Baro Hydropower Projects Pre-Feasibility Study

FEDER\L DEMOCRATIC REPl BLIC OF ETHIOPI \
MINISTRY OF WATER RESOURCES
MEDIUM SCALE HYDRO POWER STL DY PRO JEU 1
Baro Hydropow er Projects
Pre-feasibility Study
NORPLAN A.S
Norconsult International A.SBaro Hydropower Projects BA J and BA2 Executive Summary - Volume 1
Pre-Feasibility Study roc
CHAPTER I
TABLE OF CONTENTS
summary and recommendationsI
I I SUMMARY OF COSTS AND CAPACITIES 1.2     ECONOMIC ANALYSIS
1A R ECOMMEN D ATION
CHAPTER 2             TECH N1CAL SI1MMARY 2 I      INTRODUCTION
2
22
2 3
PROJECT MAIN CHARACTERISTICS
hydrology
+
. |b .F
2.4
2.5
TRANSMISSION LINES
BARO I- PROJECT DESCRIPTION
+ •* .
»•
2;5.1
2.5.2
2.53
Geology and Geotechnics............ 
! him and Reservoir....................
Waterways and Powerhouse........
■
2.6      BAKO 2- PROJECT DESCRIPTION
2 6.1 Geology and Geotechnics .............
2.6.2     I Him and Reservoir ........................
2.6 J Wuterwuys ami Power house.......... 
CHAPTERS           ECONOMIC ANALYSES
II ECONOMICAJ ANALYSIS
CHAPTER 4 ENVIRONMENTAL ACCEPTABILITY.... 
LIST OF TABLES Table I - 1       Key Data of Selected Alternatives
■-
7
. 7
8
1
Table I - 2
Summary of the Economic Analysts
Table 3 - I
Summary of the Economic Analysis
1
7
Table 3 2
Summary Key Cost Indicators
7
LIST OF FIGURES
Figure 4 - l       Quantitative Comparison of Site Alternatives, Barn ENCLOSED DRAWINGS
8
D4
06
BA 1 - 01
BA 1 - 02
BA 2 - 0]
BA 2 - 02
Interconnected Power Sy si rm Baro River, Cascade Development Project Area Map
1 ongitudinal Section of Waterway Project Area Map
Longitudinal Section of Waterway
16.04.99
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Executive Summary - Volume I
Chapter 1 SUMMARY AND RECOMMENDATIONS 1.1    SUMMARY OF C OSTS AND CAPACITIES
Pre-Feasibility Study Page I
The table below summarises the key data of the selected aWnaUves for Baro nver
Taft/r /-/            AO'
infected A /terwotfve*
—
Site
Reservoir
MWRL
Finn                    Costs Energv              (LSD m) fGWii)        Hydro        Tians
Baro 1 - dam           1505
Capacity (MW) tutiltad    Depaidable
170          151.8
647
Baro 2 + dam          1505               483          482.5              20<M
_________
The optimisation  works for the cascade development of Baro  River resulted  in  projects at installed capacity of 170 MW and 483 MW, both with a plant factor of 0 4 Baro 1 includes a reservoir regulating the flow for both BA 1 and BA 2 power plants
During the optmusatxjii work, power plant design with plant factor of 0 4, 0 6 and 0.8 has been  Studied  It should  be expected  that feasibility  level studies would  change the power plant factor s lightly
1.2     ECONOMIC ANALYSIS
A summary of the economic analysis is shown m table below. This table displays the values of the dccisicwi parameters for the base cases of four options extracted  from the economic analysis
f'ahfr 1-2 Summary of the Ewmomic Analysis
1 Taraf
653          6J43                 3731
103 6
315 9          126,0 //W.5             /2tf
Alternative
-
ERR %
NPV •
(USD mi
B-C Ratio"
Bare 1 * Bare 2 + reservoir dam
13 Ye
198,1
1.4
Baro 2 -i~ reservoir dam
12%
110.7 *>
1.3
Barn 1 - reservoir dam
16%
 — —
72 S
I 6
* I JibOnrt rac
1J RE CO MMEN DA T1QN
During  the further studies of Baro  River, both  projects should  be considered. The preliminary  optimisation  work  indicates that Bare 2  and  the reservoir dam should  be constructed  first However after completion  of the dam, Baro  1  should  follow immediately due to a high ERR.
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C hapter 2 TECHNIC AL SUMMARY
2.1     INTRODUCTION
Pre-Fcasihdity Study Page 2
The Bare I and  Bare 2  Hydropower Projects are located  south  of the Addis Ababa - Crambe la Road, between Gore and Bonga nil the upper and eastern part of the Barn Akobo has tn in western Ethiopia
