Hydropower

1. 1
Perennial Rivers –
• Rivers that flows throughout the year called Perennial
rivers
• Rain fall and melting of snow are the major source of these
river.
• There are two types
Permanent Rivers
Exotic Rivers
Types of Rivers

2. Types of Rivers
• Non Perennial Rivers – flow in rainy season
Periodic Rivers
Episodic Rivers
2

3. 3
Permanent Rivers
• These rivers are located in more humid climates
where rainfall exceeds evaporation rates.
• These rivers may experience seasonal fluctuations in
their water levels
• Flow all year round
• River channel reaches water table throughout the year
• Indus River is example

4. 4
Exotic Rivers
• An exotic river starts out from a humid region and flows into a
dry region.
• A river flowing through a desert can be considered exotic due
to its existence in an otherwise arid region.
• The Nile is an example of an exotic river. Its headwaters begin
in the humid highlands. of East Africa. This river flows
through the deserts of Sudan and Egypt before emptying in the
Mediterranean Sea.

5. 5
Episodic Rivers
• These rivers are actually the runoff channels of very dry
regions.
• Where there is only a slight amount of rainfall, it often
evaporates quickly. Thus, this type of stream-flow occurs
rarely.
• Only flow for short periods after heavy rain e.g. Nassob
(Namibia).
• After a thunderstorm a river may only flow for a few
hours
• A river may flow for a few days or weeks after an
extended episode of rain

6. 6
Periodic Rivers
• These rivers are characterized by an intermittent (not
continuous) stream-flow.
• Only flow after a period of rain
• Is a seasonal flow – winter, summer
• Rivers may flow for 3 to 6 months

7. DAMS

8. Dams
• Dam is a solid barrier constructed at a suitable
location across a river valley to store flowing water.
Storage of water is utilized for following objectives:
• Hydropower
• Irrigation
• Water for domestic consumption
• Drought and flood control
• Other additional utilization is to develop fisheries

9. Dams - Advantages
• Dams are used for various purposes. Some
advantages of dams are:
– Used for renewable hydroelectric power
generation
– Storage of water & energy on demand
– Lifecycle of a few decades
– Flood control
– Irrigation of agriculture
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10. Dams - Disadvantages
• Some disadvantages include:
– High costs of construction which take decades
to be profitable
– Large areas are flooded causing relocation of
people and destruction of natural environment
– May cause political tensions between countries
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11. Structure of DAM

12. • Heel: The junction of the upstream face of a concrete gravity dam or
arch dam with the ground surface.
• Abutment: Sides of the valley on which the structure of the dam rest
• Galleries: small rooms like structure left within the dam for checking
operations.
• Diversion tunnel: Tunnels are constructed for diverting water before the
construction of dam. When a dam is built, a tunnel is bored in order to
divert water away from the dam construction site so that it essentially
bypasses it, hence the term diversion tunnel.
Spillways: It is the arrangement near the top to release the excess water
of the reservoir to downstream side
• Sluice way: An opening in the dam near the ground level, which is used
to clear the silt accumulation in the reservoir side.

14. Dams - Classification
• Dams are the most commonly known types of
hydraulic structures.
• Most common classification of dams is based on
the materials & basic design of the dam.
• Types of dams include:
– Concrete dams
• Concrete gravity dams
• Concrete arch dams
• Concrete buttress dams
– Earthfill dams
– Rockfill dams
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15. Dams - Classification (2)
• Dams can also be classified according to their
functions:
– Storage dams (most common) used for storing water
for developmental uses (irrigation, hydropower &
water supply). Include gravity, earth, rockfill & arch
dams.
– Diversion dams: Diverting stream flow into canals or
other water transport systems. Include weirs and
barrages
– Detention dams: Used hold the water
temporary to retard flood flows
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16. Concrete Dams – Gravity Dam
• Concrete gravity dams are very commonly used and have
certain features
– Solid concrete structures
– Triangular cross section
– A rock solid foundation with steep walls is required for
construction
– These dams are heavy and massive wall-like structures of
concrete in which the whole weight acts vertically downwards
– requires great quantities of material for construction. & costly
to build
– Fairly low maintenance once built.
– All of the force of the dam rests of the foundation
– Highest dams in the world are of this type.
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17. TYPES OF DAMS
• Gravity Dams:
• These dams are heavy
and massive wall-like
structures of concrete
in which the whole
weight acts vertically
downwards
Reservoir
Force
As the entire load is transmitted on the small area of foundation, such
dams are constructed where rocks are competent and stable.

