Wind Energy ABCT 1D11D PDF

Wind Energy ABCT 1D11D KF Yung Room Y834 Tel:34008863 Email: [email protected] 1  What is Wind Energy Suggest an example in which you’ve encountered the use of wind as a power source? 2  Hist...

Wind Energy ABCT 1D11D KF Yung Room Y834 Tel:34008863 Email: [email protected] 1  What is Wind Energy Suggest an example in which you’ve encountered the use of wind as a power source? 2  History of Wind Energy Windmill in Greece ©Wiki Dutch type windmill in Denmark ©Wiki 3  History of Wind Energy The Persian vertical windmill ©Wiki Reconstruction of Chinese vertical wind power water pump © amc.stust.edu.tw 4  First Wind Turbine First invented in 1888 In Cleverland, Ohio By Charles Brush 144 blades with diameter of 17 meters 12 kW © Alternative Energy, NCCER 5 Modern Development of Wind Turbine © Alternative Energy, NCCER 6  Main Development for Wind Energy Scale per wind turbine increase Individual to group operation Private to commercialization Share in overall energy production increase Profit margin increase Running cost decrease Integrated to existing power grid 7  Wind Energy Basic Wind - Movement of the air in the atmosphere Origin of energy – Solar radiation (heat) – A range of surface available on earth – Heat absorption is varying – Partial mass of air receive more heat – Hot air rise up and cold air flow back – Heat energy become kinetic energy 8 Origin of Wind © Alternative Energy, NCCER 9  Variations in Wind Intensity Intensity of wind vary across the latitude Due to friction on earth Measure as wind shear turbulence & © Alternative Energy, NCCER laminar Extremes intensity : hurricane & typhoon 10 World Wind Resources © US-DOE in 1985 using wind data compiled in 1980 11  Availability of Wind Energy Resources 40 times of world’s annual consumption 5 times the current energy production from all energy forms Available for all countries More available for costal area Seasonal and daily variation of intensity Intermitted supply of emission free energy 12  Wind Power Calculations Wind energy = ½ x density x (area x velocity x time) x velocity2 = ½AtV3 Wind Power generation depends on: – mass of air / density (natural) – velocity of air (natural, latitude) – volume amount of air (human, radius of rotor) 13 © Alternative Energy, NCCER  Limitation of Wind Power Generation Efficiency Power efficiency limit – Comparison of wind kinetic energy before (Pi) and after (Pf)passing through the wind turbine – Cp = Pf/Pi – If Cp = 100% efficiency (wind stop after passing through) => not possible!!! Betz Limit is the best theoretical Cp = 16/27 The best efficiency of wind turbine should lower than 59% 14  Capacity Factor for Wind Power Capacity Factor = Average Output / Peak Output ≈ 30% Depends on both wind turbine and site © MIT open courseware 15  Design of Wind Turbine Vertical Axis Wind Turbines (VAWTs) Darrieus VAWT Savonius VAWT Eggbeater VAWT 16 © Alternative Energy, NCCER © WIKI © Alternative Energy, NCCER  Design of Wind Turbine Horizontal Axis Wind Turbine (HAWTs) Mutliblade HAWT 3-blade airfoil HAWT 2-blade small scale © WIKI © WIKI HAWT © Alternative Energy, NCCER17  HAWTs Most common type of modern wind turbine 2-3 blades are the most efficient Power output is determined by the blade length Upwind or downwind design 18 © Alternative Energy, NCCER  Interaction of Wind with Blades Lift and Drag Force By the difference in air flow velocity above and below the blade By the correct air attack angle, a lift force will produce So called airfoil design 19 Design of a typical HAWT 20 © Alternative Energy, NCCER  Blades Design avoid even number of blade due to stability problems each blade is rotatable to control the maintain the optimize attack angle Also adjust to decelerate the turbine under strong wind Usually design to work at wind speed at 15m/s – Higher wind speed not usual and cost higher damage to the wind turbine 21  Nacelle, Shaft and Generator Nacelle – Streamlined housing for the shaft and generator Shaft – Low-speed shaft – connected directly to the rotor and rotating at the same speed (30-60 rpm), transmit energy to the gearbox – High-speed shaft – connected to the gearbox so that the rotating speed is increase (up to 2000 rpm) , transmit energy to generator for electricity generation 22  Yaw Drive and Brake Yaw drive is a controlled system to adjust the facing direction of the rotor – ensure the wind turbine can always operate at highest efficiency – or avoid strong wind to prevent damage Brake is a mechanical system to slow down or stop the rotor for maintenance or avoid damage at high wind speed 23  Tower design Guyed tower Lattice tower Tubular tower © Alternative Energy, NCCER 24 Size vs Energy 25  Location Consideration Discussion Question Suggest what location requirement is required for setting up wind turbine with high efficiency. 26  Location Consideration Land based – Hillside with higher wind speed – Country side with large flat land with medium wind speed – Urban / city area normally not suitable as turbulence caused by high rise building Off-Shore – Near the sea shore – in shallow water level – Floating on the sea 27  Different Foundation Design © NREL 28 Shallow Water Foundation © http://offshorewind.net/ 29  Shallow Water Foundation Mono pile – steel pile – driven approximately 32-64 ft into the seabed. Gravity foundation – most popular for offshore wind projects – gravity foundation consists of concrete or steel which rests on seabed – turbine stability is dependent on gravity Tripod foundation – common used by the oil and gas industry – each piles are driven 32-64 ft into the seabed – used at deeper depths – not very common due to the high cost 30 Deep Water Foundation Prototype © http://offshorewind.net/ 31 Wind Turbine Design Consideration 1. Basic design – orientation and blade number 2. Onsite survey and desired parameters – wind speed, direction and potential power output 3. Optimize the blade size – for efficiency balance 32 Wind Turbine Design Consideration 4. Maximum operating speed – Higher speed - more complex design and noise 5. Design of blade – including angle of attack, lift and drag characteristics – Increase blade number to increase efficiency 6. Modeling (computer or small scale wind tunnel experiment ) to determine optimum blade shape 33 Current World Wind Energy Capacity 34  Cost of Wind Energy "The Economics of Wind Energy." EWEA, March 2009. 35  How a 5MW Wind Turbine Cost "The Economics of Wind Energy." EWEA, March 2009. 36  Advantages for Wind Energy Renewable No emission Potential reserve is huge Safe Complementary to solar and hydro to provide energy Peripheral land is possible to use for other application (Farming, industry, transportation etc ) 37  Disadvantages for Wind Energy Intermittent and unpredictable Destruction of natural landscape High setup cost High maintenance cost High transmission cost High storage cost for off peak time generation Threat to wildlife like birds Noise problem 38 Discussion Question Is Hong Kong suitable to adopt Wind Power? 39