Energy is a critical factor in developing
countries for economic growth as well as for social development and human
welfare. Hydropower is a renewable source of energy, which is economical,
non-polluting and environmentally friendly. In this paper, a prototype mini
hydroelectric power generation system was developed. Locally available
materials were utilized for the design and development. Some of the
materials includes: Primary and secondary reservoirs, Dynamo, Rotor,
developed pelter wheel turbine, pump etc. The results of the mechanical
power of the system were found to be 30.65MW and 10.14MW at total flow rates
of 88.67m3/s and 35.68m3/s respectively. The turbine efficiencies were found
to be 79.52% and 58.34% at 10.06m and 4.10m water inlet velocities. The
generator efficiencies were found to be 88.45% and 69.85% at 10.06m and 410m
inlet water velocities respectively. The generator efficiencies were found
to be 88.45% and 69.85% at net head of 337.1 m and 364.29m respectively. The
turbine efficiencies were found to be 79.52% and 58.34% at net head of
337.61 and 364.29m. The project was evaluated and concluded that the
designed mini hydropower plant was found to be economical. The hydroelectric
power plant was able light three (3) bulbs of 10Watts each
Thousands
of years ago, people started using hydro-power to produce mechanical work for
mainly agriculture purposes. In 1882 first hydro-power plant was built to
produce electric energy which consider the hydro-power as the first technology
used to produce electricity from renewable source (Nasr et al., 2018).
Hydro-power is considered as one of the most
desirable sources of electrical energy due to its environmentally friendly
nature and extensive potential availability throughout the world. Within the
scope of hydro-electric power, small power plants have gained much attention in
recent years. Small Hydro power Plants being a mature technology may be
optimally employed for sustainable power generation in rural communities.
Hydropower plants convert potential energy of water at a height to mechanical
energy which is used to turn a turbine at a lower level for generation of electricity
(Anyaka, 2013). In rural areas, small run-of-river hydro turbine is suitable
for electrification because it is green, inexpensive not fuel dependent and is
simpler to implement than other green energy technologies. A small hydropower
scheme requires both water flow and a drop in height called a head to produce
useful power. Water in nature is considered a source of power when it is able
to perform useful work particularly turnning water wheels to generate
electricity at a rate such that the development of power can be accomplished in
a most efficient and economical way (Adejumobi, 2011). About two-third of Nigeria lies in the watershed of the Niger River which empties into the Atlantic at the Niger
Delta with its major tributaries; The Benue in the Northeast, the Kaduna in the
North Central, the Sokoto in the Northwest, and the Anambra in the Southeast.
The Niger is African’s third longest river and fifth largest in terms of
discharge. Several rivers of the watershed flow directly into the Atlantic notably
the Cross river in Southeastern Nigeria and the Ogun, Osun and Oyan in the
Southwest. (Muhammadu 2020).
Nigeria has a
gross exploitable large hydro potential of 14,750MW which 14% of the power is amounting
to 1930MW is harnessed contributing approximately 30% of the total installed
grid connected electricity generation (Karki et al, 2010).
Several rivers of Northeastern Nigeria
including the Komadugu Gana and its tributaries flow into Lake Chad. The lake
rests in the centre of a major drainage basin at the point where Nigeria,
Niger, Chad and Cameroon meet. Kainji Lake created in the late 1960s by the
construction of the Kainji Dam on the Niger River in Nigeria. The country's
topography ranges from lowlands a1ong the coast and in the lower Niger valley
to high plateau in the North and mountain along the eastern border, most part
of the country is linked with productive rivers which are scattered virtually
all over the country (Gerald, 2018). In Nigeria, electricity is seen as an
essential infrastructure in the same category as roads, telecommunication and
water. In fact, it is the life-blood of our national development and industrial
growth. Although electricity is treated as an essential social service. After
slightly over 100 years ago the industries are still characterized by erratic
supply of inadequate coverage in term of geographical spread covering less than
40% of the population and a record of low per capita consumption. (Gerald, 2018).
Energy is a critical factor in developing countries for economic growth as well
as for social development and human welfare (Gerald, 2018).
About two-third of Nigeria lies in the watershed
of the Niger River which empties into
the Atlantic at the Niger Delta with its
major tributaries. The Benue in the North central, the Kaduna in the North
Central, the Sokoto in the Northwest, and the Anambra in the Southeast. The
Niger is African's third longest river and fifth largest in term of discharge.
