29-12-2012, 03:04 PM
Electricity Generation Using Small Wind Turbines at Your Home or Farm
Introduction
The wind is a clean and plentiful source of energy. The Canadian Wind Energy Association (CanWEA) believes that wind energy could potentially supply up to 20% of Canada's electricity requirements.
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, (see Figure 1), 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.
Wind Availability
Whether constructing a wind turbine is economically viable at your home or farm depends most strongly on the quality of your wind resource. Generally, average annual wind speeds of at least 4.0-4.5 m/s (14.4- 16.2 km/h; 9.0-10.2 mph) are needed for a small wind turbine to produce enough electricity to be cost-effective. A very useful resource for evaluating a site for its wind energy potential is a wind resource potential map. (See wind maps Figure 13 and Figure 14 end of the Factsheet.)
It may be useful to check wind speed measurements that have been recorded at a local weather station. It is important to consider that siting factors at these weather stations, such as nearby trees and buildings, might influence any wind speed measurements. Also, keep in mind that the equipment at these stations is often located close to the ground, and that weather stations located at airports are usually sheltered from the wind.
This means that wind speed measurements recorded at these stations might under represent the wind potential at your site.
For the most precise evaluation of the wind speed at your site, you need to purchase a wind resource evaluation system. While wind resource evaluation systems can be expensive, if your property is hilly and has unusual terrain features then it might be worth obtaining one.
Types of Wind Turbines
There are two basic types of wind turbines: horizontal axis wind turbines and vertical axis wind turbines (Figure 4). 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.
How Much Will it Cost Me to Purchase a Wind Turbine?
It costs $2,000-$8,000/per kilowatt to purchase a small wind turbine. However, the wind turbine costs represent only 12%-48% of the total cost of a small wind electric system. You also need to pay for other components of your wind energy system, such as inverters and batteries, as well as sales tax, installation charges and labour.
Keep in mind that the costs of wind power, unlike other sources of electrical power, are almost entirely due to the cost of purchasing and installing the system. Once the turbine has been installed, there is no fuel costs associated with its operation; you will only need to pay for maintenance of your wind turbine.
The cost of the energy produced by small (<10 kW) wind turbines over their lifetimes has been estimated to vary from $0.07/kWh, for a low cost turbine constructed in a windy area, to $0.96/kWh, for a high cost turbine constructed in a low wind area (Figure 9).
Being Neighbourly
Many people feel strongly about the need to preserve the landscape, views, history, and peace and quiet of their neighbourhoods. Make sure you discuss your plans to build a wind turbine with your neighbours. Understand your neighbours' natural fear of the unknown and be prepared to respond to their concerns.
Some of the concerns raised about wind turbines are not true. Wind turbines are not, as many people believe, dangerous to birds. A sliding glass door is more dangerous to birds than a small wind turbine. Wind turbines also have a very low potential to interfere with radio and television reception. All modern turbines, large and small, have blades made of fibreglass or wood. These materials are transparent to electromagnetic waves such as radio and television.
Wind Turbine Noise
Your neighbours' concerns relating to wind turbine noise are important. No matter the size of the wind turbine, the potential for turbine noise to bother other people always exists. Even if a wind turbine does not emit enough sound to violate any noise regulations, the noise it produces may still be objectionable to other people. Before building a wind turbine, familiarize yourself with the types of noise your wind turbine could make:
• Aerodynamic noises may be made by the flow of air over and past the blades of the turbine. Such noises tend to increase with the speed of the rotor. For blade noise, lower blade tip speed results in lower noise levels. Of particular concern is the interaction of wind turbine blades with atmospheric turbulence, which results in a characteristic "whooshing" sound.
• Mechanical noises may also be produced by components of a wind turbine. Normal wear and tear, poor component designs or lack of preventative maintenance may all be factors affecting the amount of mechanical noise produced.
How Loud Might a Wind Turbine Be?
At a distance of 250 m, a typical wind turbine produces a sound pressure level of about 45 dB(A) (decibels). As Figure 12 shows, this sound level is below the background noise level produced in a home or office. Most small wind turbines, in fact, make less noise than a residential air conditioner.
Small Wind Turbines
The blades rotate at an average range of 175-500 revolutions per minute with some as high as 1150 rpm. Large turbines turbine blades rotate in the range of at 50-15 rpm at constant speed, although an increasing number of machines operate at a variable speed.
