Planning and Development process

Chapter 3
Chapter Three
Planning and Development Process
By Yimam Alemu
December 16, 2020
By Yimam Alemu Chapter 3 December 16, 2020 1 / 55

Chapter 3
Outline
1 Methodology of HEPP Development
2 Surveys needed for hydro power plants
3 Selection of Site for a Hydroelectric Power Plant
4 Types of Development
5 Eﬃciency of hydropower

Chapter 3
Learning Objectives
At the end of this chapter the students should be able to:
Understand the methodology of HEPP development Understand elements and equip-
ment’s needed to be taken into consideration while designing a hydroelectric power
plant.
Understand factors should be considered while selecting the site for a hydroelectric
power plant.
Understand the diﬀerent types of developments of hydroelectric power plant.
Understand the environmental, social and economic analysis of HEPP.

Chapter 3
Methodology of HEPP Development
Site Survey: Hydrological and geological Survey.
Regulations and Environmental Concerns
Feasible Supply(feasibility study)
Estimation of Potential
Turbine Selection
Costing and Payback

Chapter 3
Measuring parameters
Measurement of river(water body ﬂow data.)
Measurement of head ( Power and available head )
Topographical and geological condition of site
Site accessibility – need to be address during planning stage
Power transmission point distance – determine power loss
Power demand assessment

Chapter 3
Hydrological Survey
Power demand assessment
To measure the flow-rate vs time at a given site
The more robust option is to find out the flowrate by working out the volume of water
that was entering the river.
This uses the rainfall data from metrology office for two lean seasons.

Chapter 3
Flow Rate Measurement
There are numerous ways to measure ﬂow rate, such as:
Bucket Method
Float Method
Weirs
Meters

Chapter 3
1.Bucket method
The Bucket method is a simple way to measure the flow rate using household items.
It requires a stopwatch, a large bucket, and preferably two to three people to measure
the flow rate using the bucket method:
Direct measurement with a bucket
Good for small flow in conduit.

Chapter 3
Cont....
Measure the volume of the bucket or container
Find a location along the stream that has a waterfall
With a stopwatch, time how long it takes the waterfall to ﬁll the bucket with water
Record the time it takes to ﬁll the bucket.
Figure: Bucket measuring method

Chapter 3
2. Float Measuring Method
Figure: Float measuring method

Chapter 3
Cont....
The float method (also known as the cross-sectional method) is used to measure the
flow rate for larger streams and rivers.
Locate a spot in the stream that will act as the cross section of the stream.
Using a meter stick, or some other means of measurement, measure the depth of the
stream at equal intervals along the width of the stream.
Decide on a length of the stream, typically longer than the width of the river, to send
a floating object down.
Using a stopwatch, measure the time it takes the float to travel down the length of
stream.

Chapter 3
3. Weir Measuring Method
Weirs are small dams that can be used in measuring flow rate for small to medium
sized streams (a few meters or wider).
They allow overflow of the stream to pour over the top of the weir, creating a waterfall.
Weirs increase the change in elevation making the streamflow more consistent which
makes flow rate measurements more precise.

Chapter 3
Figure: Weir measuring method

Chapter 3
4.Meters
Meters are devices that measure the stream flow by directly measuring the current.
There are many different types of meters, the most common is the Pygmy meter, the
vortex meter, the flow probe, and the current meter:
Measured by Electromagnetic current or propeller type current meter.

Chapter 3
Measuring Instruments
Altimeter: – for altitude measurement
GPS: for location coordinate
Camera: for capturing the location image
Current meter: measuring the ﬂow of water
Distance meter
Depth meter: depth of the water body
Clinometer measures vertical slope, usually the angle between the ground or the
observer and a tall object
Compass
Hand level

Chapter 3
Various studies during the preliminary site survey
Hydrological studies : Overall rain fall ,run off data ,principal river flow data , flood
characteristics, from record of gov’t. department . Min ,avg and flood details.
Topological studies : Tachometric survey and survey required depending upon the
existing info and maps.
Geological studies : Overall geological characteristics and local features for trans-
portation of material.
Power demand assessment : Overall power demand scenario in the project near by
area and existing infrastructure for power evacuation.

Chapter 3
Site Survey
Pre Feasibility Report
Basic Design
Various Graphs and Pictures

Chapter 3
Surveys needed for hydro power plants
The following surveys are carried out for a hydro plant installation.
General surveys
Special surveys

Chapter 3
A) General surveys
They constitute the following:
1. Topographical surveys such as
i) The dam site topographical survey plans including the area of accommodate dam,
spillway, outlet works, diversion works etc.
ii) The reservoir submergence plans Contour plan of
a) Surge tanks
b) Tunnels
c) Penstock
d) Tail race channels.
iii) River surveys
iv) For a barrage structure detailed survey maps to cover the area under the barrage.

Chapter 3
Cont....
2. Geological and foundation investigations.
A study should be carried out for the following:
i) Seismic condition of the region
ii) Water ﬂow in reservoir
iii) Sub-surface conditions
iv) Foundation investigations for dams.

