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 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…the original wind powered vehicle…on the Nile.
• The first recorded use of windmills was in Sistan, Afghanistan in the 7th 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. There are references to windmills that date back even farther, to the 1st Century
• The modern windmill, with a horizontal axle and vertical blades, dates back to Europe in the 1100s: a rental note from 1185 refers to a windmill in Yorkshire, England. These early windmills still used sails instead of rotors. Small scale versions of this design are used to this day to draw water in rural communities around the world.
• The first great innovation in wind power was windmills that could rotate so they always faced the prevailing winds. Back then, the windmill operator had to manually turn the whole building to catch the strongest breeze!
• The Dutch, who are still the leaders in windmill technology, 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 to do several jobs at the same time. The Dutch also introduced the idea of windmills that used blades instead of sails.



• 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 in the mid-1800s. Today, we are working to replace fossil fuel generators with wind turbines, and even supertankers are experimenting with new, high-efficiency sails as a way to cut fuel use. Another example of history coming full circle.
• Small, muti-blade windmills, used to pump water from wells, were an icon of America’s westward expansion. More than six million were installed between 1850 and 1970. That’s right: 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 for sure 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 high-power wind turbine was developed in Russia in 1931. It featured a 100 kilowatt generator, 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 a rotor snapped! These early designs looked more like giant erector sets, and the rotors more like fan blades, than today’s sleek, aerodynamic turbines.



• 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. By 1980 America was considered the world leader in wind technology. But interest died down in the 1990s, as oil got cheap again, 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 the 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 actually a form of solar energy. The heat from the sun warms the earth more in some places than others. The earth warms the air above it, creating pockets of warmer and cooler air. The warmer air rises, and the cooler air rushes in to fill the space. That’s where wind comes from.
• The wind power created by the sun’s uneven warming of the earth could, theoretically, generate enough electricity in ten hours to meet global demand for a year.



• The United States has an estimated 11 billion kilowatt hours per year in wind resources. That’s almost twice as much electricity as we generate from all energy sources, including fossil fuels, right 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 one quarter to one half of an acre of space and interferes minimally with planting and ranching. This is a dependable income…leases can run for 20 years or more…and no crop can match the return 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

• Wind turbines work on a simple principle: a large, rotating blade generates a lot of energy, even when it turns slowly. The larger the blade, the larger the generator you can attach to it, and the more energy you get. A gear box converts the slow rpm of the blade to the 1500 rpm necessary to run the generator.
• The tiny blades of microturbines can move as fast as 50 rpm. The massive blades of commercial turbines rotate lazily at 12-15 rpm.
• Today’s wind turbine utilizes sophisticated aerodynamics for maximum efficiency. Onboard instruments track wind speed and direction, and direct a geared motor, called a yaw motor, to keep the turbine facing the wind. The blades can also be rotated in their sockets to get the maximum energy out of the prevailing winds. We’ve come a long way from windmill operators rushing outside to turn their building!
• Wind turbines require a minimum wind speed of 11 mph to operate efficiently, and reach maximum efficiency at wind speeds around 33 mph. Maximum wind speed is around 50 mph; at that point, braking mechanisms lock the blades in place. Turbines are tested at wind speeds greater than 150 mph, so they can withstand the strongest hurricane.

• Most wind turbine blades are made of fiberglass or a wood-expoxy mix, and the towers are made of stainless steel.
• There are hundreds of windmill designs in operation today, using both vertical and horizontal axles. The three-rotor horizontal design known as the Danish Concept remains the most widely used. It is considered the most efficient and the easiest to maintain.
• 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 of the local wind resources against the cost to manufacture, transport and install. Bigger turbines produce more power, but you don’t want to waste money on a turbine that is too big for the 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 would hit the ground on the first turn!), and is usually set at 1 to 1.5 times the 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 in places where there is little to obstruct the free movement of the wind: on open plains, on hilltops, in mountain passes and on open water. The US has more wind resources off our coastlines than anywhere else in the country.



• Most major American cities are located close to the open water of oceans and lakes, so many of the largest future wind farms will probably be located out at sea.
• Wind will most likely never generate 100% of our electricity, because the wind doesn’t always blow. This is also true for solar power, which doesn’t generate at night. That does not mean we will always require fossil fuels, because green sources such as hydro and biofuels can provide the necessary backup.
• One of the keys to a fossil-fuel-free future is the development of large-scale batteries to store electricity. Right now this technology doesn’t exist, but if it can be developed, it will give a major leg up to wind and solar power. Then wind and solar farms can generate at full capacity when the sun shines and the wind blows, and use the battery backup to fill in the gaps.
• There is a lot of innovative thinking at work trying to solve the battery question. One possibility is using natural systems to store potential energy that can be used later. Example of natural batteries include systems that move water to uphill locations, where it can later power hydro systems, or that pressurize air or gas.

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 power has dropped 80% since 1980. It will drop even more as increased domestic production of wind turbines, and the resulting economies of scale, come into play. The wind, of course, will always be free.
• When you compare the “energy payback” for different fuel sources…that’s the amount of energy produced compared to the amount of energy spent to produce it…wind farms have a payback of 17-39 times the energy expended. Nuclear power plants have a payback of 16 and coal plants a payback of just 11. Which payback would you choose?
• Although the wind is unpredictable, most wind turbines are sited so they generate 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.



• Wind energy is one of the safest energy technologies. In 25 years of operation, and with more than 70,000 turbines installed around the world, no member of the public has ever been injured during the normal operation of a wind turbine.
• When people complain that wind power requires government subsidies, consider this: the 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 brings with it the fear of the unknown. When Thomas Jefferson introduced tomatoes to America, many people believed that they were poisonous. Some people thought electricity was the work of the devil. You may have heard some similar “urban myths” about wind power. Here are some of the most common ones.

• Wind turbines are noisy. Actually, at a range of 1,000 feet, a typical wind turbine makes as much noise as a refrigerator…and requirements in America call for a setback of 1,250 feet or more. You can stand at the base of a wind turbine and carry on a normal conversation. Try standing within 1,000 feet of a typical power plant!
• Wind turbines turn into ice catapults when they get cold. You will hear this one discussed a lot on the Web. It continues to be debated…with much science being offered by both sides…but at this point, it’s all science fiction because it has never actually happened. When turbines ice up, the blades lose their aerodynamic shape, and the turbine slows to a stop. This is the same reason 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 a turbine on a cold day. People who live in cold climates know this!
• Wind turbines will make you sick from “shadow flicker.” Shadow flicker occurs when the rising or setting sun passes directly behind a moving wind turbine. The wind industry recognizes that flicker can happen for a few minutes at sunup or sundown, under very specific circumstances, and this is taken into account during site planning. Flicker is an annoyance, but it has never actually made anyone sick.
• Wind turbines kill birds. This is true. Birds and bats can hit towers or be caught in the rapid pressure change behind the spinning turbine blades. But a lot of other things kill birds: factories, telephone poles, cars, trucks, boats, planes, antennas, plate glass windows, power lines, family cats…and, of course, smokestacks and poisonous smog from fossil fuel plants. Wind planners work with environmental groups to ensure that turbines aren’t sited along migratory routes or habitats. There is genuine concern to minimize impact. We wish all industries were this conscientious.

Every form of human technology impacts the environment and our society. It is important that we don’t hold wind power to a standard of absolute environmental perfection, while at the same time accepting strip mining, oil well blowouts, releases of processing byproducts, tanker spills, pipeline spills, explosions at storage facilities and the inevitable smog and greenhouse gas emission as “business as usual” for fossil fuels.