Text Size:   A+ A- A   •   Text Only
Site Image

Wind Resource Assessment

Wind Resource Assessment
A useful introduction for evaluating the wind resource for small wind turbines can be found at this USDOE article page:
Map courtesy of Oregon Department of State Lands(PDF)
Long duration wind characteristics data for specific sites in the state can be found at http://me.oregonstate.edu/ERRL/

Wind Measurement
Wind resources vary with the time of day, season, height above ground and type of terrain. Proper siting in windy locations away from large obstructions enhances a wind turbine's performance. 
Oregon has proven wind resource areas on the Oregon Coast and in the Columbia River Corridor. Many other sites may offer significant wind but have limitations on a seasonal or time of day basis. Those sites may provide marginal resources. To know if your specific site has a good wind resource you need to measure the wind speed and direction with an anemometer (wind speed gauge) and direction gauge. Wind speed, wind direction, roughness of the terrain, seasonal cycles, air pressure or temperature and obstacles affect the amount of wind energy available at your site. 
To assure that the wind resource at your site will provide you with an appropriate return on you investment, you should collect wind speed and direction data. Those data should be collected at a height as close as possible to the hub height of the wind turbine you consider installing.

See also http://www.awea.org/faq/basicwr.html.
The wind turbines in the megawatt range have towers of 60 to 80 meters (about 200 feet or higher). Fifty-meter high meteorological towers with measurements at two heights are preferably being used for those projects. For more information on towers and wind speed measurement equipment:
http://www.nrgsystems.com or http://www.secondwind.com

Several anemometers mounted at different heights or at several locations will provide more detailed data and give any potential developers or partners higher confidence. Recording data from the meters can be done on strip charts or computer data loggers. You can learn how to collect and analyze the data yourself or hire a professional. A good study of wind resources will include data from at least one year, but two years of data would be better.
If you are a customer of PacifiCorp or Portland General Electric, you can obtain annual average wind speed data at your site from the Energy Trust of Oregon.  This service uses a Web-based wind map. The Energy Trust will be validating wind speeds for all proposed projects with its in-house wind map data. This service is also available if you are located outside the service area of  PacifiCorp or Portland General Electric but the energy produced by your project will be delivered to these utilities. 
If you live outside the service areas of PacifiCorp and PGE and the energy of your project will not be delivered to these utilities, you will have to decide whether you want to install monitoring equipment or not. You can find links to manufacturers of wind speed monitoring equipment and towers in the text above. If you decide not to monitor the wind at your site, you may be able to use data from nearby sites such as airports or publicly-administered meteorological stations. Correlation to long-term local weather data can help provide insight into the magnitude of annual variations you may experience. The links on top of this page provide several sources of long term data. Web-based mapping systems are available to help estimate your own wind resource, see for example http://firstlook.3tiergroup.com/.
Wind does not blow at the same speed all the time, but the best wind resources have stable high speeds. If winds frequently cause tree branches to bend in the wind direction or a flag to extend straight from the pole, you may have a good wind resource to generate electricity. A rule of thumb for a good wind resource is that the general direction of branch patterns of all trees at the site are visibly affected by the wind.
Annual average wind speeds of about 11 miles per hour (mph) are generally needed for grid-connected wind generating systems to be an economical resource. Annual average wind speeds of 7 to 9 mph may be adequate for electrical or mechanical applications for water pumping, residential or small on-site commercial loads. These systems may be interconnected to the grid under net-metering agreements with the local utilities. They may be operated independent of the grid using battery storage to provide electric supply during times of low or no wind.
Oregon Wind Working Group
Renewable Energy
Wind Energy
Wind Energy Atlas Viewer
National Wind Resource Assessment
National Wind Technology Center (NREL)
United States Department of Energy Wind Energy Program
Lands and Realty: Wind Energy