The uneven heating of the earth's surface from the sun creates wind. Air has mass, and it moves to form wind. Wind turbines, or wind generators are machines that transform the power of the wind into electricity. The velocity of the air causes the blades on a wind turbine to turn the rotor. The wind generator in the picture below has a rotor that spins permanent magnets around a stationary coil. The moving magnetic field induces currents in the coil. Generators can also use electro-magnets as the field.
Wind speed is the key factor of the performance of a wind generator. Power is cubed in the formula for rotor power in a wind turbine. Power in the area swept by the wind turbine rotor is found in the equation:
P = 0.5 x rho x A x Cp x V3
P = power in watts (746 watts = 1 hp) (1,000 watts = 1 kilowatt)
rho = air density (about 1.225 kg/m3 at sea level, less higher up)
A = rotor swept area, exposed to the wind (m2)
V = wind speed in meters/sec (20 mph = 9 m/s) (mph/2.24 = m/s)
Tower height is a very important factor related to wind speed. The higher the tower the better. Wind Turbines are designed to furl, or move away from the wind during very high winds. The picture below is of a small scale wind turbine furling.
Large scale wind turbines use reduction gears to reduce the blade rotor speed while increasing the speed of the generator. The image below is from the National Renewable Energy Lab.
This site is maintained by the Electronics Engineering Department at Cape Fear Community College in Wilmington, North Carolina.
A lot of work has been completed, and we are continuing to develop the lab. We are looking for student volunteers in the Engineering Program to help develop the lab and get their hands on this technology. If you are a CFCC student and you would like to get involved, simply complete the form below.