S.1 Introduction to the Case Study on Micro-Hydro Power Plants

Transcription

1 S.1 Introduction to the Case Study on Micro-Hydro Power Plants Micro-Hydro power is an alternative technology for power generation. This section provides a case study on the design and development of a micro-hydro power plant Micro-hydro powerplant 1

2 P1.1 Acknowledgements Center for Micro-Hydro Technology for Rural Electrification (CEMTRE); 2

3 S.2 Micro-Hydro in the Philippines The Philippines is an archipelago of 7,107 islands It is divided into 3 geographical areas: Luzon, Visayas and Mindanao Land Area: 299, 764 sq. kilometers Population: 76.5 M (as of 2000) For more information, go to 3

4 S.3 Rural Electrification in the Philippines Rural electrification is considered as one of the key components of the national economic development program As of the end of 2000, 8,300 barangays (19.8% of total barangays) remain unelectrified The country s Department of Energy believes that the provision of electricity is necessary for national development The O-Ilaw Program intends to improve the quality of life of Filipinos by providing them with adequate and sustainable energy For more information please go to: 4

5 S.4 Philippine Energy Mix Because of its inherent geographic characteristics, the Philippines requires decentralized energy systems As of 2002, 43% of the country s energy source is derived from renewable energy technologies (see Energy Mix of the Philippines in 2001) The Philippines is fortunate to have the potential for many renewable energy systems Currently, the major renewable energy systems in the country include hydropower, geothermal, biomass and solar power 5

6 P4.1 Energy Mix in the Philippines, 2001 Energy Mix in The Philippines, 2001 Renewable Energy in Philippines oil condensate gas coal renewable energy imported coal 72% 11% 17% Hydropower Geothermal Biomass, Solar, etc imported oil Energy Mix in the Philippines, 2000 Department of Energy, Philippines Renewable Energy allocation in the Philippines, 2000 Department of Energy, Philippines 6

7 S.5 Micro-Hydro Potential in the Philippines Currently, 436 potential micro-hydro locations have been identified in the country The total energy potential of which amounts to 28 MW At present there are 68 micro-hydro systems installed with an aggregate capacity of 233 kw For more information please go to: 7

8 P5.1 Potential Micro-Hydro Locations 8

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10 S.6 Policy on Micro Hydro The local policy supporting the promotion of micro-hydro installation is the Republic Act 7156 Republic Act 7156 Mini-hydroelectric power Incentives Act - provides tax incentives to companies, industries and corporations involved in mini-hydro power generation 10

11 S.7 Project Considerations The construction of a micro-hydro power plant involves the consideration of the following: Project Funding and Capitalization Site evaluation Degree of electrification based on economic development and population growth projections Micro Hydro plant design Social impacts and acceptability (benefits to quality of life) Long-term benefits of electrification Benefits vs. grid connection Project sustainability Forecasting, training, education, trends See Flow Chart for developing a micro hydro plant. 11

12 P7.1 Flow Chart of Micro-Hydro Development 12

13 START IDENTIFICATION OF PROJECT SITE COORDINATION WITH LOCAL GOVERNMENT UNITS SITE ASSESSMENT PREPARATION OF PROPOSAL APPROVAL OF PERMITS BARANGAY ALTERNATIVE POWER ASSOCIATION CONSTRUCTION TRAINING OPERATION AND MAINTENANCE MONITORING 13

14 S.8 The Case Study The province of Mataragan, Abra, Philippines which is located more than 300 km from Manila in the region of Luzon, is one of the many barangays in the Philippines which is unsuitable for grid electrification. In the barangay resides a community of 25 households with 6 members each Livelihood activities in the community is based on small-scale farming and barter of goods Trade with major urban centers is restricted to vital supplies due the site inaccessibility After continuing his education from a nearby city, a native of Mataragan, Abra realized the benefits of having a community electrified. He coordinated with Local Government Units (LGU) to help in the electrification of his barangay 14

15 P8.1 Mataragan Abra Philippines The site is located on elevated ground at the north eastern portion of the island of Luzon. 15

