Theme 5: Small-scale Hydropower. By: Dr Khamphone Nanthavong Faculty of Engineering, National University of Laos

Transcription

1 Theme 5: Small-scale Hydropower By: Dr Khamphone Nanthavong Faculty of Engineering, National University of Laos

2 Fundamentals of Hydropower Why Small-scale Hydropower? Small-scale hydropower Potential assessment Hydrological Analysis Site survey

3 Hydrological cycle 44,000 km 3 km 3 68,000 km 3 445,000 km 3 401,000 km 3 112,000 44,000 km 3 E2M Introduction to RE 11:15 AM 3

4 Hydropower: Principle Hydro Electric Power Plant Transform er H=h u -h 1 h u Generator Gear Grid h 1 Rack Flow rate Q, Turbine m 3 /s E2M Introduction to RE 11:15 AM 4

5 Hydropower Power Plant components E2M Introduction to RE 11:15 AM 5

6 HP Classification By installed capacity PICO <1 kw, (somewhere <5 kw) MICRO: kw (somewhere <200 kw) Mini kw Small 1-10 MW (In Lao case: <15 MW) Large or full scale: > 10 MW By Heads Low head (<15 m) Medium Head (15-50 m) High head (> 50 m)

7 PICO ( 1 kw)

8 80kW MICRO kw 70kW 55 kw

9 MINI ( kw) 500 kw

10 Small (< 15MW) 2 MW

11 ofull scale hydropower (> 10 MW) Dam Name Country Installed capacity Nam Ngum 1 Laos 150 MW NamTheun 2 Laos 1098 MW ITAIPU Brazil-Paraguay 14,000 MW Three Gorges China 22,000 MW 11:15 AM 11

12 Run-off river scheme with Enlarged forebay

13 Supply Destination stand alone or captive (with isolated mini grid) grid-connected: to feed power to grid network

14 Components of Small scale-hydropower Scheme Aqua Duct Settling basin Forebay tank Channel Intake & Diversion weir Penstoc k Power house

15 Advantages of Small-scale Hydropower Uses Renewable energy resources Relies on a non-polluting, indigenous and locally available source of energy Can replace petroleum-based generating systems Uses a well-proven technology, well beyond research and development stage environmental impacts can be kept at very low level

16 Advantages to other renewables High efficiency (70-90%) High capacity factor - 50% (PV-10%, Wind-30%) reliable for captive systems High level of predictability, varying with annual rainfalls Slow rate of changes: gradually from day to day Good correlation with demand Proven, robust and long lasting equipment

17 Other Advantages: Alternatively, SHP can be used as shaft power (mechanical works): grain mill, water pumping Due to small size allow involvement of local villagers during the construction phase Suitable locations are widely spread good for decentralized electrification Encouraged local production of parts/ equipment wide range of design and construction materials are available locally

18 Disadvantages: Associated with higher capital cost (usually > 2000 US$/kW) Requires a considerable amount of specialist know-how require a simple but continuous effort for operation and maintenance: o Lack of organizational capacities o Lack of cash

19 P E o Power of Falling Water Potential energy of body of mass m (kg and elevated on h (m): gross E t m P P net gross g h Gross Power produced: P net m g h t o gross V t g h gross Q g h (V- falling water volume; -water density) e = Overall efficiency of energy conversion (%) g Qh gross gross m (P net - Net Output Power ) h Falling Times (t) 0

20 Power of falling Water P P o net channel P o gross penstock Q g h o 5.0 Q, output h gross turbine kw e gross generator transformers transmissi on Q hgross, g=9.8 m/s 2; = 1000, kg/m 3; W e

21 Stages of SHP Potential assessment : 1) Desk study (or hydrology study) To study on geological, hydrological and socio-economic conditions of the proposed site May identify appropriate site without site visit May know that there is no any potential at the proposed site, and hence no need to do site visit save money Accuracy of project costs estimation at this stage is 30%

22 2) Reconnaissance visit: a short site visit (usually 1 day visit) to verify the desk study results: Existing hydropower potential Appropriate power demand Site Accessibility

23 3) Pre-Feasibility Study to determine which of several proposed projects, sites or technical options are most attractive for SSHP development Preliminary assessment are reviewed and worked out with more details Accuracy of cost estimates: 20-25%

