Nuclear fusion works. If you doubt that fact, look at the sun (metaphorically, rather than literally: avoid frying your eyeballs). As hydrogen atoms are compressed they fuse together to create helium, releasing colossal amounts of energy. For decades, the dream on Earth has been to replicate that process, creating the ultimate, carbon-free energy source from water and a little lithium.
The trouble is that fusion is “really, really hard” to do, as Ian Chapman, the chief executive of the UK Atomic Energy Authority, forensically explained in a 2019 Royal Society lecture. Without the sun’s enormous gravitational force, nuclear reactor fuel has to be heated to 150m degrees Celsius (about 10 times as hot as the sun’s core) to overcome repulsion between charged particles. To prevent that superheated plasma from melting the reactor, it needs to be suspended by giant magnets. And that experiment is only ever worth running if it generates more energy than it consumes. Even if the technology can be proven at commercial scale, building enough fusion reactors — and quickly enough to make a difference to global warming — will require enormous sums.
Astonishingly, given the awe-inspiring nature of those challenges, scientists, governments and investors are growing increasingly excited that fusion reactors may begin powering our electricity grids as early as the next decade.