This document provides details on the proposed hydroelectric power station "Mala Dubravica" to be built on the Drina River in Serbia. It discusses two proposals for the station's capacity and presents technical specifications for the higher capacity Proposal B, which would have an installed capacity of 122 MW. The document outlines the steps required to construct the power station, including conducting studies, drawing up projects, and addressing legal issues. It provides preliminary investment estimates totaling over 172 million euros, covering construction, equipment, and project development costs. The power station would create a 17 km long reservoir and require relocating local infrastructure.

1. HYDROELECTRIC POWER STATION
“MALA DUBRAVICA”
Beograd, 2009.

2. BASIC HYDROLOGIC, TECHNICAL AND INVESTMENT DATA FOR
THE
HYDROELECTRIC POWER STATION “MALA DUBRAVICA”
1. General data and requisite technical documentation
The hydroelectric power plant (HPP) “Mala Dubrava” is located in the Municipality of Ljubovija
on the river Drina, and borders on The Republic of Srpska.
The HPP is situated in the canyon of the Drina river, about 15 km upstream from the town
Ljubovije in Serbia and downstream from the town Bratunac in the Republic of Srpska. The location of a
dam is supposed to be constructed at the entrance of the narrowest part of the canyon, by the village
Nadpolje in Serbia and the village Dubravica in the Republic of Srpska.
The dam would cause a 17 km long accumulation lake, which would flood several villages on
the very banks of Drina as well as a part of the road infrastructure.
This is why an expropriation of the land and a new road infrastructure are absolutely necessary.
The height of the dam should be about 25 m, and its length about 320 m.
Two suggestions concerning the installed capacity have been brought forward, both of which
shall be presented in this text, whereas only the proposition indicating a higher installed capacity and
fewer working hours during the year is to be furtherly discussed in terms of technical and economical
details.
PROPOSITION A
General technical data for this HPP are the following:
- Watercourse ....................................................................................................................... Drina
- Peak height of the dam ....................................................................................................... 40 m
- Peak elevation of the upper course of the river ........................................................ 177,5 mnm
- Peak elevation of the lower course of the river ............................................................ 160 mnm
- Peak flow rate per year (1%) ...................................................................................... 5831 m3/s
- Mean flow rate per year ................................................................................................ 371 m3/s
- Minimal flow rate per year ............................................................................................... 55 m3/s
- Duration of the installed flow rate, per year..................................................................... 60 days
- Duration of the minimal flow rate, per year....................….............................................. 60 days
- Installed flow rate........................................................................................................... 630 m3/s
- Net head of the plant ....................................................................................................... 17,5 m
- Installed capacity.............................................................................................................. 90 MW
- Number and type of the turbine ................................................................................... 6, Kaplan
- Production of the electrical energy, per year............................................. about 397,5·106 kWh
- Working hours of the HPP, per year ......................................................................... 4416 hours
PROPOSITION B
General technical data for this HPP are the following:
- Watercourse ...................................................................................................................... Drina
- Peak height of the dam ....................................................................................................... 25 m
- Peak elevation of the upper course of the river ........................................................ 177,5 mnm
- Peak elevation of the lower course of the river ............................................................ 160 mnm
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3. - Peak flow rate per year (1%) ...................................................................................... 5831 m3/s
- Mean flow rate per year ................................................................................................ 371 m3/s
- Minimal flow rate per year ............................................................................................... 55 m3/s
- Duration of the installed flow rate, per year .................................................................... 90 days
- Duration of the minimal flow rate, per year….……….….....................…......................... 60 days
- Installed flow rate .......................................................................................................... 857 m3/s
- Net head of the plant ....................................................................................................... 17,5 m
- Installed capacity ........................................................................................................... 122 MW
- Number and type of the turbine ................................................................................... 6, Kaplan
- Production of the electrical energy, per year ............................................... about 435·106 kWh
- Working hours of the HPP, per year ......................................................................... 3565 hours
The difference between the two propositions is in the installed capacity and the production of
the electrical energy. The proposition B offers greater installed capacity, fewer working hours during the
year, but it has a greater production of the electrical energy than the proposition A. Since the
construction and the size of the dam are the same in both propositions, the proposition B is naturally in
advantage, because it provides a greater production of the electrical energy.
This is why this technical and economic analysis takes only the proposition B into account.