24 4) Feasibility Study(FS): Assessment whether the implementation of the proposed scheme is desirable or not Project Developer will make final decision and to locate funding on the base of FS Accuracy of cost estimates: 10-15%

25 Hydrological data analysis (desk study) To estimate minimum flow Necessary to visit the stream during the smallest flow (usually driest period) Involve a Hydrograph and Flow Duration Curve Two approaches: Area-Rainfall method Correlation method

26 Area-Rainfall method Local map scale 1:50,000; better 1:20000 or 1:10000 Necessary Statistic data/ information Rainfalls Hydrograph Flow Duration Curve (FDC)

27 Rainfall-area method Example : how to define project location on the map B B1 C Power House A A1

28 Rainfalls-area method Catchment area definition B B1 Power house location C A A1

29 Rainfalls Areas method Rain gauge

30 Area-Rainfalls method Calculation of rainfalls in catchment areas 4 W w=2000 mm/year Area W Area Z A B 1 2 Area Y Proposed Power House Y C y=2700 mm/y Z z=3000 mm/y 3

31 Area-Rainfalls method Example of rainfalls calculation W w=2000 mm/ ປ Area W Area Z A B Area Y Area Total 9.1 2,633 Proposed Power House Y rain falls C Proportion rainfalls W Y Z ,253 y=2700 mm/ ປ Z Area Z Area W Area Y Average rainfall= z w y Area total Area total Area total z=3000 mm/y

32 Area-Rainfalls method Example W w=2000 mm/ ປ Area W Area Z A B Area Y Area Proposed Power House Y Rain falls C Proportion W Y Z ,216 total ,651 compared to case 1 2,633 Accuracy increased 0.70% y=2700 mm/ ປ Area Z Area W Area Y Z Average rainfall= z w y Area total Area total Area total z=3000 mm/ປ

33 Area-Rainfalls method Example W w=2000 mm/ ປ Area W B Area Total ,666 Proposed Comapred to case 1 2,633 Power House C Rain falls Proportion W Y Z ,306 Accuracy 1.23% Area Z A Area Y Y y=2700 mm/ ປ Area Z Area W Area Y Z Average rainfall= z w y Area total Area total Area total z=3000 mm/ປ

34 Area-Rainfalls method Catchment area of site A Size of square =(30x63.36)x(22x63.36) =2.652x10 6 m 2 B Proposed Power House C A 1: mm Map scale 1: mm Actual Catchment area =area 1 square x number of squares =2.652x10 6 m 2

35 Area-Rainfalls method Catchment area of site A Size of a square =(4x63.36)x(4x63.36), m 2 = 144,658 m 2 Annual Discharge Flow Discharge (ADF) 4 mm x 4 mm 1:63360 A B Map scale 1:63360 Number of squares(a)= 21 Catchment Proposed area (A): = 21x144,658 Power House =3.04x10C 6 m 2 Rainfalls = 2666 mm/year =2.666 m/year Water volume = Catchment area x Rainfalls =3.04x10 6 x = 8.1x10 6 m 3 /year ADF A =8.1x10 6 m 3 /year /(365x24x60x60 s/year) = 0.26 m 3 /s

36 Area-Rainfalls method Catchment area of site B Square size =(4x63.36)x(4x63.36), m 2 = 144,658 m 2 4 mm x 4 mm B No. of squares (B)= 46 Area Proposed of Catchment (B): = 46x Power House =6.654x10 C 6 m 2 1:63360 A ມາດຕາສ ວນຂອງແຜນທ : 1:63360 Rainfalls= 2666 mm/year =2.666 m/year Water volume = Catchment area x Rainfalls =6.654x10 6 x2.666 = 17.74x10 6 m 3 /ປ ADF B =17.74x10 6 m 3 /year /(365x60x60 s/year) = m 3 /s

37 Rainfalls-Area Method: Run-off : Rainfalls = 2666 mm/year=2.666 m/year Water volume = Catchment area x Rainfalls Proposed Power House =6.654x10 6 (m 2 )x2.666 B (m/year)= 17.74x10 6 C m 3 /year A ADF B =17.74x10 6 m 3 /ປ /(365x60x60 s/ປ ) = m 3 /s Run-off = Annual rainfalls - Evaporation

38 Area-Raifall method In case of no Rain gauge But there a map with Isohyets B Proposed Power House C A Low accuracy 1: Map scale1:

