By : - SEEMA VERMA,
M. Sc. Degree.
Hydropower is the most significant renewable
Hydropower is the only renewable energy source
that is in some measure competitive with fossil
Hydropower is the force of energy of moving water.
Hydropower is clean renewable energy source that
doesn't pollute environment.
Hydropower uses the Earth's water cycle to generate
electricity because movement of water as it flows
downstream creates kinetic energy that can be then
converted into electricity.
Hydropower, hydraulic power, hydrokinetic power or water
power, has been exploited for millenia.
The amount of power that can be obtained from a stream
- the amount of water flow
- the height which the water falls (head)
- the efficiency of the plant to convert mechanical energy to
The most common type of hydroelectric power plant uses a
dam on a river to store water in a reservoir. But
hydroelectric power doesn't necessarily require a large
dam. Some hydroelectric power plants just use a small
canal to channel the river water through a turbine.
HISTORY OF HYDROPOWER
Hydropower is one of the oldest sources of energy. It was
used thousands of years ago to turn a paddle wheel for
purposes such as grinding grain. Our Nation's first
industrial use of hydropower to generate electricity
occurred in 1880, when 16 brush-arc lamps were powered
using a water turbine at the Wolverine Chair Factory in
Grand Rapids, Michigan.
In the late 19th century, hydropower became a source for
generating electricity. The first hydroelectric power plant
was built at Niagara Falls in 1879. In 1881, street lamps in
the city of Niagara Falls were powered by hydropower. In
1882 the world’s first hydroelectric power plant began
operating in the United States in Appleton, Wisconsin.
DIFFERENT FORMS OF HYDROPOWER
A conventional dammed - hydro facility is
the most common type of hydroelectric
Conventional hydroelectric, referring to
Run-of-the-river hydroelectricity, which
captures the kinetic energy in rivers or
streams, without the use of dams.
Pumped-storage hydroelectricity, to pump
up water, and use its head to generate in
times of demand.
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
Pumped-storage schemes currently provide the
most commercially important means of large-
scale grid energy storage.
Run-of-the-river hydroelectric stations are those
with small or no reservoir capacity, so that the water
Marine current power, which captures the
kinetic energy from marine currents.
Osmotic power, which channels river water
into a container separated from sea water by
a semi-permeable membrane.
Ocean thermal energy, which exploits the
temperature difference between deep and
Wave power, the use ocean surface waves
to generate power.
Tide : makes use of the daily rise and fall of ocean
water due to tides; highly predictable.
Tidal power, which captures energy from the tides
in horizontal direction.
Tidal stream power, usage of stream generators,
somewhat similar to that of a wind turbine.
Tidal barrage power, usage of a tidal dam.
Dynamic tidal power, utilizing large areas to
Underground: makes use of a large natural
height difference between two waterways, such
as a waterfall or mountain lake.
Tides are caused by the gravitational pull of the moon and
sun, and the rotation of the Earth. Near shore, water levels
can vary up to 40 feet due to tides.
A large enough tidal range — 10 feet — is needed to
produce tidal energy economically.
Dam of the Tidal Power Plant on the Estuary of the Rance River, Bretagne, France
A simple generation system for tidal plants involves a dam,
known as a barrage, across an inlet. Sluice gates (gates
commonly used to control water levels and flow rates) on
the barrage allow the tidal basin to fill on the incoming high
tides and to empty through the turbine system on the
outgoing tide, also known as the ebb tide.
Tidal turbines are basically wind turbines in
the water that can be located anywhere there
is strong tidal flow. Because water is about
800 times denser than air, tidal turbines have
to be much sturdier than wind turbines. Tidal
turbines are heavier and more expensive to
build but capture more energy.
THE PELAMIS WAVE POWER DEVICE IN USE IN
Source: Marine and Hydrokinetic Technologies Program, U.S. Department of Energy, Energy Efficiency and
Renewable Energy (Public Domain)
Underwater Wave Energy Device
Source: Tuscanit, Wikimedia Commons
author (GNU Free Documentation
License) (Public Domain)
Wave Energy Site
One way to harness wave energy is to
bend or focus the waves into a narrow
channel, increasing their power and size.
