RETROFITTING HYDROPOWER TO SOUTH AFRICAN DAMS

Transcription

1 RETROFITTING HYDROPOWER TO SOUTH AFRICAN DAMS Arno Ottermann / Bo Barta ( Dept of Water Affairs / Innovation Hub )

2 Introduction Overview : Dams in South Africa - small scale hydropower potential Pilot retrofit : Hartbeespoort dam Comparison: greenfield vs retrofit Key challenges : Unlock small hydro potential Look at local impact Look at hybrid solutions Look at off-grid use

3 South Africa Dams & Hydropower

4 RSA needs dams to secure water RSA is a semi-arid country RSA is 11 th most dammed country in the world RSA needs inter-basin transfer schemes RSA has limited dam positions RSA dams cannot adapt to hydro - hydro must adapt to dams (RETROFIT)

5 DWA investment in WR infra R Original Cost (in 2008 CRC values) Millions R R R R R Other Measuring facilities Tunnels Treatment works Reservoirs Pump stations Pipelines Dams and weirs R 0 Canals Buildings Original Construction Date (10yr intervals)

6 RSA dams by type of owner 4395 dams on Dam Safety Register (2828 Farm dams) (359 DWA owned) (259 municipal owned)

7 Retrofit Hydro what to look for? Hydropower ~ Height x Flow Height = Certain! dam wall height or height to canal Flow = Uncertain!! subject to size of catchment, rainfall, runoff, releases, etc. Type of outlet & spillway

8 Height: RSA dam safety register ± 4000 water dams 135 Large / 865 Medium / 3000 small 359 DWA owned (M/L) >34 billion m 3 storage 70 of DWA dams have a hydro-power potential DWA can generate > 55MW (450GWh/a) RSA total > 250MW Province Height < m 30-60m >60m Count of Dams EC FS GT KN LP MP NC NW WC Total

9 Flow releases from Dams RSA is semi-arid & climate is variable Seasonal flow variations Regulated / unregulated flow River, canal or piped releases

10 Underutilized Dams (All) 100% 80% - 99% 60% - 80% 40% - 60% 20% - 40% 0% - 20%

11 Dams with Retrofit Hydropower Potential Bloemhof Vaal Dam Blydereviersp. Heyshoop Spioenkop Goedertrou Inanda Grassridge Darlington

12 Pilot Study: Dam Retrofit Hartbeespoort Dam Head = 42m (30+12)

13 Hydrologic Analysis: 32yr daily flows Hydrologic Analysis: 32yr daily flows Understand the hydrology! Base flow? What % of spillage? A2H083l: River Flow (down-stream of Hartbeespoort Dam m3/s) 1981/1/1 1984/1/9 1987/1/ /1/ /1/2 1997/1/ /1/ /1/ /1/3 2010/1/ /2/ /2/ /2/4 1991/2/ /2/ /2/ /2/5 2004/2/ /2/ /2/ /3/6 1985/3/ /3/ /3/ /3/7 1998/3/ /3/ /3/ /3/8 2011/3/ /4/ /4/1 1989/4/9 1992/4/ /4/ /4/2 2002/4/ /4/ /4/ /5/3 1983/5/ /5/ /5/ /5/4 1996/5/ /5/ /5/ /5/5 2009/5/ /6/ /6/ /6/6 1990/6/ /6/ /6/ /6/7 2003/6/ /6/ /6/ /7/8 1984/7/ /7/ /7/1 1994/7/9 1997/7/ /7/ /7/2 2007/7/ /7/ /8/ /8/3 1988/8/ /8/ /8/ /8/4 2001/8/ /8/ /8/ /8/5 1982/9/ /9/ /9/7 1992/9/ /9/ /9/ /9/ /9/2 2009/9/ /10/ /10/1 1987/10/9 1990/10/ /10/ /10/2 2000/10/ /10/ /10/ /10/3 1981/11/ /11/ /11/4 1991/11/ /11/ /11/7 2001/11/ /11/ /11/ /11/ /12/ /12/7 1989/12/ /12/ /12/ /12/8 2002/12/ /12/ /12/1

