Notes

Every 24 hours, wind generates enough kinetic energy
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to produce roughly 35 times more electricity than humanity uses each day.
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And unlike coal or oil, this resource is totally renewed each day.
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So how can we harness this incredible amount of energy,
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and is it possible to create a world powered entirely by wind?
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The basic principle of wind energy is simple.
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A series of sails or blades mounted around a rotor catch the wind
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and translate its kinetic energy into rotational energy.
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Traditional windmills use that rotational energy to grind wheat or pump water.
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But in modern wind turbines, it turns a generator that creates electricity.
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This conversion from wind to rotational energy to electricity
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has defined wind turbines since their invention in the late 19th century.
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And there are three primary factors that determine just how much energy
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they can produce: the size and orientation of the blades,
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the blade’s aerodynamic design, and the amount of wind turning the rotor.
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First up, blade orientation.
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Wind turbines can be designed with their rotor
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on a vertical axis or a horizontal axis.
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Vertical blades can pick up wind coming from any direction,
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but with much less efficiency than horizontal axis rotors.
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Horizontal designs allow blades to capture the wind’s full force
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by tracking the wind’s direction and turning to face it.
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This turning process is called yawing,
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and older windmills achieved it through manual monitoring.
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Today, wind sensors and computer systems automatically adjust the blades
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with expert precision to capture as much energy as possible.
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Outside rotor orientation,
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the blades themselves need to be shaped to maximize efficiency.
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While early designs used flat blades,
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modern blades are curved like airplane wings.
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Wind travels faster over the curved surface,
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creating a low-pressure pocket above the blade that forces it upwards.
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Since the amount of lift depends on the angle
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at which the wind is moving relative to the blade,
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modern blades also incorporate a twist,
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optimizing how much of the blade can cut into the wind.
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Made of fiberglass and resin layers, these blades are strong enough
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to operate through rain, lightning, and blistering sunlight for over 20 years.
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Even with aerodynamic blades and a horizontal rotor,
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a wind turbine can only capture wind if it's in a windy environment.
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Wind speeds typically increase the higher into the atmosphere you travel.
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So today, most turbines are well over 100 meters tall,
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with equally large rotor diameters.
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A turbine of this height and size can capture a huge amount of wind,
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generating enough electricity every year to power 750 American homes.
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A wind farm of 200 similarly sized turbines
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could power over 150,000 American homes— or twice as many European homes—
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for an entire year.
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Offshore wind farms contain an even greater number of even larger turbines.
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In 2019, the largest wind turbine ever built
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began operating off the coast of the Netherlands.
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With a rotor diameter of 220 meters, just one of these turbines
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can meet the annual power needs of 16,000 European households.
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Despite its amazing potential, wind energy still faces challenges.
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Wind may be a free and unlimited fuel,
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but no matter how large or efficient a turbine is
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there's a mathematical limit to how much wind it can convert into electricity.
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German physicist Albert Betz calculated
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that since some wind must remain to keep the blades spinning,
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a turbine can only ever capture 59.3% of the wind’s energy.
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Additionally, some people feel turbines disrupt natural scenery,
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and wind energy’s intermittent availability
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can make it difficult to integrate into electrical grids.
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But even with these challenges, modern wind turbines have made wind energy
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the most efficient and inexpensive source of electricity.
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Wind turbines already provide essential energy for communities around the world.
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And for many farmers, hosting a wind turbine
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can be a reliable source of additional income.
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With continued improvements in wind forecasting,
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electrical grid infrastructure and energy storage,
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wind power might blow away all our energy problems.