Hydro Power 21 Oct 2010 Monterey Institute for International Studies Chris Greacen [email protected] Outline Microhydro • Solar, wind, hydro – brief comparison • Hydro system overview • Some.
Download ReportTranscript Hydro Power 21 Oct 2010 Monterey Institute for International Studies Chris Greacen [email protected] Outline Microhydro • Solar, wind, hydro – brief comparison • Hydro system overview • Some.
Hydro Power 21 Oct 2010 Monterey Institute for International Studies Chris Greacen [email protected] Outline Microhydro • Solar, wind, hydro – brief comparison • Hydro system overview • Some examples from Thailand and elsewhere • Site assessment – – – – Head Flow Penstock length Transmission line length • Civil works • Mechanical • Electrical Large Hydro • The good, the bad, and the ugly… Two Lao Hydro stories: NT2 and pico-power Sun, Wind, & Water Micro-hydropower overview Source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook. Thai Potential: 1000s of projects - 700 MW (?) Mae Kam Pong, Chiang Mai DEDE + community 40 kW $130,000 cost Sell electricity to PEA – $13,000 per year Huai Krating, Tak Power: 3 kW Head: 35 meter Flow: 20 liters/second Cost: <$6,000 (turbine - $700 baht) Kre Khi village, Tak Province 1 kW for school, clinic, church Cost: <$3,500 (turbine $250) Head: 10 meters Flow: 15 lit/sec Mae Klang Luang, Chaing Mai 200 watts $120 (turbine: $90) Installed: 2007 Head: 1.7 meters Micro-hydroelectricity: Estimating the energy available Power = 5 x height x flow height Watts meters liters per second Image Source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook. Measuring height drop (head) • Site level • Pressure gauge Sight level method Hose & Pressure Gauge • • • • • Accurate and simple method. Bubbles in hose cause errors. Gauge must have suitable scale and be calibrated. Use hose a measuring tape for penstock length. Feet head = PSI x 2.31 H1 Measuring Flow • Bucket Method • Float Method design flow = 50% of dry-season flow Bucket Method Float Method Flow = area x average stream velocity Civil Works – some golden rules • Think floods, landslides • Think dry-season. • Try to remove sediment • Maximize head, minimize penstock – “wire is cheaper than pipe” Image source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook. Source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook. Weir A Sluice allows sediment removal. Locating the Weir & Intake Silt Basin Trash Rack Intake Head Race Weir Penstock Intake directly to penstock • If spring run-off sediment is not severe, the penstock may lead directly from the weir. Screened Intake Weir Penstock Side intake Trash rack: keeps the big stuff out Screens • Screen mesh-size should be half the nozzle diameter. • A self-cleaning screen design is best. • The screen area must be relatively large. Screen Head Race Silt Basin Penstock Source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook. Power Canal (Head Race) • It may be less expensive to run low pressure pipe or a channel to a short penstock. Head Race 6” Penstock 4” Penstock Forebay (Silt basin) • Located before penstock • Large cross-sectional area, volume Water velocity reduced sediment (heavier than water but easily entrained in flow) has opportunity to drop out. Source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook. Penstocks • A vent prevents vacuum collapse of the penstock. • Valves that close slowly prevent water hammer. • Anchor block – prevents penstock from moving Vent Valve Pressure Gauge Valve Anchor Block Penstock Penstock diameter Hazen-Williams friction loss equation: headloss friction (meters) =(10.674*(F/1000)^1.85)/(CoefFlow^1.85*D^4.87)*L Where: F = flow (liters/sec) CoefFlow = 150 for PVC D = penstock diameter (mm) Penstock materials • • • • Poly vinyl chloride (PVC) Polyethylene (PE) Aluminium Steel Anchor and Thrust Blocks Source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook. Locating the Powerhouse • • • Power house must be above flood height. Locate powerhouse on inside of stream bends. Use natural features for protection. Micro-hydro technology Pelton Turgo Crossflow Kaplan Centrifugal pump Turbine application http://www.tycoflowcontrol.com.au/pumping/welcome_to_pumping_and_irrigation/home4/hydro_turbines/turbine_selection (April 18, 2003) Efficiency and Flow 100% Efficiency Pelton and Turgo Crossflow Propeller 50% Francis 0% 0 0.2 0.4 0.6 0.8 Fraction of Maximum Flow 1.0 (break?) Generators • Permanent magnet • Wound rotor synchronous • Induction (Asynchronous) Permanent Magnet Generator • Rotor has permanent magnets • Advantages – No brushes – Efficient • Disadvantages – Generally limited in size to several kW • Some do AC • Some do AC and rectify to DC Adjustable permanent magnet generator DC Alternator (automotive) • • • • Readily available. Easy to service. Brushes need replacing. A rheostat controls excitation. (wound rotor) Synchronous Generator • • • • Used in many all stand-alone applications. Single phase up to 10 kW. 3-phase up to >100,000 kW Advantage: – Industrial standard – Frequency and voltage regulation • Disadvantage – Wound rotor – not tolerant to overspeed – Harder to connect to grid (wound rotor) Synchronous Generator • Most large machines use field coils to generate the magnetic field. • Rotating magnetic field induces alternating current in stator windings. Exciter Field Winding Rectifier Stator Output Winding Rotor Field Winding Exciter Winding AVR (wound rotor) synchronous generator small 2,000 watts Big 50,000,000 watts Asynchronous (Induction) Generator • Just an induction motor with negative slip. • Used with: – grid-tie system (up to 1 MW) – Off-grid stand-alone (often in ‘C-2C’ configuration) – Can be used with battery based systems Induction motor/generator Induction Generator • Advantages – – – – Simple and robust. Tolerant to overspeed Readily available inexpensive • Disadvantages – Frequency regulation ‘loose’ in stand-alone applications – Requires external excitation • When used in off-grid, an electronic load controller (ELC) controls voltage Induction generator (mini) grid-tie example Wires from electrical panel to flow switch 5.5 meters Single-phase 230 volt power to the resort grid N L Single-phase 230 vac 50 Hz kWh meter V Volt-meter (0-500 volt) Fused cutout, 230 volt A AC Ammeter (0 to 5 Amp) X flow switch (open-circuit when no-flow) HFS-25 Outflow pipe Indicator lamp Wires from electrical panel to pump 5.5 meters Induction grid-tie example 1 MW Mae Ya Huai Krating: ‘pump as turbine’ off-grid induction “C-2C” 3kW Ballast Load ELC Motor Run Capacitors in Box Ballast Current 10A 15A 380V 6A 235V C 25μF 2C 50μF 3000W 4 kVA 380V Total Current To Village Capacitors for external excitation of induction motors: theoretical overview of LC oscillators Mae Wei: ‘pump as turbine’ off-grid induction To village loads… A V School Ammeter 15 amp Volt-meter (0-500 volt) Knife switch A Powerhouse Ammeter 15 amp power lines: single phase 230 vac to village. 2 @ 25 mm Al Leonics controller A V Ballast load Ammeter 15 amp Volt-meter (0-500 volt) Capacitor 70 microfarad Capacitor 140 microfarad Three phase 230 vac delta Mae Wei – ‘pump as turbine’ off-grid induction Regulation With batteries AC direct Permanent magnet Trace C-40 type, etc. Wire to output of Outback ELC (voltage) Synchronous Trace C-40 type Governor (frequency) AVR (voltage) Induction Trace C-40 type Wire to output of Outback ELC (voltage) Capacitors for frequency Regulation – synchronous generators… typically both voltage and frequency • Voltage decreases as load current increases. • The Automatic Voltage (AVR) regulator increases the field excitation to compensate. • Prolonged underspeed can damage an AVR. • Still required with a load controller because load power factor can change. Mechanical Governing • As load varies, mechanical control keeps frequency constant by varying water flow – Advantage: • Saves water – Disadvantage: • Electro-mechanical moving parts • Slower reacting • More expensive Deflector Electronic Governing • Types 1. Phase angle 2. Binary controller 3. Pulse Width Modulation • Dump load: – water heating – air heating – lightbulbs (not recommended) Applying Common Property Theory to Village Power Systems Definition of a common pool resource (Oakerson 1992; Ostrom 1994): • System has limited yields • difficult to exclude individual users from using too much 0 0 Current 1 Current 2 Current 3 Voltage Volts 50 8/8/01 18:05 5 8/8/01 12:05 100 8/8/01 6:05 10 8/8/01 0:05 150 8/7/01 18:05 15 8/7/01 12:05 200 8/7/01 6:05 20 8/7/01 0:05 250 8/6/01 18:05 25 8/6/01 12:05 300 8/6/01 6:05 30 8/6/01 0:05 Amps Mae Kam Pong Microhydro Unit #2 Voltage and Current (15 minute intervals) 6 Sept to 8 Sept 2001 Low evening time voltage: symptom of a common property problem • Rules governing user behavior should match with the technical characteristics of the system • kWh Meters are a mismatch for microhdyro • Should be concerned with kW, not kWh • Low voltages… kWh meter is a culprit Circuit breakers: a technical fix for a common property problem 600 kWh meter 500 400 watts X 300 200 100 S1 11pm 9pm 7pm 5pm 3pm 1pm 11am 9am 7am 5am 0 Mini-circuit breaker can encourage peak load reduction OK Mini-circuit breaker 7000 6000 5000 4000 Watts 3000 2000 2000 1000 1997 1994 0 23:00 1985 22:00 21:00 20:00 19:00 18:00 17:00 16:00 15:00 Time of day Year 1988 14:00 13:00 12:00 11:00 10:00 9:00 8:00 7:00 6:00 5:00 1991 Hourly load curve, by year from 1985 to 2000. Graph based on an appliance usage survey of 35 families in Mae Kam Pong village, April and June 2001. 