I am at one of the tallest wind farms in Europe.
Look at that! Isn't that beautiful?
You can't tell right now, but basically,
when the cloud goes over, that is so high
that it casts a shadow on the cloud as it's passing by.
But the reason I' m here is because of something you might not know,
which is why,
when it's windy wind farms aren't always on and rotating.
And there are a couple of reasons.
One, is that wind farms aren't built to take extremely high wind speeds-
above 50-55 mph it starts to get dangerous
and this beautiful thing could rip itself apart.
So, at high winds they slam the brakes on
and they stop them running,
because the amount of energy they would lose from doing that
is much less than the amount of energy you would constantly lose
if you had to build this thing
to withstand hurricane force winds.
The other reason is that the national grid
can't cope with more than enough power
being dumped into it.
There are no giant storage batteries,
that can hold the entire output of a power station.
So, what happens is,
if the demand is low,
then they will just turn off the ones,
that are easy to turn off, like this.
And when demand rises again,
they will turn on this and hydroelectric power plants,
in order to deal with instant demand.
Nuclear, coal, gas-
all much harder to shut down,
all much harder to start up.
And so, the national grid keeps us balanced at 50 Hertz--
50 cycles a second, 60 in America, 50 in Britain--
by monitoring the plants like this
and turning them on or off,
as needs be.
And that is something you might now have known.
[Closed captions by MM. Translating these subtitles? Add your name here!]