In order to construct this HPP (upon reaching the agreement), the following steps should be
applied:
- conducting a research in the field and gathering the necessary information for drawing a
plan,
- drawing up a detailed project analysis and studies based on hydrology, geohydrology,
geology, geodesy, soil science, seismology, which should also incorporate the estimated
effect on the environment,
- making a feasibility study with detailed description and data on the district and the
construction site, including a detailed analysis of the possible consumption area in terms of
electrical energy and the analysis of the data on the power network of the local power plant
and its willingness to take over the total production of the electrical energy from the HPP;
with a detailed analysis of possible risks at local and state level concerning legal and other
regulations; with a detailed analysis of acquisitons of foreign and domestic equipment along
with its exact prices and dates of delivery; with precisely defined duration of the
construction of the HPP, visually presented in form of the Gantt chart showing phases of
the project, and finally a résumé and a suggestion whether the construction of the HPP
should be undertaken.
- Drawing up the feasibility study of the project includes the following:
1. Introduction.
2. Hydrologic, geodesic, geologic and pedological basis as the starting point.
3. Description and analysis of the quality of water.
4. Desctiption of the protection of water.
5. Presentation of the elemental physical indexes of the river basin to which the river Ibar
belongs.
6. Presentation of the analysis of the low waters.
7. Selection of the installed flow rate.
8. Selection between the different types of hydroelectric power stations.
9. Basic financial estimate and selection of hydromechanical and machine armature.
10. Selection of the turbine in accordance with the defined hydraulic and energy parametra.
11. Selection of the generator in accordance with the parametra on the shaft of the tubine.
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4. 12. Selection of other electrical equipment.
13. Selection of the flow rate regulator.
14. Estimate of the production of electrical energy.
15. Fixing a working regime for the HPP.
16. Defining a powerhouse with elemental geometric dimensions at the appropriate cross
sections and vertical sections.
17. Presentation of the powerhouse with the lower course of the river.
18. Approximate investment.
19. General conclusion.
20. Annex.
- Construction of the Main project consists of the following:
• Hydrologic part
1. Gathering data and analysing the following bases:
- topographic basis with sections in ratio of 1: 25000 and 1: 100000,
- selecting the location of the HPP in ratio of 1 : 500,
- geologic basis in accordance with the maps of the entire river basin surrounding
the location of the HPP and the dam
- pedological map in ratio of 1 : 5000,
- detirmining how much the terrain is overgrown with vegetation on the basis of
sections and aerial photographs,
- complete construction and technical documentation for the dam “Mala
Dubravica”,
- complete hydrologic basis for the microlocation of the HPP on the river Drina
- precipitation on the basis of the meteorologic data for the microlocation of the
HPP on the river Drina
2. Complete hydrologic analysis and estimate for each month of the year
3. Estimate of the high waters (for ten years, a hundred, a thousand years).
4. Estimate of the low waters.
5. Verifying the defined biological minimum.
6. Calculating and defining the biological minimum under the new conditions.
7. Calculating the possible waterpower for each month and defining the installed H and Q on
the basis of engineer and economic analysis.
8. Calculating the annual production of the electrical energy.
9. Defining the drainage channel and the (water) flow calming system.
• Mechanical part
1. Description of the hydroelectric power station with authoritative data on the system of
supply pipes and safety parts.
2. Determining net head of the plant and nominal strength for the HPP “Mala
Dubravica”.
3. Estimate of the electric resistance of the pipeline system for the power station.
4. Estimate of the gross and net head.
5. Estimate of the power specifications of the turbines for the power station.
6. Estimate of the regulation specifications of the turbine aggregates for the power
station.
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5. 7. Calculating time constants of the inertia of the rotational masses of the turbine
aggregates and water in the pipeline for the power station.
8. Verifying the minimal pressure behind the turbine-inlet valve.
9. Selecting the type of the turbine.
10. Selecting the flow rate regulator.
11. Estimate of the production of the electrical energy.
12. Specifications and preliminary measures and estimate for the construction,
mechanical and electrical part for the power station.
13. Drawing up a dynamic benefit-cost analysis for the power station.
14. Drawing up a complete technical documentation for the power station.
• Electric part
1. Estimating and selecting the generatior and generator protective devices.
2. Defining, estimating and selecting equipment which runs the generator.
3. Defining, estimating and selecting other electrical equipment (measuring instruments, signal
system etc.)
4. Estimating and selecting a cable which connects the generator and the transformer.
5. Estimating and selecting the transformer and transformer protective devices (external
installation).
6. Estimating and selecting the switches/circuit breakers and disconnectors (external
installation).
7. Estimating and selecting the surge arrestors (external installation).
8. Estimating and selecting a high-voltage cable (110 kV) with the cable head from the
transformer to the connection duct (external installation).
9. Making a plan of the distribution network of 35kV.
10. Inspecting the plan of the existing installation 0,4 kV (for the purposes of its own
consumption).