Several rivers of the watershed flow directly into the Atlantic notably the
Cross river in Southeastern Nigeria and the Ogun, Osun and Oyan in the
Southwest. (Gerald, 2018)
The first generating plant was built in Lagos
in 1898 by the colonial government and was managed by the Public Works Department (PWD). Native and Municipal
Authorities thereafter set up understating by 1950, the federal government
established electricity corporation of Nigeria (ECN)
through the instrument of ordinance No. 15 of 1950, which was vested with the
responsibility of running the generating stations subsequently in 1962 the Niger Dam Authority (NDA) was established to build
dam. However, the first large scale hydro power station in Nigeria was built in
Kainji on the river Niger with an installed capacity of 760MW and with
expansion to 1,150MW in 1968 then followed by Jebba in 1984 and Shiroro in 1990
with installed capacity of 570MW and 600MW respectively. (Zarma 2017)
Small and micro-hydro power plants have a
long tradition in Africa, but never reached a massive dissemination. Although,
the geographical conditions in some regions are favorable. In most of the
countries the existing MHP plants were funded by international donors or NGOs
and remained isolated projects, which are rarely well documented and were never
scaled up (Gaul, et al., 2010).
The aim of this work is to develop a mini
self-contained hydroelectric power plant that can generate electricity to
homes.
3.0 MATERIALS AND METHODS
3.1 Materials
The materials used
for the fabrication of the self-contained
hydroelectric power generation mini plant are: Pipe, Generator fan coil, Abro PVC gum, 1inch
mild steel stanchion, KCDT 6A control switch, 100 and 50 litre reservoirs,
P.T.F.E Teflon tray tape, inch and inch reducer, coil, Dynamo, rotor, inch ball gate, PVC adaptor pipe socket, 12V DC pump,
12V DC Battery, 1 inch Ash back knot.
3.2 Method of Assembling
Water
which was stored in the primary reservoir (downstream) was made to fall onto a
Pelton wheel turbine. The turbine was connected to a permanent magnetic motor
through a primary shaft. The motor was connected to the rotor. The rotor was
connected to dynamo. The rotor was connected to a stator. The stator was
connected to 12V bulb. The dynomo was connected to the 12V battery. The battery
was connected to the pump. The secondary reservoir (downstream) collects the
fallen water. The pump was connected to the upstream and downstream reservoirs.
3.3 Stages of the
self-contained hydroelectric power generation
3.3.1 Energy Supply
The up-stream
reservoir of 30 litres holds water (potential energy) and mounted on a
stanchion of head height 338.59m. This head height directly influences the
pressure exerted by the water fall on the turbine (kinetic energy) and consequently
affecting the electricity out-put.
3.3.2 Energy Conversion
The water stored in
the reservoir has potential energy. When the water flows from higher altitude,
the potential energy is converted to kinetic energy. The force of the fallen
water drives the turbine and creates torque hence kinetic energy is converted
to mechanical energy. The generator converts mechanical energy into electrical
energy. The electrical output generated is used to power three (3) 10W bulb and
to charge 12V battery.
3.3.3 Return
Fig 3.1 Stages of the
Self-contained Hydroelectric Power Generation
In this final stage,
the battery was used to power a 12V d.c pump which is used to recirculate water
collected at the down-stream back to the up-stream making it a closed system
and reducing water wastage
3.4 Fabrication of the Pelton Wheel
The
mini pelton wheel is made up of a paint bucket cover with eight 45-degree pipes
(2 inches in diameter), evenly divided into two vertical sections. From the
center of the cover, eight lines, each 45 degrees apart, are drawn. Along these
lines, marks are placed 6.5 centimeters from the tip of the cover, indicating
the points for drilling and attaching turbine blades. Using a hacksaw, holes
are cut at these marked points, forming eight openings on the cover. The
turbine cups are created from the 2-inch diameter pipes, each with holes bored
6.5 centimeter from a specific chosen end.
Fig. 3.2 Fabricated
Pelton Turbine
3.5 Fabrication of the Vane
Fig. 3.3 The Vane
2 Inch pipe was used
to develop the turbine vane. The pipe was cut 5cm into eight (8) different
sizes. The vane was cut using a hacksaw and the edges were polished and grinded
to give a curved edge.
3.6 Determining the Head
Head
can be defined as the vertical distance that water falls from the upstream
level to the downstream level. Head produces a pressure and the greater the
head, the greater the pressure to drive the turbines. To determine head, we
need to consider the gross head and the net head. Gross head is the maximum
available vertical fall in the water. It is the vertical distance between the
top of the penstock that conveys the water under pressure and the point where
the water discharges from the turbine. Head is typically measured rather than
calculated (Olumide et al., 2012
3.7 Determining the flow rate
Area
and speed method is used in streams with a higher flow. Water flow can be
measured by constructing a weir of known dimensions and measuring the time
necessary for the pooled water to rise to a known height. An object can be
placed and timed to float from the upstream to the downstream line. Flow rate is
the product of water volume and cross sectional area as given in equation 3.1 (Yulianus
and Adelhard, 2014).
