Is Wind Energy Practical?
Small wind energy systems may provide an economical source of electricity if you live in an area with fairly steady strong winds and at least one-half acre of open land.
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Personal impressions of the windiness of a site are often not accurate; it is better to use an objective method. The most useful information will be obtained from placing an anemometer (a device which measures wind speed) on your site for at least one year. Some states have anemometer loan programs. You can also find wind data from state wind resource maps and state anemometer loan programs. Winds on your site should be at least class 2 (annual wind speeds averaging 9.8 to 11.5 mph) to be suitable for wind generation. These should be average sustained wind speed, not strong gusts interspersed with calm. The U.S. Department of Energy has more information on siting turbines, and the American Wind Energy Association has a siting handbook.
You will have to make sure your local zoning codes or covenants allow wind turbines and the fairly tall towers that make them work. Wind turbines are growing and evolving rapidly, so you need to do enough research to learn whether a turbine will pay for itself quickly enough to meet your financial requirements.
Small wind systems designed for individuals, businesses, and farm or ranch operators are growing dramatically. The industry group American Wind Energy Association predicts a thirty-fold increase in the United States in the next five years.
How does it work?
A wind turbine works by catching the energy in the wind, using it to turn blades, and converting the energy to electricity through a generator in the part of the turbine called a nacelle. The turbine is only one part of the system, however. A tower will put the blades high in the air where the wind is better. Winds are more powerful and less turbulent higher off the ground; thus, the taller tower, the greater the turbine’s energy production (for more information, go to Windustry’s presentation on the importance of tower height. In addition, the presence of ground clutter greatly reduces the wind resource and increases wind turbulence. One rule of thumb is that the bottom of the blade-swept area should be a minimum of 30 feet above any trees or buildings within 300 to 500 feet. For systems with batteries, a controller manages the electrical input to the batteries or the inverter. In an off-grid system, or an on-grid system with battery backup, batteries will store the power. An inverter will convert direct current (DC) electricity to alternating current (AC).
Grid-tied vs. off-the-grid
Until recently, most of the small wind turbines were installed by people who lived “off-the-grid," that is, away from a power company that supplied them electricity. They relied on their own ability to make power with a wind turbine, perhaps solar panels, and backup batteries to store power.
Many states have now passed net-metering laws which allow consumers to sell back electricity to the utility company, making it more economical for even grid-tied consumers (people who already receive electricity from a utility) to offset their electricity bill by generating wind.
How big a system do I need?
Most small wind turbines have a rating or size based on the maximum electricity they can generate such as 1.8 kilowatts or 5 kilowatts. But that is not a very useful number for most consumers. This is because rated output is the peak production at a specific (and usually high) wind speed, and different manufacturers use different wind speeds to determine rated output.
It is better to use turbine power curves to estimate output. Any reputable small wind turbine representative will supply you a power curve, showing how much electricity the machine produces at a given wind speed. Use this to estimate how much energy (kWh) the turbine will produce each month or year at the average wind speed you expect or measure at your site. Match this output with your annual energy consumption. To determine this number, check your monthly bills to come up with the annual total of kilowatt hours of electricity you use.
Once you have determined your annual electricity use, you can decide how much electricity you want to offset with a turbine, based on budget and other considerations. For example, if you want to offset nearly all your electricity use and have determined you have annual usage of 10,000 kilowatt hours, select a turbine that will produce that much power over the course of year at your average wind speed. Generally speaking, it is not a good idea to get a bigger turbine than you need unless you have some type of agreement with your utility to buy the excess power at a premium.
For more information, watch this wind sizing webcast given by Tony Jimenez, National Renewable Energy Lab.
How much will it cost?
Residential wind turbines vary depending on how much power they can produce and other factors. A rough range is $4,000 to $8,000 per rated kilowatt. A system that would offset most of an average home’s electricity use (10,000 kWh/year) will cost roughly $50,000 before incentives. Again, if you don’t have consistent wind speeds high enough to spin the turbine regularly (10 to 12 mph), the investment probably doesn’t make sense.
How do I calculate a payback?
Determine the amount you paid on electricity bills before you installed your system. If your system offsets all your electricity, once you know its cost, you can divide that by the annual bill and determine how many years it will take to pay off.
If you are only offsetting part of your use, you will need to adjust the calculation accordingly.
No matter what kind of electricity you are using, the best way to make it cheaper is to use less. That means both making your home more efficient and also finding ways to cut your use, such as opening your windows on cool nights and closing them as the day heats up. Turning off lights and unplugging appliances when not in use can also really add up.
What are the rebates or other incentives?
There has never been a better time to buy a small wind turbine in terms of incentives. The federal Investment Tax Credit now offers 30 percent of the total cost of an installed system, the first time small wind has had such a generous federal incentive. Some local utilities may also have rebate programs. The Database for State Incentives for Renewable Energy and Efficiency maintains a list of these.
Your small wind turbine may be eligible for a grant and/or guaranteed loan through the Rural Energy for America Program (REAP) if the power produced will be used in a rural farm or business. In addition, some equipment may be depreciated for tax purposes.
