Wind Power & Wind Turbine
Download as PPTX, PDF1 like1,945 views
Wind power works by using wind turbines to harness the kinetic energy of the wind. Wind turbines capture wind energy through their rotor blades and convert it into mechanical rotation to spin a generator that produces electricity. Key components of a wind turbine include the blades, shaft, gearbox, generator, and tower. As wind speed increases, power output also increases up to the turbine's rated capacity, after which the turbine's design limits further power production. Larger turbines with taller towers and wider rotors can generate more electricity. Advantages of wind power are that it is a renewable domestic source of energy generation with no pollution.
Wind Power & Wind Turbine
- 1. Alternative Sources of Energy
- 2. WIND POWER & WIND TURBINE • What is it? • How does it work? • Components of wind turbine • Design considerations
- 3. WIND POWER - What is it? All renewable energy (except tidal and geothermal power), ultimately comes from the sun The earth receives 1.74 x 1017 watts of power (per hour) from the sun About one or 2 percent of this energy is converted to wind energy (which is about 50-100 times more than the energy converted to biomass by all plants on earth
- 4. WIND POWER - What is it? Differential heating of the earth’s surface and atmosphere induces vertical and horizontal air flow that are affected by the earth’s rotation and contours of the land WIND. e.g.: Land Sea Breeze Cycle The surface of the earth heats and cools unevenly, creating atmospheric pressure zones that make air flow from high- to low-pressure areas.
- 5. History and Development of Wind Power Technology • The sailboat is the earliest known use of wind power. • The first windmills were made to automate the tasks of grain grinding and water pumping in Persia 500-900 AD. • The first use of a windmill to generate electricity was in Cleveland, Ohio in 1888. • Bulk Power Wind Energy was first made in Russia in 1931 (100 kw Balaclava Wind Generator). • The largest bulk wind energy producer was the Smith-Putnam Machine (Installed in Vermont, 1941)
- 6. Design considerations of a Wind Mill • When designing a windmill, one must decide on the size of the turbine, and the size of the generator. • Type of turbine- horizontal axis and vertical axis orientation of the blades • Height and location of the tower. i.e. site (off shore, desert, hilly area, valley etc) • Number of blades of the turbine • Air mass and wind speed/velocity • Materials of the blades (wood, fiberglass, metal etc) • Shapes of the blades (pitch control) • Roughness and obstacle of the surface of the earth • Rotor diameter and rotor sweep area in square meter
- 7. The Mechanics/design of a Wind Mill • A Windmill captures wind energy and then uses a generator to convert it to electrical energy. • When designing a windmill, one must decide on the size of the turbine, and the size of the generator.
- 8. Two types of turbine design are possible – Horizontal axis and Vertical axis. In horizontal axis turbine, it is possible to catch more wind and so the power output can be higher than that of vertical axis. But in horizontal axis design, the tower is higher and more blade design parameters have to be defined. In vertical axis turbine, no yaw system is required and there is no cyclic load on the blade, thus it is easier to design. Maintenance is easier in vertical axis turbine whereas horizontal axis turbine offers better performance. Wind Turbine Design Horizontal axis Turbine Vertical axis Turbine
- 9. Wind Turbines: Number of Blades Most common design is the three-bladed turbine. The most important reason is the stability of the turbine. A rotor with an odd number of rotor blades (and at least three blades) can be considered to be similar to a disc when calculating the dynamic properties of the machine. A rotor with an even number of blades will give stability problems for a machine with a stiff structure. The reason is that at the very moment when the uppermost blade bends backwards, because it gets the maximum power from the wind, the lowermost blade passes into the wind shade in front of the tower.
- 10. Main components of a Horizontal Axis Wind Turbine Gear box: Wind turbines rotate typically between 40 rpm and 400 rpm. Generators typically rotates at 1,200 to 1,800 rpm. Most wind turbines require a step-up gear-box for efficient generator operation (electricity production). Blades and rotor: Converts the wind power to a rotational mechanical power. Generator: Converts the rotational mechanical power to electrical power.
- 11. •The generator is attached at one end to the wind turbine, which provides the mechanical energy. • At the other end, the generator is connected to the electrical grid. WIND TURBINE GENERATORS
- 12. Wind turbine components : 1-Foundation 2-Connection to the electric grid, 3-Tower, 4-Access ladder, 5-Wind orientation control (Yaw control), 6-Nacelle, 7-Generator, 8-Anemometer, 9-Electric or Mechanical Brake, 10-Gearbox, 11-Rotor blade, 12-Blade pitch control, 13-Rotor hub. Main components of a Wind Turbine
- 13. Main components of a Wind Turbine The portion of the wind turbine that collects energy from the wind is called the rotor. The rotor usually consists of two or more wooden, fiberglass or metal blades (new design) which rotate about an axis (horizontal or vertical) at a rate determined by the wind speed and the shape of the blades. The blades are attached to the hub, which in turn is attached to the main shaft. Rotor Rotor
- 14. Main components of a Wind Turbine
- 15. Shaft- Two different shafts turn the generator. One is used for low speeds while another is used in high speeds. Tower- Tall tubular metal shaft. The taller the tower, the more power produced. Anemometer - measures the wind speed Brake - A disc brake can be used to stop the rotor in emergencies The controller - starts up the machine at wind speeds of about 8 to 16 miles per hour (mph) and shuts off the machine at about 55 mph. Turbines do not operate at wind speeds above about 55 mph because they might be damaged by the high winds. The nacelle - sits atop 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 - Blades are turned, or pitched, out of the wind to control the rotor speed and keep the rotor from turning in winds that are too high or too low to produce electricity. Wind vane - Measures wind direction and communicates with the yaw drive to orient the turbine properly with respect to the wind. Yaw drive - Upwind turbines face into the wind; the yaw drive is used to keep the rotor facing into the wind as the wind direction changes. Downwind turbines don't require a yaw drive, the wind blows the rotor downwind.
