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Power from renewable energy

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POWER FROM RENEWABLE ENERGY & DIRECT ENERGY CONVERSION SYSTEMS

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Power from renewable energy

  1. 1. POWER PLANT ENGINEERING S.BALAMURUGAN - M.E ASSISTANT PROFESSOR MECHANICAL ENGINEERING AAA COLLEGE OF ENGINEERING & TECHNOLOGY UNIT 4 – POWER FROM RENEWABLE ENERGY
  2. 2. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  3. 3. HYDRO ELECTRIC POWER PLANT ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  4. 4. Water reservoir: Continuous availability of water is the basic necessity for a hydro-electric plant. Water collected from catchment area during rainy season is stored in the reservoir. Water surface in the storage reservoir is known as head race. Dam: The function of a dam is to increase the height of water level behind it, which ultimately increases the reservoir capacity. The dam also helps to increase the working head of the power plant. Spillway: Water in the dam after a certain level in the reservoir overflows through spillway without allowing the increase in water level in the reservoir during rainy season. Pressure tunnel: It carries water from the reservoir to surge tank. Penstock: Water from surge tank is taken to the turbine by means of pen stocks, made up of reinforced concrete pipe or steel. Surge tank: There is sudden increase of pressure in the penstock due to sudden backflow of water, as load on the turbine is reduced. The sudden rise of pressure in the penstock is known as water hammer. The surge tank is introduced between the dam and the power house to keep in reducing the sudden rise of pressure in the penstock. Otherwise penstock will be damaged by the water hammer. HYDRO ELECTRIC POWER PLANT ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  5. 5. Water turbine: Water through the penstock enters into the turbine through an inlet valve. Prime motors which are in common use are pelton turbine, francis turbine and kalpan turbine. The potential energy of water entering the turbine is converted into mechanical energy. The mechanical energy available at the turbine shaft is used to run the electric generator. The water is then discharged through the draft tube. Draft tube: It is connected to the outlet of the turbine. It allows the turbine to be placed over tail race level. Due to its shape, the water flowing through the tube is decelerated & it comes out with minimum kinetic energy. Tail race: Tail race is a water way to lead the water discharged from the turbine to the river. The water held in the tail race is called tail race water level. Step-up transformer: Its function is to raise the voltage generated at the generator terminal before transmitting the power consumers. HYDRO ELECTRIC POWER PLANT ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  6. 6. TYPES OF HYDRO ELECTRIC POWER PLANT Conventional Plants: Conventional plants use potential energy from dammed water. The energy extracted depends on the volume and head of the water. The difference between height of water level in the reservoir and the water outflow level is called as water head. Pumped Storage Plant: In pumped storage plant, a second reservoir is constructed near the water outflow from the turbine. When the demand of electricity is low, the water from lower reservoir is pumped into the upper (main) reservoir. This is to ensure sufficient amount of water available in the main reservoir to fulfill the peak loads. Run-Of-River Plant: In this type of facility, no dam is constructed and, hence, reservoir is absent. A portion of river is diverted through a penstock or canal to the turbine. Thus, only the water flowing from the river is available for the generation. And due to absence of reservoir, any oversupply of water is passed unused. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  7. 7. TYPES OF HYDRO ELECTRIC POWER PLANT ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  8. 8. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  9. 9. KAPLAN VS FRANCIS TURBINE • Radially in ward or mixed flow Turbine • very large number of blades 16 to 24 • France Turbine disposition of shaft is in vertical or horizontal direction • Runner vanes are not adjustable • medium head is required • medium flow rate is required • Kaplan Turbine is partially axial flow • very small number of blades 3 to 8 • Kaplan Turbine disposition of shaft is only in vertical direction • Runner vanes are adjustable • very low head is required • very large flow rate is required ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  10. 10. GOVERNING OF TURBINES Steam Turbine Governing is the procedure of monitoring and controlling the flow rate of steam into the turbine with the objective of maintaining its speed of rotation as constant. The flow rate of steam is monitored and controlled by interposing valves between the boiler and the turbine ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  11. 