The projects exploit the potentials of a 30  kin  long  stretch  of the upper part of Baro  River with  a total gross head  of 690  meter, where the upper Baro  1  and  the lower Baro  2  are developed  as cascaded  schemes with  gross head  of 185  and  505  meter respectively  Bara 1 and Baro 2 are located close to each other, as the distance between the outlet of Baro I and the intake of Baro  2  ls approximately  10  km Baro  land  Barg  2  are integrated  schemes, as both share the reservoir established at Bato 1
Drawings showing the mam layout of the project are enclosed
2.2     PROJECT MAIN CHARACTERISTICS
Th? preliminary  design  and  optimisation  of the Baro  River Projects gaw Lhe following characteristic salient features for the two schemes, where the regulation darn is linked to BA
2:
Cftrrf
BAI
RA2
Hydrology
Catchment area
Irm3
2,210
2,332
Mean annual rainfall at reservoir
mm
1,830
1,83?
Menn annual evaporation
mm
1,546
1,546
Moan annual discharge
m’/s
73 8
77 5
Mean annual runoff
Mm’
2.328
2,445
1 OOQ-year discharge flood
m’/s
1,115
1 11 5
Probable Maximum Flood
mVs
1.897
3.020
Highest regulated water Id vol (HRWL)
m
1,505
1,320
Lowest regulated watei level (LRWL)
rii
1,485
1,318
Total storage
Mur1
800
60
Live storage
Mtn’
480
20
Live storage
%
20 6
U.K
Firm regulated flow
m17$
35 6
35.6
Civil Works
Type of dam
CFRD
RCC
Dam height
rn
81
30
Dam volume
Mm’
239
0 176
Spillway type
Overflow
Overflow
Spillway laiglh
m
105
140
Headrace tunnel length
rn
2,483
6,625
Headrace tunnel c rosy-sect inn
m1
68
68
Type of lining
L'nlwd
Uni med
Tailrace tunnel lengtli
m
994
4,800
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Prr-Feasibdrty Study Pago 3
Tailrace tunnel cross secticn
m1
6B
US
Ta 11 water level.
m
PowersUtmn type
1320 Underground
Gross head
m
185
815 Underground
505
Installations
Number of Units
Nos
Turbine typo
2
Francis
5
Francis
Max Turbine Discharge
m'/s
113
113
Installed capacity
MW
194
475
Dependable capacity
MW
173
471
Mean annual firm ^jergy (EPOS)
GWIuy
Power plant factor
647
0 4
2,094
0 4
Costs * and Lind prices
Total construction cost
mUSD
130
SOS
Cost pr kW installed
USD/kW
670
1,177
Cost pr annual kWh produced 
LSD/kWy
0.201
0.271
Unit energy cost (firm energy)
Usc/kWh
2.21
3.07
• Cast including HX. and tnmsnu-ction line
23 HYDROLOGY
30 years long flow sones have been established far the Baro I and Baro 2 dam sites with the use erf flew records from Mettn gauging station located at Sor River in lhe Sor basin The Sor basin borders with the upper Baro basin to the south-west and with upper Geba basin to the south and south-east. The Sot  gauging station has relatively kmg, continual discharge records far the period 1967-1997
Thu main hydrological data at project intakes arc: Baro I;
•        Catchment a rao
2,210   tan*
•   Mean annual flow :                                        73 8     mJ/s Baro 2:
V   Catchment area '
• Mean annua] flow r
2.332 kmJ
77.5 m’/s
There is a substantial difference between the magnitude of flows during dry and wet seasons
For Lhe simulated period I9b7-1996T the average accumulated flow during July-October period was about 87 % of the annual tota l flows
2.4     TRANSMISSION LINES
The distance from Baro I to Ghado and Gilgel Gibe is 32b km and 320 km respectively, The corresponding distance from Baro 2 is 349 km and 343 km With lhe largo installations of rhe Baro  power plants th© existing  230  kV system will be insufficient for the transfer of power towards Addis Ababa. The optimal IfansuiLSsioo lines to connect Baro 1+2 to the grid
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Ghetto  to  Addis Ababa and  the other from Barn  vifl Gilgel Gibe to  Addis Ababa. Since Geba most likely will be constructed earlier than Baro, the connection of Geba and Haro to the grid  should  be co-ordinated  by  preparing  the Geba - Ghedo  230  kV line for upgrading io 420 kV
The transmission line cost for the Bare power plants in this study is therefore bused on a
420 kV s/c, 2xMoose line via Gi I gel Gibe to Addis Ababa
2.5      BARO 1- PROJECT DESCRIPTION
2.5,1    Geology a nd Geotech n i ei
I he geology of the region is divided into two major rock types These arc the Precambrian crystalline basement and the Oligoccne-.Mioeene pre-rift volcanic rocks, i.c. Hood basalts.