Introduction
The wind is a clean and plentiful source of energy. The Canadian Wind Energy Association (CanWEA) believes that wind energy could potentially supply up to 20% of Canada's electricity requirements.
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, (see Figure 1), 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.
Wind Availability
Whether constructing a wind turbine is economically viable at your home or farm depends most strongly on the quality of your wind resource. Generally, average annual wind speeds of at least 4.0-4.5 m/s (14.4- 16.2 km/h; 9.0-10.2 mph) are needed for a small wind turbine to produce enough electricity to be cost-effective. A very useful resource for evaluating a site for its wind energy potential is a wind resource potential map. (See wind maps Figure 13 and Figure 14 end of the Factsheet.)
It may be useful to check wind speed measurements that have been recorded at a local weather station. It is important to consider that siting factors at these weather stations, such as nearby trees and buildings, might influence any wind speed measurements. Also, keep in mind that the equipment at these stations is often located close to the ground, and that weather stations located at airports are usually sheltered from the wind.
This means that wind speed measurements recorded at these stations might under represent the wind potential at your site.
For the most precise evaluation of the wind speed at your site, you need to purchase a wind resource evaluation system. While wind resource evaluation systems can be expensive, if your property is hilly and has unusual terrain features then it might be worth obtaining one.
Types of Wind Turbines
There are two basic types of wind turbines: horizontal axis wind turbines and vertical axis wind turbines (Figure 4). 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.
How Much Will it Cost Me to Purchase a Wind Turbine?
It costs $2,000-$8,000/per kilowatt to purchase a small wind turbine. However, the wind turbine costs represent only 12%-48% of the total cost of a small wind electric system. You also need to pay for other components of your wind energy system, such as inverters and batteries, as well as sales tax, installation charges and labour.
Keep in mind that the costs of wind power, unlike other sources of electrical power, are almost entirely due to the cost of purchasing and installing the system. Once the turbine has been installed, there is no fuel costs associated with its operation; you will only need to pay for maintenance of your wind turbine.
The cost of the energy produced by small (<10 kW) wind turbines over their lifetimes has been estimated to vary from $0.07/kWh, for a low cost turbine constructed in a windy area, to $0.96/kWh, for a high cost turbine constructed in a low wind area (Figure 9).
Being Neighbourly
Many people feel strongly about the need to preserve the landscape, views, history, and peace and quiet of their neighbourhoods. Make sure you discuss your plans to build a wind turbine with your neighbours. Understand your neighbours' natural fear of the unknown and be prepared to respond to their concerns.
Some of the concerns raised about wind turbines are not true. Wind turbines are not, as many people believe, dangerous to birds. A sliding glass door is more dangerous to birds than a small wind turbine. Wind turbines also have a very low potential to interfere with radio and television reception. All modern turbines, large and small, have blades made of fibreglass or wood. These materials are transparent to electromagnetic waves such as radio and television.
Wind Turbine Noise
Your neighbours' concerns relating to wind turbine noise are important. No matter the size of the wind turbine, the potential for turbine noise to bother other people always exists. Even if a wind turbine does not emit enough sound to violate any noise regulations, the noise it produces may still be objectionable to other people. Before building a wind turbine, familiarize yourself with the types of noise your wind turbine could make:
• Aerodynamic noises may be made by the flow of air over and past the blades of the turbine. Such noises tend to increase with the speed of the rotor. For blade noise, lower blade tip speed results in lower noise levels. Of particular concern is the interaction of wind turbine blades with atmospheric turbulence, which results in a characteristic "whooshing" sound.
• Mechanical noises may also be produced by components of a wind turbine. Normal wear and tear, poor component designs or lack of preventative maintenance may all be factors affecting the amount of mechanical noise produced.
How Loud Might a Wind Turbine Be?
At a distance of 250 m, a typical wind turbine produces a sound pressure level of about 45 dB(A) (decibels). As Figure 12 shows, this sound level is below the background noise level produced in a home or office. Most small wind turbines, in fact, make less noise than a residential air conditioner.
Small Wind Turbines
The blades rotate at an average range of 175-500 revolutions per minute with some as high as 1150 rpm. Large turbines turbine blades rotate in the range of at 50-15 rpm at constant speed, although an increasing number of machines operate at a variable speed.