11. SITE SELECTION FOR HYDRO ELECTRIC POWER PLANT • Availability of water • Water storage • Water Head • Accessibility of the site • Distance from the load center • Type of land of the site – Cheap & Rocky – Impervious Rock – Rock – Strong enough to withstand the stresses transmitted from Dam & Thrust of water ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  12. 12. WIND ENERGY • What is wind? Wind is air in motion. It is produced by the uneven heating of the earth’s surface by the sun. • The earth’s surface is made of various land and water formations, it absorbs the sun’s radiation unevenly. • As the sun warms the Earth's surface, the atmosphere warms too. • Warm air, which weighs less than cold air, rises. Then cool air moves in and replaces the rising warm air. This movement of air is what makes the wind blow. • Two factors are necessary to specify wind: speed and direction. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  13. 13. WIND TURBINES ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  14. 14. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  15. 15. COMPONENTS OF WIND TURBINE • Anemometer: Measures the wind speed and transmits wind speed data to the controller. • Blades: Lifts and rotates when wind is blown over them, causing the rotor to spin. Most turbines have either two or three blades. • Brake: Stops the rotor mechanically, electrically, or hydraulically, in emergencies. • It includes Brake pad, Brake shoe, brake solenoid, Oil reservior, Accumulator, Hydraulic pump & Hydraulic control • Controller: Starts up the machine at wind speeds of about 3.5 m/s and shuts off the machine at about 56 m/s. Turbines do not operate at wind speeds above about 56 m/s because they may be damaged by the high winds. • Gear box: Connects the low-speed shaft to the high-speed shaft and increases the rotational speeds from about 30-60 rotations per minute (rpm), to about 1,000-1,800 rpm; this is the rotational speed required by most generators to produce electricity. The gear box is a costly (and heavy) part of the wind turbine and engineers are exploring "direct-drive" generators that operate at lower rotational speeds and don't need gear boxes. • Generator: Produces 50-cycle AC electricity; it is usually an off-the-shelf induction generator. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  16. 16. High-speed shaft: Drives the generator. Low-speed shaft: Turns the low-speed shaft at about 30-60 rpm. Nacelle: Sits a top the tower and contains the gear box, low- and high-speed shafts, generator, controller, and brake. Some nacelles are large enough for a helicopter to land on. Pitch: Turns (or pitches) blades out of the wind to control the rotor speed, and to keep the rotor from turning in winds that are too high or too low to produce electricity. Rotor: Blades and hub together form the rotor. Tower: Made from tubular steel, concrete, or steel lattice. Supports the structure of the turbine. Because wind speed increases with height, taller towers enable turbines to capture more energy and generate more electricity. Wind direction: Determines the design of the turbine. Upwind turbines—like the one shown here—face into the wind while downwind turbines face away. Wind vane: Measures wind direction and communicates with the yaw drive to orient the turbine properly with respect to the wind. Yaw drive: Orients upwind turbines to keep them facing the wind when the direction changes. Downwind turbines don't require a yaw drive because the wind manually blows the rotor away from it. COMPONENTS OF WIND TURBINE ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  17. 17. EXPRESSION FOR POWER DEVELOPED BY WIND TURBINE • P α 1 2 m V2 • P = Cp 1 2 m V2 • Mass Flow Rate = m = ρ A V • ρ = Air Density, 1.226 kg/m3 at 1 atm & 15° C • P = Cp 𝟏 𝟐 ρ A V3 • A = π 4 d2, d-Sweep or diameter of rotor • Cp – Power Coefficient • A – Swept Area • V – Wind Velocity • P – Power in Wind Turbine ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  18. 18. Sound pressure is measured in decibels (dB). The average person can hear sounds down to about 0 dB, the level of rustling leaves. Some people with very good hearing can hear sounds down to -15 dB. If a sound reaches 85 dB or stronger, it can cause permanent damage to your hearing. The amount of time you listen to a sound affects how much damage it will cause. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  19. 19. TIDE FORMATION ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  20. 20. TIDAL POWER PLANT • It is a periodic rise & fall of water level in sea due to the attraction of moon & sun on the water of the earth. • Potential energy of the high tide is more than low tide. This difference is called Tidal Energy. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  21. 