The  Precambrian  basement  complex  comprises  undivided  gneiss,  predominantly  biotile  and hornblende   gneiss,   granitic   gneisses,   and   migmatites,   with   minor   me   rased   imentary gneisses.   The   tertiary   volcanics   arc   basalts,   which   are   found   directly   overlying   the crystalline  basement.  These  arc  known  and  mapped  as  Mokonnen  basalts.  The  Makoftnen basalts,  which  in  all  likelihood  had  once  covered  the  Precambrian  rocks  are  now  eroded and  do  not  outcrop  within  the  proper  proposed  structure  vicinities  at  BAI  However,  basalt is  present  along  higher  sections  of  the  access  road  to  the  project,  and  might  be  present within the reservoir area.
23 J Dam and Reservoir
Four different dam heights1 reservoir sizes combined  with  two  dam types have been analysed  in  this study. The preliminary  optimisation  wtls concluded  with  the selection  of a
concrete faced  rucklill dam for the optimum plant size and  optimum HRWL at EL 1305. The dam height and  reservoir size optimisation  was carried  out considering  the combination of both Baro ! and Baro 2 being developed.
With  the  preliminary  optimum  HRWL  at  El.  1,505,  the  (TR  darn  volume  is  approximately 2.39                  while the corresponding dnm height and crest length, arc 80 and 800 m respectively.  Two  45  nT  tunnels,  each  580  m  long,  facilitate  the  river  diversion  during construction. These runnels will permanently he turned into conduits for bottom outlet.
A  tree  overflow1   spillway  is  placed  on  the  terrain  surface,  between  the  dam  and  the  power intake.
A dam at HRWL at EL ! ,505 establishes a reservoir with a iota! storage of 800 mill, in1 and inundates an  area of 27  km2, stretching  20  km upstream of the dam 480  millun1 of the storage volumc makes up the live storage with a regulation bright of 20 m below HRWL.
:.5J Waterways and Powerhouse
The 185  m gross head  of the Baro  I project is developed  with  a 4.5  km waterway  conduit and  an  underground  powerhouse. The powerhouse has been  placed  on  the downstream, part of the waterway where a suitable adit area for the access tunnel can be found.
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The   headrace   tunnel   is   designed   as   an   unlined   tunnel   with   a   cross-section   of   08   m\ equivalent to a diameter-of 9.3 m
The maximum turbine discharge of U3  mVs together with  the gross head  of 185  m yield  an installation  of ly4  MW Two  gsirrartmg  units with  vertical Francis turbines are arranged  m an  underground  powerhouse, with  stqp-up  transformers barfed  in  a cavern  adjacent to  the powerhouse cavern  The power station  is linked  to  the surface with  a bOO m long  access tunnel, which also provides routing for the high voltage cables to the surface switchyard
The tailrace? tunnel is about 0,9 km long with the same cross-section as the headrace tunnel
2,6       BARO 2 PROJECT DESCRIPTION
2.6.1    Geology and Geotechnics
The  geology  of  the  region  is  divided  into  two  major  rock  types  These  are  the  Precambrian crystalline basement and the Obgoceno-Miocene pre-rift volcanic rocks, i.e flood basalts
The Precambrian  basement complex  comprises undivided  gneiss, predominantly  biotite and ho mb lai de gneiss, granitic gneisses, and migmaflles. with minor rrefta sedimentary gneisses. The tertiary  volcanics are basahs, which  are found  directly  ovwiymg  the crystalline basement These arc known  and  mapped  as Makounen  basahs The Makonnen  basalts, winch tn  all likelihood  had  cues covered  the Precambrian  rocks are now eroded, and  exist only along higher sections of the project area
2.6.2    Dun and Reservoir
The BA I dam and reservoir will provide regulated flow to BA2
The HRWL elevation of the BA2 di version dam lias beai set to l 32O,
t              corresponding to the tail water level of BAI