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17 Location Source 17

18 P8.2 Livelihood Activities Farming is the principal economic activity of the village. Some amount of trading is done with neighboring settlements for essential goods such as fuel oil. 18

19 S.9 Site Assessment After his consultation with the LGU, a team of technical experts were sent to Mataragan to survey the site. It was necessary to first convince the villagers of the benefits of having electricity. Once the project was explained to the community, the local people agreed to participate by providing information and by assisting in the manpower needs. A river flows within the vicinity of the village. The primary use of the river is for irrigating their rice fields. Interviews with the people as well as preliminary data from the government indicate that the river can be tapped to provide electricity. More extensive studies show that the river flow characteristics can be defined by its flow duration curve. They have thus concluded that they can make use of hydropower to provide their electrification. A survey of the community s potential electrification requirements was conducted. Activity 19

20 P9.1 Flow Duration Curve of River The flow duration curve illustrates the stream flow characteristics of the river It is constructed by plotting the river s volumetric flow rate during the entire year from the highest to lowest flow. Planning the hydropower plant can be designed based on the flow duration curve since this will identify the available power which can be derived from the river The flow duration curve provides information on the frequency of attaining a particular flow rate during an entire year 20

21 P9.1.1 River The River 21

22 P9.1.2 Flow Duration Curve Flow Duration Curve 0.7 Flow Rate in Cubic Meters per second Percent Exceedence in a Year Figure 1: Flow Duration Curve CEMTRE 22

23 P9.2 Electrification Requirements Generated electricity can be used to provide lighting to households at night and to operate machines to improve their livelihood activities (e.g. rice milling). With available electricity, more facilities can be operated. Computers may now be used to improve the education in the area. Except for the lighting requirement, the daily electrification load of the community is indicated in the table below Time of Day Activity 12 AM 6AM 6 AM 8 AM 8 AM 11 AM 11 AM 2 PM 2 PM - 6 PM 6 PM 12 AM Lighting?????????????????? Livelihood 3,000 W 3,000 W equipment School 2,000 W 2,000 W Other 4,000 W 4,000 W 4,000 W Facilities TOTAL Activity 23

24 P9.3 Activity Activity 1: 1. Calculate for the daily lighting requirement of the community. There are 25 households and each household will require 100 Watts of lighting to be opened from 6 PM until 6 AM W will be required between 8AM until 11 AM and from 2 PM to 6 PM. 2. Based on your answer in the previous question and on Table 1 plot the daily load distribution diagram and find the peak load requirement. 3. Plot the energy demand estimate on Figure X in the core material that shows the variation of GDP with per capita energy usage. Answer to Activity 1 24

25 Activity 2: Interpreting the Flow Duration Curve 1. Use the flow duration curve to fill up the table below Available Flow rate (m 3 /s) Availability in a Year % % 0.30??? 0.40??? Answer to Activity 2 25

26 P9.3.1 Answer to Activity 1 The total lighting requirement is P = no. of _ households watts _ reqd _ per _ HH ( )( ) 100Watts P = 25households household P = 2500Watts The required lighting load from 6 PM 6 AM is 2,500 Watts or 2.5 kw, while 1 kw will be needed from 8 AM 11 AM and 2PM 6 PM and from 6 PM to 12 midnight. Using this information we can fill in the Daily Load Requirement of the community and we can then plot the diagram as illustrated below Time of Day Activity 12 AM 6AM 6 AM 8 AM 8 AM 11 AM 11 AM 2 PM 2 PM - 6 PM 6 PM 12 AM Lighting 2,500 W 1,000 W 1,000 W 2,500 W Livelihood 3,000 W 3,000 W equipment School 2,000 W 2,000 W Other 4,000 W 4,000 W 4,000 W Facilities TOTAL 2,500 W 4,000 W 10,000 W 10,000 W 2,500 W 26

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28 Daily Load Distribution Diagram kw required 6 Series Hours in a Day 28

29 The peak load requirement is 10 kw occurring from 8 AM to 6 PM P9.3.2 Answer to Activity 2 By reading Figure 1, the table can be filled up Available Flow rate (m 3 /s) Availability in a Year % % % % 29