21. OTEC – OCEAN THERMAL ENERGY CONVERSION • OTEC takes advantage of the temperature differential between the relatively warm surface waters (25° C) and the significantly cooler deep waters (5° C at 1000 m) to drive an electrical turbine. • Open-cycle - Warmer surface water is flash evaporated in a very low-pressure environment and the water vapour is then used to drive the electrical generator. The vapour is condensed using the cold sea water pumped up from below to complete the cycle. This system has the advantage of generating desalinated water. • Hybrid - Firstly electricity is generated using the closed cycle system, however instead of discharging the warm seawater it is evaporated using the open-cycle OTEC system and then later condensed with cool water. This has the advantage of harnessing the advantages of both closed- and open-loop systems ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  22. 22. OTEC – CLOSED CYCLE • Warm water (25°C) is used to ‘flash evaporate’ a working fluid such as Ammonia, Propane or Chlorofluorocarbon (CFC) with a much lower boiling point than water by passing it over a heat exchanger. • The vaporized working fluid drives an electrical turbine before condensing as it comes into contact with a heat exchanger cooled with cool sea water (5°C), which is then pumped back to the evaporator to start the cycle once again. • Closed-cycle systems operate more efficiently than open-cycle but are often smaller in scale as the secondary working fluid operates at a higher pressure. Ammonia = Boiling Point - (-33.3°C) Titanium or Alloy of copper & Nickel ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  23. 23. FLASH CHAMBER • Flash steam is produced when high pressure condensate is discharged to a lower pressure. • The word ‘flash’ describes the way it is formed. • When this pressurized condensate is exposed to atmospheric pressure, it has energy more than it can contain at atmospheric pressure. • This excess energy is used to convert a portion of this condensate into steam. This phenomenon is called as flashing and the steam so generated is referred to as flash steam. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  24. 24. GEOTHERMAL POWER PLANT• The renewable type thermal energy that is naturally present in the interior of the earth surface. • Generated from radioactive decay and continual heat loss from Earth's formation. Temperatures at the core–mantle boundary may reach over 4000 °C. • Geo – of the earth, Thermal – Process of Heating • Mantle – the part of the earth that lies between the crust & the core. Applications Generation of Electric Power Space Heating for Buildings Industrial process heat At depth 3 km – 8 × 1021 joules At depth 10 km – 4 × 1022 joules The Effluent will be salty & contains Sodium, Potassium. In some cases, Lithium, Fluorine, Boron & Arsenic – Severe Pollution Problem. Treatment Plant ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  25. 25. GEOTHERMAL POWER PLANT Hot Solid rocks – Water don’t have a access – Absence of Ground water & Low permeability of rock Man made passages – Fractured at suitable depth Cold Water injected - Steam or Hot Water – Turbine – Power Generation MAGMATIC (Molten Rock) Chamber System Extraction of heat energy from hot magma (1450°C) Difficult – Energy recovery from deeper sources (Drilling distance) Solidification of MAGMA around heat exchanger tubes ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  26. 26. GEOTHERMAL POWER PLANT • Dry steam raised from the underground by the continuous supply of water • Centrifugal Separator – Liquid particles & suspended solid are removed • Water at high temperature coming out from hot well. It is made to flash in the flash chamber to produce steam. • Steam Turbine • Condensed steam & Brine from separator is taken back to Geo thermal field. • Corrosion Issue (Wet) – Requires large land area ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  27. 27. FLASH CHAMBER • Flash steam is produced when high pressure condensate is discharged to a lower pressure. • The word ‘flash’ describes the way it is formed. • When this pressurized condensate is exposed to atmospheric pressure, it has energy more than it can contain at atmospheric pressure. • This excess energy is used to convert a portion of this condensate into steam. This phenomenon is called as flashing and the steam so generated is referred to as flash steam. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  28. 28. BIO-GAS POWER PLANT • Anaerobic Digestion – Biomass waste ( Animal waste, aquatic waste, Agro industry waste, etc.) – Fermentation – Biogas • Biogas – Methane(55%) – Carbon dioxide(35%) – Hydrogen (5%) – Other gas & moisture (5%) • Calorific Value – 23MJ/Kg Petrol CV – 45.8 MJ/Kg ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  29. 29. SOLAR ENERGY • Sun emits 3.7 × 1026 watts. • Earth intercepted the energy of 1.7 × 1017 watts • The energy emitted by sun for 3 minutes = World energy consumption for year • Sun radiation = Visible light + Infrared (Heat) ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  30. 30. SOLAR PHOTO VOLTAIC CELL Semiconductor materials – Silicon, Cadmium, Telluride, Gallium arsenide Principle • Creation of pairs of positive & negative charges (Electron hole pairs) in the solar cell by absorbed solar radiation • Separation of the positive & negative charges by a potential gradient with in the cell ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  31. 31. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  32. 