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