10000 9000 8000 7000 other water boiler rice cooker iron fridge TV lights Watts 6000 5000 4000 3000 2000 1000 0 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 Contribution to evening maximum peak demand by appliance, for the years 1985 – 2001. Large hydro Large hydro: the good… – Seasonal energy storage – Fast ramp-up rates • Great at load following • Stabilizes grid • Supports deployment of intermittent renewables (wind, etc.) Gordon Dam, Southwest National Park, Tasmania, Australia Image Source: Noodle Snacks, Wikipedia – Low carbon (usually) – Can be inexpensive – Domestic resource – helps diversify against fossil fuel (natural gas) price volatility Large hydro: the bad & ugly… – Environmental issues • Kills fish – Too Low dissolved O2 (turbine outlet) or too high (spilling over dam), reservoir predation, fish passage blocked • Submerge land & fragment habitat • Methane (especially in tropical areas) • Low suspended solids => downstream scouring – Displaces people (40-80 million so far) – Energy security -- Low output in dry years Image Source: California Hydropower Reform Coalition Large hydro: the bad & ugly… –Energy security • Low output in dry years • Climate change Net Electricity Generation - Uganda Load Shedding – Hotter (less snowpack) – More annual precipitation variability Chinese Dams on Mekong River Manwan Dam on the Lancang River, Yunnan Province, China Myanmar Source: Myanmar Country Report on Progress of Power Development Plans and Transmission Interconnection Projects, Nov 2008. Downloaded from http://www.adb.org/Documents/Events/Mekong/Proceedings/ FG7-RPTCC7-Annex3.4-Myanmar-Presentation.pdf Greater Mekong Subregion (GMS) Transmission Grid • promoted by ADB since the early 1990s under the Greater Mekong Subregion Programme • When resistance is tough in Thailand, GMS grid allows cross-border exports of environmental & social problem • Socializes transmission costs. Nam Theun 2 • Two decades in the making… • Sponsors: Electricité de France, EGCO, Ital-Thai, Government of Laos • Cost = US$1.45 billion • Received support from World Bank, Asian Development Bank, European Investment Bank, COFACE, Agence Française de Développement and others in 2005 • Supposed to be a “poverty-reduction” project and help raise the bar for other dams in Laos Nam Theun 2 (1000 MW) • 95% of electricity goes to Thailand • 6,200 people in Laos resettled • Endangered species, elephant habitat to be flooded • Opened floodgates to Chinese, Vietnamese, Russian, Thai investment with reduced social & environmental safeguards A contrast in support...Nam Theun 2 versus pico-hydro in Laos Vs. Pico-hydropower use (installation) 83 Flat Influences Seasonality Type of Installation Mountainous Mattijs, Smits, presentation at Chulalungkorn University Pico-hydropower use (river) 84 Mattijs, Smits, presentation at Chulalungkorn University Pico-hydropower use (river) (2) 85 Mattijs, Smits, presentation at Chulalungkorn University Pico-hydropower use (river) (3) 86 Mattijs, Smits, presentation at Chulalungkorn University Pico-hydropower problems 87 Hardware Lower output than indicated Low efficiency Winding failure Bearing failure Voltage fluctuations No regulation Burning out of light bulbs Broken devices Cables Breaking Bare cables Mattijs, Smits, presentation at Chulalungkorn University Financial analysis pico-hydropower (3) 88 US Dollar per hh/year 350 300 250 200 150 100 50 0 Pico-hydro (Laos) Pico-hydro Community Solar home Diesel/petrol (Vietnam) pico-hydro system gensets Mattijs, Smits, presentation at Chulalungkorn University ESMAP, 2005 Conclusions technography (1) 89 Important technology for rural electrification (estimated 60.000 units throughout Laos) Diversity in uses and geographical contexts Cheapest source of electricity available (compared to e.g. solar and diesel generators) Poor people are willing and able to pay for electricity Dissemination by word of mouth Mattijs, Smits, presentation at Chulalungkorn University Conclusions technography (2) 90 Whole supply chain oriented toward lowest costs little awareness about quality differences Unsustainable practices (regulation problems, breaking devices, etc) No support from government or other organizations Why? Mattijs, Smits, presentation at Chulalungkorn University Political ecology: actors 91 Government (Ministries, institutes) Multilateral organizations (World Bank, ADB, ...) International NGOs Private sector Mattijs, Smits, presentation at Chulalungkorn University Narratives about pico-hydro 92 Common narrative: “We do not support pico-hydropower, because ... Risks Seasonal limitations No increased productivity Mattijs, Smits, presentation at Chulalungkorn University Interpreting actors’ narratives on picohydropower (1) 93 Government Maximizing foreign investment and export revenues Preference centralized supply of electricity Control over remote rural areas: grid extension Multilateral organizations Following line of government Main focus on grid extension Using ‘universally applicable’ solutions Mattijs, Smits, presentation at Chulalungkorn University Interpreting actors’ narratives on picohydropower (2) 94 International NGOs Not many activities on renewable energy Electricity usually not considered one of the most important basic needs Private sector Very little private sector activity (outside picohydropower and batteries) Hardly viable: rock-bottom electricity price Mattijs, Smits, presentation at Chulalungkorn University Thank you … and please bring tools for Saturday hands-on PV workshop blender (!) wrenches pliers screw drivers leatherman For more information, please contact [email protected] This presentation available at: www.palangthai.org/docs