Wind power is one of the most sustainable and abundant forms of renewable energy. According to three reports released by the U.S. Wind Energy Technologies Office, America’s wind industry is growing quickly, adding significant production capacity and supporting new job creation. But how does energy from the wind actually bring electricity to our homes, apartments, and businesses?
What is wind energy?
In the most basic terms, wind is air flow. More specifically, it’s a kind of kinetic energy created by air moving from high to low-pressure areas. Air from a high-pressure zone will always rush into a low-pressure zone, trying to create a balance. The air is in continual motion and where there is movement, there is energy. (To understand energy, and energy vs. power, read our blog about kilowatt-hours).
Converting wind energy to electricity
One of the most basic laws of physics tells us that it takes energy to make energy. You can’t create energy from nothing, but you can’t destroy energy, either. Energy from one source must be transferred to another source or converted from one kind of energy to another.
Wind loses some of its kinetic energy as it bumps into wind turbine blades, but the turbine gains the exact same amount of energy. The longer the wind turbine blades are, the more energy it can gain. Harder wind will give the turbine more energy as well.
How wind turbines work to generate electricity
The most common kind of wind turbine, as described in our blog, What It’s Like to Be Inside a Wind Turbine, consists of a tall tower (pole) with two or three large windmill-like blades at the top. The blades are gigantic – usually 60 or 70 meters across, which is 230 feet. The tower is typically 85 meters – or 280 feet – off the ground, because the higher you go, the windier it is. Large turbines are most effective at capturing energy.
The blades are connected to the central shaft, called a rotor. The rotor spins a series of gears that increase the blade rotation by a factor of 100 – creating a speed fast enough to produce electricity. There’s also a computer at the top of the tower that keeps the blades pointed in the best direction.
The key mechanism of the turbine, called the nacelle, sits on top of the tower, behind the blades. The nacelle contains both the gearbox and a generator, which takes kinetic energy from the spinning rotor shaft and converts it to direct current (DC) electrical energy.
The DC current travels down the interior of the tower, where a converter changes it to AC – alternating current – the kind we use in our households. A transformer then boosts the voltage by a factor of about 50 so it can be transmitted efficiently to a substation, through underground cables. From the substation, the electricity is distributed across the power grid to consumers in homes and businesses.
Wind farms around the world
The Earth’s rotation and the irregularities of its surface also play a role in wind creation. In the Northern Hemisphere winds circulate in a clockwise direction, and in the Southern Hemisphere, counterclockwise.
Wind volume always varies, so the electrical production of a single turbine also varies. For maximum efficiency and a more dependable supply, we link many wind turbines together into a farm and link multiple wind farms across the country into a national power grid.
Wind farms can be built on land or in bodies of water – offshore or in the Great Lakes. The Energy.gov website provides interesting data on wind farm locations in the U.S., and wind flow maps.
Although we’ve described the most common type of wind turbine in this blog, there are many other types of wind turbines that create energy from this natural resource.
Read more in Types of Wind Turbines Used Today.