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IIUM Engineering Journal, Vol. 14, No. 2, 2013 Karimov et al.
173
THE ECONOMICS OF MICROHYDRO POWER PLANTS
K
H
.
S.
K
ARIMOV
1,2
,
M.
A
BID
1
,
M.W.
A
L
-G
RAFI
3
,
S.I.
I
SLOMOV
4
AND
N.H.
K
ARIMOVA
4
1
GIK Institute of Engineering Sciences and Technology, Topi, Pakistan.
2
Physical Technical Institute of Academy of Sciences, Tajikistan.
3
Department of Mechanical Engineering, Taibah University,
Al-Madina Al-Munawara, Saudi Arabia.
4
Institute of Economics of Academy of Sciences of Tajikistan, Dushanbe, Tajikistan.
khasan@giki.edu.pk, abid@giki.edu.pk
ABSTRACT:
In this paper economics of a micro-hydropower plant installed in the
village named Pashmi-Kuhna of Tajikistan and of a battery-based micro-hydropower
plant on catamaran for free water flow operation designed, fabricated and tested in GIK
Institute of Pakistan are discussed. For the economic evaluation of these power plants,
the life-cycle costing approach is used. Finally the costs of the produced energy by the
micro-hydropower plants are calculated.
ABSTRAK:
Menerusi kertas kerja ini, bidang ekonomi loji hidrokuasa mikro yang
dibina di perkampungan Pashmi-Kuhna, Tajikistan diperbincangkan. Loji hidrokuasa
mikro di atas katamaran yang membolehkan gerakan air bebas berasaskan bateri direka,
dicipta dan diuji di Institut Pakistan GIK. Untuk penilaian ekonomi loji ini, pendekatan
pengekosan kitar hidup telah digunakan. Akhirnya, kos dihitung berdasarkan kuasa yang
dihasilkan oleh loji hidrokuasa mikro.
KEYWORDS:
micro-hydro; power plants; economics; life-cycle costing; annualized life-cycle
cost
1. INTRODUCTION
Economics of renewable energy and, in particular, of hydropower systems are
described in detail in [1-10]. The cost of the micro-hydropower system depends on a
number of factors including costs of equipment, transportation and preparation of the
necessary documents concerning the conditions of area, head (water level), flow rate, type
and class of the micro-hydropower system [1]. Usually the cost of the station is in the
range of US$ 1500-2500 for 1 kW of installed power. Depending on the power and
location the cost of micro-hydropower system of power less than 5 kW is approximately
US$ 2500 for 1 kW [1]. It seems costly as the power produced is low, but in this cost
calculation, the cost of batteries is included.
If the head is higher and flow rate is lower, then the cost of the station is less than the
case of lower head and higher flow rate. This is due to the lower costs and smaller sizes of
water pipes and turbine in the case of high head and low flow rate. The cost of micro-
hydropower system depends on quality and quantity of equipments and materials that will
be used for the project, and of the cost of construction of powerhouse, laying of pipes and
other factors. If the work will be done by the contractor, then the total cost of micro-
hydropower system will be higher with respect to the case when these works are done by
the owner of the station. The project of every micro-hydropower system is unique. At the
same time it is observed that 25 % of the cost of equipment is the cost of the
IIUM Engineering Journal, Vol. 14, No. 2, 2013 Karimov et al.
174
electromechanical equipment, and 75 % of all the expenses depend on the location of the
system and condition of the micro-hydropower system [1]. In this work, the economics of
the micro-hydropower plants (MHP) installed in the village named Pashmi-Kuhna of
Tajikistan and of the battery-based micro-hydropower plant on catamaran for free water
flow operation designed, fabricated and tested in GIK Institute of Pakistan are discussed
[5].
2.
ECONOMICS OF MICRO-HYDROPOWER PLANT INSTALLED
IN THE VILLAGE PASHMI-KUHNA OF TAJIKISTAN
A micro-hydropower plant manufactured by Turbine Constructing Industrial Union
“Leningrad Metallic Plant” [11] was selected and installed by Karimov U.Kh. and
Karimov Kh.S. Table 1 shows technical parameters of this micro-hydropower system. In
this micro-hydropower system, a three-phase asynchronous generator (4
100L2
) with
squirrel-cage-type rotor is used. The stator of the generator is delta-connected, with
maximum power of 5.5 kW and synchronous rotation velocity of rotor of 3000 RPM. The
shaft of the propeller turbine was connected directly to the shaft of the generator.
Excitation of generator is made by 30 capacitors (10 pieces for each phase) with
capacitance of 10 mF each, which are installed in the voltage regulator BARS-004.
Table 1: Technical parameters of the micro-hydropower plant manufactured by
“Leningrad Metallic Plant” [11-13].