30 S.10 Power Potential of River Activity The current maximum electrification requirement of the community is 10kW. However, they project that the demand will increase up to 20 kw. The potential of a river or stream to provide the required or desired Power may be evaluated using equation 1. P = 9.8 e t Q H (1) Where P = Power required (kw) e t = total efficiency Q = volumetric flow (m 3 /s) H = Head (m) The head is the vertical distance from the micro-hydro intake to the location of the turbine. The total efficiency is affected by the power losses due to the penstock, turbine, generator and transmission line efficiencies 30

31 P10.1 Activity 31

32 Activity 3: Identifying the power potential of the river 1. What is the total effective efficiency given the following efficiencies? (Note: These efficiencies will vary from one equipment supplier to another, efficiency performance data must be obtained from manufacturers of equipment) Transmission Line: 96% Generator: 85% Penstock: 90% Turbine: 80% 2. The head at the site is 35 m. And the flow duration curve is as illustrated in Figure 1, fill in the table below Maximum Load Availability in a year Attainable 70 kw??? % 60 kw???%??? 80%??? 95% 3. To accommodate peak load requirement of 20 kw what volumetric flow rate is required? 4. How much power can be supplied all year round? 5. If a minimum stream flow of 0.10 m 3 /s must be maintained in the river to avoid disrupting aquatic life. How does this affect the power generating potential of the river? Answer to Activity 32

33 P Answer to Activity 3 The over all efficiency is: e = e e e e t penstock turbine transmissi online generator e t = = Given the over-all efficiency of Referring to the Flow Duration Curve, 80 % of the year the flow rate is 0.26m 3 /s And at 95% the flow rate is 0.22m 3 /s 33

34 Using Equation 1: P = 70kW = Q 35 Q = % _ of _ year P = 60 = Q 35 Q = % _ of _ year P P P P 80% 80% 95% 95% = kW = kW Maximum Load Availability in a year Attainable 70 kw 50% 60 kw 65% 50 kw 80% 45 kw 95% The peak load requirement is 20 kw at this power the required Q is 34

35 Q = kW ( 0.587)( 35m) Q = 0.10 m 3 /s This can be supplied by the river 100% of the time If 0.10 m 3 /s must be maintained in the river then a flow rate of 0.20 m 3 /s is required to produce the 20 kw, which can be supplied by the river approximately 98% of the year. This requirement for 0.1 m 3 /s of water in the river increases the total required flow rate from the river. Such that it can provide for the electrification requirements as well as the environmental requirements S.11 Designing the micro-hydropower plant Based on the projections, the expected peak load requirement is 20 kw This requires a volumetric flow rate of 0.10 m 3 /s. However, if 0.10 m 3 /s must be maintained in the river, the total river flow rate must be 0.20 m 3 /s The identified potential location of the penstock is located 400m away from the stream 35

36 In order to reduce costs, an open channel was used to convey the water much nearer to the power house. This will retain a head of 35m and will just require 40 m of penstock The water stream must be diverted and conveyed through the penstock until it reaches the turbine Frictional and turbulence losses occur when water is conveyed through the penstock, reducing the available head of the water. 36

37 P11.1 Open Channel The material to be used for the construction of the channel will depend on the characteristics of the soil which will convey the water flow Since the soil in Mataragan was permeable, sufficient losses of water will occur in the open channel. Thus, it was lined with rubble to prevent seepage of water into the soil 37

38 Concrete may also be used to line the channel, however this will be more expensive 38

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40 P11.2 Selection of Penstock Activity A 40 m long penstock is to be used. Head losses due to friction occur in the penstock and this varies with the material of the as penstock The community provides the manpower to assist in the transportation of the penstock 40

41 P Activity Activity 4: Selection of Penstock 1. If only 10% head loss due to friction is allowable find the required penstock diameter when using steel or PVC pipe. The available pipe diameters are in increments of 50 mm 2. What then is the net available head after consideration of the frictional losses in the penstock? 3. Which pipe do you recommend to be used? (Hint: Refer to the Core Material for Help) Answer to Activity 4 41

