") delivers water to the turbine.
This method produces electricity to supply high peak demands by moving water between reservoirs at different elevations.
At times of low electrical demand, excess generation capacity is used to pump water into the higher reservoir. When there
is higher demand, water is released back into the lower reservoir through a turbine. Pumped-storage schemes currently
provide the most commercially important means of large-scale grid energy storage and improve the daily capacity
factor of the generation system. Pumped storage is not an energy source, and appears as a negative number in listings.
Run-of-the-river hydroelectric stations are those with small or no reservoir capacity, so that the water coming from
upstream must be used for generation at that moment, or must be allowed to bypass the dam. In the United States, run of
the river hydropower could potentially provide 60,000 MW (about 13.7% of total use in 2011 if continuously available).
A tidal power plant makes use of the daily rise and fall of ocean water due to tides; such sources are highly predictable,
and if conditions permit construction of reservoirs, can also be dispatch able to generate power during high demand
periods. Less common types of hydro schemes use water's kinetic energy or undammed sources such as
undershot waterwheels. Tidal power is viable in a relatively small number of locations around the world. In Great Britain,
there are eight sites that could be developed, which have the potential to generate 20% of the electricity used in 2012.
An underground power station makes use of a large natural height difference between two waterways, such as a
waterfall or mountain lake. An underground tunnel is constructed to take water from the high reservoir to the generating
hall built in an underground cavern near the lowest point of the water tunnel and a horizontal tailrace taking water away
to the lower outlet waterway
1. Once a dam is constructed, electricity can be produced at a
2. 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.
3. Dams are designed to last many decades and so can contribute to
the generation of electricity for many years / decades.
4. 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.
5. The lake's water can be used for irrigation purposes.
6. The build up of water in the lake means that energy can be stored
until needed, when the water is released to produce electricity.
7. When in use, electricity produced by dam systems do not produce
green house gases. They do not pollute the atmosphere.