WEBVTT
Kind: captions
Language: en

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I am at one of the tallest wind farms in Europe.

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Look at that! Isn't that beautiful?

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You can't tell right now, but basically,

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when the cloud goes over, that is so high

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that it casts a shadow on the cloud as it's passing by.

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But the reason I' m here is because of something you might not know,

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which is why,

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when it's windy wind farms aren't always on and rotating.

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And there are a couple of reasons.

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One, is that wind farms aren't built to take extremely high wind speeds-

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above 50-55 mph it starts to get dangerous

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and this beautiful thing could rip itself apart.

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So, at high winds they slam the brakes on

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and they stop them running,

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because the amount of energy they would lose from doing that

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is much less than the amount of energy you would constantly lose

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if you had to build this thing

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to withstand hurricane force winds.

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The other reason is that the national grid

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can't cope with more than enough power

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being dumped into it.

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There are no giant storage batteries,

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that can hold the entire output of a power station.

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So, what happens is,

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if the demand is low,

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then they will just turn off the ones,

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that are easy to turn off, like this.

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And when demand rises again,

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they will turn on this and hydroelectric power plants,

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in order to deal with instant demand.

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Nuclear, coal, gas-

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all much harder to shut down,

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all much harder to start up.

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And so, the national grid keeps us balanced at 50 Hertz--

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50 cycles a second, 60 in America, 50 in Britain--

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by monitoring the plants like this

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and turning them on or off,

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as needs be.

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And that is something you might now have known.

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[Closed captions by MM.
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