Is Nuclear Fusion About To Have A Theranos Moment? Ep 277: Sir Steven Cowley

There's an old joke that energy from nuclear fusion is 30 years away and always will be. For many decades, the industry did little to spoil the fun, running mammoth and unwieldy research projects, hoovering up a few billion dollars every science funding cycle and announcing breakthroughs that were scientifically interesting, but did little to move us towards actual production of electricity.

Then three things happened. First, perhaps emboldened by Elon Musk's successful disruption of the space industry with SpaceX, a bunch of wealthy investors started to invest in much nimbler startups. Second, in December 2022, the National Ignition Facility at the US's Lawrence Livermore National Lab announced that it had finally got more energy out of a fusion experiment than it had put in. And third, AI exploded on the scene, offering dramatic acceleration in everything. These developments have turned the slow-moving world of fusion on its head.

Over $14 billion has now flowed into fusion startups, and that is on top of the tens of billions already committed to national and international programs, like the International Thermonuclear Experimental Reactor (ITER) in France, the UK's Spherical Tokamak for Energy Production (STEP) and a variety of US national labs. This week on Cleaning Up, Michael Liebreich sits down with the director of one of those labs.

Professor Sir Steven Cowley has been entrusted with leading one of the jewels in the US's scientific crown. He has dedicated his academic career to trying to make fusion energy work, and he's been known to joke that he hopes it does so before he dies.

Michael and Steven discuss the breakthrough experiments that have shown fusion is possible, why getting from a successful experiment to a commercial power station is such a huge leap, and whether fusion can ever deliver affordable, dispatchable electricity. Steven puts forward the idea that fusion might have a Theranos moment, where over-promises in the industry come back to bite.

Topics discussed in this episode:

• How fusion actually works
• From experiments to electricity
• Laser versus magnetic fusion
• The commercial fusion challenge
• How AI can transform fusion research
• Fusion versus renewables and batteries

Leadership Circle

Cleaning Up is proud to be supported by its Leadership Circle. The members are Actis, Alcazar Energy, Arup, Climate Imperative Foundation, Copenhagen Infrastructure Partners, Cygnum Capital, Davidson Kempner, EcoPragma Capital, EDP, Eurelectric, KKR, Mitsubishi Heavy Industries, National Grid, Octopus Energy, Quadrature Climate Foundation, Schneider Electric, SDCL and Wärtsilä. For more information on the Leadership Circle, please visit cleaningup.live.

Links:

• Steven's TED Talk from 2009: https://www.ted.com/talks/steven_cowley_fusion_is_energy_s_future
• Steven’s talk at IPAM 2026: https://www.youtube.com/watch?v=USPd6zvA8pk
• Steven's talk at SOSV Steven’s talk at DeepTech Live, 2026: https://www.youtube.com/watch?v=f-kb3784BPY
• Princeton Plasma Physics Lab: https://www.pppl.gov/
• Hax Plasma Forge Incubator: https://hax.co/
• Aneeqa Khan on Cleaning Up: https://www.youtube.com/watch?v=zhEoMd7DEho
• Subscribe to our newsletter: https://cleaninguppod.substack.com/

Acronyms:

• ITER: International Thermonuclear Experimental Reactor
• STEP: Spherical Tokamak for Energy Production
• JET: Joint European Torus
• TFTR: Tokamak Fusion Test Reactor
• DOE: Department of Energy (US)
• FLiBe: Fluoride Lithium Beryllium
• NIF: National Ignition Facility

Chapters:

• 00:00 Intro
• 03:24 Career in fusion
• 06:39 Commercial fusion
• 10:26 Laser fusion
• 18:40 Breeding tritium
• 23:33 Fusion startups
• 25:24 Laser versus magnets
• 29:21 Magnetic fusion
• 35:35 Reactor optimisation
• 40:35 AI controls fusion
• 44:52 Spherical tokamaks
• 46:33 Reversed-field fusion
• 49:24 Private fusion
• 53:07 Fusion economics
• 56:30 The future
• 57:14 Outro