- Benefits of Wind Power
- Is Wind Energy Practical for You?
- Conditions for Stand-Alone Systems
- Conditions for Grid-Connected Systems
- Is Your Site Right?
- Additional Considerations
- Frequently Asked Questions
Wind Energy System Basics
Unlike yesteryear’s windmill, today’s wind turbines use technological innovations that have substantially reduced the cost of electricity generated from wind power. In the 1920s and ’30s, farm families throughout the Midwest used wind to generate enough electricity to power their lights and electric motors. The use of wind power declined with the government subsidized construction of utility lines and fossil fuel power plants. However, the energy crisis in the 1970s and a growing concern for the environment have generated an interest in alternative, environmentally friendly energy resources. Today, homeowners in rural and remote locations across the nation are again examining wind power to provide electricity for their domestic needs.
Benefits of Wind Power
A wind energy system can provide a cushion against electric power price increases. Wind energy systems help reduce U.S. dependence on fossil fuels; and they are nonpolluting. If you live in a remote location, a small wind energy system could help you avoid the high costs of having utility power lines extended to your site.
Although wind energy systems involve a significant initial investment, they can be competitive with conventional energy sources when you account for a lifetime of reduced or altogether avoided utility costs. The length of the payback period – the time before the savings resulting from your system equal the cost of the system itself – depends on the system you choose, the wind resource on your site, electricity costs in your area, and how you use your wind system.
Small wind energy systems can be used in connection with an electricity transmission and distribution system (called grid-connected systems), or in stand-alone applications that are not connected to the utility grid. A grid-connected wind turbine can reduce consumption of utility-supplied electricity for lighting, appliances, and electric heat. If the turbine cannot deliver the amount of energy you need, the utility makes up the difference. When the wind system produces more electricity than the household requires, the excess can be be returned to the grid. With the interconnections available today, switching takes place automatically. Stand-alone wind energy systems can be appropriate for homes, farms, or even entire communities (a co-housing project, for example) that are far from the nearest utility lines. Either type of system can be practical if the following conditions exist.
- You live in an area with average annual wind speeds of at least 9 miles per hour (4.0 meters per second).
- 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.
- You live in an area with average annual wind speeds of at least 10 miles per hour (4.5 meters per second).
- 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.
- Net metering is available
The U.S. Department of Energy (DOE) has compiled wind resource maps that are available from Wind Powering America. DOE maps are good sources for regional information and can show whether wind speeds in your area are generally strong enough to justify investing in a wind system.
Wind-turbine manufacturers can use computer models to predict machine performance at a specific location. They can also help size a system based on your electricity needs and the specific local wind patterns. However, you will need site-specific data to determine the wind resource of your exact location. If you do not have on-site data and want to obtain a clearer, more predictable picture of your wind resource, you may wish to measure wind speeds at your site for a year. You can do this with a recording anemometer, which generally costs $500 to $1,500. The most accurate readings are taken at “hub height” (i.e., the elevation at the top of the tower where you will install the wind turbine). This requires placing the anemometer high enough to avoid turbulence created by trees, buildings, and other obstructions. The standard wind sensor height used to obtain data for the Department of Energy maps is 33 feet (10 meters).
Maps available in the table at right give general information on the average wind resources available across the country and in Montana. Of course, the actual wind resource on your site will vary depending on such factors as typography and structure interference.
You can have varied wind resources within the same property. If you live in complex terrain, take care in selecting the installation site. If you site your wind turbine on the top or on the windy side of a hill, for example, you will have more access to prevailing winds than in a gully or on the leeward (sheltered) side of a hill on the same property. Consider existing obstacles and plan for future obstructions, including trees and buildings, which could block the wind. Also realize that the power available in the wind increases proportionally to its speed (velocity) cubed (V3). This means that the amount of power you get from your generator goes up exponentially as the wind speed increases. For example, if your site has an annual average wind speed of about 12.6 miles per hour (5.6 meters per second), it has twice the energy available as a site with a 10 mile per hour (4.5 meter per second) average.
- Research potential legal and environmental obstacles;
- Obtain cost and performance information from manufacturers;
- Perform a complete economic analysis that accounts for a multitude of factors;
- Understand the basics of a small wind system, and
- Review possibilities for combining your system with other energy sources, backups, and energy efficiency improvements.
You should establish an energy budget to help define the size of turbine you will need. Since energy efficiency is usually less expensive than energy production, making your house more energy efficient first will likely result in being able to spend less money since you may need a smaller wind turbine to meet your needs.
Before you invest any time and money, research potential legal and environmental obstacles to installing a wind system. Some jurisdictions restrict the height of the structures permitted in residentially zoned areas, although it’s often possible to obtain a variance. 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.
Frequently Asked Questions :: Wind