Head, m 4 to 10
Flow rate, liter/second 75 to 83
Electric power, kW 0.5 to 4.0 depending on the head
Number of phase 3
Nominal output voltage, V 220
Frequency, Hz 50
Mass, kg
•
Power block, kg
•
Voltage regulator BARS-004, kg
97
50
Water inlet hose-pipe , kg 15
This micro-hydropower system was installed in a remote mountain village named
Pashmi-Kukhna situated in the national park “Shirkent” in Tursun-zoda district. Due to the
absence of the roads for automobile, all equipments including plastic pipes was
transported by the beast of burden (donkeys) for a distance of around 30 km. Micro-
hydropower system was installed on the derivative canal from river Shirkent. Water
current power was calculated to be almost 8-12 kW in the derivative canal by the
estimation of head and flow rate using well known approaches described in [11]. The
MHP was installed close to the village houses, and by using short transmission lines (100-
300 m), electical power is supplied from station to the houses (Fig.1).
In order to achieve the required water head, plastic pipes of internal diameter 0.19 m
and length of 5.5 m were fixed at an angle of 45 degree to the horizontal surface. Several
pipes were joined by winding two layers; one of rubber and other of firm rubber cloth and
then joints were fixed with metallic horse collar. It was important to fix the energy block
(generator and turbine) well. This was done using ropes and stones on two sides of the
IIUM Engineering Journal, Vol. 14, No. 2, 2013 Karimov et al.
175
generator and turbine. In order to clean water from sand and stones, a small settling basin
of size 3
3
1.5 m
3
was also constructed.
Fig. 1: Micro-hydro-electric power station installed in the village named Pashmi-
Kukhna.
The tests of the micro-hydropower system showed that for a water head of 4-6 m,
station was not working well even at the load power of 0.1-0.2 kW in each phase. After
this the water head was increased up to 10-12 m, it provides stable operation of the station
at different loads. During tests, angular velocity of the generator’s shaft was controlled by
a tachometer. At an angular velocity of almost 3000 RPM, self-excitation of the generator
was observed which confirmed that the output voltage and rotor’s angular velocity
relationship is non-linear for the asynchronous generators. The successful operation of the
micro-hydropower system replaced the kerosene lamps into electric lamps at all nine
houses at the village. Later on a similar type of micro-hydropower plant was installed in
the village Hakimi in the same district.
For the economic evaluation of a MHP system, the parameters that are usually
considered are [14]: life-cycle cost (LCC), payback period (PP) and rate of return (RR).
LCC is the sum of all the costs of a system over its lifetime, expressed in today’s money.
For the analysis of the MHPs, the lifetime of the MHP can be taken as 10 years. For a
detailed analysis, it is important to use parameters including: present worth (PW) which is
the equivalent value in today’s economy of the future costs (future cost should be
multiplied by a discount factor calculated from a discount rate), period of analysis (the
lifetime of the longest-lived system under comparison), excess inflation (the rate of price’
increase of a component above general inflation), discount rate (the rate at which money
would increase in value if invested), capital cost (the total initial cost of buying and
installing the system), operation and maintenance (the amount spent each year in keeping
the system operational) and replacement cost (the cost of replacing each component at the
end of its lifetime). The calculations are made on the basis of the approach described in
reference [14]:
PW= Cr
ɯ
Pr (1)
where PW is the present worth for a single future payment, Cr is a single future cost, Pr is
discount factor for a single future payment. In the case of repeating payments [5]:
PW = Ca
ɯ
Pa (2)
IIUM Engineering Journal, Vol. 14, No. 2, 2013 Karimov et al.
176
where PW is the present worth for annual future payment, Ca is annual future cost and Pa
is a discount factor for annual future payment . The Pa and Pr is determined as [14];
Pr = [(1+i)/ (1+d)]
N
(3)
and Pa = [(1+i)/(1+d)]·{[(1+i)/(1+d)]
N
-1}/{[(1+i)/(1+d)]-1} (4)
where N is the period of analysis, d is discount rate and i is excess inflation ( it is “the rate
of price increase of a component above or below general inflation that is usually assumed
to be zero” [14]) .
The annualized life-cycle cost (ALCC) is determined as = LCC/Pa (5)
The Pr and Pa can be found using tables presented in [14]. Table 2 shows life-cycle
costing calculation for the micro-hydropower plant installed in the village Pashmi-Kukhna
of Tajikistan.
Table 2: Life-cycle costing calculation of MHP installed in the village Pashmi-Kukhna
of Tajikistan.
