Wind Power Facts

Your RECs support wind power providers…also known as wind farms…across America. Here’s some of the history, some of the science, and some of the more interesting facts about the green energy source you are supporting.

Wind Power: The History

Wind power is one of the oldest sources of green energy on the earth

• Wind power may date back as far as 5,000 B.C. The earliest known depiction of wind power is an Egyptian vase from 3,500 B.C. that shows a sailboat on the Nile.
• The first recorded use of a windmill was in Sistan, Afghanistan in the 7th Century, though there are references that date back to the 1st Century. These early devices, called panemones, were very different from today’s windmills. They had a vertical axis, and featured six to twelve sails, so they looked a bit like someone hanging out their wash. They were used for drawing water from wells and for grinding grain.
• Today, we think of windmills that have horizontal axles, with their blades to the side. These date back to at least 1180 (there is a rental note from 1185 that mentions a windmill in Yorkshire, England), when they first appeared in Europe. These early windmills still used sails instead of rotors. Small scale windmills like these are still used to draw water in rural communities around the world.
• The first windmills were built to face the prevailing wind. The first innovation was windmills which could rotate to face shifting winds. Back then, the windmill operator had to manually turn the whole building to keep it facing the wind!
• The Dutch, who are still the leaders in windmill design, developed the first windmill where just the top of the tower rotated. Windmill operators appreciated it! This design allowed windmills to become very large and do several jobs at the same time. The Dutch also introduced the idea of windmills that used blades instead of sails.


Wind power was the major source of power before we started using fossil fuels.

• Wind power, in the form of sailing ships and windmills, was the main source of energy in the world when we started using fossil fuels for power in the mid-1800s. Today, we consider the possibility of replacing fossil fuel generators with wind turbines, and even supertankers are experimenting with adding new, high-efficiency sails to their design. Another example of history coming full circle.
• The small, muti-blade windmill, used to pump water from wells, was a staple product of America’s migration west. More than six million were installed between 1850 and 1970. Yes, they were still being installed in the 1970s.
• Charles F. Brush in Cleveland, Ohio and James Blyth in Glasgow, Scotland both generated electricity with a wind turbine in 1887; no one knows who did it first. Blyth offered his electricity to the neighboring town of Marykirk. They declined, believing electricity to be the "work of the devil."
• The first modern high-power wind turbine was developed in Russia in 1931. It was a 100 kilowatt system, and ran for almost two years. Ten years later, a 1.25 megawatt wind turbine, with blades that were 175 feet in diameter, was installed in Vermont. It only lasted for a few hundred hours before the rotor snapped! These early designs looked more like erector sets, and the rotors more like fan blades, than today’s sleek, aerodynamic turbines.


The Danish Design has become the standard for the modern, commercial wind turbine.

• The modern design for wind turbines, with three blades atop a tall, enclosed tower, is called "the Danish concept." The prototype was built in 1956 by Johannes Juul, and it ran for eleven years without maintenance.
• The Oil Embargoes of 1973 and 1979 spurred American interest in wind power, but interest died down in the 1990s, and America’s wind industry is only beginning to catch up to the world’s leaders. Only one US company, GE Wind, is among the world’s top ten wind turbine manufacturers.
• In 2008, the United States took over top spot for wind-powered electricity from Germany, with Spain, China and India rounding out the top five. But the United States still produces less than 1% of electricity from wind power. Denmark, by comparison, produces more than 20% of its electricity from wind.

Wind Power: The Potential

• Wind power is, in fact, a kind of solar power. The heat from the sun warms the earth, and the air, more in some places than others. Warmer air rises, and cooler air rushes in to fill the space. That’s where wind comes from.
• The power of the sun, turned into the power of the wind, could generate enough electricity in ten hours to meet global demand for a year.


America has the wind resources to meet its energy needs.

• The total estimated wind resources of the United States are almost 11 billion kilowatt hours per year. That’s almost twice as much as we generate from all sources now. The combined wind resources of North Dakota, South Dakota, Texas and Kansas would be enough to power the entire country.
• Development of 10% of the wind resources of the 10 windiest states would provide the same amount of electricity as all the coal-fired plants in the country.Click here to see the wind resource map of the United States.

  Click here to see a map of all the US wind power projects currently in development.

• Wind developers typically lease space for their turbines at a rate of $2,000 or more per year per turbine. For farmers, a turbine requires just 1/4-1/2 acre of space and interferes minimally with other activities such as planting and ranching. This is dependable income (leases can run for 20 years or more), and no crop can match the income per acre.
• During the next 20 years, the Department of Energy’s Wind Powering America Initiative will create $60 billion in capital investment in rural America, provide $1.2 billion in new income for farmers and rural landowners, and create 80,000 new jobs.

Wind Power Basics

While the large turbine blades rotate slowly, at 15 rpm, gears transform that energy to power 1,500 rpm generators.

