Wind

Wind Generator

Wind generation technology is probably the most iconic source of renewable energy. Pictures depicting windmills are often used in literature talking about renewable energy. But have you ever wondered how wind can be used to power your house?

How it Works

Windmills, called wind-electric turbines, are composed of three parts: rotor blades, a shaft, and a generator. Let′s take a closer look at each one these components.

Rotor Blades

Rotor blades are probably the most recognizable part of the wind turbine. They are essentially the ″wings″ of the wind turbine. The blades are turned when wind blows across them and creates lift. Understanding how lift works takes advanced knowledge in math and physics, but in simpler terms it can be explained like this:

The rotor-blades are shaped like an airfoil. The useful thing about an airfoil shape is how it creates distinct regions of high and low pressure when air moves across its surface. The top part of the airfoil creates low pressure by first compressing the air as it travels ″over the hump″ and then quickly expanding it as it moves down the sloped wing. At the same time, the bottom part of the airfoil creates high pressure by compressing the air as it travels along the downward angled surface. The faster wind travels across the airfoil the more pronounced the difference in low and high pressure becomes. Eventually, the difference is large enough to create a net force from high to low pressure, which causes the airfoil to move.

Newer wind turbines are able to adjust the angle and pitch of the rotor blades in order to take advantage of varying wind conditions.

Shaft

The shaft is the part that is actually turned by the spinning rotor blades. There is a low-speed and high-speed shaft in a typical wind generator. The low speed shaft is attached directly to the rotor blades and spins just as fast as the blades turn. In order to generate electricity in a generator, the shaft needs to be turning a lot faster then the blades can safely spin. Engineers have solved this problem by using a gearbox. The larger low-speed shaft turns the gears which, through carefully tuned gear ratios, turns another shaft a lot faster. This high-speed shaft is what actually turns the generator that makes electricity.

Generator

The generator is the heart of the wind turbine. The way it works is through the principles of electromagnetic induction. If you ever want to look at the math equations that actually govern such phenomena take a look at Maxwell′s equations. Otherwise, the way it basically works is this:

Permanent magnets surround coiled wire. The high-speed shaft turns this ring of permanent magnets, which in turn creates electrical currents through the wires. How do spinning magnets create electrical currents in a wire that is not even touching them? One of Maxwell′s equations states that a changing magnetic flux through any closed surface creates an electrical current. Think of it like a fan blowing through a hoola-hoop. Changing the speed at which the fan blows will also change the amount of air blowing through the hoola-hoop (flux). This changing flux will create a current inside the hoola-hoop (which is made of a conductive material).

The electricity that is generated is then directed through a transformer that prepares the electricity for long-range transmission.