System description:
4 kW micro-hydropower plant
Parameters:
Period of analysis = 10 years; Excess Inflation
i
= 0; Discount Rate
d
= 10%
Capital Cost
of Hardware (micro-hydropower plant, pipes, poles, cables, bulbs):
Hardware $ 1900
Installation $ 400
Transportation $ 200
Total
$ 2500
Operation and Maintenance:
Annual Cost $ 200
Discount factor (Pa) 6.14
Present Worth
$ 1228
Fuel:
Annual Fuel cost: $ Nil per year
Discount Factor (Pa):
Present Worth $ Nil
Replacements:
Item Year Cost Pr PW
Pipes 5 $ 200 0.62 $ 124
Total: $ 124
Total Life-Cycle Cost : $ 3852
Annualization Factor (Pa): 6.14
Annualized Life-Cycle Cost: $ 627.4
Assuming that micro-hydropower plant is working 16 hours a day during 350 days in a
year, Electricity produced per year (kWh) = 4 kW x 16 hr x 350 x 0.9 = 20160 (kWh)
Efficiency of transmission lines assumed is almost 90%.
Electricity cost ($ / kWh) = 627.4 ($) / 20160(kWh) = 0.03 ($/kWh) = 3 Cent/kWh.
It is known that for small and large hydropower plants the cost of electricity is in the range
of 3-10 Cent/kWh and 2-5 Cent/kWh respectively [15].
IIUM Engineering Journal, Vol. 14, No. 2, 2013 Karimov et al.
177
3.
ECONOMICS OF BATTERY-BASED MICRO-HYDROPOWER
PLANT ON CATAMARAN FOR FREE WATER FLOW
OPERATION DESIGNED IN GIK INSTITUTE OF PAKISTAN
Micro-hydropower plants for free water flow operation provide unique chance to use
hydropower of canals and small rivers where no waterfalls or sufficient large water heads
is available. In this case only kinetic energy of water flow can be converted into electric
power. As battery based micro-hydropower systems can operate and store energy
continuously, almost 24 hours per day, electric energy produced daily will be sufficient
for the main electric and electronic appliances of an average family.
The battery-based micro-hydropower systems with storage of electric energy in the
electrochemical batteries are economically advantageous to use if the peak load is
considerably larger than the hydropower plant [1]. In this case hydro power is converted
into electric power using micro-hydropower system and stored in the batteries and is used
during shorter time at peak/maximum load. The batteries in this case undergo deep
discharge of up to 50% of their total capacity and after that these are charged. The
battery-based micro-hydropower systems belong to the systems that are not connected
with the grid and can work jointly with photo-voltaic and wind power plants on common
load. This type of system is called as hybrid system. The battery-based micro-hydropower
systems as compared to the AC-direct micro-hydropower systems have the advantage as
they can work at relatively low water flow rates but at the same time being able to provide
the necessary peak power in the load when it is required [1]. Block-diagram of the battery-
based micro-hydropower system is shown in Fig. 2. It is assumed that a DC generator is
used however if an AC generator is used then an alternating current should be rectified by
a rectifier. As seen from block-diagram (Fig. 2) the battery-based micro-hydropower
systems can feed DC loads directly from batteries and AC loads are fed through an
inverter. If the DC voltage exceeds nominal value in the input of the battery, the charge
regulator turns on ballast loads, providing normal charging regime of the battery.
Fig. 2: Block-diagram of the battery-based micro-hydropower systems.
It is noted that the battery-based micro-hydropower systems can provide a peak
power in the load that is much more than the installed power of the system. For example,
the battery-based micro-hydropower system of power of 400 W can provide 5 kW peak
power at the corresponding capacity of the batteries. The industry produces battery-based
micro-hydropower systems for DC voltage of 12, 24, 36, 48, 120 and 240 V. Selection of
output voltage depends on the power of the micro-hydropower systems and the distance
between of generator and consumer: as the distance is larger the voltage should be higher
to decrease the losses in the power transmission lines. There are commercially available
Turbine and
generator
Battery bank Inverter
AC loads
DC loads Overcharge controller
Ballast loads
IIUM Engineering Journal, Vol. 14, No. 2, 2013 Karimov et al.
178
battery-based micro-hydropower systems from power of 100 W to 1600 W. In Table 3,
data on mechanical and electrical parameters and properties of battery-based micro-
hydropower systems are given [1]. These micro-hydropower systems are adapted for
operation in autonomous regime.
In some countries floating, barge or catamaran micro-hydropower systems are used
where the turbine and generator are installed on the small raft that is fixed by ropes to the
bank of river or canal as shown in Fig. 3. Figure 4 shows battery-based micro-hydropower
plant of power of 1 kW on catamaran for free water flow operation designed and
fabricated in GIK Institute of Pakistan. This battery-based micro-hydropower plant on
catamaran has three turbines (wheels) blades having phase angle of 15-25
0
from each other
to provide uniform rotation of the turbines shaft. Table 3 shows parameters and properties
of the battery-based micro-hydropower systems.
Fig. 3: Floating micro-hydropower system: 1-raft, 2–turbine, 3–generator, 4–reducer, 5–
rope.
