What is wind power?
Every day, the sun unevenly heats the atmosphere, land surfaces, and bodies of water; these differences in temperature and pressure create the movement of air that we call wind. Wind turbines capture energy by using the motion of wind to power a generator. So how exactly does this work?
Wind turbines rotate as wind pushes the blades to generate energy. As the wind blows on the front side of the blade, the blade is pulled towards a pocket of low pressure created on the blade's backside. This pull is actually the strongest force on the blade. Combined with the wind’s push on the front side, the blade is set in motion, thereby spinning the generator housed within the turbine to create electricity.
The amount of electricity each turbine produces depends on its size and amount of wind in the area, but the average utility-scale turbine ranges between 1 and 5 megawatts, which is enough to power roughly 1,100 homes. Their added height gives them access to less volatile, stronger winds that blow at higher altitudes. In the United States right now, there is enough wind energy to generate electricity for 15 million homes.
Potential energy from a wind turbine is directly proportional to the cube of the wind’s speed, so an increase in average wind speed by even just 2 mph can produce a significantly larger amount of electricity. This is why turbine size increases every year, along with the push for offshore wind farms. Just as wind at higher altitudes is stronger and less volatile, offshore wind tends to blow even stronger and more uniformly than on land, meaning offshore wind energy resources have immense potential.
Overwhelmingly in national polls, Americans support clean energy expansion, especially wind power. Yet, when projects are proposed they often meet a fair amount of community opposition, a stance commonly referred to as ‘not in my backyard’ or NIMBY. So what creates this local opposition despite support at the national level?
Noise: Wind turbines are critisized for producing unpleasant noise within a certain radius of where they operate. In general, turbines are placed at least 300 meters (about .2 miles) from residences. The average sound level at this distance is around 43 decibels while at 500 meters (.3 miles), the sound decreases to 38 decibels. For reference, the average refrigerator runs at 40 decibels while an air conditioner runs at around 50 decibels (see the comparison here).
Aesthetic: Wind turbines can be perceived as an intrusion on an otherwise pristine landscape, a visual effect that can discourage residents. Before construction, there are visual impact assessments conducted with the goal of protecting the scenic quality of the landscape. These kinds of analyses of well-sited wind farms can help residents visualize what a project will look like, increasing acceptance after construction is completed. The rotating blades can cause a 'flicker' effect when the sun is low on the horizon. In most cases, flicker is only an issue a couple of hours per year, can be mitigated by effective site planning from developers, and is often addressed in local ordinances to prevent nearby residents from being affected.
Ecological: While collisions with wind turbines cause the deaths of an estimated 140,000 to 328,000 birds per year, studies have estimated that collisions with glass buildings account for 365 million to 988 million bird deaths along with 8-57 million from collisions with utility lines. This is not to say that the wind turbine deaths are insignificant, but citing the number of bird deaths without context is an inaccurate representation of ecological impacts. As for offshore turbines, construction can temporarily displace wildlife. However, research has shown that the wildlife not only returns after construction, but that the base of a turbine can function as an artificial reef.
Making wind a fan favorite
If you are in an area with a proposed wind project, take the time to contact the developer and your local legislator to collaborate on a clean, carbon-free energy system that works for everyone. If there aren't potential projects in your area, keep encouraging your representatives to push forward renewable energy legislation!
*Looking for an even more in depth analysis of impacts of wind power? Our own Jean Ann Ramey co-authored a report on the cost of different power generation sources. Included on pages 67-72 is an analysis of visual, noise, and wildlife impacts of both on and offshore wind farms. Check it out!