Wind Power FAQ
Q1: What is a wind turbine and how does it work?
Q2: What size tower is used for a small wind turbine?
Q3: How much does a residential wind turbine cost?
Q4: How much electricity can one wind turbine generate?
Q5: How many turbines does it take to make one megawatt (MW)?
Q6: Why is wind power considered a fixed cost resource?
Q7: Are wind turbines noisy?
Q8: Do wind turbines pose a safety hazard?
Q9: Are wind turbines hazardous to birds?
Q10: Do wind turbines require any special approvals?
Q1: What is a wind turbine and how does it work?
A: Wind energy systems transform the kinetic energy of the wind into mechanical or electrical energy that can be harnessed for practical use. Mechanical energy can be used to pump water at remote locations. Electrical energy can be used to produce electricity for homes and businesses, and for sale to utility companies.
There are two designs of wind electric turbines; vertical axis, or 'egg-beater style', and horizontal axis such as the propeller type. Most utility turbines are the horizontal type.
Turbine consist of…
- A rotor or blades which convert the wind's energy into rotational shaft energy
- A nacelle containi9ng a drive train or gearbox and generator
- A tower to support the turbine
- Electrical equipment such as controls, inverters, controllers, wiring and batteries
Q2: What size tower is used for a small wind turbine?
A: Small turbines ranges in size from 250 watts to 50 kW (50,000 watts). Towers 80 feet to 120 feet tall may often be used with a turbine. The tower has to be sized to raise the turbine above the turbulence generated by obstacles (such as buildings and trees). The turbine will not perform as well if it was located in the area of turbulence. It will perform better in the laminar wind flow above the turbulent layer.
Q3: How much does a residential wind turbine cost?
A: That depends on the size of the turbine, the height of the tower and the type system (grid-tie or stand alone) it is. For example a 1 kW may cost between $5,000 and $7,000 before rebates or incentives; a 10 kW between $30,000 and $35,000. The initial investment cost may be reduced quite dramatically be the level of rebates, incentives and tax breaks available in your area. Check www.dsireusa.org for incentives in your area.
The other important cost component is the level of return on investment offered by generating savings over electricity generated conventionally. After the one-time investment in a wind system has been made the cost of producing electricity is virtually fixed. Many state of the art wind plants are generating power at costs as low as 4 cents/kWh (kilowatt hour), a price that is competitive with many conventional energy technologies. With wind power the resource is free and the cost of wind generation remains fixed. Wind does not have to be extracted processed or transported and is not disrupted by political, military, economic or social events nor does it have to bear the enormous indirect costs of such disruptions. Not so with conventional power; with conventional power generation the resource, whether it is coal, oil or gas, is costly and will increase in cost over time.
Q4: How much electricity can one wind turbine generate?
A: The ability to generate electricity is measured in watts. A kilowatt (kW) is 1,000 watts. A megawatt (MW) is 1 million watts. Electricity production or consumption is measured in kilowatt-hors (kWh). A kilowatt-hour means 1000 watts of electricity produced or consumed for one hour. For example; one 100 watt bulb left on for 10 hours consumes one kilowatt-hour of electricity (100 watts x 10 hours = 1,000 watt-hours = 1 kilowatt-hour).
The output of a wind turbine depends on the turbine's size and the wind's speed through the rotor. Wind turbines being manufactured now have power ratings from 250 watts to 1.65 megawatts. Example: A 10-kW wind turbine can generate about 16,000kWh annually, more than enough power for a typical home (the average U.S. household consumes about 10,000 kWh of electricity per year). A 1.65-MW turbine can produce more than 4.7 million kWh per year, enough to power 470 households.
Q5: How many turbines does it take to make one megawatt (MW)?
A: Most manufacturers of utility-scale turbines offer machines in the 700-kW to 1.65-MW range. Ten 700-kW units would make a 7-MW wind plant. Wind plants can range in size from a few megawatts to hundreds of megawatts of capacity. Wind power plants are 'modular'. The turbines can be made larger or smaller as needed. Turbines can also be added as electricity demand grows. Today, a 50-MW wind farm can be completed in 18 months including resource assessment.
Q6: Why is wind power considered a fixed cost resource?
A: After the one-time investment in a wind system has been made the cost of producing electricity is virtually fixed. Many state of the art wind plants are generating power at costs as low as 4 cents/kWh (kilowatt hour), a price that is competitive with many conventional energy technologies. With wind power the resource is free and the cost of wind generation remains fixed. Wind does not have to be extracted processed or transported and is not disrupted by political, military, economic or social events nor does it have to bear the enormous indirect costs of such disruptions. Not so with conventional power; with conventional power generation the resource, whether it is coal, oil or gas, is costly and will increase in cost over time.
A: Today's wind turbines are quiet! Measured in decibels (db) the noise level of a typical residential wind turbine is somewhere between whispering at 20 db and a kitchen refrigerator at 50 db.
Q8: Do wind turbines pose a safety hazard?
A: Unlike most conventional electrical generation technologies wind turbines do not burn anything and do not produce air emissions. They contain relatively small amounts of lubricating oils, and hydraulic and insulating fluids, though contamination of ground water or soils is highly unlikely. The primary safety consideration is limiting public access to electrical equipment, tall towers and moving rotors.
Q9: Are wind turbines hazardous to birds?
A: Although bird mortality is a serious concern for the wind industry, structures such as smoke stacks, radio, TV and cell towers have been associated with far larger numbers of bird kills than have wind turbines. More birds die by flying into glass surfaces. Other sources of bird mortality, such as highways and pollution, are responsible for a much higher proportion of total bird deaths.
Q10: Do wind turbines require any special approvals?
A: For residential applications a good place to start is to get a building permit. The local code enforcement officer will tell you all the approvals you may need to get. Many municipalities will require that the permit be approved by their planning/zoning authorities at public hearings. Conservation commissions may have to approve sites located close to wetlands or watercourses. Boards of health may have to approve construction close to wells or sewage disposal facilities. Fire departments may have to approve any construction over a certain height.
