Retrofit of Small-scale Hydropower at Hartbeespoort Dam Pre-investment Investigation. Arno Ottermann (PULA) Bo Barta, Willem Slabber, UJ

Transcription

1 Retrofit of Small-scale Hydropower at Hartbeespoort Dam Pre-investment Investigation Arno Ottermann (PULA) Bo Barta, Willem Slabber, UJ

2 Introduction RSA overview : Pilot retrofit: Dev. Potential: Key challenges: Dam retrofit (green vs brown field) Hartbeespoort dam - pilot past / current / future DWA policy (PPP) motivate small opportunity multi-faceted use LED / hybrid

3 Critical Considerations of Retrofit Hydropower ~ Height x Flow Height ~ dam wall height / height to canal (certain!) Flow ~ subject to dam operating rules (uncertain!) daily environmental releases daily down-stream needs seasonal dam spillages Size and type of outlet works Access to outlet pipe to connect penstock (Dam safety) Hydraulic impact on existing outlet (incl. water hammer) Type of spillway (affects location of hydro-power plant)

4 Height: RSA dam safety register ± 4000 water dams 135 Large / 865 Medium / 3000 small 359 DWA owned (M/L) 70 of DWA dams have a hydro-power potential DWA can generate > 100MW base load (450GWh/a) RSA > 250MW Province Height < m 30-60m >60m Count of Dams EC FS GT KN LP MP NC NW WC Total

5 Pilot Study: Dam Retrofit Hartbeespoort Dam

6 Study Funder: Acknowledgements Dept of Economic Affairs Gauteng Implementing Agent: The Innovation Hub Management Company Dr Charity Mbileni: Manager Green & Sustainable Dev. Public Entity / Owner: Dept of Water Affairs (owner & operator of dam & WR) Service Provider: PULA srm Consortium (UJ, B.Barta, W.Slabber)

7 PHASE-1: NEEDS ASSESSMENT

8 Motivation-1: Growing Energy Shortage

9 Motivation-2: Removal of Sediment (1)

10 Motivation-2: Removal of Sediment

11 Motivation-3: Water Quality

12 Motivation-3: Water Quality (2)

13 Motivation-4: Social & Recreational Use

14 PHASE-2: HYDROLOGICAL ANALYSIS

15 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 Hydrologic Analysis: 32yr daily flows Understand the hydrology! Base flow? What % of spillage? A2H083l: River Flow (down-stream of Hartbeespoort Dam m3/s)

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

17 Hydrologic Analysis: Selection of Optimum Generating Capacity Power (MW) Flow (m3/s) Assurance (avg year) Assurance (wet year) Utilization % 70% 12-16hrs per day every day % 40% 50% to 80% of rainy season / 25% of dry season (peak 6hrs) 2x 4, % 20% 20% to 40% of rainy season

18 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

19 PHASE-3: TECHNICAL OPTIONS

20 Technical Options: No river outlet Right Bank of the dam: RB1: Refurbish & upgrade existing hydro installation (80 kw) RB3: New installation from un-pressurized tunnel / canal (1500 kw) RB4: New installation from pressurized tunnel (1800 kw) Left Bank of the dam: LB1: Single unit new installation retrofitted between existing isolating and sleeve valve control rooms (max 500 kw) LB2: Enlarged hydropower facility to utilize unallocated yield which is currently spilled through crest gates (max 10MW)

21 Location: Technical Options Combined RB3 LB1 RB1 LB2

22 RB1 Refurbish & upgrade existing yester-year installation

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

24 Excellent Exhibits of Old Hydro Power

25 Existing Hydropower Installation

26 RB1: Upgrade existing Installation One turbine unit of Francis type Manufacturer: Gilbert Gilkes & Gordon in UK (1923) Effective head: 22 m Rated flow: 0,22 cub m per second Installed capacity: 37 kw with provision for 2nd unit Plant production between 1924 and mid 1960s Rehabilitated/upgraded capacity potential: 80kW Upgraded potential annual output: 0,672 GWh Estimated cost of rehab: about Rand 2,5 million Est. Unit Cost = R62m/MW