18. • Bhakra Dam is the highest
Concrete Gravity dam in Asia
and Second Highest in the world.
• Bhakra Dam is across river
Sutlej in Himachal Pradesh
• The construction of this project
was started in the year 1948 and
was completed in 1963 .
• Length at top 518.16 m (1700 feet); Width at base 190.5 m (625 feet),

20. Buttress Dam:
• Buttress dams are derived from gravity dams.
• Uses thin concrete slab which is supported from downstream side
by buttresses.
• In this type face is held up by a series of supports
• Relatively thin structure
• This type of structure can be considered even if the foundation rocks
are little weaker
• Amount saving of concrete material

21. Buttress
Dam

22. • These type of dams are concrete or masonry dams which are curved or
convex upstream in plan
• This shape helps to transmit the major part of the water load to the abutments
• Arch type dams can store greater amounts of water
• Arch dams are built across narrow, deep river gorges, but now in recent
years they have been considered even for little wider valleys.
Arch Dams:

24. Earth Dams: • Earth fill dams are made of
selected soils that are
compacted together uniformly
into thin layers with controlled
moisture and permeability.
• They are trapezoidal in shape
• Earth dams are constructed
where the foundation or the
underlying material or rocks are
weak to support the masonry
dam or where the suitable
competent rocks are at greater
depth.
• Earthen dams are relatively
smaller in height and broad at
the base
• They are mainly built with clay,
sand and gravel, hence they are
also known as Earth fill dam or
Rock fill dam

25. Earthfill Dam - Tarbela Dam
• Tarbela Dam (Urdu/Pashto: ‫بند‬ ‫تربیال‬
) ) is an earth fill dam
on the Indus River in Pakistan.
• It's the largest earth-filled dam in the world and fifth-
largest by structural volume.
• The dam is 485 feet (148 m) high above the riverbed. It
forms the Tarbela Reservoir, with a surface area of
approximately 250 square kilometres (97 sq mi)
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26. Tarbela Dam - Pakistan
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27. Rockfill dams
• A rockfill dam is an embankment which uses variable sizes of
quarried stones(rocks) to provide stability. Features of a rockfill dam
include:
• An impervious membrane at the core of the dam
• Outer layer of compacted granular soil
• Shape of a bank/hill so effective force of water is downwards towards
the foundation
• Economical & easier to build than concrete dams
• Can be built quickly even under adverse weather conditions and fairly
high depending on the foundation material
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28. Rockfill dams
• Rockfill dams tend to use aggregate extracted from nearby mining sites
to make them impermeable.
• The parts of a rockfill dam include the main rockfill, which is the
structural support; the impervious zone, which combats against the
force of the reservoir; and the central core, which transfers the force and
maintains stability.
• these types of dams are economical and the rocks make an effective
barrier against the strong forces created by rivers.
• Unlike earth or concrete dams, workers can work in wet weather
conditions and still construct a strong and durable dam.

30. HEP 30
TARBELA DAM
Dam Type: Earth and Rockfill
Height:
485 ft. (above
riverbed)
Reservoir Area: 95 sq. miles
Gross Storage
Capacity:
11.62 MAF
Live Storage
Capacity:
9.7 MAF
Main Spillway
Capacity:
6.5 million cusecs
Year of Completion: 1977
Power Generation: 3,478 MW

31. HEP 31
Mangla Dam
• Mangla Dam is an earthfill type dam constructed on river
Jhelum in 1967 as a part of Indus Basin Development
Plan.
• It is a multipurpose Project designed to conserve and
regulate the floodwater of the River Jhelum for irrigation
purpose and power generation.
• Due to deposition of silt during 34 years of its operation
the gross capacity has reduced from 5.88 MAF to 4.82
MAF
• Initially it’s life was estimated as 120 years but later on
with the implementation of watershed management
practices in catchment area, its expected life is now
estimated as 170 years.

32. HEP 32

33. HEP 33
MANGLA DAM
Dam Type: Earthfill
Height: 380 ft. (above riverbed
Length: 10,300 feet
Lake Area: 97.7 sq. miles
Catchment Area: 12,870 Sq miles
Gross Storage Capacity: 5.88 MAF
Live Storage Capacity: 5.34 MAF
Main Spillway Capacity: 1.01 million cusecs
Year of Completion: 1967
Hydropower Generation:
1,000 MW from 10 units of
100 MW each
No. of people to be displaced by
raising of dam:
40,000

34. HEP 34
Ghazi-Barotha HEPP
Total area of barrage 1140ha
Public road crossing of the Indus
river
01
Design flow 1600 cumcs
Longitudinal slope 1:9600
Length 52km
Depth 09m
Width 58.4m
Water velocity 2.33m/s
Road bridges 34
Railway bridges 01
Total area 850 ha
Total output (Five turbo generators)
1450 MW (each one
having output of 290 MW)

