How in the world do those windmills we see on the hills around the Bay Area generate and deliver electricity?
That’s a common question posed to us, so let’s take a minute to explain the inner workings of a wind turbine that’s capable of producing up to 1.8 megawatts of power when the wind is blowing. That’s enough to power 500 homes. Take a look at the graphic animation from the U.S. Department of energy that shows the different working parts. (Be sure to click through the slide show to see all of the different working parts described below.)
First of all, there are the blades. Most turbines have two or three blades that are attached to the rotor, or hub. That connects to the main shaft, which spins to power a generator. The electricity from that turbine is fed into the grid for widespread distribution.
You can see from the graphic that there are more components, especially as turbines get larger. Turbines are designed to spin facing either upwind or downwind. The one pictured in the animation is an upwind type, facing the wind with the aid of a yaw drive that keeps it headed into the wind. Downwind turbines are naturally spun by the wind to face away from the wind and do not require the yaw drive.
Most modern turbines have blades connected to a pitch system much like that of a propeller-driven airplane. The blades can be turned, or pitched, to control how much wind they utilize to spin the windmill or to minimize the impact of wind when the turbine needs to be turned off, such as when winds exceed 55 miles-per-hour. A brake may complete the stopping process.
Sometimes you’ll see some or all the turbines on a wind farm stopped even when the wind is blowing. Electric utility customers are probably getting all the power they need from other sources. Since electricity is an on-demand source of energy, there is no place for the wind power to go. In the future when power storage battery technology has advanced to the point where saving excess energy is feasible, we may see this change.