Fig. 4: Battery-based micro-hydropower plant on catamaran for free water flow operation
designed and fabricated in GIK Institute of Pakistan.
The battery-based micro-hydropower systems with storage of electric energy in the
electrochemical batteries are economically advantageous to use if the peak load is
considerably larger than the hydropower. In this case the hydro power is converted into
electric power using micro-hydropower system and stored in the batteries and is used
during short time at peak/maximum load. The battery based micro-hydropower systems
can operate and store energy continuously, almost 24 hours per day. Table 4 shows life-
cycle costing calculation sheet for battery-based micro-hydropower plant on catamaran for
free water flow operation designed and fabricated in GIK Institute of Pakistan.
2
1
3
4
5
Ri
IIUM Engineering Journal, Vol. 14, No. 2, 2013 Karimov et al.
179
Table 3: Parameters and properties of the battery-based micro-hydropower systems.
Systems Output
power
(W)
ɇ
ead
(m)
Flow rate
(m
3
/s)
DC voltage
(V)
Type of
turbine and
generator
Very low head 100-1000 1-3 0.03-0.065 12/24/48/120 Propeller.
Permanent magnet
DC generator
Low and
medium head
50-1600 3-60 0.0006-0.01 12/24/48/120
urgo.
Permanent magnet
DC generator
High head 100-1500 6-180 0.00025-0.016 12/48 Pelton.
Permanent magnet
DC generator
Water current 100 flowing 0.25 12/24 Propeller.
Submersible
generator
Table 4: Life-cycle costing calculation sheet for battery-based micro-hydropower plant on
catamaran for free water flow operation designed in GIK Institute of Pakistan.
System description:
1 kW micro-hydropower plant
Parameters:
Period of analysis = 10 years; Excess Inflation
i
= 0; Discount Rate
d
= 10%
Capital Cost:
Hardware (micro-hydropower plant, batteries, cables, bulbs ):
Hardware : $ 2694.6
Installation $ 100
Transportation $ 90
Total
$ 2884.6
Operation and Maintenance:
Annual Cost $ 50
Discount factor (Pa) 6.14
Present Worth
$ 307
Fuel:
Annual Fuel cost: $ Nil per year
Discount Factor (Pa):
Present Worth $ Nil
Replacements:
Item Year Cost Pr PW
Battery 5 $ 200 0.62 $ 124
Total: $ 124
Total Life-Cycle Cost: $ 3315.6
Annualization Factor (Pa): 6.14
Annualized Life-Cycle Cost: $ 540
IIUM Engineering Journal, Vol. 14, No. 2, 2013 Karimov et al.
180
Assuming that micro-hydropower plant is working 24 hours a day during 350 days in a
year, Electricity produced per year (kWh) = 1 kW x 24 hr x 350 x 0.9 x 0.75= 5672
(kWh).
Taking efficiencies of battery and transmission lines of 75% and 90% respectively.
Electricity cost ($ / kWh) = 540 ($) / 5672 (kWh) = 0.1 ($/kWh) = 10 Cent/kWh.
It is known for small and large hydropower plants the cost of electricity is in the range of
3-10 Cent/kWh and 2-5 Cent/kWh respectively [15].
In this paper, expenses including cost of design, rent of land, license of land,
unpredictable expenses, investigation of feasibility of the project, rent of water may also
be considered in the capital cost as in above calculations these costs are nt considered.
4. CONCLUSION
The unit electricity cost determined from the life-cycle cost and annual life-cycle cost
analysis is the main parameter in the economics of the renewable energy resources
equipment and in particular, in the micro-hydropower systems. Calculations showed that
the costs of the electric energy generated by the MHPs installed in Tajikistan and Pakistan
is almost 3 and 10 cent/kWh respectively. The cost of the micro-hydropower plants can be
reduced by using state of the art technology, cost effective generators and turbines as these
are the most expensive parts in MHP and by controlling the cost of construction. Similarly
cost can be controlled by using induction motors as generators and pumps as turbines. The
calculation of the electricity cost done in this paper may be considered as an internal cost.
The calculations of the hydropower electricity should also include the external cost
including environmental (cost of risks of damages to the environment and human health
due to pollutions) and non-environmental costs (costs are associated with employment,
security aspects etc). Considering external costs, hydropower will be more economical and
attractive as compared to the non-renewable sources. Catastrophes and land effects are
much less for the micro-hydropower systems compared to the large power hydro-electric
systems. However only visual intrusion can be taken into consideration. It is therefore
concluded that the future development of the micro-hydropower systems can bring more
environmental and economical benefits as compared to the larger power energy
technologies.
ACKNOWLEDGEMENT
The authors are thankful to authority of GIK Institute of Pakistan and Academy of
Sciences of Tajikistan for the support of the projects. Authors also grateful to researchers,
technicians and students of both organizations for their help in completing these projects.
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