RETROFITTING HYDROPOWER TO SOUTH AFRICAN DAMS Arno Ottermann / Bo Barta ( Dept of Water Affairs / Innovation Hub )
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
South Africa Dams & Hydropower
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)
DWA investment in WR infra R 60 000 Original Cost (in 2008 CRC values) Millions R 50 000 R 40 000 R 30 000 R 20 000 R 10 000 Other Measuring facilities Tunnels Treatment works Reservoirs Pump stations Pipelines Dams and weirs R 0 Canals 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Buildings Original Construction Date (10yr intervals)
RSA dams by type of owner 4395 dams on Dam Safety Register (2828 Farm dams) (359 DWA owned) (259 municipal owned)
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
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 <15 15-30m 30-60m >60m Count of Dams EC 379 73 28 2 482 FS 346 39 7 3 395 GT 115 13 4 1 133 KN 796 59 11 2 868 LP 238 40 16 3 297 MP 346 55 20 2 423 NC 92 9 1 102 NW 31 11 3 45 WC 941 264 42 4 1251 Total 3284 563 132 17 3996
Flow releases from Dams RSA is semi-arid & climate is variable Seasonal flow variations Regulated / unregulated flow River, canal or piped releases
Underutilized Dams (All) 100% 80% - 99% 60% - 80% 40% - 60% 20% - 40% 0% - 20%
Dams with Retrofit Hydropower Potential Bloemhof Vaal Dam Blydereviersp. Heyshoop Spioenkop Goedertrou Inanda Grassridge Darlington
Pilot Study: Dam Retrofit Hartbeespoort Dam Head = 42m (30+12)
50 45 40 35 30 25 20 15 10 5 0 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 1987/1/17 1990/1/25 1994/1/2 1997/1/10 2000/1/18 2003/1/26 2007/1/3 2010/1/11 1981/2/19 1984/2/27 1988/2/4 1991/2/12 1994/2/20 1997/2/28 2001/2/5 2004/2/13 2007/2/21 2010/2/29 1982/3/6 1985/3/14 1988/3/22 1991/3/30 1995/3/7 1998/3/15 2001/3/23 2004/3/31 2008/3/8 2011/3/16 1982/4/24 1986/4/1 1989/4/9 1992/4/17 1995/4/25 1999/4/2 2002/4/10 2005/4/18 2008/4/26 1980/5/3 1983/5/11 1986/5/19 1989/5/27 1993/5/4 1996/5/12 1999/5/20 2002/5/28 2006/5/5 2009/5/13 1980/6/21 1983/6/29 1987/6/6 1990/6/14 1993/6/22 1996/6/30 2000/6/7 2003/6/15 2006/6/23 2009/6/31 1981/7/8 1984/7/16 1987/7/24 1991/7/1 1994/7/9 1997/7/17 2000/7/25 2004/7/2 2007/7/10 2010/7/18 1981/8/26 1985/8/3 1988/8/11 1991/8/19 1994/8/27 1998/8/4 2001/8/12 2004/8/20 2007/8/28 2011/8/5 1982/9/15 1985/9/26 1989/9/7 1992/9/18 1995/9/29 1999/9/10 2002/9/21 2006/9/2 2009/9/13 1980/10/24 1984/10/1 1987/10/9 1990/10/17 1993/10/25 1997/10/2 2000/10/10 2003/10/18 2006/10/26 2010/10/3 1981/11/12 1984/11/23 1988/11/4 1991/11/15 1994/11/26 1998/11/7 2001/11/18 2004/11/29 2008/11/10 2011/11/21 1982/12/30 1986/12/7 1989/12/15 1992/12/23 1995/12/31 1999/12/8 2002/12/16 2005/12/24 2009/12/1
Hydrology: Flow-Duration Curves 30 Daily River Flows (A2H083) (12yrs split into dry/avg/wet) 25 20 Flow (M3/s) 15 10 wet years avg years dry years 5 0 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Duration (% of time)
Hydrology: Seasonal Analysis
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) 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% 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% 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 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 163000000 2010 217000000 33% 54000000 2035 292396754 79% 75396754 40% 9.5 2060 374978952 >100% 82582198 83% 20.0
Artificial Recharge Name Of WWTW Hartbeespoort Estimated effluent volume catchment (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 Good news = more water Bad news = more nutrients
Technical Options Combined RB3 LB1 RB1 LB2
RB1: : Upgrade yester-year year Installation 1923-1964 37kW capacity Gilkes (UK) Potential to double Defunctional
Excellent Exhibits of Old Hydro Power
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
LB1: : In-line Hydro at Canal Outlet
LB1: : In-line turbine installation Hydropower Hydropower installation installation area area
LB1: : In-line hydropower installation 500kW 3 m 3 /sec at 14m head R16m/kW R18m/kW
LB2: : Utilizing Spillage Water 4,2MW 4,2MW River outlet 25 m3/s
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
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
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)
Benefits : Local Energy Supply
Benefits : Removal of Sediment
Benefits : Energy to Clean the Dam
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)
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