Arno Ottermann / Bo BartaArno Ottermann / Bo Barta

( Dept of Water Affairs / Innovation Hub )( Dept of Water Affairs / Innovation Hub )

RETROFITTING HYDROPOWER RETROFITTING HYDROPOWER

TO SOUTH AFRICAN DAMSTO SOUTH AFRICAN DAMS

IntroductionIntroduction

•• Overview : Overview : Dams in South AfricaDams in South Africa-- small scale hydropower potentialsmall scale hydropower potential

•• Pilot retrofit : Pilot retrofit : Hartbeespoort dam Hartbeespoort dam

•• Comparison: Comparison: ““ greenfieldgreenfield”” vs vs ““ retrofitretrofit””

•• Key challenges : Key challenges : Unlock Unlock ““ smallsmall”” hydro potentialhydro potentialLook at local impactLook at local impactLook at hybrid solutionsLook at hybrid solutions

Look at offLook at off--grid usegrid use

South Africa Dams & HydropowerSouth Africa Dams & Hydropower

•• RSA is a semiRSA is a semi--arid countryarid country

•• RSA is 11RSA is 11thth most dammed country in the worldmost dammed country in the world

•• RSA needs interRSA needs inter--basin transfer schemesbasin transfer schemes

•• RSA has limited dam positionsRSA has limited dam positions

•• RSA dams cannot adapt to hydroRSA dams cannot adapt to hydro-- hydro must adapt to dams (RETROFIT)hydro must adapt to dams (RETROFIT)

RSA needs dams to secure water RSA needs dams to secure water

DWA investment in WR infraDWA investment in WR infra

R 0

R 10 000

R 20 000

R 30 000

R 40 000

R 50 000

R 60 000

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Ori

gin

al

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in 2

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8 C

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lue

s)

Mil

lio

ns

Original Construction Date (10yr intervals)

Other

Measuring facilities

Tunnels

Treatment works

Reservoirs

Pump stations

Pipelines

Dams and weirs

Canals

Buildings

RSA dams by type of ownerRSA dams by type of owner

4395 dams on 4395 dams on Dam Safety Dam Safety

RegisterRegister(2828 Farm dams)(2828 Farm dams)(359 DWA owned)(359 DWA owned)

(259 municipal (259 municipal owned)owned)

•• Hydropower ~ Hydropower ~ HeightHeightx x FlowFlow

•• HeightHeight= = Certain !Certain !–– dam wall height dam wall height

or height to canalor height to canal

•• FlowFlow = = Uncertain !!Uncertain !!–– subject to size of catchment, rainfall, runoff , releases, etc.subject to size of catchment, rainfall, runoff , releases, etc.

•• Type of outlet & spillwayType of outlet & spillway

Retrofit Hydro Retrofit Hydro –– what to look for ?what to look for ?

•• ±± 4000 water dams4000 water dams•• 135 Large / 865 Medium / 3000 small135 Large / 865 Medium / 3000 small•• 359 DWA owned (M/L) >34 billion m359 DWA owned (M/L) >34 billion m33 storagestorage•• 70 of DWA dams have a hydro70 of DWA dams have a hydro--power potentialpower potential•• DWA can generate > 55MW (450GWh/a)DWA can generate > 55MW (450GWh/a)•• RSA total > 250MWRSA total > 250MW

ProvinceHeight

<15 15-30m 30-60m >60mCount of

Dams

EC 379 73 28 2 482FS 346 39 7 3 395GT 115 13 4 1 133KN 796 59 11 2 868LP 238 40 16 3 297MP 346 55 20 2 423NC 92 9 1 102NW 31 11 3 45WC 941 264 42 4 1251

Total 3284 563 132 17 3996

Height: Height: RSA dam safety registerRSA dam safety register

Flow Flow releases releases

from Dams from Dams

•• RSA is semiRSA is semi--arid & climate is variablearid & climate is variable

•• Seasonal flow variationsSeasonal flow variations

•• Regulated / unregulated flowRegulated / unregulated flow

•• River, canal or piped releasesRiver, canal or piped releases

Underutilized Dams (All)Underutilized Dams (All)

100%100%80% 80% -- 99%99%60% 60% -- 80%80%40% 40% -- 60%60%20% 20% -- 40%40%0% 0% -- 20%20%

Dams with Retrofit Dams with Retrofit Hydropower PotentialHydropower Potential

Bloemhof

Vaal Dam

Blydereviersp.