The waves can then be channeled into a
catch basin or used directly to spin
PRINCIPLE OF HYDROPOWER GENERATION
Hydropower is generated from the water flowing in the
river or oceans. There are two water cycles involved in the
generation of electricity : -
1) Water cycle in nature. 2) Water cycle in the hydraulic
power plant :
2) Water cycle in the hydraulic power plant .
Source: National Energy Education Development
Project (Public Domain)
water turbines may depend on the impulse of the working
fluid on the turbine blades or the reaction between the
working fluid and the blades to turn the turbine shaft which in
Source: National Energy Education Development Project (Public Domain)
1. Water in a reservoir behind a hydropower dam flows through an intake screen,
which filters out large debris, but allows fish to pass through. 2. The water travels
through a large pipe, called a penstock. 3. The force of the water spins a turbine at
a low speed, allowing fish to pass through unharmed. 4. Inside the generator, the
shaft spins coils of copper wire inside a ring of magnets. This creates an electric
field, producing electricity. 5. Electricity is sent to a switchyard, where a
transformer increases the voltage, allowing it to travel through the electric grid. 6.
Water flows out of the penstock into the downstream river.
HOW HYDROPOWER WORKS
Hydropower plants capture the energy of falling water to
generate electricity. A turbine converts the kinetic energy
of falling water into mechanical energy. Then a generator
converts the mechanical energy from the turbine into
Mechanical Energy Is Harnessed from
The amount of available energy in moving water is
determined by its flow or fall.
In either instance, the water flows through a pipe,
or penstock, then pushes against and turns blades
in a turbine to spin a generator to produce
electricity. In a run-of-the-river system, the force of
the current applies the needed pressure, while in
a storage system, water is accumulated in
reservoirs created by dams, then released as
needed to generate electricity.
Most hydroelectric power comes from the potential
energy of dammed water. 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.
Most hydroelectric power comes from the potential
energy of dammed water. 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.
Here are two pictures of the actual generators in hydroelectric power
HOW MUCH ELECTRICITY CAN A HYDROELECTRIC PLANT MAKE?
How Far the Water Falls. The farther the water falls,
the more power it has. Generally, the distance that
the water falls depends on the size of the dam. The
higher the dam, the farther the water falls and the
more power it has. Scientists would say that the
power of falling water is "directly proportional" to
the distance it falls.
Amount of Water Falling. More water falling through
the turbine will produce more power. The amount of
water available depends on the amount of water
flowing down the river. Bigger rivers have more
flowing water and can produce more energy. Power
is also "directly proportional" to river flow. A river
with twice the amount of flowing water as another
Engineers have found that we can calculate the power of a dam
using the following formula:
Power = (Height of Dam) x (River Flow) x (Efficiency) / 11.8
The electric power in kilowatts (one kilowatt equals 1,000 watts).
Height of Dam
The distance the water falls measured in feet.
The amount of water flowing in the river measured in cubic feet
How well the turbine and generator convert the power of falling
water into electric power. For older, poorly maintained
hydroplants this might be 60% (0.60) while for newer, well
operated plants this might be as high as 90% (0.90).
Converts units of feet and seconds into kilowatts.
For the dam in an area, lets say a turbine and generator with an
efficiency of 80%.
Then the power for dam will be:
Power = (10 feet) x (500 cubic feet per second) x (0.80) / 11.8 = 339
To get an idea what 339 kilowatts means, let's see how much electric
energy can be made in a year.
Since electric energy is normally measured in kilowatt-hours, multiply
the power from dam by the number of hours in a year.
Electric Energy = (339 kilowatts) x (24 hours per day) x (365 days per
year) = 2,969,000 kilowatt hours.
The average annual residential energy use in the U.S. is about 3,000
kilowatt-hours for each person. So, figure out how many people that
dam could serve by dividing the annual energy production by 3,000.
People Served = 2,969,000 kilowatts-hours / 3,000 kilowatt-hours per
person) = 990 people.