35. Selection of type of dam & site
• Many factors decide the type of dam to be built
and location of site to be selected include
– Topography:
• Narrow Steam with high rocky walls concrete dam
• Lower wider plane suggest rock/earth fill dam
– Geologic characteristics of foundation
• Solid rock foundation can support all types but concrete
or arch type dams are preferred
• Gravel foundation are suitable for earthfill, rockfill, and
low concrete gravity dams.
• Silt and fine sand foundations support earthfill and low
concrete gravity dams but not suitable for rockfill dams.
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36. Selection of type of dam & site
(2)
• Availability of materials
– If materials needed to build the dam are close by the costs
maybe significantly reduced.
• Costs
– One of the most important factors deciding the type of dam
– Economic evaluation of the project and financing potential
• Labor/Technology
– The availably of skilled labor and machinery also decide
the type of dam that can be constructed.
• Political Factors
– Building a dam in a certain location may cause political
conflict and may be regulated by agreements.
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37. HydroPower

38. What is Hydro Power Engineering ?
The word “Hydro” means “water” )in Latin)
“hydro power” is made from water.
Water (Renewable energy source) is used to make electricity
HEP 38
Hydro Power

39. What is Hydroelectric
Power?
Harvesting the energy of moving water to produce
electricity for our own needs.

40. How A Hydropower
plant works:
•Dam: Controls the flow of water and creates a reservoir of
water above for energy use when needed
•Penstock: Pipe channeling water from the dam to the turbines
•Turbines: Large blades attached to a cylinder that move when
the water pushes against it
•Generator: Parts connected to the turbines that create the
electricity by moving large magnets
•Inductor: Changes the form of electricity to one that can be
used
•Transmission lines: Transport energy to places that need it

41. Classification of Hydropower

42. According to Capacity
 Large plants : capacity >100 MW
• Medium: 25 – 100 mw
• Small: 1-25 mw
• Mini: 100 kw - 1mw
• Micro: 5 – 100 kw
• Pico: < 5 kw

43. Schemes Classification
• Schemes are generally classified according
to the “Head”:
– High head: 300-m and above
– Medium head: 30 - 300 m
– Low head: 2 - 30 m
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44. Low head hydro power
• Low head hydro power applications use river current or
tidal flows of 30 meters or less to produce energy.
• These applications do not need to dam or retain water to
create hydraulic head, the head is only a few meters.
• Using the current of a river or the naturally occurring tidal
flow to create electricity may provide a renewable
• Energy source that will have a minimal impact on the
environment.

45. MEDIUM HEAD:
A power station operating under heads from
30m to 300m.
Figure- sectional view of medium head hydropower plant

46. HIGH HEAD:
A power station operating under heads above about 300m.
A head of 200m/250m is considered as the limit between medium and high head power
stations.
Figure- high head hydropower plant

47. Figure-(a) single stage hydropower development scheme
(b) cascade or multistage hydropower system
SINGLE STAGE- When the run
off from a single hydropower plant is
diverted back into river or for any
other purpose other than power
generation, the setup is known as
Single Stage.
CASCADE SYSTEM- When two
or more hydropower plants are used
in series such that the runoff
discharge of one hydro power plant is
used as the is a intake discharge of
the second hydro power plant such a
system is known as CASCADE
hydropower plant.

48. SINGLE PURPOSE: When the whole soul purpose of a project is
to produce electricity then such a project is known as a Single
Purpose Hydro Power Project.
MULTIPURPOSE : When the water used in hydropower project
is to be used for other purposes like irrigation, flood control or
fisheries then such a project is known as Multi Purpose Hydro
Power Project.

49. These are hydro power plants that utilize the stream flow as it comes , without any storage being provided.
RUN-OF-RIVER TYPE
Figure-Run-of-River hydropower plant

50. Hydropower plants with storage are supplied with water from large storage reservoir that have been
developed by constructing dams across rivers.
 Assured flow for hydro power generation is more certain for the storage schemes than the run-of-river schemes.
STORAGE (RESERVOIR) TYPE
Figure-pumped storage hydropower plant

51. PUMPED STORAGE TYPE
Figure-pumped storage hydropower plant
 Pumped storage type hydropower plants are those which utilize the flow of water from a
reservoir at higher potential to one at lower potential.
During off-peak hours, the reversible units are supplied with the excess electricity
available in the power grid which then pumps part of the water of the tail-water pond back
into the head-water pond.

52. IN-STREAM
When the velocity of water i.e kinetic
energy flowing in the stream is used
for conversion into electrical power,
then the system is known as In-stream.
Photograph of In-stream hydro power system

53. ISOLATED: Whenever a hydropower plant is set up in a remote area in
order to meet the local demands then such a hydropower plant is known as
Isolated System.
CONNECTED TO GRID: Whenever the hydropower plant is set up to
meet the demands of areas which are at a fair distance from the plant, then
the transmission of power takes through the grid system. Such a setup is
referred to as Connected to grid.