• Wind turbines work on a very simple principle: the large, slow moving blades are connected by a gear box to an electrical generator. The gear box converts the blade’slow rotation, about 15-50 rpm, to the 1500 rpm necessary to run the generator.
• Wind turbines have instruments to measure wind speed and direction. A geared motor, called the yaw motor, turns the turbine to face the wind. The rotors can be rotated in their sockets to get the maximum energy out of the prevailing winds.
• Wind turbines require a minimum of 13 mph wind speed to operate efficiently. They reach maximum efficiency at wind speeds around 33 mph, and can operate at wind speeds of up to 50 mph. When the wind speed gets higher than that, they are locked in place. Most turbines are tested to stand wind speeds greater than 150 mph.
• Most wind turbine blades are made of fiberglass or a wood-expoxy mix, and the towers are made of stainless steel.
• While there are many designs available, including both vertical and horizontal axles, the three-rotor horizontal design known as the Danish concept is the most widely used and is considered the most efficient and easiest to maintain.
• The bigger the rotor, the more powerful the turbine. The most powerful turbine in the world is the Enercon E-126 in Emden, Germany. The tower is 453 feet high and the rotor, 413 feet in diameter, takes 5 seconds to complete a revolution (12 rpm). It will produce 20 million kilowatt hours per year. Larger turbines are already in development.
• How big should a turbine be? It’s a question of balancing the generating power in the local wind resources with the costs to manufacture, transport and install. Bigger turbines produce more power, right up to the point that you have built too big for your available wind.
• How high should a turbine be? The height of a wind turbine tower must be at least half the diameter of the rotors (otherwise they wouldd get stuck on the first turn!), and are usually set at 1 to 1.5 times rotor diameter. Taller towers set the blades higher, where the wind is stronger and steadier, but aesthetically, people prefer the look of wind turbines where the tower is roughly the same height as the rotor diameter.
• Once installed, modern wind turbines are 98% reliable, which means just 2% downtime.Wind turbines work best on open plains, where there is little to obstruct the free movement of the wind, on hilltops, in mountain passes and on open water. The US has more wind resources off our coastline than anywhere else.


Turbines located on the open water of oceans and major lakes will allow wind power to be located closer to major cities.

• Most major American cities are located close to open water (oceans or lakes), so many future wind farms will probably be located out at sea.
• Wind will probably never provide 100% of our electricity, because the wind doesn’t always blow. This is also true for solar power. That does not mean we will always require fossil fuels, because green sources such as hydro and biofuels can provide the necessary backup.
• A lot of work is being done to develop large-scale batteries to store electricity. Some systems use a small portion of generated power to set up natural batteries, such as systems that move water to uphill locations, where it can later power hydro systems, or that pressurize air or gas to power turbines.

Wind Power Facts Which We Bet You Didn’t Know

• Wind energy provides more jobs per dollar invested than any other energy technology. Every megawatt of new wind capacity creates 15-19 new jobs.
• The cost of wind energy has dropped 80% since 1980, and that drop will continue as increasing domestic production and economies of scale for wind turbines come into play. The wind will always be free.
• When you compare "energy payback" for different fuel sources…that’s the amount of energy produced compared to the amount of energy spent to get it…wind farms have been shown to have a payback of 17-39 times the energy expended, while nuclear power plants show a payback of 16 and coal plants a payback of just 11. Which payback would you pick?
• Even though the wind can be unpredictable, most wind turbines are sited so they will run 65-90% of the time. Because wind speed changes, they do not always run at 100% efficiency. However, wind speeds tend to pick up during the day and diminish at night, which is a similar pattern to typical daily electric demand.


We're pretty sure you wouldn't enjoy walking this close to a coal-fired power plant.

• Wind energy is one of the safest energy technologies. No member of the public has ever been injured during the normal operation of a wind turbine, with over 25 years operating experience and with more than 70,000 machines installed around the world.
• When people complain that wind power requires government subsidies, consider this: federal government has paid out $35 billion over the past 30 years to cover the medical expenses of coal miners who suffer from black lung disease. The coal companies didn’t pay for this. The taxpayers did. This is just one small example of the way that the government subsidizes fossil fuels.

Wind Power Non-Facts: Some Things You May Have Heard That Aren’t Completely True

Every new technology seems to bring with it the fear of the new and the unknown. When Thomas Jefferson introduced tomatoes to America, many believed the rumors that they were poisonous. Some people thought electricity was the work of the devil. You may have heard some similar "urban legends" about wind power. Here are some of the most common ones. Many of the myths surrounding wind power come from people believing that if wind turbines are placed in their communities, they will be right next door to their houses. You don’t put commercial wind turbines right next to houses, because houses block the wind. You put wind turbines in isolated fields, valleys and hilltops, removed from the houses, because that is where the wind blows free and steady.

Whatever your species, the truth about wind power is that wind turbines make good neighbors.

• Wind turbines kill birds. Do birds sometimes fly into wind towers? Yes. They also fly into houses, factories, telephone poles, cars, trucks, boats, planes, antennas, plate glass windows…and, of course, smokestacks and poisonous smog from fossil fuel plants. Birds fly into every man-made structure ever made. Wind farm planners generally work with environmental groups to ensure that their towers aren’t sited along migratory routes. There is genuine concern to minimize impact. We wish all industries were so conscientious.
• Wind turbines are noisy. At a range of 1,000 feet, a typical wind turbine makes as much noise as a refrigerator. For comparison, try standing within 1,000 feet of a typical power plant or factory. Wind turbines also make a gentle, whooshing sound, like the wind itself. Compare that to your neighbor’s air conditioner or furnace.
• Wind turbines hurl ice around. Scary, huh? A wind turbine icing up and throwing chunks of ice like a catapult. Only problem is, this doesn’t happen. When turbines ice up, the rotors lose their aerodynamic shape, and the turbine slows to a stop. Same reasons planes don’t fly until they’re de-iced. With the turbine stopped, ice may fall to the ground…just as it falls from the eaves of your house. You want to be careful walking directly underneath them, just as you want to be careful walking near you home. People who live in cold climates know this! This issue continues to be argued…with much science being offered by both sides…but at this point, it’s all science fiction because it’s never actually happened.
• Wind turbines will make you sick from "shadow flicker." Another scary one, this time medically scary. The idea is that the sun, passing directly behind a moving wind turbine as it rises or sets, will "flicker," causing illness. Once again, this very scary thing has never actually happened. The wind industry does recognize that the "flicker" can happen for a few minutes at sunup or sundown, under very specific circumstances, and that it can be an annoyance, and this is taken into account during site planning.