42 P Answer to Activity 4 If only 10% head loss due to friction is allowable find the required penstock diameter if using either steel or PVC pipe (Hint: the frictional losses decrease with increasing diameter). For steel n = 0.012; PVC n = (Inversin, 1986). Use Equation 2 h 2 2 f n Q = 10 (2) 5. 3 L D h f = head loss due to friction (m) L = penstock length (m) n = roughness coefficient D = internal pipe diameter (m) Q = volumetric flow rate (m 3 /s) The available diameters are in increments of 50 mm. 42

43 For Steel: D h f n Q L = 10 h ( )( ) 0 2 ( 0.012) ( 0.10) f = m = D = 10 = m 4 For PVC: 2 ( 0.010) ( 0.10) D = 10 = m 4 To minimize the frictional losses and since the available pipes are in increments of 50mm a bigger pipe with internal diameter of 200 mm steel pipe or a 200 mm PVC pipe can be used. Therefore, the head loss due to friction is: 2 n Q h f = 10L D For Steel Pipe: For PVC: ( ) ( ) 2 ( ) m ( 0.200) 5. 3 h f = 10 40m h f = 2. 92m h f = 2. 03m h f = ( ) ( ) ( 0.10 ) ( 0.200)

44 Then the net head will be ( ) = m if a steel pipe is used And ( ) = m if a PVC pipe is used. The eventual selection between these two options will depend on their availability, ease of transport, cost and required power generation. 44

45 S.12 Designing the Micro-hydro power plant Selection of Turbine Turbine selection depends on the specific speed required The relationship between the required power, available head, turbine working speed and specific speed are defined by equation 3. Activity N P N S = (3) 5 H 4 N = working speed of turbine (rev/min) P = maximum turbine output (hp) = 1.4 x maximum turbine output in kw H = net head (m) Turbine efficiency performance varies with flow rate and can be obtained from the turbine manufacturer 45

46 P12.1 Activity Activity 5: Selection of Turbine Part A. It is necessary to determine the best turbine type for direct coupling with the generator. The operating speed is 1800 rev/min. Each turbine operates within a range of specific speeds Calculate for the Specific speed and Find the appropriate turbine Part B. What will happen if the turbine runs at a lower speed of 900 rpm? Answer to Activity 5 46

47 P Answer to Activity 5 Part A. If the turbine is to drive the generator directly, its working rpm must be 1800 as well N S 1800 = ( 32. ) 1.4* 20 = Appropriate turbine is a Crossflow or a Francis Turbine. Note: Crossflow turbines are generally cheaper than Francis turbines Performance data of these turbines depend on the manufacturer The turbine can be designed to accommodate constant or variable flows. Turbines which can accommodate variable flows require flow regulating valves, which can moderate the water flowing into the turbine depending on the load requirement Part B. 47

48 If the turbine is intended to run at lower speeds, pulleys may be utilized to gear up the turbine speed 48

49 S.13 Fabrication of a Cross flow Turbine For the requirements of Mataragan Abra, a crossflow turbine was identified to be appropriate since they are cheaper. A cross flow turbine was fabricated to produce the required 20 kw under a head of 35 m. In order to accommodate the changes in load requirement, guide vanes were included in the turbine assembly to moderate the flow entering the turbine 49

50 P13.1 Turbine Assembly Guide Vanes Machining the Guide Vane 50

51 Runner Disk Runner Assembly 51

52 Cross Flow Turbine Assembly Turbine Operation 52

53 S.14 Governing The power delivered to appliances and other equipment must be maintained at a certain frequency and voltage Deviations from the required frequency/voltage can cause damage to appliances or reduce their service life In micro-hydro power plants, the frequency of the electricity produced by the generator is determined by its speed. Its speed is dependent on the water flow and the power load on the generator. Thus, power generated or delivered by a micro-hydro power plant must be regulated to meet the load requirement while maintaining a uniform frequency output. The commonly used approaches to governing utilizes o Governor o Electronic Load Controller Deciding on the appropriate mechanism will depend on the ability of the community to operate the governor 53

54 P14.1 Governor The governor may either be mechanical or oil pressured It consists of a flyball assembly which is driven electrically or by a turbine Increased load requirements in MHP will cause the flyball assembly to reduce its speed The governor is configured so that the centrifugal force is utilized to adjust valve position and thus compensate for speed variations. This in turn triggers a mechanism for opening the turbine valve thus allowing increased water flow. 54

