Many of the turbines were installed during workshops to expose as many people as possible to the process and technology. Students from the Appropriate Technology program at Appalachian State University and staff members of the Small Wind Initiative were involved in all of the installations. The turbines installed are listed in the table, along with their rated output, tower height, and tower type.
In addition to demonstrating the technology, SWI has also been involved in assessing the performance of the turbines. We are keeping a log of our activities and repairs, power and energy output, wind speeds and direction, temperature, barometric pressure, solar insolation, wind shear, sound, and avian impacts.
The datalogging system uses a Campbell Scientific CR1000 datalogger, a Windows-based computer, twelve anemometers, seven wind vanes, a temperature sensor, a barometric pressure sensor, and six power transducers. Each turbine is being individually monitored for power and energy production. Wind speed is being monitored at two elevations on each tower, and wind direction is being monitored on each tower as well. Data is being recorded every second. We have constructed power curves of the turbines on our site and have documented that all produce their rated power output.
An activity log has been kept for each turbine at the site. The log documents in text and photographs each of the eight turbines tested. It describes the problems encountered and the repairs undertaken (and can be found at www.wind.appstate.edu/swiwind/swi.php). We have had more than our fair share of problems. The average availability for all the turbines was 79 percent.
The SWI team met with a regional Audubon Society representative to develop an avian impact study. Using the Audubon procedures, we searched the site for bird carcasses at least weekly and after significant weather events (such as low cloud ceiling and fog). Searches were conducted as early in the day as possible to reduce the chance of carcass removal by other scavenging animals.
A “bird sweep” involves inspecting the ground around each tower in a back-and-forth manner, looking for bird carcasses. The inspected area covers the guy-wire diameter, plus about 3 meters (10 ft.). If the tower has no guy wires, the diameter of the inspected area is approximately the tower height. We searched the site under all of the turbines using the Audubon’s recommended procedures a total of twenty times during the fall and spring migration period. In addition, we always kept our eyes open while at the site working on other things. Over the last year, we found what was left of one bird carcass.
Noise can be a problem associated with any piece of machinery. Most permitting guidelines now being developed for wind turbines around the country address noise, and specify allowable noise at the adjacent property line, the nearest dwelling, or at a certain distance from the turbine. While there is no completely satisfactory way to measure the subjective effects of noise, typically 50 to 60 decibels is considered the maximum allowable, with some exceptions for short-term events.