Wind Turbines Basics

How a wind turbine works Simply stated, a wind turbine works the opposite of a fan. Instead of using electricity to make wind, a turbine uses wind  to make electricity. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity. The electricity is sent through transmission and distribution lines to a substation, then on to homes, business and schools. High-tech turbines equal low environmental impact.  That’s why wind power is gaining public approval and generating increased awareness. It is also becoming economically competitive with more conventional power sources – a fact that’s greatly improving its prospects as a viable energy source. Components of Wind Energy Systems The basic components of a typical wind energy system are shown below: Components of a wind energy system. (Source: Natural Resources Canada) These basic components include: A rotor, consisting of blades with aerodynamic surfaces. When the wind blows over the blades, the rotor turns, causing the generator or alternator in the turbine to rotate and produce electricity. A gearbox, which matches the rotor speed to that of the generator/alternator. The smallest turbines (under 10 kW) usually do not require a gearbox. An enclosure, or nacelle, which protects the gearbox, generator and other components of the turbine from the elements. A tailvane or yaw system, which aligns the turbine with the wind. If you plan on building a horizontal axis wind turbine, you will need a tower on which to mount the turbine (vertical axis turbines are usually built on the ground). Several types of towers are available: Guyed lattice towers, where the tower is permanently supported by guy wires. These towers tend to be the least expensive, but take up a lot of space on a yard. A radio broadcast tower is a good example of a guyed lattice tower. Guyed tilt-up towers, which can be raised and lowered for easy maintenance and repair. Self-supporting towers, which do not have guy wires. These towers tend to be the heaviest and most expensive, but because they do not require guy wires, they do not take up as much space on a yard. An important factor in how much power your wind turbine will produce is the height of its tower. The power available in the wind is proportional to the cube of its speed. This means that if wind speed doubles, the power available to the wind generator increases by a factor of 8 (2 x 2 x 2 = 8). Since wind speed increases with height, increases to the tower height can mean enormous increases in the amount of electricity generated by a wind turbine. Relationship between wind speed and wind power. Wind speeds increase with height. Wind turbine schematic. (Modified image from Natural Resources Canada) Picking the Best Location for a Wind Turbine Where you choose to build your wind turbine is important. Remember that if nearby houses, tree lines and silos obstruct the full force of the wind from your wind turbine, you will not be able to generate as much power. Also keep the following in mind: Wind speeds are always higher at the top of a hill, on a shoreline, and in places clear of trees and other structures. Remember that trees grow over the years; wind turbine towers do not. Inform neighbours of your plans to avoid conflict later on. Be courteous. Keep the turbine as far away from neighbours as possible. 250-300 m away is typical. Check with the local government for any other bylaws and regulations about zoning. Wind speeds tend to be higher on the top of a ridge or hill, and for that reason it is a good idea to locate wind turbines at hilly locations Just remember to keep your turbine away from high turbulence. Neighbours must also be taken into consideration when picking a spot to build your turbine. The farther your wind turbine site is from neighbouring houses, the better. Do not expect your wind turbine to generate the same amount of power all the time. The wind speed at a single location may vary considerably, and this can have a significant impact on the power production from a wind turbine. Even if the wind speed varies by only 10%, the power production from a wind turbine can vary by up to 25%! Example of wind speed distribution by hour of the day. Values shown are monthly averages of measurements made by anemometers. (Source: US Department of Energy) Types of Wind Turbines There are two basic types of wind turbines: horizontal axis wind turbines and vertical axis wind turbines. Horizontal axis turbines (more common) need to be aimed directly at the wind. Because of this, they come with a tailvane that will continuously point them in the direction of the wind. Vertical axis turbines work whatever direction the wind is blowing, but require a lot more ground space to support their guy wires than horizontal axis wind turbines. Two basic wind turbines, horizontal axis and vertical axis. (Source: Ontario Ministry of Energy) Choosing an appropriate wind turbine size To determine the appropriate size of wind turbine to use, review your monthly electricity consumption in kilowatt-hours (kWh). To do this look at your electricity bills for the last year, add the kilowatt-hours you consumed, and divide by 12. Then compare this total to estimates of the power production for different wind turbines, a figure available from a wind turbine dealer. Read the whole document here.