The dam site is characterised by a relative flat topographv The diversion dam will be a RCC type of dam with  i maximum height of 30  m and  a crest length  of around  790  m Only  a smaller pond  (20  mill m3) will be established  at the BA2  intake, however sufficient to regulate the BA2 turbine flow in co-opcraOcwi with the release from the BAI reservoir One 45  m tunnel, 170  m long, facilitate Lhe river diversion  during  ccnstrucpon  'rhe tunnel is pc rm an eml y turned into conduit for bottom outlet
2.63 Waterways and Powerhouse
The 505 m gross head of the Baro 2 project is developed with a 11.4 km waterway conduit and  an  underground  powerhouse The powerhouse has been  placed  on  die downstream part of the waterway where a suitable adit area foe the access runnel can bo found
A short circular dropshaft is placed: downstream of the intake, and establishes the start of die headrace runnel at El 1,278  From this point, die headrace tunnel is descending  1:126  m downstream direction, towards a vertical breakpoint around  3  km upstream of the powerhouse. From this breakpoint the headrace tunnel dips 17  towards the penstock  inlet just upstream of tho powerhouse The surge chamber ie established by excavation of a tunnel
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from the surface to the vertical breakpoint of the headrace tunnel at El 1,252 The headrace
tunnel is designed as uni med tunnel with n cross section of 68 m . equivalent to a diameter of
3
9.3 m
The maximum turbine discharge of 113 mJ/i together with the gross bead of 505 m yields an installed  capacity  of 480  MW Five generating  urnLs with  vertical Francis turbines art1 arranged  in  an  underground  powerhouse, with  step-up  transformers located  in  a cavern adiacent to the powerhouse cavern The power station is linked to the surface with a J.500 m long  access tunnel sloping  1:10  The access Uinnd  provides routing  for the high  witage cables to the surface switchyard
The tailrace tunnel is about 4 8 km long with the same cross-section as (he headrace tunnel
An intermediate excavation and Lai I waler surge adit is planned at the mid-pomt of the tailrace stretch
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iHaro Hydropower Projects; BAl and BA2 Executive Summary - Volume I
Chapter 3 ECONOMIC ANALYSIS 3.1     ECONOMICAL ANALYSIS
ProFca-sibilhy Study Page 7
An  economic  analysis  with  costs  based  on  the  hydroelectric  and  irnnsmission  investments and a bene Gt based on energy sales has been undertaken for the different projects.
A summary of ibe economic analysis is shown in Table 3-1. This r,ah]c displays die values of the decision  parameters for the base cases of four options extracted  from the economic analysis.
TaMe 3-1 tSHJfimfflry ff/f/ie Economic Anafyffc
Alternative
ERR %
NPV *
(USD mill)
R/C Ratio . —   —------- —
_
Bare I * iJaro 2^ reservoir dam
13 %
191.1
1.4 _
Biro 2 + reservoir dam
12%
110.7
13
Bare 1 - reservoir diim
16%
L
1.7
* Al IC% diioouM rare
The key  cost indicators arc shown  in  Table 3-2. Of the configurations dial includes die reservoir Jam, Bare 1  constructed  in  conjunction  with  Itao  2  returns the lowest cost per kilowatt installed, as well as the cheapest supply of energy .
TaNe 3-2 Summary Key Cast fndrcaiors
Project
Total Coit
USD/kW*       Lnit energy
(USDni)*            tnsinlkd
cost
USc/kWli <
Bara 1 *■ Raru 2 + reservoir dam
717             l.OT’J                    2,95
1 Baro 2 +■ reservoir dam
368
IJ77
3 07
I Barn I reservoir dam **
130               764
2 2«
■ faEtodinn 11K_' rrinsTiiiivinn caw i&el uhat relevant
□ Al '<hi- pail'll of pnd ennne:!lcr
' * The Rdcraun inn and Tnr-uiwinoo hhb nre Kiraraeij tp Kite been inewred at rui ralief si site rtf dewtaipmoii
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BaroHydropower Projects BAI arid BA2 
Executive Summary - Volume 1
Chapter 4 ENVIRONMENTAL ACCEPTABILITY
Pre-Feasibility Study Page K
From the FEA process undertaken the environmental acceptability of die proposed Baro HPP is summarised for the two alternative sites
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Summery

