4.2.3 Making use of fusion

Stars are mostly made - at least our sun is mostly made - of hydrogen and helium. And what's happening inside the sun is that hydrogen is being converted into helium by sticking together the hydrogens, the nuclei of hydrogens, in order to build up the nucleus of helium. And this process is called fusion, and it is because the binding, the strong force wants to pull together a bigger nucleus.

Now, the tough thing for all stars is that if you've got hydrogen this far apart, they repel each other because they're charged. It's only when you get them almost as close as they're absolutely touching that they pull themselves together, and they will fuse, and they will make helium. And out of helium they can make carbon, and out of carbon they can make oxygen and nitrogen, all the things that you're made of.

In fact, we are just stardust, right? We are made of stars, and all the elements in our body are made by sticking together smaller elements to make heavier elements by this process of fusion. And you release energy from that because you've released the binding energy - the energy that pulls them together has to be released somehow. And that makes stars hot.

So this process of doing fusion, of sticking together small atoms to make bigger ones, would be a marvellous way to make energy. Just a fantastic way to make energy, because it's so powerful that it can power the stars. But the difficulty is in order to get them close enough that they will fuse, they have to rammed together, at great energy.

And stars do that because they're hot, and the hydrogen inside the sun is running around, and every now and again it smashes into each other, and they get close enough, and they bind. So you've got to have temperature to make fusion happen, because you've got to ram together your nuclei at great speed. Sometimes they glance off each other, but often they'll hit them smack on and fuse.

So, here at Cullen, we're trying to do this process to eventually make electricity to power the planet. And we're trying to create the conditions like the middle of a star, so we need tens, or even hundreds of millions of degrees in temperature in order to have our fuel, which is two kinds of hydrogen, run around fast enough that it will stick and fuse.