------------------------------------- 3.1
3.8 Power Generation
The
power potential was determined by measuring the flow rate and the head. The
power generation is given by:
----------------------------- 3.2
3.9 Mechanical
Efficiency
The
Mechanical efficiency is the ratio of the mechanical output power to the mechanical
input power and given by equation 3
-------------- 3.3
3.10 Water outlet
velocity is given by
---------------------------------- 3.4
3.11 Electrical
generator efficiency
∫------------------------------------- 3.5
3.12 Efficiency of the self-contained
hydroelectric power generation plant
∫
------------------------------ 3.6
Fig. 3.4 Pump Assembly
Figure 3.5: The Mini Hydro Power Plant
4.0 RESULTS AND DISCUSSIONS
4.1 Results: The
results of the experiment conducted on the mini hydroelectric power plant are
shown in table 4.1 and 4.2.
Table 4.1:Result from the Measurements by Flow
Rate
Test number
Opening of the tap
gate
Y [%]
Mechanical power
Pmech
[MW]
Flow rate
Qrate
[m3/s]
Leakage flow
Qk
[m3/s]
Cooling flow
Qcooling
[m3/s]
Total flow
Qturbine
[m3/s]
Net head
Hn
Efficiency
[%]
1
78.8
30.65
87.78
0.6
0.0
88.67
42.40
85.10
2
80.7
30.71
81.02
0.6
0.0
81.67
42.75
87.80
3
78.4
28.03
74.43
0.6
0.0
75.14
43.09
91.16
4
68.5
25.04
67.03
0.6
0.0
68.74
43.18
89.91
5
60.4
21.56
59.29
0.6
0.0
60.99
43.27
87.84
6
50.9
18.02
50.10
0.6
0.0
52.90
43.52
84.92
7
45.5
14.72
43.41
0.6
0.0
46.11
43.64
80.08
8
36.7
10.14
34.98
0.6
0.0
35.68
45.00
65.89
Table 4.2: Calculated
variables
Water inlet velocity [m/s]
Water outlet velocity [m/s]
Net head [m]
Generator Efficiency [%]
Mechanical power [W]
Turbine efficiency [%]
10.06
1.56
337.61
88.45
9.57
79.52
9.64
1.50
338.76
86.44
8.42
87.43
9.28
1.44
339.86
85.43
7.20
86.59
8.93
1.39
340.81
82.41
6.07
85.03
8.37
1.30
342.23
80.40
5.41
81.31
7.70
1.20
345.59
79.35
4.31
69.94
7.13
1.11
350.19
77.26
3.49
65.47
6.17
0.96
358.80
75.97
3.58
63.13
5.09
0.79
360.64
72.50
2.28
60.34
4.10
0.64
364.29
69.85
2.12
58.34
Fig. 4.1 Graph of
Mechanical Power against Flow Rate
Fig. 4.2 Graph of Turbine efficiency against
Water inlet velocity
Fig. 4.3 Graph of
Generator Efficiency Against inlet Velocity
Fig. 4.4 Graph of
Generator Efficiency against Net Head
Figure 4.5 Graph of Turbine Efficiency
against Net Head
4.2 DISCUSSIONS
Figure
4.1 shows the graph of Mechanical power against flow rate, it can be seen from
the graph that the highest mechanical power was recorded to be 30.65 MW and the
lowest was recorded to be 10.14 at total flow rates of 88.67% and 35.68%
respectively. The graph shows that as the total flow rate increases the
mechanical power also increases.
Figure
4.2 shows the graph of Turbine efficiency against water inlet velocity. The
highest turbine efficiency was recorded to be 79.52% and the lowest was
recorded to be 58.34 % at water inlet velocity of 10.06m/s and 4.10m/s
respectively. It can be seen from the graph that as the water velocity
increases the turbine efficiency also increases.
Figure
4.3 shows the graph of Generator efficiency against the water inlet velocity.
The highest generator efficiency was recorded to be 88.45 and the lowest was
recorded to be 69.85at 10.06% and 4.10% water inlet velocity. It can be seen
that as the inlet water increases the generator efficiency also increases.
Figure 4.4 shows the graph of Generator
efficiency against Net Head. The highest Generator efficiency was recorded to
be 88.45% and lowest was recorded to be 69.85% at net heads of 337.61m and
364.29m respectively. It can be seen from the graph that decrease in net head
increases the generator efficiency because the water is closer to the turbine
and produces more energy.
Figure 4.5 shows the graph of Turbine
efficiency against the net head. The highest turbine efficiency was recorded to
be 79.52 and the lowest turbine efficiency was recorded to be 58.34 at net heads
of 337.61m and 364.29 m respectively. It can be seen from the graph that as the
net head decreases the turbine efficiency increases because the water height is
closer to the turbine
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Cite this Article:Bwala, EB; Nathan, C; Adamu, GG; Oluwapelumi, BO (2024). Design and
Construction of a Mini Self-Contained Hydroelectric Power Generation Plant. Greener Journal of Science, Engineering
and Technological Research, 13(1): 61-68, https://doi.org/10.15580/gjsetr.2024.1.112024173.
