BBC: 'Wind theft': The mysterious effect plaguing wind farms

Today's episode is about something...invisible. 

It's also renewable... and powerful- it's wind. 

That's right. Wind is a growing source of clean energy around the world. But did you know that wind farms can actually...steal each other's wind?

Yes- it's a real thing, and it's called wind theft. But before we explain, let's test your knowledge. 

OK, here's your quiz question for today:

What is the "wake effect" in wind farms?

A. A strong wind that helps turbines spin faster. 

B. A drop in win dspeed caused by spinning turbines. 

C:A  storm caused by offshore wind turbines. 

D. A sudden blackout caused by overproduction. 

We'll reveal the answer after the break. But now, let's get into today's story. 

Imagine this: when wind turbines spin, they take energy from the wind. That energy doesn't just disappear- it slows down the air behind them. 

That's the wake effect. The wind behind the turbines is weaker than the wind in front. And if another wind farm is downwind- behind it- it might not get as much energy. 

In fact, researchers say this can reduce the second wind farm's energy output by up to 10% or more. That's a big deal when countries are trying to reach their net zero climate goals. 

Let's take a moment to explain some key words from today's story. 

First up: wind theft. This is a casual or informal way of talking about the wake effect. No one is actually stealing the wind...

,,,because no one owns the wind! But if your wind farm is affected by the one next to it, people sometimes say it's wind theft. 

Next is wake. In this story, a wake means the air that is distributed or slowed down behind a moving object- like a boat, or a wind turbine. 

Now, offshore. If something is offshore, it means it's out at sea- not on land. Offshore wind farms are built in the ocean, where the wind is often stronger and more reliable. 

And here's another: net zero. That means the amount of carbon a country adds to the atmosphere is balanced by the amount it removes. It's a big target for many governments. 

Number five: deploy. To deploy something means to put it into use or action- like building and starting a new wind farm. 

Anf finally, cross-border. This refers to something that involves more than one country. Cross-border wind problems mean wind farms in one country could affect farms in another. 

So why is wind theft becoming a bigger issue now?

Because wind farms are getting bigger- and more crowded. Especially in places like the North Sea and the Baltic Sea. 

Experts say that in the UK, the number of turbines could triple by 2030. And the turbines themselves are getting taller, with longer blades- over 100 meters long!

The creates even longer wakes- and stronger wake effects. 

To study this, the University of Manchester has started a research project. They want to help governments and wind companies plan better- and avoid future conflicts. 

But it's not just a local problem. Some experts worry that wind theft could lead to cross-border tensions. 

For example, one planned wind farm in Norway might affect a wind farm in Denmark.