Chapter 3
Cont....
3. Metrological and hydrological studies:
The following data should be collected
i Precipitation, evaporation.
ii Water flows such as maximum and minimum water flows.
iii Rainfall-run off relation data.
iv Mean latitude, and longitude, mean elevation, mean monthly temperature.
v Location of raingauge station near power plant site.

Chapter 3
Cont....
4. Construction material investigations:
Data should be collected for the following:
i Materials to be used for
a) Concrete and masonry dams
b) Earth and rock ﬁll dams.
ii Tests to be carried out for materials.

Chapter 3
Cont....
5. Transportation and communication:
Data should be collected for the following:
Road, water and rail routes
Telephone and telegraph lines.
6. Environmental considerations
Navigation
Fish culture.

Chapter 3
B) Special surveys
Special surveys include the following:
1. Load surveys: They are made of
i Power-station capacity
ii Power to be generated
iii Details for major loads to be served
iv Peak load
v Load factor
vi Future energy demand
vii Inter connection with other power systems

Chapter 3
Cont....
2. Lay-out studies: This includes the following
i Type of power plant such as storage type, run of river plant,pumped storage type etc.
ii Structural components like
a) Dams
b) Canals
c) Tunnels
d) Penstock
e) Draft tube
f) Surge tanks
g) Power house
h) Switch yard

Chapter 3
Pre feasibility report
Pre feasibility report is required to investigate weather project is technically or ﬁnan-
cially feasible or not.
Aim of PFR is to examine next step to project formulation
Preparation of PFRs involves
Conceptual planning,
Preparation of project and equipment layouts,
Infrastructure requirement,
Environmental and geological studies,
Power evacuation arrangement, cost estimates and
economic evaluation.

Chapter 3
Cont....
Executive summary
Introduction
Project location
Map
Project description
Salient feature
Hydrology
Climate
Catchment area
Rainfall

Chapter 3
Cont....
When designing a hydroelectric power plant a number of elements and equipment’s
need to be taken into consideration.
Site selection
Technical data
Intake position
Penstock length and diameter
Turbine and generator systems
Electrical and control equipment
The Power House
Distribution system

Chapter 3
Cont....
Based on the ﬁrm power:
Dams, canals, intakes, penstocks, tailraces and power houses are designed by civil
engineers.
Mechanical Engineers design the hydraulic turbines.
Electrical Engineers design the generators, transformers, the switch yards and the
protection system.
♣ Firm power is also one of the main factors that decides the feasibility of HPP.

Chapter 3
Cont....
Civil Engineers, Mechanical Engineers, Electrical Engineers, Geologists, Economists,
Ecologists, Sociologists and many other experts combine their skills in order to develop
an optimum design considering technical, ﬁnancial, environmental and social aspects
of hydropower development.
Feasibility study contains:
Site visit and selection
Capacity analysis
Economic analysis
Environmental impact analysis
♣ Feasibility study is the ﬁrst step in HPP construction.

Chapter 3
Selection of Site for a Hydroelectric Power Plant
The following factors should be considered while selecting the site for a hydroelectric
plant.
1 Availability of water
2 Water storage capacity
3 Available water head
4 Accessibility of the site
5 Distance from the load Centre
6 Water pollution
7 Sedimentation
8 Large catchment area
9 Availability of Land

Chapter 3
1.Availability of water
The recorded observation should be taken over a number of years to know within
reasonable limits the maximum and minimum variations from the average discharge.
The river flow data should be based on daily, weekly, monthly and yearly flow over a
number of years.
Then the curves or graphs can be plotted between river flow and time. These are
known as hygrographs and flow duration curves.

Chapter 3
2. Water Storage capacity:
The output of a hydropower plant is not uniform due to wide variations of rain fall. To
have a uniform power output, a water storage is needed so that excess ﬂow at certain
times may be stored to make it available at the times of low ﬂow.
Since storage of water in a reservoir at a height or building of dam across the river is
essential in order to have continuous supply during the dry season.
The storage capacity can be determined from the Hydrograph, Mass Curve or by using
analytical methods.

Chapter 3
3. Available water head
Available water head depends upon the topography of the area.
The level of water in the reservoir for a proposed plant should always be within limits
throughout the year.
Availability of head of water has considerable eﬀect on the cost and economy of power
generation.
An increase in eﬀective head reduces the quantity of water to be stored and handled
by penstocks, screens and turbines and therefore capital cost of the plant is reduced.

Chapter 3
4. Distance from Load Center
Most of the time the electric power generated in a hydro-electric power plant has to be
used some considerable distance from the site of plant.
For this reason, to be economical on transmission of electric power, the routes and the
distances should be carefully considered since the cost of erection of transmission lines
and their maintenance will depend upon the route selected.
Power plant should be set up near the load center, this will reduce the cost of mainte-
nance of transmission line

Chapter 3
5. Accessibility of the Site
The site where hydroelectric plant is to be constructed should be easily accessible.
This is important if the electric power generated is to be utilized at or near the plant
site.
The site selected should have transportation facilities of rail and road.