Heyshoop

Spioenkop

Goedertrou

Inanda

Grassridge

Darlington

Pilot Study: Dam RetrofitPilot Study: Dam RetrofitHartbeespoort DamHartbeespoort Dam

Head = 42m (30+12) Head = 42m (30+12)

Hydrologic Analysis: 32yr daily flowsHydrologic Analysis: 32yr daily flows

•• Understand the hydrology!Understand the hydrology!

•• Base flow?Base flow?

•• What % of spillage?What % of spillage?

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A2H083l: River Flow (down-stream of Hartbeespoort Dam m3/s)

Hydrology: FlowHydrology: Flow--Duration CurvesDuration Curves

0

5

10

15

20

25

30

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Flo

w (

M3

/s)

Duration (% of time)

Daily River Flows (A2H083)

(12yrs split into dry/avg/wet)

wet years

avg years

dry years

Hydrology: Seasonal AnalysisHydrology: Seasonal Analysis

Hydrologic Analysis: Selection of Hydrologic Analysis: Selection of Optimum Generating CapacityOptimum Generating Capacity

Power

(MW)

Flow

(m3/s) % of time hrs/day

6hrs

peak rate (6:00-9:0018:00-21:00)

7 hrs

std rate (9:00-18:00)

9hrs off-

peak rate (21:00-6:00)

1.5 4.2 dry years 20% 5 80% 0% 0%

only avg years 44% 11 100% 65% 0%

wet years 70% 17 100% 100% 42%

4.2 12 dry years 8% 2 32% 0% 0%

only avg years 25% 6 100% 0% 0%

wet years 40% 10 100% 51% 0%

5.7 16 dry years 5% 1 20% 0% 0%

(1,5+ avg years 16% 4 64% 0% 0%

4,2) wet years 34% 8 100% 31% 0%

Duration of Generation (of 24hrs) Utilisation of ESKOM Tariffs

Power

(MW)

Flow

(m3/s)

Assurance

(avg year)

Assurance

(wet year)Utilization

1.5 4.2 50% 70% 12 - 16hrs per day every day

4.2 12 25% 40% 50% to 80% of rainy season / 25% of dry season (peak 6hrs)

Hydrologic Analysis: Future ScenarioHydrologic Analysis: Future Scenario

Year MAR (m3/a)%

Increase

Surplus Yield

(m3/a)

Surplus as % of

4,2MW dry-season

flow need

hrs/day generating

capacity for 2nd

4,2MW turbine

1923 163 000 000

2010 217 000 000 33% 54 000 000

2035 292 396 754 79% 75 396 754 40% 9.5

2060 374 978 952 >100% 82 582 198 83% 20.0

Artificial RechargeArtificial Recharge

•• Good news = Good news = more watermore water

•• Bad news = Bad news = more nutrientsmore nutrients

Name Of WWTW

Hartbees-

poort

catchment

Estimated effluent volume

(mil m3/ann) (m3/s)

Northern Work Y 134.69 4.3

Olifantsfontein Y 21.35 0.7

Sunderland Ridge Y 18.07 0.6

Percy Stewart Y 9.86 0.3

Driefontein Y 9.86 0.3

Ester Park Y 0.13 0.0

Magalies Y 0.11 0.0

Randfontein Y 6.57 0.2

200.6 6.4

Technical OptionsTechnical Options

RB1RB1

RB3RB3

LB2LB2

CombinedCombined

LB1LB1

RB1RB1: Upgrade yester: Upgrade yester--year Installationyear Installation

1923 1923 --19641964

37kW capacity37kW capacity

Gilkes (UK)Gilkes (UK)