11. Drawing up the appropriate technical documentation [unipolar and tripolar schemes
(energetics, own consumption, automation, measurement setup etc.), disposition of
equipment, descriptions, specifications, etc.].
• Electromechanical part
1. Defining, estimating and selecting the equipment which controls the flow of water
through the turbine (electromechanical, regulatory and turbine-inlet valve with a liquid
level gauge).
2. Defining, estimating and selecting the control, measuring and regulatory equipment
which runs the mentioned valve (regulation of the constant flow).
3. Defining, estimating and selecting all the protective devices at the HPP.
4. Defining, estimating and selecting of equipment for high voltage switchyard.
5. Defining, estimating and selecting the equipment for managing and controlling the
parallel functioning of the turbine-inlet valve and the automation of the generator
(start/stop automat).
6. Drawing up the appropriate technical files.
Along with these parts of the main project, a section dealing with ecological problems and
possible negative influence of the HPP on the environment shall be included.
The production of the main project requires a field work of up to 5 days for certain fields of
activity.
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6. At this moment, it is possible to give a rough estimate of the necessary investment for
constructin the HPP “Mala Dubravica”. A rough estimate implies that the estimates in the subsequent
studies and projects may differ in ± 10 %.
2. Additional data
Microlocation of the dam and the powerhouse of the HPP “Mala Dubravica” is situated
immediately by the road Loznica-Ljubovija-Rogačica-Bajina Bašta. This is where a concrete spillway
dam is supposed to be set up with the powerhouse on the right bank of the river Drina, which would be
an integral part of the dam. Gross height of the dam (from the foundation up to the roof of the
powerhouse) shall be 40 m. It is necessary to build access roads and a ramp from the road Loznica-
Bajina Bašta to the dam. The accumulation which will be caused by the rising of the water level will be
17 km long, its volume will be about 30,000.000 m3, and it will flood a relatively populated area with
some cultivable soil. The land belongs to municipality, that is, to waterworks and private owners.
Peak elevation of the normal deceleration of the accumulation is beneath the highway Loznica-
Bajina Bašta.
The accumulation can be made use of not only for the purposes of producing electrical energy,
but also for irrigarion and recreation purposes.
The powerhouse, which is to be an integral part of the dam, will be situated immediately by the
access road. Two types of turbines can be installed in the powerhouse – Kaplan (this type is specified in
the preliminary investment), Bulb and Pit (tubular) turbine.
A possible appearance of the powerhouse can be seen in Picture 1:
Picture 1
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7. 3. Geological data
The site of the dam is located on the river Ibar and it is situated among volcanic rocks dating
from the Neogene period which are exposed at the sides. The rocks possess good physical and
mechanical features.
The foundational rock in the riverbed and in low elevations on the left side is covered with river
alluvium made of pebbles and sand, whose possibility moves from 2 – 3 m on the banks and up to 0,5
m in the riverbed close to the banks. There is a wide river terrace made of clay-coated pebbels and
sand under the future construction site of the dam.
4. Data on preliminary investment
The exact value of the investment in the HPP “Mala Dubravica” will be known upon finishing the
Feasibility study and preliminary design, whereas at this moment it is possible to provide a preliminary
estimate which should not differ much form the actual one.
1. Construction works
- Dam (concrete).................................................................................................60,000.000 €
- Powerhouse..................................................................................................... 12,500.000 €
- River path ............................................................................................................ 250.000 €
- Drainage channel ..............................................................................................2,000.000 €
- Construction works with unexpected difficulties (10%) ..................................... 7,475.000 €
- Transportation and assembly (15%) ............................................................... 19,808.750 €
TOTAL: 102,033.750 €
2. Mechanical and hydromechanical equipment
- Turbines (6 turbines) ....................................................................................... 21,010.000 €
- Turbine-inlet valves (6 valves) .......................................................................... 2,060.000 €
- Segmented ball valves (7 valves) ..................................................................... 2,700.400 €
- Overhead crane ................................................................................................... 850.750 €
- Regulatory equipment with automatic regulator ................................................ 1,010.000 €
- Transportation and assembly (15%) ................................................................. 4,559.140 €
- Unexpected costs (10%) ................................................................................... 2,763.115 €
TOTAL : 34,953.405 €
3. Electrical equipment
- Generators (6 generators with actuating system) ............................................18,500.000 €
- Automatic and protective devices and management ........................................ 1,350.000 €
- High-voltage equipment and installations ......................................................... 8,000.000 €
- Aerial cable line .................................................................................................... 640.000 €
- Other equipment .................................................................................................. 160.500 €
- Transportation and assembly ........................................................................... 3,624.352 €
- Unexpected costs ............................................................................................. 2,865.100 €
TOTAL : 35,140.452 €
4. Drawing up technical files and supervision
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8. - Costs of practical work with solving ownership and legal problems (expropriation)2,520.000 €
- Feasibility study and Preliminary design............................................................... 650.000 €
- Main project ..........................................................................................................900.000 €
- Supervision and other expenses of the investor ................................................1,250.000 €
TOTAL: 5,320.000 €
TOTAL INVESTMENT: 177,447.607 €
Thus defined investment enables making a section on investment and economical data based on
which a profit of this HPP and the price of the electrical energy with a net production of the HPP is
determined.
