What is a wind turbine?

A wind turbine transforms the kinetic energy of the wind into mechanical or electrical energy.

Wind turbines consist of a foundation, a tower, a nacelle, and a rotor. The foundation prevents the turbine from falling over and is usually 13m across and 1-2m deep. The tower holds up the rotor and a nacelle (or box).

The nacelle contains large primary components such as the main axle, gearbox, generator, transformer, and control system. The rotor is made of the blades and the hub, which holds them in position as they turn. Most commercial wind turbines have three rotor blades. The length of the blades can be more than 60 meters.

How fast do the blades turn?

The blades rotate at between 15 and 20 revolutions per minute at constant speed. However, an increasing number of machines operate at variable speed, where the rotor speed increases and decreases according to the wind speed.

How long does a wind turbine work?

Wind turbines can carry on generating electricity for 20-25 years. Over their lifetime they will be running continuously for as many as 120,000 hours. This compares with the design lifetime of a car engine, which is 4,000 to 6,000 hours.

How many wind turbines are there in the EU?

In 2010, there were 70,488 onshore wind turbines and 1,132 offshore turbines across the EU. As technology progresses, turbines are becoming bigger and more efficient as the generation of the same amount of energy can be generated with fewer machines.

Why do some of the turbines in a wind farm sometimes stand still?

Turbines sometimes have to be stopped for maintenance, repairing components, or if there is a failure that needs to be checked. Another reason can be too little or too much wind; if the wind is too strong, the turbine needs to be shut down to keep it from being damaged.

How efficient are wind turbines?

The theoretical maximum energy at which a wind turbine can extract from the wind blowing across is just under 60%.

How much energy can wind realistically supply to the U.S.?


Wind energy could supply about 20% of the nation’s electricity, or 600 billion kilowatt-hours annually, according to Battelle Pacific Northwest Laboratory, a federal research lab. Wind energy resources, which are useful for generating electricity, can be found in nearly every state.

In the U.S., how fast is wind energy growing compared to other sources of energy?

Wind Energy has grown 35% since 2007, faster than coal (14%) and nuclear (1%).

What are America’s current sources of electricity?

Coal, the most polluting fuel and the largest source of the leading greenhouse gas, carbon dioxide (CO2), is currently used to generate more than half of all of the electricity (52%) used in the United States. Other sources of electricity are natural gas (15%), oil (4%), nuclear (19%), and hydropower (9%).

How much energy can wind supply worldwide?

According to the U.S. Department of Energy, the world’s winds could theoretically supply the equivalent of 5,800 quadrillion BTUs (quads)  each year–more than 15 times current world energy demand. (A quad is equal to about 172 million barrels of oil or 45 million tons of coal.)

A recent study performed by Denmark’s BTM Consult for the European Wind Energy Association and Greenpeace found that by the year 2017, wind could provide 10% of world electricity supplies, meeting the needs of 500 million average European households.

The potential of wind to improve the quality of life in the world’s developing countries – where more than two billion people live with no electricity or prospect of utility service in the foreseeable future – is vast.

How big is a wind turbine?

The average size of onshore turbines being manufactured today is around 2.5-3 MW. One 2.5 MW onshore turbine produces power for over 1,500 average households.

The largest onshore turbine is a 7 MW turbine with a rotor diameter of 127m.

Offshore turbines can reach up to 5 MW or more with a rotor diameter of 120m – longer than a football field – with the potential to power around 3000 average households.

What is the U.S. wind potential for onshore wind? What is the U.S. wind potential for offshore?

Onshore: 10,400,000 MW

Offshore: 4,150,000 MW

Combined, it’s enough energy to power 25 million homes.

What is the installed cost of wind energy?

A February 2012 analysis by the Lawrence Berkeley National Laboratory puts the current cost of wind energy – without the inclusion of any government incentives – at $60-90/MWh (6-9 cents/kWh). Coal, nuclear, and natural gas generation is no match for the price of wind power.

What are the environmental benefits from wind?

Over 1,500 tons of carbon dioxide, 6.5 tons of sulfur dioxide, 3.2 tons of nitrogen oxides, and 60 pounds of mercury are the annual emissions eliminated by generating energy from a 1 MW wind turbine instead of 1 MW of conventional sources.

Wind power farms generate between 17 and 39 times as much power as they consume compared to 16 times for nuclear plants and 11 times for coal plants, according to a study of Midwestern wind farms by the University of Wisconsin.

How many people work in the U.S. wind industry?

According to AWEA, an estimated 85,000 Americans are currently employed in the wind power industry and related fields. Many workers are found on wind farms, which are frequently located in the Midwest, Southwest, and Northeast regions of the United States. Texas, Iowa, and California are the leading states in wind power generating capacity, but many others—including Illinois, Indiana, Oregon, and Washington are in the process of substantially increasing their wind generating capacity.

Over 400 U.S. manufacturing facilities make wind-related components across 44 states. American wind power is a $10 billion-per-year industry.

Source: EWEA.org, AWEA.org, Wind Energy Resource Atlas