Crowder College Wind Turbine

The MARET Center wind turbine is a Nordtank 65 kW machine originally manufactured in Denmark.  The turbine had spent several decades generating power for a wind farm in California when the next generation large wind turbines replaced it.  The Nordtank was transported and refurbished by Ozark Energy Services of Joplin, MO, and it was subsequently purchased by Crowder College.

The Nordtank 65 is an “upwind” machine that is oriented into the wind by a geared yaw drive controlled by a wind direction finder.  The turbine begins to produce power when the rotor reaches 42 rpm at about 10 mph wind speed, and it generates its rated power at 44 rpm at 33 mph wind speed.

In its first month of operation, the Crowder turbine produced 10.2 MWh (10,200 kWh), or enough energy for 8-10 homes.  Some of its technical specifications are as follows:



Generator – Induction type
Rated power: 65 Kw at approximately 33 mph.
Max of 68Kw
@ 40 mph
Type: 3 phase, 60 Hz, asynchronous 480 VAC
RPM: 1200 (3 phase)
Rotor and Blades
3 blades, fixed pitch
Orientation: Upwind
54’ diameter (16.5 m)
Fiberglass reinforced polyester blades
Weight – approx. 800 lbs each
Area swept: 2,289 ft2 (214 m2)
Nacelle, Bedplate, Rotor and Blades: 9,300 lbs
Tower (3 sections): approx 20,000 lbs
Tower Height at hub: 120 ftOperational
Cut in speed: 8 mph (3.6 m/s)
Cut-off speed: None (stall regulated blades)
Survival wind speed: 120 mphSafety Features
All new electronic controls (PLC) located in tower base
Induction generator has inherent anti-islanding
Fail-safe hydraulic disk brake
Centrifugally actuated tip brakes for over-speed control
Thermal protection on generator
Vibration sensor for fault shutdown
Thermal protection for yaw controls
Grid isolation circuits for shutdown

Wondering about making your own windmill? Watch this video of the inspiring story of William Kamkwamba.To read all about wind turbines visit the American Wind Energy Association.

Turbine photo used with permission, copyright dwclaborn