Chapter 3
6. Water Pollution
Polluted water may cause excessive corrosion and damage to the metallic structures.
This may render the operation of the plant unreliable and uneconomic
It is necessary to see that the water is of good quality and will not cause such troubles.

Chapter 3
7. Sedimentation
Gradual deposition of silt may reduce the capacity of the storage reservoir and may
also cause damage to the turbine blades.
Silting from forest covered areas is negligible. On the other hand the regions subject
to violent storms and not protected by vegetation contribute lot of silt to the run oﬀ

Chapter 3
8. Large Catchment Area
The reservoir must have a large catchment area so that level of water in the reservoir
may not fall below the minimum required in dry season.

Chapter 3
9. Type of the land of the site
The land to be selected for the site should be cheap in cost and rocky in order to
withstand the weight of the large building and heavy machinery.
There should be a stream diversion during period of construction.
The necessary requirements of the foundation rocks for a masonry dam are as follows:
The rock should be strong enough to withstand the stresses transmitted from the dam
structure as well as the thrust of the water when the reservoir is full.
The rock in the foundation of the dam should be reasonably impervious
The rock should remain stable under all conditions.

Chapter 3
Main design parameters
The power capacity of a hydropower plant is primarily a function of two main variables
of the water
Water flow
Hydraulic head
Design flow is the maximum flow for which your hydro system is designed.
It will likely be less than the maximum flow of the stream (especially during the rainy
season) or more than the minimum flow during dry season.
If a system is to be independent of any other energy or utility backup, the design flow
should be the flow that is available 95 percent of the time or more.

Chapter 3
Cont....
Therefore, a stand-alone system such as a micro hydropower system should be designed
according to the flow that is available year-round; this is usually the flow during the
dry season.
Reserved flow: it is the minimum flow required to avoid aquatic life damage in the
water stream.
Firm flow: The firm flow is defined as the flow being available X% of the time, where
X is a percentage specified by the user and usually equal to 95%.

Chapter 3
Types of Development
In studying the subject hydropower engineering it is important to understand the
diﬀerent types of development.
Run-oﬀ river development
Diversion and canal development
Storage regulation development
Pumped storage development
Single purpose development
Multi purpose development
Cascaded development

Chapter 3
1. Run-oﬀ river development
A dam with short penstock (supply pipe) directs the water to the turbine using the
natural ﬂow of the river.

Chapter 3
2. Diversion and canal development
The water is diverted from the natural channel into canal, thus changing the natural ﬂow
of the water in the stream for a considerable distance.

Chapter 3
3. Storage regulation development
An extensive impoundment at the power plant or at the reservoir up stream of the
power plant permits changing the flow of the river by storing the water during high
flow periods to enlarge the water available during the low flow periods, thus supplying
the demand for energy in a more efficient manner.
Storage refers to long time impounding of water to meet the seasonal fluctuation in
water availability and the fluctuations in energy demand.
Pondage refers to short-time impounding of water to meet short-time changes of de-
mand.

Chapter 3
4. Pumped storage development
Water is pumped from lower reservoir to a higher reservoir during period of low energy
demand. The water then run down through turbine to produce power to meet peak
demand.

Chapter 3
5. Single and multi purpose development
In single-purpose development the water is used only for the purpose of producing
electricity.
In multi-purpose development hydropower production is just one of many purposes for
which the water resource is used.
e.g. irrigation, ﬂood control, navigation, industrial water supply, etc

Chapter 3
6. Cascaded development

Chapter 3
Cont....
Example:
Gibe III 1870 MW
The Gibe III dam is part of the Gibe cascade, a series of dams including the existing
Gibe I dam (184 MW) and Gibe II power station (420 MW) as well as the planned
Gibe IV (1472 MW) and Gibe V (560 MW) dams.

Chapter 3
Efficiency of hydropower
The potential for energy production in a hydropower plant is determined by the fol-
lowing parameters:-
The amount of water available
Water loss due to flood spill, bypass requirements or leakage
Head
Hydraulic losses in water transport due to friction and water velocity change.
The efficiency in energy conversion of electro mechanical equipments.

Chapter 3
Cont....
In hydropower plant the energy transformation
Potential energy(stored water in dam)
Kinetic energy(water falling from height)
Mechanical energy(Turbines)
Electrical energy(Generator)
The energy transformation in modern hydropower plants is highly eﬃcient usually well
over 90%.

Chapter 3
Cont....
Efficiency of hydropower plant is dependent on
Hydraulic loss (intake, turbine, tailrace)
Mechanical and electrical loss (turbines and generators)
Absorption of sediments
Due to heat in the water and generator
The total efficiency of a hydropower plant is determined by the sum of these three loss
components.
Hydraulic losses, it can be reduced by increasing turbine capacity or reservoir capacity
for better regulation of flow.
Head loss, it can be reduced by increasing the area of headrace and tailrace, by de-
creasing roughness in the pipes.
By avoiding too many changes in flow velocity and direction.

Chapter 3
Questions
Thank You!

Planning and Development process

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