Potential to doublePotential to double

DefunctionalDefunctional

Excellent Exhibits of Old Hydro PowerExcellent Exhibits of Old Hydro Power

RB3RB3: New installation + un: New installation + un--pressurized tunnelpressurized tunnel

•• The turbine design to take in consideration The turbine design to take in consideration

–– Head of Head of 30m30m

–– design flow = design flow = 5 m3/sec5 m3/sec

•• Estimated generating capacity of Estimated generating capacity of 1500kW1500kWor 8 GWh/a or 8 GWh/a

•• Cost estimated at Cost estimated at R 30 milR 30 mil

•• Est. Unit Cost = Est. Unit Cost = R17m/MW R17m/MW -- R20m/MWR20m/MW

LB1LB1 : In: In --line Hydro at Canal Outletline Hydro at Canal Outlet

LB1LB1 : In: In --line turbine installationline turbine installation

HydropowerHydropower

installation areainstallation area

LB1LB1: In: In --line hydropower installationline hydropower installation

500kW500kW

R16m/kW R16m/kW –– R18m/kW R18m/kW 3 m3 m33/sec at 14m head/sec at 14m head

4,2MW4,2MW

4,2MW4,2MW

25 m3/s25 m3/s

LB2LB2 : Utilizing Spillage Water: Utilizing Spillage Water

River outletRiver outlet

•• Maximum water heads are 39 to Maximum water heads are 39 to 42 m42 m

•• The design flow is suggested at The design flow is suggested at 25 m3/sec 25 m3/sec

•• Est. generating capacity = Est. generating capacity = 4,2MW4,2MW

•• Utilized Utilized 50%50%-- 80%80%during rainy season during rainy season

LB2 LB2 : Utilizing spillage water: Utilizing spillage water

PhasePhase--1: (20 GWh/a)1: (20 GWh/a)1,5 1,5 MW firmMW firm--yield generation from RB4 yield generation from RB4 4,2 4,2 MW seasonal generation from LB2MW seasonal generation from LB2

PhasePhase--2: (+4 GWh/a)2: (+4 GWh/a)add add 4,24,2 MW after 10 to 15 years from LB2MW after 10 to 15 years from LB2

CombinedCombined

RetrofitRetrofit vs vs New dam New dam projectsprojects

•• HBP retrofit unit cost = R17m/MW HBP retrofit unit cost = R17m/MW

•• HBP greenfield unit cost (incl.dam wall) > R60m/MWHBP greenfield unit cost (incl.dam wall) > R60m/MW

•• Retrofit = low environmental impact (dam exists)Retrofit = low environmental impact (dam exists)

•• Greenfield = high environmental impactGreenfield = high environmental impact

•• Retrofit = short implementation (2 Retrofit = short implementation (2 –– 3 years)3 years)

•• Greenfield = long implementation (8Greenfield = long implementation (8--10 years) 10 years)

Benefits Benefits : Local Energy Supply: Local Energy Supply

Benefits Benefits : Removal of Sediment: Removal of Sediment

Benefits Benefits : Energy to Clean the Dam: Energy to Clean the Dam

ConclusionConclusion

•• Acknowledge the role of Acknowledge the role of ““ smallsmall”” hydrohydro

•• Look at the local benefits / offLook at the local benefits / off--gridgrid–– Energy to clean the damEnergy to clean the dam

–– Value of environmental improvementValue of environmental improvement

–– Social / property valueSocial / property value

–– Value of affordable energyValue of affordable energy

•• Look into hybrid solutions Look into hybrid solutions –– Hartbeespoort is an ideal demonstration for renewable Hartbeespoort is an ideal demonstration for renewable

energy options (hydro, wind, solar, biomass)energy options (hydro, wind, solar, biomass)

ENDEND