How Does Wind Energy Work?
How do wind turbines convert wind into electricity? And can living near one really affect your health? Ask Science explains.
Sabrina Stierwalt, PhD
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How Does Wind Energy Work?
In the U.S. 8% of our energy generating capacity comes from wind turbines—that’s more than any other renewable resource—and wind power has more than tripled over the past decade. More than half of that capacity comes from just five states: Texas, Iowa, Oklahoma, California, and Kansas. According to the American Wind Energy Association, there are over 56,000 wind turbines across the country that provide a capacity of ~96,000 megawatts, enough to power more than 15 million homes. The Department of Energy projects that by 2050, that wind capacity will increase to more than 400 gigawatts.Â
How can you get in on this growing wind energy action? Many electric utilities allow you to tap into wind—and other renewable—sources of power if you pay a little bit more for a “green” option. More consumers signing up for green energy means those utilities will work to procure more of it. Let’s take a look at how wind turbines work and some of the potential pros and cons.Â
How Do Wind Turbines Work?
Wind power actually starts with the Sun. In order for the wind to blow, the Sun first heats up a section of land along with the air above it. That hot air rises since a given volume of hot air is lighter than the same volume of cold air. Cooler air then rushes in to fill the void left by that hot air and voila: a gust of wind.Â
Wind power actually starts with the Sun. In order for the wind to blow, the Sun first heats up a section of land along with the air above it.
The Office of Energy Efficiency and Renewable Energy describes a wind turbine as “the opposite of a fan.” Simply stated, the turbine takes the energy in that wind and converts it into electricity. So how does it do that?Â
First, the wind applies pressure on the long slender blades, usually 2 or 3 of them, causing them to spin, much like the wind pushes a sailboat along its path through the water. The spinning blades then cause the rotor, or the conical cap on the turbine, and an internal shaft to spin as well at somewhere around 30 – 60 revolutions per minute.Â
The ultimate goal is to spin an assembly of magnets in a generator which will, well, generate voltage in a coil of wire thanks to electromagnetic induction. Generators require faster revolutions, however, so a gear box typically connects this lower speed shaft to a higher speed shaft by increasing the spin rate to around 1000 to 1800 revolutions per minute. These gear boxes are costly as well as heavy, so engineers are looking to design more “direct-drive” generators that can work at the lower speeds.
So wind turbines take the kinetic energy in the wind (that’s the energy due to the motion of the particles in the air) and turn it into mechanical power. That power can be used directly (for example as it often is in windmills for doing things like grinding grain or pumping water) or the generator converts it into electricity. Check out the great graphic on the U.S. Department of Energy’s website that walks you through the process.Â
Wind turbines take the kinetic energy in the wind (that’s the energy due to the motion of the particles in the air) and turn it into mechanical power.
To maximize efficiency, turbines have a wind vane that measures the direction of the wind so the turbine can orient itself to be most directly in the wind’s path. The blades also sit at 100 feet or more above the ground so they are subjected to the faster winds found at higher altitudes. Most turbines further require winds of 8–16 miles per hour to operate and have a shut off function to prevent them from operating at wind speeds higher than 55 miles per hour because they could be damaged.
Wind power is also more space efficient than solar power. Just one large wind turbine can power 600 homes, a task that would require a much larger spread of solar panels. The space between wind turbines can also be used for other purposes.Â
What Happens When the Wind Stops Blowing?
When we turn on our televisions or start running the A/C, we get that energy from an interconnected grid, which pools together the electricity generated by many turbine locations, rather than a single wind farm. So the wind doesn’t have to be blowing in your own backyard, it just has to be blowing somewhere that’s contributing to your grid, whether that be Iowa, Texas, or California.Â
However, the wind is unpredictable. The wind does blow at night, which is an obvious advantage of wind over solar power, but at least we know the Sun will rise again in the morning. The wind will always blow on our planet. We are just not always sure of when or where. This unpredictability is one of the biggest barriers to using wind power exclusively and also why your utility company doesn’t rely completely on one energy source. Most use a mix, including natural gas.Â
Do Wind Turbines Affect Your Health?
There is a large amount of anecdotal evidence, mostly in the form of complaints from those living nearby, that wind turbines can cause health problems due to the low frequency noise they produce. Those complaints include reports of everything from anxiety to headaches to nausea to vertigo. (Notably, this list does not include cancer.) However, no scientific studies have been able to draw a clear link between wind turbines and health. And they’ve tried.Â
The Australian government established a Select Committee on Wind Turbines which reported in 2015 that there was a lack of evidence to link any of the reported illnesses to the wind turbines. The Australian Medical Association agreed with them. In an article published in the Journal of Occupational and Environmental Medicine titled “Wind Turbines and Health: A Critical Review of the Scientific Literature,” the authors combed the archives for existing studies and the worst they found was an association with “annoyance.” They further concluded that “infrasound near wind turbines does not exceed audibility thresholds.”
Further research into the claims of adverse health effects of living near wind turbines is needed to explain their strong anecdotal support. And developments of carefully interspersed and well-connected grids of wind farms would clearly be needed if we were to increase our dependency on wind power. High upfront investment costs are also a barrier to increasing our use of this clean, renewable, and sustainable resource. Because fossil fuel rates are so much lower, estimates claim it takes anywhere from 10 to 20 years to break even on a newly constructed wind turbine.Â
The return on that investment, in the form of the potential reduction in greenhouse gases plaguing our planet, however, is priceless.Â
Until next time, this is Dr. Sabrina Stierwalt with Ask Science’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Ask Science on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.comcreate new email.Â
Wind turbines image courtesy of Shutterstock.
