Nuclear fusion could solve the world’s energy problems, says physicist and Everest-climber Melanie Windridge, who reveals some of the latest innovations

Melanie Windridge’s company has heated plasma to sun-like temperatures

Fusion could solve the world’s energy problems and curb climate change, says physicist and Everest-conquering adventurer Melanie Windridge, who reveals some of the latest innovations.

What inspired you to get into fusion energy as a career?

When I realised that it could solve the world’s energy problems if only we could do it, and that it would decarbonise our energy system, helping to curb climate change. And that was just for starters.

What does your work involve?


I work with a fusion start-up called Tokamak Energy, which is aiming to show the commercial feasibility of fusion by 2030. We have an experimental machine called the ST40, which is a spherical tokamak. Tokamak reactors are the best performing fusion device that scientists have come up with so far. The reaction chamber is a torus shape, a bit like a ring doughnut, though ST40 is squashed up like an apple. The world’s biggest fusion reactor, ITER, being built in France, is a tokamak machine, but we want to use advanced superconducting magnets to bring the size down.

Learn more at New Scientist Live: Where Melanie Windridge will be speaking about nuclear fusion and the sun’s power on Earth

How do we get fusion energy?

Scientists have already achieved fusion. It’s just that no one has yet got more energy out of the reaction than they put in – quite important if you want to make a power station!

To do it, we first have to create the conditions that are found inside of stars. In fact, even hotter than that, because we want to use a slightly different reaction that won’t take millions of years to get going. 100 million °C is the threshold we’re looking to reach, to get fusion going. We may even operate at 150 million °C or more. Then, of course, you need to contain that plasma, that hot fusion fuel. Magnetic fields are used for that.

How close are you to creating star-like conditions?

This year, we hit 15 million °C, though I was on Mount Everest at the time. That temperature milestone was really good news – that’s hotter than the sun.

To heat the plasma we used an experimental technique called merging compression – joining two rings of plasma and then compressing it with an intense magnetic field. We didn’t have any external heating from things like neutral beams, which is an additional way to heat plasma. We’re now starting to upgrade to use neutral beams; we want to achieve 100 million °C in the next year or so.

If the magnetic field fails to contain superheated plasma, what happens to the machine?

This is a really good thing about fusion energy. It’s inherently safe, because there’s so little plasma in the machine at any one time. If you lose control of it, there’s not enough fuel there for a big explosion or anything catastrophic. It would simply cool very quickly, though that can put strain on the machine structure.

When are we likely to see fusion power become a reality?

Science is an exploration and we don’t know what we’re going to find along the way, but I think I could speak for the whole fusion community when I say we want it as soon as possible. At Tokamak Energy we’re aiming for the 2030s.

What innovations will improve fusion?

One thing is high-temperature superconductors. They can operate at around 76 degrees above absolute zero – about -200 °C – instead of about 4 degrees above absolute zero, which is what conventional superconductors operate at. Tokamak Energy is developing high-temperature superconductors for fusion, though we would still cool them to between about 20 and 30 kelvin (-256 °C and -246 °C), because their performance is better in that range. It’s a fivefold energy saving compared with conventional superconductors, and they produce stronger magnetic fields.

The world’s biggest fusion reactor, ITER, is due to start up in 2025. What can we expect?

They are aiming to get about 10 times more energy out of the fusion reaction than they put in. That will prove fusion energy is possible. ITER is going to test other systems as well, because ultimately, fusion is just a heat source, and once you start developing experimental reactors into real power stations, you need lots of other systems – like how do you extract that heat energy?

There’s still lots to do then?

Loads to do, yes. But it’s not intractable: there are clear steps along the pathway and things that we need to do. Humans have done incredible things – we’ve flown to the moon, for goodness sake. It just takes money, people and time. But the politics takes its toll. ITER, for example, has been hugely delayed because it turned into a big political thing. It’s a worldwide collaboration, which means it’s bureaucratic, really slow and inefficient. Before the delays and inefficiencies with ITER led the costs to spiral, one country could have built it for less than it costs to run the Olympics. Now, everyone’s quite happy for one country to run the Olympics, but apparently nobody wants one country to solve the world’s energy problem.

You seem to enjoy tough challenges in life as well as science. Congrats on reaching the summit of Mount Everest in June.

Thank you! I was really lucky to have such a positive experience up there. I arrived at the summit with my Sherpa partner at 4:30am, just as the sun was coming up. We were the first of the day to arrive, which is amazing, because it meant that I had this really pure experience. We spent almost an hour there alone.

What prompted you to go to Everest?

I loved mountains already, but five years ago I read the 1953 book The Ascent of Everest by John Hunt, and I realised that the main reason that the British got up in 1953 and had failed in previous decades, was mostly to do with the scientific understanding and the technology that was available. I am really interested in science and exploration and how they drive each other.

• Melanie Windridge is a physicist, speaker and writer. She is Communications Consultant for fusion start-up Tokamak Energy, Academic Visitor at Imperial College London and author of Aurora: In Search of the Northern Lights. Learn more about Melanie’s work on nuclear fusion at New Scientist Live in London from 20-23 September.