It is time to bet big on fusion energy

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.

The first phase of ITER, a vast $20bn experimental fusion reactor being built by a multinational government consortium in France, is due to become operational in 2025. At least 35 private fusion companies have also been launched, raising more than $2.3bn of funding, according to the Fusion Industry Association. Among them, US-based Helion this month raised $500m, backed by some prominent Silicon Valley investors.

Breakthrough Energy Ventures, a sustainable energy investment fund founded by former Microsoft boss Bill Gates, argues that recent technological advances mean fusion has ceased to be a theoretical scientific experiment and is rapidly becoming a practical commercial challenge. Just as transistors turned computers from an intellectual curiosity into a world-redefining industry, so small-scale tokamak reactors, one 50th the size of ITER, can revolutionise the energy industry.

“Fusion is a step change in the way humans get energy. In the history of humanity this might rank alongside the mastery of fire,” says Phil Larochelle, an expert at Breakthrough Energy Ventures. “We think it can be deployed ubiquitously across the world.”

One of the fusion companies backed by Breakthrough Energy Ventures is Commonwealth Fusion Systems, a Boston-based start-up spun out of the Massachusetts Institute of Technology that has raised $250m. In September, it announced that demonstrations of its high temperature superconducting electromagnet had opened the way to net power output. The company has already broken ground on an experimental reactor, due for completion in 2025. And, if that proves successful, it plans to build a fully commercial power plant early in the next decade.

Such reactors could be built on the same spot as existing power plants and plugged into the same grid. “It should be able to scale quickly. That is what the hope is for fusion,” says Bob Mumgaard, chief executive of CFS.

To power the entire US electricity grid, he estimates that 3,000 commercial fusion reactors would be needed, at a cost of more than $1tn. The industry has overcome its first big obstacle: the belief that fusion could never work on Earth, he says. The next big obstacle will be mobilising sufficient capital.

Some would argue that such vast sums of money would be better spent on proven technologies, such as wind and solar. The counterargument is that given the scale of the challenge, we have to throw everything at the problem. “We need the now and we need the new,” says John Doerr, chair of Kleiner Perkins, the venture capital firm that has been at the forefront of climate tech investment. “Deployment is a form of innovation. We have to execute at scale and speed”.

It is clear that several enormous bets have to pay out before we can dream of fusion energy powering the world. But given the faltering progress made at the environmental talks at COP26, it is surely time to increase those bets. Prof Chapman concluded his lecture by quoting Lev Artsimovich, the late Soviet physicist who helped invent the tokamak reactor. “Fusion will be ready when society needs it,” Artsimovich said. It is hard to argue that society does not need it now.

john.thornhill@ft.com