39 Hydrograph and Flow duration curve Hydrograph Mean flows) Daily average flow Monthly average flow Annual average flow Flow Duration curve Annual and monthly Mean discharge of Nam Lik River 1991

40 Discharge, Cub. M per second Flow Duration Curve (FDC) Percentage of discharge

41 Flow Duration Curve of Nam Ou River

42 FDC of Nam Lik River

43 Flow Duration Curve characteristics Steep FDC Flat FDC

44 Absence of Rain gauge to use data from near by gauged sites E - Gauged site B ungauged site 1) To do measurements at B at random dates

45 Absence of Gauged data Comparison of actual (measured) and found (correlated) FDC Actual FDC FDC found by correlation 2) Plot the corresponding flows on a graph of flow at E vs. flow at B 3) Use the FDC of the gauged site to select a flow at a specific exceedence value 4) Not much different in dry season

46 Example of FDC

47 Head Measurement Head, h (m)

48 Head Measurement: water-filled clear tube and person Y H(m) =Y1+Y2+Y3+Y4

49 Head Measurement: water-filled tube and rode B1 A2 A1 A1= B1= H1=A1-B1 A2= B2= H2=A2-B2 A3= B3= H3=A3-B3 H=H1+H2+H3+ H(m) =Y1+Y2+Y3+Y4

50 Head Measurement: water-filled tube with pressure Can measure penstock Gauge length; p (kpa) h(m) h(m) p (psi) 9.8

51 Head Measurement: Carpenter s spirit level

52 Head Measurement: altimeter Useful for medium and high height Sensitive to changes of air pressure, temperature and humidity Skills needed to get high accuracy

53 Head Measurement: Clinometers 1 L1 1 H1 H 1 =L 1.sin( 1 )

54 Head Measurement: Sighting and Theodolites

55 Site Flow Measurement: Bucket/Oil drum method Q V water V t m water water Bucket: suitable for flow rate < 5 L/s 200L Oil drum: < 50 L/s m water =m (bucket+water) - m bucket

56 Site Flow Measurement: Cross area & Velocity method Q A v mean Q Flow rate, m 3 /s A Cross-sectional area, m 2 v mean - average velocity, m/s

57 Site Flow Measurement: A & V method Cross section area of a stream/river n n d d d d d d w A d1 d2 d3 dn w n-odd number (1,3,5,...)

58 Site Flow Measurement: A & V method Cross section area calculation: Simple cross section W=2.2 m D=0.3m A wd 2.2* m

59 Site Flow Measurement: A & V method Un-uniform Cross section w=0.55 m n=3 w A 3 w 3 4 d d... d 2d d... d ( d d ) 2( d ) 4 ( ) 2(0.51) 0.62 m n 2 4 n1

60 Site Flow Measurement: A & V method Measuring average flow velocity V v s L t Average velocity, v or v mean L V C v C=0.85- for smooth, rectangular concrete channels C=0.75- for large, slow, clear stream C=0.65- for small but regular stream with smooth stream bed C=0.45- for shallow (0.5 m) turbulent flow C=0.25- for very shallow and rocky stream s

61 Site Flow Measurement: A & V method Average velocity in a partial area V s Velocityina Partialarea v cv s c=0.75-shalow stream c=0.95-deep stream v v s

62 Site Flow Measurement: A & V method Propeller Flow meter can measure: Partial area velocity Average stream velocity

63 Site Flow Measurement: A & V method Propeller Flow meter use

64 Site Flow Measurement: A & V method Total Flow rate = Sum of Partial Area Flow rate Q a v a v a n v n where a1, a2, partial areas Example: partial area between d 2 and d 3 a 3 d 2 2 d 3 w

65 Site Flow Measurement: Weir method Rectangular weir L Q 3/ 2 L 0.2h 1.8 h

66 ວ ດແທກອ ດຕາການໄຫ ຂອງແມ ນາ (Site Flow Measurement) ວ ທ ສາງຝາຍກ ນນາ ແລະ ປະຕ ປ ອຍ ນາ ຊະນ ດອ ນໆ Q 1.4h 5/ 2 Q 1.9Lh 3/ 2 ປະຕ ສາມຫ ຽມ (ມ ມສາກ) ປະຕ ເປ ນຮ ບຄາງໝ

67 Site Flow Measurement: salt gulp' or salt dilution method Quick measurement High accuracy Conductivity meter needed Conductivity meter calibration

68 Thank You!