Wind Power
The terms wind energy or wind power describe the process by which the wind is used to generate mechanical power or electricity. Wind turbines convert the kinetic energy in the wind into mechanical power. Wind systems, like solar, can be sized for small or large applications.
Height is one of the most important aspects to consider in a wind power system. Putting a wind turbine on too short of a tower is like putting a solar panel in the shade! As a general rule, you should install the turbine on a tower with the bottom of the rotor blades at least 30 ft. above any obstacle within 500 ft. of tower. You will double your power for every 20’ you gain in height. The average height of a small wind turbine (of any capacity) is about 80 ft. - about twice the height of a neighborhood telephone pole. Plus, sound decreases significantly with distance from the source, making it another good reason to use tall towers.
Is wind right for me?
One of the first steps to developing a wind energy project is to assess the area's wind resources and estimate the available energy. Correct estimation of the energy available in the wind can make or break the economics of a project. The National Renewable Energy Laboratory (NREL) has many great resources, including state wind maps, to aid in assessing your general area, and Home Energy can assist you in an assessment of your specific site.
Quality in wind turbines is very important, as wind generators have working parts. The quality varies widely between manufacturers. The height of the tower is also very important. It should be 50' higher than anything within 100'. Small wind systems can be practical if the following conditions exist (from the U.S. Department of Energy):
Conditions for stand-alone systems
- You live in an area with average annual wind speeds of at least 4.0 meters per second (9 miles per hour)
- A grid connection is not available or can only be made through an expensive extension. The cost of running a power line to a remote site to connect with the utility grid can be prohibitive, ranging from $15,000 to more than $50,000 per mile, depending on terrain
- You have an interest in gaining energy independence from the utility
- You would like to reduce the environmental impact of electricity production
- You acknowledge the intermittent nature of wind power and have a strategy for using intermittent resources to meet your power needs
Conditions for grid-connected systems
- You live in an area with average annual wind speeds of at least 4.5 meters per second (10 miles per hour)
- Utility-supplied electricity is expensive in your area (about 10 to 15 cents per kilowatt-hour)
- The utility's requirements for connecting your system to its grid are not prohibitively expensive
- Local building codes or covenants allow you to legally erect a wind turbine on your property
- You are comfortable with long-term investments
Before you invest any time and money, research potential legal and environmental obstacles to installing a wind system. Some jurisdictions, for example, restrict the height of the structures permitted in residentially zoned areas, although variances are often obtainable. Your neighbors might object to a wind machine that blocks their view, or they might be concerned about noise. Consider obstacles that might block the wind in the future (large planned developments or saplings, for example). If you plan to connect the wind generator to your local utility company's grid, find out its requirements for interconnections and buying electricity from small independent power producers. Check out our Wind section in our Frequently Asked Questions page for more helpful information.
Hybrid Systems
A renewable energy system that combines wind with photovoltaic (PV) technologies, or a "hybrid" system, offers many advantages.
In much of the United States, wind speeds are low in the summer when the sun shines brightest and longest. The wind is strong in the winter when there is less sunlight available. Because the peak operating times for wind and PV occur at different times of the day and year, hybrid systems are more likely to produce power when you need it.
For the times when neither the wind generator nor the PV modules are producing electricity (for example, at night when the wind is not blowing), most stand-alone systems provide power through batteries and/or an engine-generator powered by fossil fuels like diesel. Or in a grid-tied system, you would pull power from the utility.
If the batteries run low, the engine-generator can be run at full power until the batteries are charged. Adding a fossil-fuel-powered generator makes the system more complex, but electronic controllers can operate these complex systems automatically. Adding an engine-generator can also reduce the number of PV modules and batteries in the system. Keep in mind that the storage capability must be large enough to supply electrical needs during noncharging periods. Battery banks are typically sized for one to three days of windless operation.
With integrity and expertise, you can count on Home Energy to advise you in finding the system best suited for your conditions.
Featured Wind Installations
EDUCATIONAL INSTALLATION
Ball State University
1kW Solar PV, Solar Thermal & Bergey Wind
Muncie, Indiana
June 2008
COMMERCIAL INSTALLATION
UNL Furs
2.5 kW Off-Grid Solar and Wind System
Etna Green, Indiana
September 2008
