Pumped Storage Schemes & imported hydroelectricity Date 11 May 2011 Role of pumped storage Ingula Pumped Storage Scheme Some important design criteria ydropower potential in Southern Africa Frans Louwinger Role of pumped storage 38000 36000 Summer Winter 34000 32000 MW 30000 28000 26000 24000 22000 Monday Friday 1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106 113 120 127 134 141 148 155 162 our 2011/05/14 2 1
Role of pumped storage 38000 36000 OCGT Generating Summer Winter 34000 32000 MW 30000 28000 26000 24000 22000 Monday Pumping Friday 1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106 113 120 127 134 141 148 155 162 our 2011/05/14 3 Role of pumped storage OCGT PSS Mid merit - Peaking RTS Stations and ydro Gas (Combined Cycle) Base load - Mid merit Coal Fired Nuclear 0 10 20 30 40 50 60 70 80 90 100 Load factor (%) 2011/05/14 4 2
Cost comparison of pumped storage Levelised costs of investigated hydro schemes Practical limit of PSS Possible opportunity for conventional hydro 2011/05/14 5 Indentification studies for possible pumped storage sites 2011/05/14 6 3
Indentification studies for possible pumped storage sites Mutale Tubatse Strijdom Ingula Waayhoek Impendle ogsback 2011/05/14 7 Ingula Pumped Storage Scheme Approximately 23km north-east from Van Reenen S C INGULA PUMPED STORAGE SCEME 2011/05/14 8 4
Ingula Pumped Storage Scheme 4 Units of 333 MW each = 1332 MW Rated ead = 441 m Energy storage = 21 000 MWh (15,9 hours) Distance between reservoirs = ~6km 2011/05/14 9 Ingula Pumped Storage Scheme - Layout 2011/05/14 10 5
Ingula PSS Reservoirs Size of active volume The largest of: 1) Optimum dam size determined from capital plus operating cost of total system 2) 20% Weekly load factor (for 7 hours daily pumping) plus 4 hours emergency generation Cost (Capital WL (masl) + Operating) 1728 100 1726 1724 50 1722 Bedford Dam WL vs Time Optimum Reservoir Size 1740 300 1738 1736 250 12% Discount rate 1734 200 1732 6% Discount rate 1730 150 No Emergency 4h Emergency 21 GWh 1720 0 0 0 20 5 40 10 60 15 80 20 100 25 120 30 140 35 160 180 40 Active volume Time (h)(in GWh) Note 21 GWh dam size at Ingula provides: - 6,8 h daily generation OR - 7,6 h daily generation - 4 h emergency generation - 0 h emergency generation - 23,5% weekly load factor - 25,8% weekly load factor 2011/05/14 11 Ingula PSS Upper Reservoir Fossils CFRD and rock fill with clay core L=810m =41m!00m emergency spillway 2011/05/14 12 6
Ingula PSS Upper Reservoir 2011/05/14 13 Ingula PSS Lower reservoir RCC L=310m =39m 40m ogee crest spillway 2011/05/14 14 7
Ingula PSS Lower reservoir 2011/05/14 15 Ingula PSS Lower reservoir 2011/05/14 16 8
Ingula Pumped Storage Scheme Ingula Pumped Storage Scheme Ingula PSS Waterways 2011/05/14 17 Ingula PSS - Waterways Advantages of Alternative Contractor has done it before Construction time shorter Contractor claims a more safer construction Disadvantages of Alternative Longer tunnel, more steel lining Temporary access road and tunnel required Inspections more difficult and less safe Longer inspections (Loss of generation) 2011/05/14 18 9