55 Water Power TURBINE Mechanical Power GENERATOR Electrical Power GOVERNOR 55

56 P14.2 Electronic Load controller The load controller is an electronic device which maintains a constant electrical load on a generator in spite of changing user loads. It allows the use of turbines without flow regulating devices The turbine power output is held constant 56

57 S.15 Construction of the Power House A power house must be constructed to store and protect the turbine and generating unit The location of the power house must easily be accessible for operation and maintenance 57

58 S.16 Economics A well designed micro-hydro power plant will cost around PhP 100,000 to PhP 150,000 or 1500 to 2500 per kw of capacity. Typically, the turbine and generator make up 20 25% of the cost of installation. About 4 5% of the total cost goes to planning, design and project management. The remainder of the cost goes to civil works and the power distribution system. Activity 58

59 P16.1 Activity 59

60 Activity 6: If the plant will be operated for 10 years and is assumed to have zero salvage value, the annualized cost can be obtained using the given relationship: A: Annualized Cost C: Capital Cost n r( 1 + r) ( 1 + r) 1 A = C n r: interest rate n: number of years Assuming an interest rate of 10% per annum calculate the annualized cost of the plant. Assuming that the annualized cost is 85% of the total cost of power generation with the remaining 15% made up of operating and maintenance expenses, calculate the cost of power per kwh. Answer to Activity 6 60

61 P Answer to Activity 6 n r( 1 + r) A = C A = ( Euro )( 20kW ) n ( 1 + r) 1 kw A: Annualized Cost C: Capital Cost r: interest rate n: number of years ( ) ( ) A = Total _ Power _ Gen _ cos t = = 7660Euro 0.85 Annual _ O & M _ cos t = = 1150Euro kwh = ( 20kW ) 24hours 365 days ( ) kwh year day year 0.90 = year cost 7660Euro = = Euros kwh kWh kwh year 61

62 S.17 Operation and Maintenance The people of Mataragan must be trained to operate and maintain the micro-hydro plant Operation and maintenance must be simple enough and must not require too much technical expertise Operation may include manpower for diverting or preventing the water from the river to flow into the channel and regulating guiding vanes of the turbine A payment scheme may be agreed upon in terms of barter of goods to support for the plant s maintenance 62

63 S.18 Summary A micro-hydro power plant with a capacity of 20 kw was constructed in Mataragan Abra, Philippines To cut down on cost, an open channel was utilized to convey the water stream nearer to the penstock. Rubble masonry was utilized to line the open channel in order to prevent water seepage into the soil A 40 m PVC pipe was utilized for the penstock. This was transported manually with the aid of the residents of Mataragan. Based on the required power output as well as the available head, a cross flow turbine was identified to be appropriate Power estimates compare favorably with typical grid power costs in Luzon, Philippines Rural electrification can increase efficiencies in livelihood activities and provide opportunities for improving education in the area. It improves the quality of life Many of the design choices reflect the various cost, logistical and maintenance constraints anticipated for the site. 63

64 S.19 Assessment Write a 4,000 word report on the planning, design and management of a small, off-grid hydroelectric plant. Kindly remark on the following aspects based on information derived from the core material and relevant references: Per capita power requirement as a function of quality of life and typical day to day activities Turbine type and size Provision for hybridization, for instance with small diesel-powered generators, or pumped storage Power generation cost estimates as compared to those of competing alternatives such as PV, wind or connection to the grid Provision for facility maintenance Utilization of the power for livelihood or educational activities Reductions in greenhouse gas emissions relative to the alternative of connection to the grid, and potential for emissions trading or Clean Development Mechanism eligibility. Consider the case discussed below. The electric company in the area has found it not economically viable to extend the grid supply to a village named Quakquak because of the low demand in the area. The potential of setting up a microhydro power plant in the area is being assessed. 64

