Wind turbines used to generate electricity come in a wide variety of sizes. Large wind
turbines, which are usually installed in clusters called windfarms, can generate large
amounts of electricity. Large wind turbines may even produce hundreds of megawatts (MW)
of electricity - enough to power hundreds of homes. Small wind turbines, which are
generally defined as producing no more than 100 kW of electricity, are designed to be
installed at homes, farms and small businesses either as a source of backup electricity, or to
offset use of utility power and reduce electricity bills. Very small wind turbines (20-500 watt
units) are used to charge batteries for sailboats and other recreational uses.
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.
It has been recommended that towers be 24-37 m (80- 120 ft) high. Installing a wind
turbine on a tower that is too short is like installing a solar panel in a shady area. At a
minimum, mount a wind turbine high enough on a tower that the tips of the rotor
blades remain at least 9 m (30 ft) above any obstacle within 90 m (300 ft).
Make sure to check local bylaws about height restrictions for wind turbine towers. Use a
tower approved by the wind turbine manufacturer otherwise the warranty on the
turbine may become invalid. Also ensure the tower is connected to an underground
metal object to ground the tower in case of a lightning strike.
You need a disconnect switch that can electrically isolate the wind turbine from the rest
of the wind energy system. An automatic disconnect switch is necessary to prevent
damage to the rest of the system in case of an electrical malfunction or a lightning
strike. It also allows maintenance and system modifications to be safely made to the
turbine. There are other system components you may choose or need to purchase. You
may need batteries to store excess energy generated by the wind turbine. Because
energy is stored in batteries as DC power, you may need an inverter to convert power
from the batteries to the AC power required to run electrical appliances in your home.
Wind turbines used to generate electricity come in a wide variety of sizes. Large windturbines, which are usually installed in clusters called windfarms, can generate largeamounts of electricity. Large wind turbines may even produce hundreds of megawatts (MW)of electricity - enough to power hundreds of homes. Small wind turbines, which aregenerally defined as producing no more than 100 kW of electricity, are designed to beinstalled at homes, farms and small businesses either as a source of backup electricity, or tooffset use of utility power and reduce electricity bills. Very small wind turbines (20-500 wattunits) are used to charge batteries for sailboats and other recreational uses.These basic components include: A rotor, consisting of blades with aerodynamic surfaces. When the wind blowsover the blades, the rotor turns, causing the generator or alternator in theturbine 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 othercomponents 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 tomount 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 ayard. 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 maintenanceand repair. Self-supporting towers, which do not have guy wires. These towers tend to bethe 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 ofits tower. The power available in the wind is proportional to the cube of its speed. Thismeans that if wind speed doubles, the power available to the wind generator increasesby a factor of 8 (2 x 2 x 2 = 8). Since wind speed increases with height, increases tothe tower height can mean enormous increases in the amount of electricity generatedby a wind turbine.It has been recommended that towers be 24-37 m (80- 120 ft) high. Installing a windturbine on a tower that is too short is like installing a solar panel in a shady area. At aminimum, mount a wind turbine high enough on a tower that the tips of the rotorblades remain at least 9 m (30 ft) above any obstacle within 90 m (300 ft).Make sure to check local bylaws about height restrictions for wind turbine towers. Use atower approved by the wind turbine manufacturer otherwise the warranty on theturbine may become invalid. Also ensure the tower is connected to an undergroundmetal object to ground the tower in case of a lightning strike.You need a disconnect switch that can electrically isolate the wind turbine from the restof the wind energy system. An automatic disconnect switch is necessary to preventdamage to the rest of the system in case of an electrical malfunction or a lightningstrike. It also allows maintenance and system modifications to be safely made to theturbine. There are other system components you may choose or need to purchase. Youmay need batteries to store excess energy generated by the wind turbine. Becauseenergy is stored in batteries as DC power, you may need an inverter to convert powerfrom the batteries to the AC power required to run electrical appliances in your home.
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