What zoning issues might I run into?
Zoning regulations vary dramatically across states, counties, and municipalities. Check with your local planning and zoning office before proceeding. In many communities, height restrictions may rule out a wind tower. Other factors regulated by local zoning may include setbacks, noise, tower placement, and type of tower structure. A zoning permit for a wind turbine may require a public hearing in order to issue a permit. It is a good idea to discuss possible wind turbine installations with your neighbors to prevent the surprise of a public hearing notice.
The National Renewable Energy Laboratory offers zoning guidance in Zoning for Distributed Wind Power - Breaking Down Barriers.
What kind of maintenance is there?
Maintenance varies by system, so ask when you are considering which to buy and when you are reviewing literature from different manufacturers. Many small wind turbines require periodic maintenance, which generally consists of laying the system on the ground and giving the parts of the generator a tuneup. Representatives of manufacturers can give you an idea of the expected maintenance schedule and help you arrange maintenance. A rule of thumb is to allocate about 1% of the installed cost of the wind system for operation and maintenance expenses over the life of the system. Because periodic maintenance is required, you should at least be willing to inspect your turbine on a regular basis, even if you aren't able to do the maintenance yourself.
How long will the system last?
When you are considering buying a system, ask about its anticipated lifespan. Most reputable small turbines should perform well for many years with only periodic maintenance required. Buy a turbine that has a very good track record and a good warranty — at least five years is preferable. A warranty is one indication of the manufacturer’s confidence in the product. In general, you can expect 20 years from a properly maintained turbine from a reputable manufacturer.
Where can I go to research more about specific components of my system?
Resources provided at the end of this piece will help get you started. The National Renewable Energy Laboratory is currently testing numerous small turbines and making all the information publicly available on the NREL Web site.
Where can I find an installer?
Installation is generally arranged by representatives of the manufacturer. Several have a very precise way of handling installation, including determining the best place on your property to place the turbine and catch the best wind. The American Wind Energy Association has a list of turbine manufacturers in the United States and the National Sustainable Agriculture Information Service has a state-by-state list of wind installers at the Directory of Energy Alternatives.
Do I have to think about insurance?
You will want to insure your turbine against possible damage and liability claims; some counties require insurance. Ask your property insurance company whether they will insure the turbine. Generally, the most cost-effective way to insure a wind system is under an existing homeowner’s insurance policy on your house; it is often insured as an “appurtenant structure” (an uninhabitable structure).
How will it affect the value of my house/ranch/farm?
A small wind turbine, like other capital investments, should increase the value of your property. If you can tell a prospective buyer that your electricity bills are almost nothing, the value of the installed turbine may be an attractive incentive.
What is the impact on the environment?
Small wind turbines emit no pollution and need no water. They also reduce the amount of pollutants that your utility would emit if you were relying instead on electricity from burning coal, for example. According to the American Wind Energy Association, over its life, a small residential wind turbine can offset approximately 1.2 tons of air pollutants and 200 tons of greenhouse gas pollutants (carbon dioxide and other gases which cause global warming).
Although the impact of wind turbines on wildlife, especially birds, is of concern to many people, research has shown that bird impacts with small, unlighted turbines are quite rare. House windows and outdoor cats have a much greater negative impact. The National Wind Coordinating Collaborative has a list of wildlife/wind interaction publications for more information.
Most modern residential turbines are quite quiet – similar to ambient noise levels under average wind conditions. If you can, try to visit a turbine on a windy day in order to experience the noise levels for yourself.
What other renewable energy resources should I think about?
Before considering adding any renewable energy to your home, ranch, or farm, experts advise you to do everything reasonable to reduce the energy you are using through conservation and efficiency. After that, adding renewables depends on your location and budget.
Solar photovoltaic panels may make more sense than small wind turbines in most urban areas. A combination of the two, perhaps with a diesel generator backup, often makes sense for people who want to live completely independent of the power company.
A ground-source geothermal heat pump, which takes advantage of the relatively uniform temperature of the earth, makes sense for many people, especially in new construction. And if you have water running downhill on your property, a micro-hydro generator might be a good option to consider.
For Additional Information
- Small wind for homeowners, ranchers, and small businesses from Wind Powering America
- Small Wind from American Wind Energy Association
Home and Farm Scale Wind from Windustry. Resources include:
- Planning a Small Wind Project
- Small Wind library of resources
- Wind Energy Companies: installers, dealers, and other small wind-related businesses (No endorsement implied by eXtension or the authors)
- Wind Basics - basics of wind energy and putting up a turbine
- Wind Farmers Network - Question-Answer Forum
- Wind Energy for the farm from the National Sustainable Agriculture Information Service (ATTRA)
- Rebecca Cantwell, Colorado Harvesting Energy Network
- Irene Shonle, Colorado State University Extension
- Leif Kindberg, National Sustainable Agriculture Information Service (ATTRA)
- Cole Gustafson, North Dakota State University
- Tony Jimenez, National Wind Technology Center, National Renewable Energy Laboratory NREL-National Renewable Energy Lab
- Mike Kostrzewa, Colorado State University Department of Mechanical Engineering