Design Criteria of waterways 1) Design velocities Concrete lined - 5,0m/s to 5,5m/s Steel lined - 8,5m/s 2) ydraulic stability Machine starting time/water starting time >3 3) Steel lining Required when: Minimum insitu stress < 1,2 Max. transient pressure, or < 1,3 Max. static pressure Machine starting time Water starting time 2 2 GD.n = 366000.P = m li. vi i= 1 g. 4) Design of steel linings CECT Recommendations for the design, manufacture and erection of steel penstocks of welded construction for hydoelectric installations (European committee for boilermaking and kindred steel structures) 2011/05/14 19 Ingula PSS Waterways - Surge Surge Max. Upsurge Stop pumping at T=0 Start Generation at T=173s Trip at T=277s Elevation (m) 2000 1800 1600 1400 Surge Shaft Pressure envelope Surge Chamber 1200 1000 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 orizontal Distance (m) Add safety margin of 2m Guide vane opening & closing Opening 20 sec. from 0-100% Closing 23,75 sec from 100-5% 4 sec from 5-0% Advantages of surge tanks Elevation (m) 1770 Improves response time at start-up 1760 Provides hydraulic stability 1750 Reduces water hammer pressures 1740 1730 1720 1710 1700 0 50 100 150 200 250 300 350 400 2011/05/14 Time (s) 20 173s 277s 10
Ingula PSS Waterways Steel linings Material: ROQ-tuf: Min yield 690 MPa 2011/05/14 21 Ingula PSS Powerhouse complex Intake 2011/05/14 22 11
Ingula PSS Powerhouse complex 2011/05/14 23 Ingula PSS Underground excavations Transformer hall Machine hall 2011/05/14 24 Tailrace tunnel 12
Ingula PSS Pump-turbines 2011/05/14 25 Ingula PSS Pump-turbine selection Pump-turbine selection k=n r.q p 0.5 Limit k to 3500-4000 (Ingula: k max = 3712) Rated speed n r = rated speed in r.p.m. Q p = pumping flow n r = 50x60/n p (in a 50 z system) n p = number of pairs of poles in the generator (i.e. 4,5,6,7 etc. certain numbers such as 9, 11, 13 are not preferred) (Ingula: n p = 7) 2011/05/14 26 13
Ingula PSS Pump-turbine selection Francis Pumpturbines 350 300 250 n s = n.p 0.5. -1.25 n s = Specific speed (English) Specific speed 200 150 Ingula 100 50 0 0 100 200 300 400 500 600 700 800 900 1000 ead 2011/05/14 27 Ingula PSS Pump-turbines Model test Runner blades (9 no.) 2011/05/14 28 14
Ingula PSS Pump-turbines Turbine Mode Guide vanes (19 no.) Rated condition Flow = 85m 3 /s ead = 441m Power = 342MW Efficiency= 93,36% n = 428,57 rpm Pumping Mode Runner dia: = 4,139 m Flow = 64-75 m 3 /s ead = 487-450 m Power = 326-359 MW Efficiency = 93,0-93,2% GD 2 tot = 6126 tm 2 2,5 m dia 2011/05/14 29 Ingula PSS Pump-turbines Stay ring - Dorbyl Draft tube - Kenya eavy Engineering Runner Voith 2011/05/14 30 15
ydro potential in some SADC countries Country Potential (MW) Current Percentage installed (MW) Angola 18000 527 3% DRC 100000 2446 6% Madagascar 7800 150 15% Mozambique 13000 2199 17% Zambia 6000 1760 29% 2011/05/14 31 Some Southern African hydro projects Inga III (3600MW) Congo Gabon Brazzaville Kinshasa Dem Rep of Congo Rwanda Burundi Tanzania Kenya Nairobi Dar es Salaam Luanda Angola Malawi Kafue Gorge Lower (600 MW) Kariba North bank ext (360MW) Itezhi-Tezhi (120MW) Kalungwishi (220MW) Namibia Zambia Lusaka T arare Zimbabwe Lilongwe T Mozambique Mphanda Nkuwa (1300MW) Cahora Bassa North Bank (850MW) Botswana Windhoek T Gaborone T Pretoria TT T T T T Maputo Kariba South Bank T T T Johannesburg T T Mbabane ext (360MW) T P Swaziland Lesotho South Africa ydro station N P Pumped storage scheme Cape Town P T Thermal Existing 2011/05/14 32 Proposed T 16
Some challenges Financial constraints of Eskom and regional utilities Local demand too small to justify the development of large power projects Skills challenge in project preparation. Funding challenges Suppressed and constrained regional demand growth Lack of transmission infrastructure adds substantial premiums to generation costs 2011/05/14 33 Thank you 17