We’ve all seen those creaky, old windmills
on farms.
And although they may seem about as low-tech
as you can get, those old windmills are the
predecessors for new, modern wind turbines
that generate electricity.
The same wind that used to pump water for
cattle is now turning giant wind turbines
to power cities and homes.
OK, have a look at this wind farm in the California
desert.
A hot desert… next to tall mountains…
an ideal place for a lot of wind.
Here’s another one on the windy prairies
of Wyoming.
Now today’s wind turbines are much more
complicated machines than the old prairie
windmills… but the principle is the same…both
capture the wind’s energy.
OK…
Here’s how it works.
First, a wind turbine blade works sorta like
an airplane wing.
Blowing air passes around both sides of the
blade. 
The shape of the blade causes the air pressure
to be uneven – higher on one side of the
blade and lower on the other.
  And that’s what makes it spin… the
uneven pressure causes the blades to spin
around the center of the turbine.
On the top, there’s a weather vane that’s
connected to a computer… to keep the turbine
turned into the wind so it captures the most
energy.
 
Now the blades are attached to a rotor which
only turns about 18 revolutions a minute…and
that’s not nearly fast enough to generate
electricity by itself.
So, the rotor shaft spins a series of gears
that increase the rotation up to about 1800
revolutions per minute.
And at that speed, the generator can begin
to produce electricity.
So why are wind turbines so tall?
Well… the higher up you go… the windier
it is.
More wind naturally means more electricity.
Larger turbines can also capture wind energy
more efficiently.
The blades can sweep a circle in the sky,
with a diameter longer than a football field.
Now what’s really cool is that even a small
wind farm like this one in Wyoming…
…can generate enough electricity to power
more than 9,000 homes... and larger farms
can provide much more clean energy for our
homes and businesses.
And it’s not just on land that turbines
can capture the wind.
Our oceans and the Great Lakes provide a reliable
and consistent source of wind that we can
capture and turn into electricity.
The Energy Department is supporting innovative
offshore wind projects that will help build
some of the first offshore wind turbines in
U.S. waters.
As the wind energy industry continues to grow,
offshore development has the potential to
significantly boost domestic renewable energy
production, especially in coastal areas.
With more than 50% of the U.S. population
living within 50 miles of a coastline, capturing
wind off America’s shores has the potential
to provide energy to countless homes and businesses.
Wind energy… on land or offshore…a reliable
and renewable clean energy source, helping
move America toward energy independence.