54. How Much Power can we
Extract from the Water
• Waterwheels and water turbines are great for any small
scale hydro power scheme as they extract the kinetic
energy from the moving water and convert this energy into
mechanical energy which drives an electrical generator
producing a power output.
• The maximum amount of electrical power that can be
obtained from a river or stream of flowing water depends
upon the amount of power within the flowing water at that
particular point.
• As the water is moving a hydroelectric system converts
this kinetic input power into electrical output power.

55. How Much Power can we
Extract from the Water
• Power (P) = Flow Rate (Q) x Head (H) x Gravity (g) x Water Density (ρ)
• Where Q is in m3/s, H in metres and g is the gravitational constant, 9.81
m/s2 and ρ is the density of water, 1,000kg/m3 or 1,0kg/litre.
• Available Power from Hydro System

56. Numerical
• A small stream drops 20 meters down the
side of a mountain producing a water flow
rate of 500 litres per minute past a fixed
point. How much power could a small scale
hydro power plant generate in kilo-watts, if
the type of water turbine used has a
maximum efficiency, (η) of 85%.

57. • Head = 20m,
• Flow rate = 500 Lts/min,
• Efficiency = 0.85
• Gravity = 9.81 m/s2.
1,000 litres is equal to 1m3,
• Flow rate 0.00833 m3 per second.

59. Types Of Hydropower

60.  An impoundment is simply a dam that holds water in a reservoir. The water
is released when needed through a penstock, to drive the turbine.
 This illustration shows the parts of a standard hydroelectric dam. Most large,
high-head hydropower facilities use impoundments.
Impoundment System

61. Diversion/ Run-of-the-River
Hydropower System
• A run-of-the-river system uses the river’s natural flow and requires little or no
impoundment. It may involve a diversion of a portion of the stream through a canal
or penstock, or it may involve placement of a turbine right in the stream channel.
Run-of-the-river systems are often low-head.

62. Pumped Storage
 When the demand for electricity is low, a
pumped storage facility stores energy by
pumping water from a lower reservoir to
an upper reservoir. During periods of high
electrical demand, the water is released
back to the lower reservoir to generate
electricity.

63. Pumped Storage
• Operation: two pools of water
• Upper pool – impoundment
• Lower pool – natural lake, river or storage reservoir
• Advantages :
– Production of peak power
– Can be built anywhere with reliable supply of
water The Raccoon Mountain project

64. Tide
• A tidal power plant makes use of the daily rise and fall of water
due to tides; such sources are highly predictable, and if
conditions permit construction of reservoirs
• can also be dispatchable 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.

65. Major Components of Small Hydro
Project

67. Weir and intake
• A weir can be used to raise the water level and ensure a constant
supply to the intake.
• The intake structure is located at the end of the trench weir and is
provided with a gate to control the release of water in power canal

68. Desilting tank
• It is constructed to remove pebbles(stones) and coarse suspended
material in order to prevent erosion of the turbine blade.
• For high head silt size more than 0.2 mm is trapped.
• For medium head silt size more than 0.5 mm trapped
• The speed of water flow is maintained within 40-60 cm/sec to control
cavitations.

69. Water Conductor system
• Water conductor system is from intake to forebay.
• It is designed to minimize head loss
• An aqueduct is provided to cross hilly stream.
• A forebay is a large rank constructed with reinforced concrete and stone masonry.
• It is at downstream at the end of the canal having sufficient capacity to provide
small change in generation
FOREBAY

70. Penstock
• The penstock is the pipe which conveys water under pressure from the forebay tank to
the turbine
• An opening is provided in the forebay at the maximum water level and the spilled
water is dischared in the river
• A spilway arrangement is provided at the penstock intake and it doesnot allow the
water level to rise
SPILWAY

71. Power House
• In power house, turbine generator control panels and auxiliary equipments are
installed and operated
• It is water channel used to drain down the water discharged from the draft tube to the
river
TAIL RACE

72. Power = the electric power in kilowatts or kW
Head = the distance the water falls (measured in feet)
Flow = the amount of water flowing (measured in cubic feet per second or cfs)
Efficiency = How well the turbine and generator convert the power of
falling water into electric power. This can range from 60% to 80% for older,
poorly maintained hydro plants
90% (0.90) for newer, well maintained plants.
Z is the net height of the water head in m
Δ ( v2 ) is the difference in the square of the inlet and exiting fluid velocity
A STANDARD EQUATION FOR CALCULATING
ENERGY PRODUCTION: