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Difficulty in Achieving Fusion Power

# Difficulty in Achieving Fusion Power

### Difficulty in Achieving Fusion Power

Scientists haven't yet been able to sustain nuclear fusion reactions and have a positive net energy.

First of all, what is nuclear fusion?

Is the new nucleus that is created in nuclear fusion radioactive?

Does nuclear fusion or nuclear fission produce more energy?

Scientists are very excited about being able to use nuclear fusion on Earth to generate energy.

1

Nuclear fusion generates enormous amounts of energy!

Much much more energy even than nuclear fission.

2

Nuclear fusion produces no radioactive waste

Nuclear fusion produces only stable nuclei. Nuclear fission, on the other hand, produces radioactive daughter nuclei.

So why aren't we just generating energy by nuclear fusion on Earth?

The problem with nuclear fusion on Earth

1

For nuclear fusion to happen requires extremely high temperatures and extremely high pressure!

We can create those conditions on Earth, but it takes more energy to do that than we can get out of nuclear fusion.

2

That basically means that there is no point in generating energy by nuclear fusion

Until we can actually get more energy out of nuclear fusion than it costs to achieve nuclear fusion in the first place, we get less energy overall out of using nuclear fusion.

Why can nuclear fusion occur naturally in stars like our Sun? Pick all the options you think are correct.

Now, why does fusion require such high pressure and such high temperatures?

1

True or false? All nuclei are positively charged.

2

Will two nuclei naturally attract or repel each other?

3

That means that there exists an _______________ force of repulsion between two nuclei.

4

So in order for two nuclei to fuse there has to be other forces that can overcome the electrostatic force of repulsion between them

Inside the Sun, the pressure coming from the Sun's gravitational force raises the temperatures so high that the particles move fast enough that they actually smash together and fuse, even though they naturally repel each other.

Do we have the same gravitational force and pressure on Earth as inside the Sun?

We don't have the same pressure on Earth as inside the Sun, so instead we have to increase temperatures even higher to make nuclear fusion happen. We need 100-200 million degrees Celsius!

Have scientists managed to achieve nuclear fusion on Earth yet?

Summary

1

Nuclear fusion releases tremendous amounts of energy!

Much much more than nuclear fission even, so scientists are very interested in finding a way to make nuclear fusion reactors on Earth to generate energy.

Also, nuclear fusion produces no radioactive waste (as opposed to nuclear fission).

2

Nuclear fusion requires extreme pressure and extremely high temperatures

This is because the forces have to overcome the electrostatic force between positively charged nuclei that causes them to naturally repel each other.

3

Nuclear fusion happens naturally inside the Sun

This is because the Sun has a huge gravitational force that creates such high pressure that temperatures rise to $15,000,000^{\circ} \space C$

Particles then fly around so fast that they simply smash into each other and fuse, even though they are otherwise repelled by each other.

4

On Earth, we don't have that kind of gravitational force and that kind of pressure

So on Earth, we have to raise temperatures to 100-200 million degrees Celsius to make fusion happen!

5

This has in fact been done!

Scientists at the JET experiment near Oxford in England have actually managed to create nuclear fusion at these temperatures.

6

But we don't have any nuclear fusion reactors on Earth that actually generate energy

This is because getting to those temperatures that make fusion happen on Earth requires more energy than the fusion generates. So it's not currently an economical way to generate energy.