5. SECTION ON INVESTMENT AND ECONOMICAL DATA
Section on investment and economical data is an integral part of investment and technical
documentation. The main goal of this investment and economical analysis is to gather enough
information about:
- Fixed expenses, Ef
- Variable expenses, Ev
Fixed expenses include the complete investment referring to the construction of the HPP “Mala
Dubravica”, which has already been presented in the previous table.
Variable expenses Ev refer to:
- costs of current and investment maintenance,
- amortization costs,
- costs of contract obligations referring to investments (insurance costs),
- wages costs,
- costs of building material, equipment and other services,
- costs of capital (loan repayment and interest),
- costs of fulfilling legal obligations,
VARIABLE EXPENSES Ev
a) Current and investment maintenance costs
These costs include resources (money) which must be set aside for the maintenance of the
complete building, that is, the HPP. The costs are shown in a table, for a clearer presentation. The
currency used for the estimate is €o (€):
Current and
No. Name of the object Estimated value (€) investment Total (currency - €)
maintenance (%)
1. Powerhouse 12,500.000 1,0 125.000
2. Drainage channel 2,000.000 0,4 8.000
3. Turbinеs 21,010.000 0,5 105.050
4. Gеnеrаtоrs 18,500.000 0,5 92.500
5. Other mech.and hydro mech. eq. 6,620.750 1,0 66.208
6. Other electrical eq. 5,511.000 2,0 110.220
TOTAL 506.978 €
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9. b) Amortization costs
These costs do not affect much the total expenses, but the duration of amortizing certain objects
can significantly affect the sum of total expenses. This is why it is important to calculate them as well and
they are also presented in table:
No. Name of object Estimated value ( €) Amortization rate (%) Annual amortization ( € )
1. Powerhouse 12,500.000 2,0 250.000
2. Drainage channel 2,000.000 1,0 20.000
3. Turbinеs 21,010.000 4,0 840.400
4. Gеnеrаtоrs 18,500.000 5,0 925.000
5. Other mech.and hydro mech. eq. 6,620.750 5,0 331.038
6. Other electrical eq. 5,511.000 2,0 110.220
TOTAL 2,476.658 €
c) Costs of contract obligations referring to investments (insurance costs)
In the whole system of the HPP, there are a few main objects which should be insured against
damage and fire. The insurance varies, depending on insurance companies.
Values of insurance rates presented here are valid for «Dunav» insurance company. The
insurance costs are presented in the table below:
Insurance rate Total annual repayment
No. Name of the object Estimated value (€)
Fire (%) Damage (%) amount (€)
1. Powerhouse 12,500.000 0,5 0,1 75.000
2. Drainage channel 2,000.000 - 0,2 4.000
3. Turbinеs 21,010.000 - 0,1 21.010
4. Gеnеrаtоrs 18,500.000 0,5 0,2 129.500
5. Other mech.and hydro mech. eq. 6,620.750 - 0,5 33.104
6. Other electrical eq. 5,511.000 0,5 0,1 33.066
TOTAL 295.680 €
d) Salary and earnings of the labour
At the HPP itself, a high level of automatization will be applied, that is, the HPP shall function
without human resources, however, on the very location of the HPP the appropriate labour which will
monitor the functioning of all installed devices and systems is needed. Other than this, the same labour
must be also involved in the current maintenance of the HPP.
For the work on the HPP, personal income (salary) of seven workers with university-level
specialist's training for 12 months in a year, 15 workers with vocational training for 12 months in a year
and 20 skilled workers for 12 months in a year have been taken.
Number of Tax-free Time of commitment Annual amount
NO. Workers
workers income (€) (months) (€)
1. University-level training 7 800 12 67.200
2. Vocational training 15 500 12 90.000
3. Skilled worker 20 400 12 96.000
TOTAL 253.200 €
Costs on salaries directly affect the price of the produced kWh in the HPP.