So here local irrigation or recreation dam could provide enough
renewable energy to meet the residential needs of 990 people if added
a turbine and generator.
The photo shows the Alexander Hydroelectric Plant on the Wisconsin
River, a medium-sized plant that produces enough electricity to serve
about 8,000 people.
HYDROELECTRIC POWER GENERATION EFFICIENCY
Smaller plants with output powers less than 5 MW may
have efficiencies between 80 and 85 %.
Pmax =½ηρQv2 where v is the velocity of the water flow
and Q is the volume of water flowing through the turbine
per second. Q is given by : Q = A v where A is the swept
area of the turbine blades.
Thus the power generated by one cubic metre of water
flowing at one metre per second through a turbine with
100% efficiency will be 0.5 kW or slightly less taking into
account the inefficacies in the system.
To generate the same power with the same volume of
water from a run of river installation the speed of the
water flow should be 4.5 m/sec.
CALCULATION OF EFFICIENCY
A hydroelectric power plant operates under the following conditions:
Water flow rate: 1.25 m3/s
River inlet: 1 atm., 4.7°C
Discharge: 1 atm., 5.1°C, 254 m below intake.
Assuming that water inlet and discharge ducts have the same areas,
and that no heat is transferred to or absorbed from the surroundings.
Given: acceleration of gravity = 9.81m/s2
Heat Capacity of Water = 4.17 kJ/(kg.K)
Solution : -
1.25 m³ of water flows. density of water = 0.998 g/cm³ = 998 kg/m³
1.25m³ x 998 kg/m³ = 1248 kg
PE of the water is 1248 kg x 9.81 x 254 = 3.108e6 joules
E lost due to heating is
E = 4.17 kJ/(kg.K) x 1248 kg x 0.4K = 2082 kJ
E gained = 3108 kJ - 2082 kJ = 1026 kJ
eff = 1026/3108 = 33%
PRESENT SCENARIO IN INDIA
India is blessed with immense amount of hydro-electric
potential and ranks 5th in terms of exploitable
hydropotential on global scenario.
Present Hydro Capacity:- 36497.76 MW (As on 31.10.2008)
The sector wise Hydro Capacity as on 30.10.2008 are as
• Central : 8592.00 MW
• State : 26825.76 MW
• Private : 1230.00 MW
India is endowed with economically exploitable and viable
hydro potential assessed to be about 84,000 MW at 60%
load factor (1,48,701 MW installed capacity). In addition,
6780 MW in terms of installed capacity from Small, Mini,
and Micro Hydel schemes have been assessed.
Name Location Operator
Babail Uttar Pradesh Uttar Pradesh Jal Vidyut
Bhandardara-1 Maharashtra Dodson-Lindblom Hydro
Power Pvt Ltd
Belka Uttar Pradesh Uttar Pradesh Jal Vidyut
Chenani-1 Jammu & Kashmir Jammu & Kashmir Power
Bhatgar Maharashtra Maharashtra State Power
Generation Co Ltd
Indira Sagar Madhya Pradesh Narmada Hydroelectric
Development Corp Ltd
Little Ranjit West Bengal West Bengal State Electricity
Distribution Co Ltd
WORLD HYDRO POWER - OVERVIEW
Worldwide the total hydro capacity in operation is
807GW excluding pump storage.
Annual hydro production currently stands at more
than 3030TWh per year.
There is at least 150GW of hydro under
construction in 106 countries worldwide.
Hydro is contributing more than 50% of national
electricity supply in about 60 countries.
In all parts of the world, except Australia,
electricity production from hydropower has
In Asia hydropower has risen from 933 TWH per
Hydroelectric power provides almost one-fifth
of the world's electricity.
China, Canada, Brazil, the United States, and
Russia were the five largest producers of
hydropower in 2004.
One of the world's largest hydro plants is at
Three Gorges on China's Yangtze River. The
reservoir for this facility started filling in 2003.
The biggest hydro plant in the United States is
located at the Grand Coulee Dam on the
Columbia River in northern Washington. More
than 70 percent of the electricity made in
Washington State is produced by hydroelectric
Asia has the greatest amount of hydro
development under way. At present the Hydro
capacity under construction has increased by
In the United States today, hydropower
projects provide 81 percent of the nation’s
renewable electricity generation and about 10
percent of the nation’s total electricity.