14 Hydrology: Flow-Duration Curves 30 Daily River Flows (A2H083) (12yrs split into dry/avg/wet) Flow (M3/s) wet years avg years dry years 5 0 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Duration (% of time)

15 Hydrology: Seasonal Analysis

16 Hydrologic Analysis: Selection of Optimum Generating Capacity Duration of Generation (of 24hrs) Utilisation of ESKOM Tariffs Power (MW) Power (MW) Flow (m3/s) % of time hrs/day 6hrs peak rate (6:00-9:00 18:00-21:00) 7 hrs std rate (9:00-18:00) 9hrs offpeak rate (21:00-6:00) dry years 20% 5 80% 0% 0% only avg years 44% % 65% 0% wet years 70% % 100% 42% dry years 8% 2 32% 0% 0% only avg years 25% 6 100% 0% 0% wet years 40% % 51% 0% dry years 5% 1 20% 0% 0% Flow Assurance Assurance (1,5+ avg years 16% 4 Utilization 64% 0% 0% (m3/s) (avg year) (wet year) 4,2) wet years 34% 8 100% 31% 0% % 70% 12-16hrs per day every day % 40% 50% to 80% of rainy season / 25% of dry season (peak 6hrs)

17 Hydrologic 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 % % % >100% % 20.0

18 Artificial Recharge Name Of WWTW Hartbeespoort Estimated effluent volume catchment (mil m3/ann) (m3/s) Northern Work Y Olifantsfontein Y Sunderland Ridge Y Percy Stewart Y Driefontein Y Ester Park Y Magalies Y Randfontein Y Good news = more water Bad news = more nutrients

19 Technical Options Combined RB3 LB1 RB1 LB2

20 RB1: : Upgrade yester-year year Installation kW capacity Gilkes (UK) Potential to double Defunctional

21 Excellent Exhibits of Old Hydro Power

22 RB3: : New installation + un-pressurized tunnel The turbine design to take in consideration Head of 30m design flow = 5 m3/sec Estimated generating capacity of 1500kW or 8 GWh/a Cost estimated at R 30 mil Est. Unit Cost = R17m/MW - R20m/MW

23 LB1: : In-line Hydro at Canal Outlet

24 LB1: : In-line turbine installation Hydropower Hydropower installation installation area area

25 LB1: : In-line hydropower installation 500kW 3 m 3 /sec at 14m head R16m/kW R18m/kW

26 LB2: : Utilizing Spillage Water 4,2MW 4,2MW River outlet 25 m3/s

27 LB2 : Utilizing spillage water Maximum water heads are 39 to 42 m The design flow is suggested at 25 m3/sec Est. generating capacity = 4,2MW Utilized 50% - 80% during rainy season

28 Combined Phase-1: (20 GWh/a) 1,5 MW firm-yield generation from RB4 4,2 MW seasonal generation from LB2 Phase-2: (+4 GWh/a) add 4,2 MW after 10 to 15 years from LB2

29 Retrofit vs New dam projects HBP retrofit unit cost = R17m/MW HBP greenfield unit cost (incl.dam wall) > R60m/MW Retrofit = low environmental impact (dam exists) Greenfield = high environmental impact Retrofit = short implementation (2 3 years) Greenfield = long implementation (8-10 years)

30 Benefits : Local Energy Supply

31 Benefits : Removal of Sediment

32 Benefits : Energy to Clean the Dam

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34 Conclusion Acknowledge the role of small hydro Look at the local benefits / off-grid Energy to clean the dam Value of environmental improvement Social / property value Value of affordable energy Look into hybrid solutions Hartbeespoort is an ideal demonstration for renewable energy options (hydro, wind, solar, biomass)

35 END