Wind Turbine Summary

Wind Climate: Since June of 2001 the wind cl= imate around the Gustavus campus has been monitored continuously. The project beg= an with one semi-automated weather station and a great deal of student effort = and enthusiasm. It has continued = with the addition of five additional weather stations allowing us to collect wind speed and direction data at 10 minute intervals 24 hours per day, seven day= s a week. In October 2003, the Minnesota Commerce Department installed a monitoring tower on campus, allow= ing us to collect data at five heights up to 50 m. This system functioned well until = it came down (not entirely intentionally) in October of 2005. The data from the 10 m anemometer = on the tower were correlated with the data from the other stations. Wind shear analysis from the tower data at different heights allowed us to calculate t= he wind speed at other heights, particularly turbine hub heights, for all of t= he sites. As a result, we have a= lmost five years of data from which to estimate energy production. We have made use of power curves f= or several wind turbines to calculate annual energy production and explore seasonal variations in production.

Figure 1: Monthly power production for t= wo potential turbines based on data from the soccer field weather station (adjusted to 80 m hub height) show annual trends (lower production in summer months).

We began working with the= Vestas V66 turbine because it was most readily availa= ble and had the most favorable power curves for our wind climate. Lately, however, we have done prod= uction calculations with the power curves for the Suzlon S88 turbine, as all of the Vestas units on the mark= et are already spoken for. We have u= sed these power curves to estimate energy production in Excel and in the WaSP (Wind Analysis Software Package) software and in= both cases estimate our annual production at 4.2 million kWh for the Vestas turbine and up to 5.8 million kWh for the Suzlon Turbine. Our average wind speed at hub height is just over 15 mph (6.8 m/s) g= iving us a capacity factor of almost 29% for the V66 and 33% for the S88.

Turbine Information: The Suzlo= n S88 turbine is rated to produce 2,100 kW in moderate winds. It is typically installed on an 80= m (~263 ft) free standing tubular tower.&nbs= p; The asynchronous generator is driven through a gearbox by three 44 m (~144 ft) pitchable blades which rotate at 15.1-17.7 rpm. The generator produces grid synched power at 690 V and is brought on line with a series of thyristors to minimize disruption to the grid and wear and tear on the gearbox.

Noise Issues: Noise from wind turbines is typical= ly difficult to distinguish from background noise. At a distance of 125 m (410 ft) fr= om the base of a turbine typical measured values would be 50 db or less.

Warning Lights: Wind tu= rbines are equipped with a single red light, mounted on the top of the nacelle, to warn aircraft. Although this = light is steady, it will appear to blink as the turbine blades rotate.=

Birds: Birds are sel= dom bothered by wind turbines. Th= e only known site with bird collision problems is located in the Altamont Pass in <= st1:place w:st=3D"on">California. Even there, collisions are= not common, but they are of extra concern because the species involved are protected by law.