27 RB3 New installation from un-pressurized tunnel or siphoning from canal 1500kW

28 RB3: Possible Location Optional combination with LB2

29 RB3: New Installation from tunnel or siphoning from Canal

30 RB3: New installation + un-pressurized tunnel Existing yester-year hydro plant to be extended by new building Large new penstock pipe connected to the existing outlet tunnel to replace present 600 mm dia pipe Alternative: siphon from tunnel outlet (higher environmental impact) The turbine design to take in consideration Head of 30m design flow = 5 m3/sec Estimated generating capacity of 1500kW or 8 GWh/a The costs of this development is estimated at R mil + Est. Unit Cost = R17m/MW - R20m/MW

31 RB4 New installation with pressurized tunnel 1,8MW

32 RB4: New Installation to pressurized tunnel

33 RB4: New installation with pressurized tunnel Existing yester-year hydro plant to be extended by new building to house two turbine units The outlet tunnel to be closed by a concrete structure housing two control valves for canal releases Large new penstock pipe connected to the existing outlet tunnel to replace present 600 mm dia pipe with 1300mm The turbine design to take in consideration water level fluctuation between 36 m and 39 m due to releases through the radial gates The design flow is suggested at 4,5 m3/sec Est. generating capacity = 1,8MW (10 GWh/a) The costs of this development is estimated at R38 mil + (R20/kW)

34 LB1 New retrofit installation inline between existing isolating and sleeve valve chambers 500kW

35 L/B Development of Hydro Power at Hartbeespoort Dam Actual Site

36 LB1: In-line turbine installation

37 LB1: In-line hydropower installation

38 LB1: In-line hydropower installation A single 1524 mm diameter outlet works pipe is bifurcated into three outlet pipes A hydro power unit is proposed to be retrofitted on the centre located 750 mm diameter outlet pipe Due to the spillway radial gates releases the minimum and maximum water heads are 14 and 16,7 m respectively The design flow is suggested at 3 m3/sec. Est. generating capacity = 500kW or 4,2 GWh/a The costs of this retrofit is estimated at R 8 mil + R16m/kW R18m/kW

39 LB2 Enlarged hydropower facility to utilize spillage & unallocated yield 8,4MW (4,2MW x2)

40 DAM WALL LB2: Surplus Yield Generation plan view River outlet 25 m3/s

41 LB2 : Surplus hydropower installation Connect to 1524 mm diameter outlet works pipe with Y- junction in a separate valve control room Add penstock to new hydropower plant building: 1500mm dia steel pipe 50m long (above ground and anchored) Split into 2 hydropower units and a river outlet 2 hydropower generator units with 4,2MW each Maximum water heads are 39 to 42 m The design flow is suggested at 25 m3/sec (2x12,5 m3/s) Est. generating capacity = 8,4MW The costs of this retrofit is estimated at R 120 mil + R14m/MW +

42 Combined Phase-1: (26 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

43 Retrofit vs New dam projects HBP retrofit unit cost = R12m/MW HBP greenfield unit cost (incl.dam wall) = R42m/MW Retrofit = low environmental impact (dam exists) Greenfield = high environmental impact Retrofit = short implementation (2 years+) Greenfield = long implementation (> 7 years)

44 Cost-Benefit Value of cleaning the dam? (own use) Value of environmental improvement? Social / property value? Value of affordable energy? Value of water loss in canals? (>50%) Pilot installation to demonstrate renewable energy options compare & integrate hybrid solution unlock value of small hydro solutions

45 END

46 Financials : Technical Options Operating cost = R80 /kw installed per year and R0.8 /MWh. Debt equity split of 30:70 assumed. Debt repayment period 13 years. ROE = 61c/kWh (IRR=14,7%) Interest rate of 14% assumed 2 year construction & commissioning Corporate tax rate of 30% Avg energy production of 69.4 GWh for ann.revenue calc (10MW) 25.1 GWh assumed to generate at peak hours associated tariff 44.3 Gwh assumed to generate at standard hours attracting off peak tariffs. Allowed for clean development trading mechanism (CDM) of 0.89 Kg/kWh CO2 displacement at US$ 4 /tonne.