32. Glass Reflecting surface – 10-14 panels (manufacture & transportation – Rectangular) Plastic reflecting surface – Low in reflectance – Strength – less cost – Air supported plastic bubble protects from wind load ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  33. 33. DIRECT ENERGY CONVERSION SYSTEMS Energy conversion devices accept energy as Heat & produce mechanical work Fuel - Heat(Steam) - Mechanical work – Electricity Direct Energy Conversion Devices Natural available energy – Electricity (without mechanical) • Energy Sources – Solar, Thermal, Chemical – Photo Voltaic power system – Fuel cell – Thermoelectric conversion system – Thermionic conversion system – Magneto hydrodynamic system ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  34. 34. FUEL CELL • Electro chemical device • Chemical energy of fuel Directly to Low voltage, • It is a Primary battery in which the fuel & oxidizer are stored external to the battery & fed to it as needed. • Fuel gas diffuses through the anode & is oxidized, releasing electrons to the external circuit • The oxidizer diffuses through the cathode & is reduced by the electrons • Hydrogen – Oxygen fuel cell = Potassium hydroxide (KOH) – Electrolyte • Chemically treated electrodes – To repel the electrolyte – minimum leakage of electrolyte • Conversion efficiency high • Little maintenance, can be installed near load center – reducing transmission loss • Doesn’t make noise – Little time to go into operation • High cost – Low service life ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  35. 35. • Fuel preparation – Receiving, processing, filtering, heating the fuel • Fuel cell - Chemical energy of fuel Directly to Low voltage • Electric power conditioning system – DC-AC convertor – Regulate three phase power supply • Switch gear & Supply system – Delivers power to load. It includes switches, circuit breakers, Protect & isolate the fuel cell fro the grid • Control system - To control voltage, current, fuel input & temperature. This can be done by controlling the fuel supply by feed back control • Heater – In High temperature fuel cell, to maintain the working temperature of the fuel & electrolyte • Applications – Domestic use, Automotive vehicles, Central power stations, Space power plant ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  36. 36. SOLAR PHOTO VOLTAIC CELL Semiconductor materials – Silicon, Cadmium, Telluride, Gallium arsenide Principle • Creation of pairs of positive & negative charges (Electron hole pairs) in the solar cell by absorbed solar radiation • Separation of the positive & negative charges by a potential gradient with in the cell ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  37. 37. THERMOELECTRIC CONVERSION SYSTEM •SEEBECK EFFECT – If two dissimilar materials are joined to form a loop & the two junctions maintained at different temperatures, an e.m.f will be set around the loop. E = α ΔT. •α – seebeck coefficient, ΔT – Temperature difference (Thermocouple) •Converts heat flow into DC electrical power •Two thermoelectric materials required: P-type (red) and N-type (yellow) •Material – Bismuth telluride alloyed with Bismuth selenide, Antimony telluride •Several thermocouples are connected in series to increase voltage & Power. Then DC to AC •Source of Heat – Small oil or Gas Burner, a radio isotope, Direct solar radiation Thermocouple Hot & Cold junctions 600° C & 200° C = 0.1 V & 2 A 1 kW device = 5000 couples in series ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  38. 38. THERMIONIC GENERATOR • Work function (eV) – The energy required to extract an electron from the metal. Varies with nature of material & its surface. • It comprises a heated cathode ( Electron Emitter) & an anode (Electron collector), Separated by a vacuum. Distance between anode & cathode is one millimeter. • The electrode with a large work function is maintained at a higher temperature than one with the smaller work function. • The heat is which is supplied to the cathode raises the energy of its electron to such a level that it enables them escape from the surface & flow to anode. • At anode, the energy of electrons appears partially as heat, removed by cooling & Partially received as electrical energy delivered to the external circuit. • Heat Source – Fossil fuel, Nuclear fuel, Solar energy • Emitter – High Electron Emission with a low rate of deterioration. • Collector – it should have a low work function. (Molybdenum) Thermionic Emission – Emission of Electrons when it is heated.
  39. 39. MAGNOHYDRODYNAMICS SYSTEM (MHD) • It is a device which converts heat energy of a fuel directly into electrical energy without a conventional electric generator. FARADAY’S LAW OF ELECTROMANETIC INDUCTION • When a conductor and a magnetic field move in respect to each other, an electric voltage is induced in the conductor. The conductor may be solid, Gas or liquid. • This device uses this principle by forcing a high pressure high temperature combustion gas through a strong magnetic field. • Seed Material – Potassium Carbonate – To increase the Electrical Conductivity ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET

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