- 16. Main components of a Wind Turbine
- 17. Winds are influenced by the ground surface at altitudes up to 100 meters. Wind is slowed by the surface roughness and obstacles. A wind turbine obtains its power input by converting the force of the wind into a torque (turning force) acting on the rotor blades. A typical 600 kW wind turbine has a rotor diameter of 43-44 meters, i.e. a rotor area of some 1,500 square meters. The rotor area determines how much energy a wind turbine is able to harvest from the wind. Typical Wind Turbine Operation
- 18. 0 ~ 10 mph --- Wind speed is too low for generating power. Turbine is not operational. Rotor is locked. 10 ~ 25 mph --- 10 mph is the minimum operational speed. It is called “Cut- in speed”. In 10 ~ 25 mph wind, generated power increases with the wind speed. 25 ~ 50 mph -Typical wind turbines reach the rated power (maximum operating power) at wind speed of 25 mph (called “Rated wind speed”). Further increase in wind speed will not result in substantially higher generated power by design. This is accomplished by, for example, pitching the blade angle to reduce the turbine efficiency. > 50 mph --- Turbine is shut down when wind speed is higher than 50 mph (called “Cut-out” speed) to prevent structure failure. Typical Wind Turbine Operation
- 19. How wind turbine works • The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity. • A wind turbine extracts energy from moving air by slowing the wind down, and transferring this energy into a spinning shaft, which usually turns a generator to produce electricity.
- 20. Wind Turbine Efficiency, η The theoretical maximum amount of energy in the wind that can be collected by a wind turbine's rotor is approximately 59.3%. This value is known as the Betz limit. If the blades were 100% efficient, a wind turbine would not work because the air, having given up all its energy, would entirely stop. In practice, efficiency of a rotor is not as high as 59%. A more typical efficiency is 35% to 45%.
- 21. Theoretical Power Generated by Wind Turbine Power = ½ (ρ)(A)(V)3 A = swept area = (radius)2 , m2 V = Wind Velocity, m/sec. ρ = 1.16 kg/m3 , at 1000 feet elevation ρ = 1.00 kg/m3 , at 5000 feet elevation ρ = Density of air = 1.2 kg/m3 , at sea level, 20 o C and dry air This equation states that the power is equal to one-half, times the air density, times the rotor area, times the cube of the wind speed.
- 22. Typical Power Generated by Wind Turbine Power = ½ (ρ)(A)(V)3 (η) = 0.5(1.16)(p502)(12)3(0.4) = 3.15 x 106 Watt = 3.15 MW How much power a wind turbine with 50 meters long blade can generate with a wind speed of 12 m/s? The site of the installation is about 1000 feet above sea level. Assume 40% efficiency (η).
- 23. Power Generated by Wind Turbine Wind turbines with rotors that are about 8 feet in diameter (50 square feet of swept area) may peak at about 1 kW and generate about 75 kilowatt-hours (kWh) per month with a 10 mph average wind speed. For wind turbine farms, it’s reasonable to use turbines with rotors up to 56 feet in diameter (2,500 square feet of swept area). These turbines may peak at about 90,000 watts (90 kW), and generate 3,000 to 5,000 kWh per month at a 10 mph average wind speed, enough to supply 200 homes with electricity.
- 24. Investment • The British Wind Energy Association predicts wind to overtake nuclear in U.K. in the next decade. • 9 GW of electricity from offshore wind farms by 2015 in U.K. Tower height: 140-meters Tip height: 220 meters Swept area: 21,000 m2
- 25. Investment – cont. • China expects wind output to exceed nuclear by 2020. • Currently has 12 GW of capacity. Plans to increase capacity by 20% per year. • Has targeted goal of 100 GW from wind by 2020.
- 26. • In 2008, a 27 GW increase in wind capacity was achieved moving total global wind capacity above 120 GW. • U.S. and China account for over 50% of 2008 growth with additional 8 GW and 6 GW of new capacity. Investment – cont.
- 27. Electricity generated from wind has increased from 0.1% in 1997 to 1.5% in 2008. Investment – cont.
- 28. Advantages of Wind Power The wind blows day and night, which allows windmills to produce electricity throughout the day. (Faster during the day) Wind energy is a domestic, renewable source of energy that generates no pollution and has little environmental impact. Up to 95 percent of land used for wind farms can also be used for other profitable activities including ranching, farming and forestry. The decreasing cost of wind power and the growing interest in renewable energy sources should ensure that wind power will become a viable energy source worldwide.