65 The village is consists of 100 households which mostly depend on upland farming. A satellite school is provided in the area to save the children from the long trek to the main campus located three villages away. Academic performance of the school children in the village has always lagged behind those from other villages due to shorter study hours (no light at night ) and no access to electricity powered instrumentation materials and mediums ( ex. Projector, computer, etc.). The community would like also to set-up a media center equipped with a television viewing room and two computers connected to the internet through a satellite system to facilitate the flow of information to the village and provide entertainment. Electrification requirements for this community can be estimated using either of 2 methods. The first approach uses the correlation between quality of life and per capita energy use which can be found in the core material. The second approach is activity-based, considering typical power consuming activities within the households. Both methods can also be used to provide a degree of mutual verification. Based on these considerations, the projected Electric Load Table for the area has been prepared and provided below: Table A-1 Projected electrical load in Watts for various time of the day Activity Time of Day 12 AM 6AM 6 AM 8 AM 8 AM 11 AM 11 AM 2 PM 2 PM - 6 PM 6 PM 12 AM Lighting School 2, Media Center TOTAL

66 Measurements on the site showed a potential hydraulic head of 25 m. The water flow duration curve in the area is shown in figure 1-A below. Available Flow rate (m 3 /s) Availability in a Year % % % % % % Potential Generation Assessment Assuming system efficiencies as follows: Transmission Line: 96% Generator: 85% Penstock: 90% Turbine: 80% 66

67 Is it possible to supply the electrical energy requirements of the village 100% of the time? If the it will be decided to set-up a facility with 50% reserve capacity, how many percent time in a year will the available hydraulic power supply the rated capacity of the plant. Penstock Design The geographical characteristics of the project site requires a 40 m long PVC penstock made. Considering the material and energy cost (estimated commercial price of electricity generated), determine the most cost effective penstock diameter. Assume penstock usage life of 4 years with zero salvage value. Item Cost Unit Commercial Electricity Cost 3 Pesos / KWH Pipe *D Where D is pipe diameter in inches Pesos / meter length Note that available pipe diameters are in increments of 0.5. What if Steel pipes are used instead? Turbine Selection If the facility is to be designed with 50% reserve capacity and considering that the turbine is to be directly coupled to a generator with rated speed of 1800 rpm, what type of turbine should be used and why? 67

68 S.20 Unit Assessment Task 2 Write a 1000 word essay on lessons you have learned from this case study. Write a 4,000 word report on the planning, design and management of a small, off-grid hydroelectric plant. Assume that a river with flow characteristics similar to the one described above is available. The head at the site is 25 m. It is necessary to provide enough power for a village of 2000 inhabitants. The report must consider the following aspects, to be decided by the student based on information derived from the core material and relevant references: Per capita power requirement as a function of quality of life Turbine type and size Provision for hybridization, for instance with small diesel-powered generators, or pumped storage Power generation cost estimates as compared to those of competing alternatives such as PV, wind or connection to the grid Provision for facility maintenance Utilization of the power for livelihood or educational activities Reductions in greenhouse gas emissions relative to the alternative of connection to the grid, and potential for emissions trading or Clean Development Mechanism eligibility. 68

69 S.21 References Author: Department of Energy, Philippines, 2004 Title: Guide on Micro-Hydro Development for Rural Electrification Publisher: Department of Energy and Japan International Cooperation Agency, 2004 Author: Jeremy Thake, 2000; Title: The Micro-Hydro Pelton Turbine Manual: Design, Manufacture and Installation for Small-scale Hydropower Publisher: ITDG Publishing, ISBN , 2000 Author: Adam Harvey, 1993; Title: Micro-Hydro Design Manual: A guide to small scale water power schemes Publisher: ITDG Publishing, ISBN , 2000 Author: Allen R. Inversin, 1986; Title: Micro-Hydropower Sourcebook: A Practical Guide to Design and Implementation in Developing Countries Publisher: NRECA International Foundation, ISBN ,1999 Author: Godofredo Salazar, 2005; Title: Components of a Micro-Hydro Power System Presented during the Manufacturer s training workshop on micro-hydro turbine, Negros Occidental, January CEMTRE Author: Godofredo Salazar, 2006; Title: Accomplishment/Action Plans Report of CEMTRE Presented last April CEMTRE 69