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10. e) Costs of materials, equipment and other services (operating expenses)
These expenses refer to setting the HPP in motion (on the trial run of the HPP or upon finishing
the repairs) and controlling the measurement setup upon starting it.
These expenses are virtually negligible and can be considerably small in regard to the
investments in the electrical equipment. Their value is usually 1% of the value of the electrical equipment:
OE = 5,511.000 • 0,01 = 55.110 ( € )
RECAPITULATION OF EXPENSES
1. Costs of current and investment maintenance ......................................................506.978 €
2. Amortization costs..............................................................................................2,476.658 €
3. Insurance costs.....................................................................................................295.680 €
4. Salaries and wages of the labour .........................................................................253.200 €
5. Operating and other expenses.......................................................................... 55.110 €
TOTAL : 3,587.626 €
DYNAMISM OF INVESTING AND SOURCES OF FINANCING
f) Costs of capital (loan repayment and interest),
It shall be assumed in this case that the investor has decided to apply for a loan which shall be
granted by a foreign bank or a foundation with a repayment term of 20 years with annual payments, and
with an interest rate of 6,0%. These terms of granting loan are quite favourable, taking the living
conditions in this country into account.
Such terms of granting loan result in the following sums:
- annual payment ............................................ 8,872.380 €
- interest ..................................................... 532.343 €
- annuity ................................................... 9,404.723 €
g) Legal obligations (taxes)
These obligations often vary, but now they can be settled at approximately 20% of gross salary.
LO = 435.504 • 1,2 = 522.605 €
h) Total annual expenses
Total annual expenses represent a sum of all previously calculated expenses along with the
annual payments for credit, meaning:
1. Costs of current and investment maintenance ......................................................506.978 €
2. Amortization costs..............................................................................................2,476.658 €
3. Insurance costs.....................................................................................................295.680 €
4. Salaries and wages of the labour .........................................................................253.200 €
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11. 5. Operating and other expenses............................................................................... 55.110 €
6. Interests ................................................................................................................532.343 €
7. Tax.................................................................................................................. 522.605 €
TOTAL : 4,642.574 €
ANNUAL PAYMENT: 8,872.380 €
TOTAL ANNUAL EXPENSES: 13,514.954 €
These total annual expences present the amount of money which must be collected during a
year for settling all obligations towards the state and the bank (in case it supplies the credit) or the
Foundation. When these expenses are divided with the amount of the produced electrical energy during
a year, the result presents the price of a net produced kWh of the HPP:
13,514.954 Euro Eurocents
= 0,034 or 3,4
397,500.000 kWh kWh
i) Gain or profit
As a profit The price of 3,4 c€ for a produced kWh in the HPP is enough, as we have shown, to
cover all expenses during a year. However, it is also important to think about the profit that this HPP has
to make.
Passing a new law on energetics and liberalization of the market of the electrical energy are
expected to fix the price of the produced kWh from the HPP in the following year, in Serbia, at 4,5 cents
per kWh, in parallel work with the network and with the level of voltage at 110 kV. It is important to
mention yet another thing – even today, in Serbia, it is possible to obtain an even higher price with the
authorized dealers of the electrical energy (one of which is the Serbian company “MC INVEST”).
It is realistic to expect that the price obtained for a kWh will be 6 cents, in which case the gross
annual income from the HPP “Mala Dubravica” will be:
GI = 397,5• 106 • 0,045 = 17,887.500 €
When total annual expenses are substracted from the GI, the result present a net gain:
NET GAIN = 4,372.546 €
The annual amount of 2,476.658 € for the amortization also stays in possession of the owner of
the HPP “Mala Dubravica”, therefore, it should also be considered and when it is added to the net gain
during the payments for the credit, the result is:
NET GAIN = 6,849.204 €
Upon paying off the annuity in 20 years' time, net gain drastically rises and it amounts:
NET GAIN = 16,253.927 € per year
Upon paying off the credit, the profit along with the amortization amounts:
NET GAIN = 18,730.585 € per year
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12. NOTE
If the investment does not imply applying for a credit, supposing the investor deals with cash,
time in which the HPP would gain profit is calculated when the total investment is divided with the net
gain of the production of the electrical energy, as follows:
I 177,447.607
= = 9,47 years
NG 18,730.585
Duration of constructing the HPP “Mala Dubravica”, which is about 4 years, should be added to
this value, in which case the time during which the profitability of the HPP rises to 13.5 years. The result
shows that it would take almost 14 years for the investment to become profitable without the credit.
This piece of information clearly shows that it is preferable to apply and obtain a credit since the
HPP “Mala Dubravica” pays off all its debts in 20 years' time, that is, it pays off the credit and gains
profit in the amount of 136,984.080 €.
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