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Basics of Wind Conversion

  • Wind turbines harvest wind energy and convert it to electricity

  • The height, length, and shape of propeller blades all influence the amount of energy generated by wind turbines

  • Offshore wind has the capacity to generate more electricity than onshore locations


Wind is generated on our planet through the sun’s uneven heating of the earth’s surface, subsequent air flow across different terrains, and the rotation of the earth. Humans have been harnessing the power of the wind for generations, using wind to drive mills, pump water, sail ships, and more.


Presently, wind energy is used as a renewable flow to generate electricity. Wind causes the propeller-like blades of a turbine to spin, and the rotational motion is used in a generator to create electricity. 


Wind Turbines

Modern wind technology has focused on increasing the efficiency and cost-effectiveness of wind power. By far the largest engineering advances have been height (stronger wind currents at greater heights above the ground generate more power), and the length of the blades (longer blades can harness more energy). 

In 2020, the average length of the turbine blades was 200 feet with a tower height of 295 feet, about the height of the Statue of Liberty. The average capacity for an onshore industrial wind turbine in 2020 was 2.75 megawatts.

Turbine Hub Height Chart_final.png

The shape of the blades is also important. The blades work like airplane wings or helicopter rotors. One side of the blade is more curved than the other, and when wind flows across the blade, the air pressure is higher on one side than the other, causing it to spin.

Why do commercial wind turbines have three blades? Wind resistance and “drag” limit turbine efficiency and they increase with every additional blade. Having just one or two blades is not feasible because the spinning motion would either be unbalanced, or would wobble. So three is the minimum number of blades needed.

Where to harvest wind: continental vs. offshore

The location of wind turbines and wind farms matters. Different locations have higher average wind speeds and are therefore better suited to host wind turbines. The center of the United States is particularly well-suited to wind power. 


Offshore wind is particularly attractive for generating wind power. With fewer physical obstacles or barriers, wind flows are higher and more consistent over the water and therefore can lead to higher electricity generation. These figures from NREL (National Renewable Energy Laboratory) show that average wind speeds offshore correspond to the highest wind speeds onshore. It is also possible to build and assemble larger turbines offshore, since the components can be transported by ship.


The scale and characteristics of wind power

Wind power is a large potential energy resource. An estimate from 2009 claims that onshore and offshore wind power potential in the U.S. at commercial turbine heights could provide 68,000 TWh of electricity annually, greatly exceeding 2021 U.S. electricity consumption of 3,930 TWh. Currently, ~8% of electricity in the United States is generated from wind power. The theoretical maximum efficiency of a wind turbine is 59% conversion from wind energy to electricity, and most turbines convert ~50%.


A challenge with wind power is its variability - wind energy can vary both over the short term and long term due to weather fluctuations. Because of this, it is important that electricity generation from wind power is coupled with storage options.

Environmental considerations

Wind energy is a carbon-free, renewable source of electricity. Still, wind farms, like any economic activity, have some environmental impact. Wind farms use a significant amount of land and can disturb the onshore and offshore habitats where turbines are placed. Some critics of wind argue that turbines endanger flying wildlife, such as birds and bats, but recent studies of these effects have shown that bird deaths from wind turbines are minimal. In some cases, after the short term disturbance caused from installation, offshore structures have been shown to provide an artificial reef environment with increased fish populations.


Researchers also are seeking to develop materials for turbine blades that last longer and are less resource intensive, as well as ways to repurpose and reuse old turbines.

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Questions for deeper thinking

  • What are some political and social barriers that must be considered in implementing onshore wind? Are they different for offshore wind? Who must be consulted and brought into the conversation?

  • What are potential challenges in incorporating wind energy into the electrical grid?

  • What are some of the environmental considerations for wind farms and how do these compare to environmental concerns associated with other energy sources (like fossil fuels)?

Sources and further reading

Page last updated: November 20, 2022​

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