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1. Hydropower Engineering
Lecture 2
School of Electrical &
Computer Engineering

2. Types of Developments
 In studying the subject of hydropower engineering, it is
important to understand the different types of development.
The following classification system are:
i. Run-of-river developments:
 A dam with a short penstock (supply pipe) directs the water to
the turbines, using the natural flow of the river with very little
alteration to the terrain (land) stream channel at the site and
little impoundment of the water.
ii. Diversion and canal developments:
 The water is diverted from the natural channel into canal or a
long penstock, thus changing the flow of the water in the
stream for a considerable distance.

3. Cont’…
iii. Storage regulation developments:
 An extensive impoundment at the power plant or at reservoirs
upstream of the power plant permits changing the flow of the
river by storing water during high-flow periods to augment
(enlarge) the water available during the low-flow periods, thus
supplying the demand for energy in a more efficient manner.
 The word storage is used for long-time impounding (storing) of
water to meet the seasonal fluctuation in water, availability and
the fluctuations in energy demand.
 While the word pondage refers to short-time (daily) impounding
of water to meet the short-time changes

4. Cont’…
iv. Pumped storage developments:
 Water is pumped from a lower reservoir to a higher reservoir
using inexpensive dump power during periods of low energy
demand.
 The water is then run down through the turbines to produce
power to meet peak demands.
v. Tidal power developments:
 In some estuaries, tidal power can be economically harnessed
to develop electric energy.
 These developments use the water flowing back and forth as a
result of tidal action and the fact that there is a significant
difference in elevation of the water surface in the estuary from
one stage of tide to another.

5. Cont’…
VI. Single-purpose developments:
 The water is used only for the purpose only producing
electricity.
VII. Multipurpose developments:
 Hydropower production is just one of many purposes for which
the water resources are used. Other uses might include, for
example:
 irrigation, flood control, navigation (direction finding),
municipal (public), and industrial water supply.
 Another way of classifying hydropower development is with
respect to the manner in which the hydropower plant is used to
meet the demand for electrical power.

6. Cont’…
VIII. Base-load developments:
 Energy available essentially at all times is referred to as firm
power.
IX. Peak-load developments:
 Peak demands for electric power occur daily, weekly, and
seasonally
 Five main aspects commonly used for classification of
hydropower plants
 design capacity (installed capacity)
 design head
 design type
 type of supply: grid type / destination of supply
 operation (base or peak)

7. Hydropower Efficiency


8. Hydropower Efficiency
 Hydropower is very efficient
– Efficiency = (electrical power delivered to the “busbar”)
÷ (potential energy of head water)
 Typical losses are due to
– Frictional drag and turbulence of flow
– Friction and magnetic losses in turbine & generator
 Overall efficiency ranges from 75-95%
H
Q
g
P 


 

9. Cont’…
P = power in kilowatts (kW)
g = gravitational acceleration (9.81 m/s2)
 = turbo-generator efficiency (0<n<1)
Q = quantity of water flowing (m3/sec)
H = effective head (m)
Example 1. Consider a mountain stream with an
effective ead of 25 meters (m) and a flow rate of
600 liters (ℓ) per minute. How much power could a
hydro plant generate? Assume plant efficiency ()
of 83%.

10. Cont’…
 H = 25 m
 Q = 600 ℓ/min × 1 m3/1000 ℓ × 1 min/60sec
Q = 0.01 m3/sec
  = 0.83
 P  10QH = 10(0.83)(0.01)(25) = 2.075
P  2.1 kW

11. Cont’…
Hydropower Advantages
 No fuel charges.
 an hydro-electric plant is highly reliable
 Maintenance and operation charges are very low.
 Running cost of the plant is low.
 The plant has no stand by losses.
 The plant efficiency does not change with age.
 It takes a few minutes to run and synchronise the plant.
 Less supervising staff is required.
 No fuel transportation problem.
 No ash problem and atmosphere is not polluted since no smoke
is produced in the plant.
 In addition to power generation these plants are also used for

12. Based on Generating capacity
Hydropower Disadvantages
 It requires large initial investments
 It requires long transmission lines
 Social and environmental impacts
Social impact
 Population displacement
 Loss of social networks and changing way of living
 Dams can facilitate development of diseases
 Diversion of mountain streams
 Blockage of fish passage both upstream and downstream
 Storing water in reservoir may reduce the final flow as a result
of evaporation

13. Cont’…
Environmental impacts
 Reduction in the flow of soil and nutrients
 Pollution is stored in the reservoir
 Possible dam failure
 Seismic risks
 Loss of cultural heritage
 local increase in water vapor and some temperature
effects
 Vegetation rotting under water produces methane implies
emissions

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