Project: Baro 1 and Baro 2 Hydropower Projects in Ethiopia

Prepared by: Norplan A.S in association with Norconsult International A.S.

Date: 16.04.1999

Document: Executive Summary - Volume 1

1. Project Overview

The Baro 1 and Baro 2 Hydropower Projects are located in the upper part of the Baro-Akobo basin in western Ethiopia, between Gore and Bonga. These cascaded schemes exploit a 30 km stretch of the upper Baro River with a total gross head of 690 meters.

2. Key Project Characteristics

Parameter	Baro 1	Baro 2
Installed Capacity (MW)	170	483
Dependable Capacity (MW)	151.8	482.5
Firm Energy (GWh/y)	647	2,094
Gross Head (m)	185	505
Plant Factor	0.4	0.4
Total Construction Cost (USD million)	130	568

3. Economic Analysis

Alternative	ERR %	NPV (USD million)*	B/C Ratio
Baro 1 + Baro 2 + reservoir dam	13	198.1	1.4
Baro 2 + reservoir dam	12	110.7	1.3
Baro 1 - reservoir dam	16	72.8	1.6

* At 10% discount rate

4. Technical Features

Baro 1 Project

Concrete faced rockfill dam (CFRD) with height of 81m
Reservoir with total storage of 800 million m³
Underground powerhouse with 2 Francis turbine units
4.5 km waterway conduit

Baro 2 Project

RCC dam with height of 30m
Small regulating pond (20 million m³)
Underground powerhouse with 5 Francis turbine units
11.4 km waterway conduit

5. Hydrology

The projects utilize 30-year flow series based on records from the Metin gauging station:

Baro 1: Catchment area 2,210 km², mean annual flow 73.8 m³/s
Baro 2: Catchment area 2,332 km², mean annual flow 77.5 m³/s

About 87% of annual flows occur during July-October period.

6. Transmission

The projects require connection to the grid via 420 kV transmission lines:

Baro 1 to Ghedo/Gilgel Gibe: 326/320 km
Baro 2 to Ghedo/Gilgel Gibe: 349/343 km

7. Recommendation

The study recommends constructing Baro 2 and the reservoir dam first, followed immediately by Baro 1 due to its high Economic Rate of Return (16%). Both projects should be considered in further studies.