Canada, the leading country in North America
is producing about 60% of electricity needs
from hydropower and was described as,
―Emerging Energy Superpower,‖ at recent G8
An experimental OTEC Plant on the Kona Coast of Hawaii,
Source: U.S. Department of Energy (Public Domain)
THE OCEAN THERMAL ENERGY CONVERSION
The energy from the sun heats the surface water of the ocean. In
tropical regions, the surface water can be much warmer than the deep
water. This temperature difference can be used to produce electricity.
The OTEC system must have a large temperature difference of at least
77°F to operate, limiting its use to tropical regions.
Hawaii has experimented with OTEC since the 1970s. There is no large-
scale operation of OTEC today, mainly because there are many
challenges. The OTEC systems are not very energy efficient. Pumping
water is a major engineering challenge.
Electricity generated by the system must be transported to land. It will
probably be 10 to 20 years before the technology is available to
produce and transmit electricity economically from OTEC systems.
EIA does not forecast the commercialization of OTEC systems in its
most recent Annual Energy Outlook. The U.S. Department of
Energy's Office of Energy Efficiency and Renewable Energy has
supported OTEC technology research and development, and plans to
have an OTEC resource assessment completed in 2012.
FISH LADDER AT THE BONNEVILLE DAM ON THE
COLUMBIA RIVER SEPARATING WASHINGTON
A dam to create a reservoir may obstruct migration of fish to their upstream
spawning areas. A reservoir and operation of the dam can also change the natural
water temperatures, chemistry, flow characteristics, and silt loads, all of which
can lead to significant changes in the ecology (living organisms and the
environment) and rocks and land forms of the river upstream and downstream
World-wide, about 20% of all electricity is generated by hydropower.
Hydropower provides about 10% of the electricity in the United States.
The United States is the second largest producer of hydropower in the world.
Canada is number one.
Recent data shows that in Wisconsin hydropower is produced for less than one
cent per kwh. This is about one-half the cost of nuclear and one-third the cost of
Hydropower does not experience rising or unstable fuel costs. From 1985 to 1990
the cost of operating a hydropower plant grew at less than the rate of inflation.
Only 2,400 of the nation's 80,000 existing dams are used to generate power.
It's a clean fuel source; doesn't pollute the air like po
plants that burn fossil fuels, such as
coal or natural gas.
It's a renewable power source.
Hydropower is generally available as needed. Also
engineers can control the flow of moving water
through the turbines to produce
electricity on demand.
Offer a variety of recreational activities such as ;
Impact water quality and flow; can cause low
dissolved oxygen levels in water; harmful to
Hydropower plants can be impacted by drought.
When water is not available, can’t produce
New hydropower facilities impact the local
environment and compete with other uses for the
land which may be more highly valued than
Critical Danger Zones at Dams
A Hazard area marked by buoy lines F
Slippery surfaces on dam structures and
B Sudden Water discharge from dam gates G Submerged hazards above and below dams
Strong, unpredictable currents above and
Open spillways which may not be visible from
above the dam
Sudden turbulent discharges from
automatically operated power house
I Debris passing over or through the dam
E Deceiving reverse currents below spillways J
Ice that forms near a dam is often thin and
We can reduce our exposure to future fuel
shortages and price increases, and help
reduce air pollution.
There are many factors to consider when
buying a system, but with the right site and
equipment, careful planning, and attention
to regulatory and permit requirements,
small hydropower systems can provide you
a clean, reliable source of power for years to
"Hydroelectric power - energy from falling water―.
"Hydroelectric Power". Water Encyclopedia.
"History of Hydropower". U.S. Department of
Renewables 2011 Global Status Report, page 25,
Hydropower, REN21, published 2011, accessed 2011-
National Register of Large Dams – 2009.
Website of Central Water Commission
Website of Ministry of Power (www.powermin.nic.in)
Website of Ministry of Water Resources