So how do wind turbines make electricity?

• Wind turbines use wind to make electricity. It acts like a fan, but instead of using electricity, it produces electricity from a renewable resource, and that is wind. The wind turns the two-bladed or three-bladed turbines, in which shaft also spins in the process. The shaft is connected to a generator and eventually the energy converts into the electricity people need in society. Most utility-producing turbines range in size from 50 to 750 kilowatts. Single small turbines, below 50 kilowatts, are used for homes, telecommunications dishes, or water pumping.
• More simply stated: the wind turns the rotor of the wind turbine and the rotor will then turn a generator, which makes electricity. The electricity travels through the tower by conducting it through some very thick cables located inside the tower. The electricity then passes through the transformer and then to a household or building in need of electricity.
• Uneven heating of the Earth’s surface by the sun causes the wind. The warmer air in some places rises. The resulting low-pressure area draws in cooler air. Wind patterns are affected by the spin of the planet, weather patterns, and terrain. Wind energy potential increases very rapidly with increasing wind speed. In fact, if wind speed doubles the energy content goes up by a factor of eight.

Types of Windmills

The electricity from a wind turbine is sent through transmission and distribution lines to homes, businesses, and schools.

There are two types of wind turbines:

• Three-bladed wind turbines are operated with the blades facing into the wind when the wind blows. These types of turbines works against the wind in the opposite direction.
• The two-bladed operates in a downwind turbine, and these turbines works along with the wind in the same direction.

Upwind Turbines

• Upwind machines have the rotor facing the wind. The vast majority of wind turbines have this design because it is very common.

• On the other hand, there is also some wind shade in front of the tower. For example, the wind will start bending away from the tower before it reaches the tower itself, even if the tower is round and smooth. Therefore, each time the rotor passes the tower, the power from the wind turbine drops slightly.

• The basic drawback of upwind designs is that the rotor needs to be made rather inflexible, and placed at some distance from the tower. The upwind wind turbines need a yaw mechanism to keep the rotor facing the wind.

Downwind Turbines

• The greatest advantage of downwind turbines is that the machine will bend the tower and rotor blades in the direction it is blowing. Upwind machines must resist bending, although downwind blades and towers can be allowed to bend. The blades can also be made to further reduce bending loads.
• A hinged and controlled blade system allows the blades to "flap" in the wind direction, causing the cone angle between the blades to vary continuously with changing wind and rotational speeds. This feature results in an enormous reduction of the blade-root bending loads. Reducing these loads allows safety with the wind turbines. This downwind system was a result of the design of a 2-blade downwind turbine.
• They have the theoretical advantage that they may be built without a yaw mechanism, if the rotor and nacelle have a suitable design that makes the nacelle follow the wind passively. A more important advantage is that the rotor could be made more flexible. This is an advantage both in regard to weight, and the structural dynamics of the machine, i.e. the blades will bend at high wind speeds, thus taking part of the load off the tower. The basic advantage of the downwind machine is thus, that it may be built somewhat lighter than an upwind machine.
• The basic drawback is the fluctuation in the wind power due to the rotor passing through the wind shade of the tower. This may give more fatigue loads on the turbine than with an upwind design.

Small vs. Large Wind Turbines

• Large wind turbines are used primarily in arrays, called “wind farms.” These huge machines require high wind resources because they must compete with conventional generation (coal, natural gas, oil, and nuclear) at the wholesale level.
• Large wind systems cost less when it comes to costs and has a tower height usually higher than 200 feet, with a rotor diameter ranging from 60 to 80 meters.
• Small wind systems are used primarily for individual homes, businesses, or facilities. Though they cost relatively more than large turbines, small wind turbines can be used in areas with modest wind resources because they compete at the retail level.
• Large wind turbines have gotten much bigger and much less expensive in the last 15 years. They can already produce electricity less expensively than power from coal or nuclear power plants.
• The costs of small wind turbines has not dropped very much in the last 15 years, principally because small wind systems have not been granted the subsidies that are available for large wind turbines and solar modules.
• The cost of smaller wind turbines are less than large turbines, operating costs 1 cent/kWh compared to the large wind turbines which cost at 8 cents/kWh.
• Less land is used to support smaller wind turbines than large ones.

Wind Turbine Terminology

Anemometer: This device measures the wind speed.

Blades: Most turbines have either two or three blades. Wind blowing over the blades causes the blades to "lift" and rotate.

Brake: A disc brake that is used to stop the rotor in emergencies to ensure the safety of all wind turbines.

Controller: The controller starts up the machine at set wind speeds and it will also stop the machine generator when wind speeds are very high because the generator may overheat in some cases due to high levels of friction.

Gearbox: Gears connect the low-speed shaft to the high-speed shaft and increase the low rotational speeds to a much higher rotation levels that is required by most generators to produce electricity. The gearbox is considered a costly and rather heavy part of the wind turbine.

Generator: A device that produces a 60-cycle AC electricity.

High-speed shaft: Drives the generator.

Low-speed shaft: The rotor turns the low-speed shaft at about 30 to 60 rotations per minute.

Nacelle: The rotor attaches to the nacelle, which sits atop the tower and includes the gearbox, high and low speed shafts, generator, controller, and brake. Some nacelles are large enough for a technician to stand inside while working. A cover always protects the components inside the nacelle

Pitch: Blades are turned, out of the wind to keep the rotor from winds that are too high or too low to produce electricity.

Rotor: The blades and the hub together are called the rotor.

Tower: Towers are made often made from tubular steel or steel lattice. Because wind speed increases with height, taller towers enable turbines to capture more energy and generate more electricity.

Wind direction: This is an "upwind" turbine, so-called because it operates facing into the wind. Other turbines are designed to run "downwind", facing away from the wind.

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 and 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, and the wind blows the rotor downwind.

Yaw motor: Powers the yaw drive.

Cables: The current must be fed into the electrical grid when the generator makes electricity.  The electricity is conducted through some very thick cables.

Controller: The wind turbine controller is a computer, which checks that everything works as it should. If a part breaks down, the controller will call a computer at the wind turbine owner’s house to report the problem.