HOW WIND POWER WORKS
Utilizing wind power is really nothing new. History shows us that man back in 3000 bc harnessed wind power for various uses. To discuss how wind power works, you need to begin with the sun. Yes, wind power IS a form of transferred solar energy. As the sun heats the earth, different areas heat up and cool down at different rates which creates variances in air pressures above these areas. The natural result of these air pressure variances is the flow of air from the higher pressure (warmer) area to the lower pressure (colder) area. This airflow of course is called WIND.
THE BASICS OF WIND POWER
Ok, I’m going to break this down in a very basic way. Let’s start with a quick explanation of the standard house fan. Electrical energy is fed into the electric motor of the fan. This electricity is then sent to a series of electrical coils which become electromagnets when current flows through them. The electromagnetic field from these coils interacts with opposing magnetic field within the motor coils thereby creating motion. This motion occurs on the rotor of the motor where the fan blades are connected to. The fan blades are pitched in a way that when rotated act as a screw for air which when held in a fixed position create air flow. Ok now think of this process in reverse! Can you do it? Simple.
Wind energy acts on the blades of a fan (windmill), the blades turn which are attached to a shaft which turns the rotor of the generator (similar to the motor design, but slightly different), the generator is wired so that the motion of the rotor (which is magnetized), interacts with the internal coils of the generator and through a process of the interacting magnetic fields, current flow is produced (see Homemade Wind Turbines). This current flow is of coursed called ELECTRICITY.
There are 2 major types of wind turbines; horizontal and vertical axis turbines. What most people are use to seeing on mountainside, farms, etc are the horizontal axis wind turbines; think windmills. From these you have either 2 or 3 blade turbines. For the sake of this article, we’re not going to discuss vertical axis turbines except that these are similar to the attic fan design that you see on the rooftop of most homes.
As far as electrical output or ratings for these units, this is determined by the size of the wind turbine. The larger the generator, the larger the rotor. With larger the rotor, you’ll of course need a proportionally larger blade size in order to create the proper rotation speed for a proper output. Now that was a brain full! Go back and read that section again if needed. I should take a sidebar here and be sure that you understand that the wind speed, hence rotor speed, is going to determine the electrical output of a unit.
WIND TURBINE ROTATION
Ok… one last part in order to explain how the rotors of these windmills actually spin when air is sent over the blades. Without taking you through complex mathematics, and easy analogy to think of is an airplane wing. The blades of these units are designed in a similar fashion where there is a curvature one side of the blade that creates a smooth surface which increases the air velocity that is passing over it when compared to the opposite side of the blade. Because way back in the day a real smart dude name Bernoulli figured out that increased air velocity over any surface creates a “decrease” in air pressure, we end up getting a difference in air pressures on one side of the blade vs the other. This difference in pressure, kind of like the wind phenomenon (see 1st paragraph!), creates movement from the higher pressure area to lower. Now, when you transmit this to a blade of a turbine where this is happening on all surfaces, you get..waaaahlaaaa…ROTATION!
Hopefully you have a better understanding of the How Wind Energy Works. Remember think fan in reverse and an airplane wing. Bye for now.