 Humanity's addiction to fossil fuels has to end, we all know that. But the problem of how to power our lives without them is one of the biggest challenges scientists face today. I'm on my way to meet an expert who may have found a solution. Hi, I'm Esme, nice to meet you. Hi, I'm Nick. So what's brought us here today? Behind us, we actually have the tape modern. Now the tape, before it was an art gallery, actually used to be a power station supplying energy across the city and the country. And at the UKAA we are trying to develop this new energy source called fusion energy. I've heard of fusion and I've heard people get really excited about it but what actually is it? Fusion is the process that powers the sun and in fact, the power's all stars. Right inside the centre of our sun you get atoms made of nuclei and it's the nuclei of small light elements that come together under extreme conditions inside the centre of the sun. And when they're under the pressure of those extreme conditions they can actually get so hot and so energetic that they fuse together. And that fusion is actually what produces the energy for the sun to create its heat and light. Right here you have a demonstration for me. Yeah, I certainly do. Shall we go and check it out? All right. So you're trying to create the conditions of the sun here on Earth. How is that even possible? Yeah, it does sound quite a challenge. And it is. And we need to create some very extreme conditions and we need to create a plasma inside our machines. And what is plasma? Plasma is actually what we have here inside our plasma wall. Now it's quite hard to see and that's because we've been blessed with some bright sunshine today. Plasma is actually just the fourth state of matter. We all know about solids and you can heat those up, melt them into a liquid and then you heat up a liquid, boils and evaporates into a gas but then when you heat a gas it can actually get super hot and ionized into plasma. At our fusion site in Oxfordshire we put in our hot hydrogen gas until it turns into a plasma and then we can control all of that hot plasma with powerful magnets. It all sounds very clever. How far have you got with fusion? So we've actually come quite far. Not long ago our jet machine achieved a world record for fusion energy output. We proved that you can actually produce a high level of fusion energy for a sustained amount of time and that's a really crucial thing for us to be able to prove that we can do it over a small amount of time now and then we'll make it happen over a much longer amount of time when we scale it up to power plants. Amazing and tell me about the research you're bringing to the summer science exhibition. One of the key challenges in fusion is actually dealing with high heat loads. So around the edges of the machine we have to develop materials that can withstand some level of heat and we also are trying to reduce that heat load using what's called a diverter where we can actually steer the plasma down into these exhaust channels and help us to get rid of some of the excess heat and also get rid of some by-products that might have built up to make a more efficient, stable plasma and meaning we don't need to repair and replace parts of the fusion machines when we make power stations out of this stuff. How far away are we from seeing fusion power plants here on Earth? We hope that we're not actually that far away. We're moving into what we call the delivery era where now our focus is on trying to develop the full-scale fusion power plants of the future. One of our main projects we're working on right now is STEP and this is actually a UK design for a prototype fusion power plant in this country and STEP is aiming to be on the grid by 2040 so really not that long away to wait and we're really excited about our STEP project. Incredible. Well, there you go. Harnessing the power of the sun here on Earth could give us sustainable energy in the future.