The Nuclear Fusion Energy Breakthrough, Explained

Some of the world’s richest investors have piled into startups targeting one of the biggest and toughest challenges in science: nuclear fusion. Long seen as the ultimate prize in the quest for clean and abundant energy, fusion is the process that fuels the sun, where a crushing gravitational force smashes atoms together and unleashes their energy. In late 2022, researchers celebrated a long-sought scientific milestone, a sign of progress in a field full of vexing technological challenges and skepticism about near-term prospects.

1. What was the milestone?

In December 2022, scientists at the Lawrence Livermore National Laboratory in California focused the world’s most powerful laser on a peppercorn-size diamond capsule filled with hydrogen. The beams delivered 2.05 megajoules of energy, triggering a reaction that fused the hydrogen into helium and released 3.15 megajoules. The difference, a little more than a megajoule, is roughly the amount of energy released by a hand grenade. The result, known as “ignition” or net energy gain (meaning more energy out than in), was an accomplishment that scientists had been pursuing for decades. It suggested that the core physics of controlled fusion had been cracked, creating the possibility of a process to produce cheap, carbon-free electricity. After several unsuccessful attempts, the same lab was able to replicate the achievement in July.

2. How close is commercial fusion?

Even with the US and other governments pushing bold visions and various technologies, the most optimistic experts say we’re about a decade away from the first fusion power plant delivering electricity to the grid. Most peg it at 20 or 30 years from now. As the science advanced in recent years, fusion began to attract a new class of investors, and more private companies jumped into the race. Investment surged to $2.6 billion in 2021 from about $300 million in 2020. It fell back to $521 million in 2022.

3. What are the technologies?

Fusion research has benefited from advancements in supercomputing, 3D printing and superconducting magnets. There are different approaches:

• Inertial confinement: The December milestone proved that this method — shooting lasers at hydrogen-filled pellets — can work. But the reaction was exceptionally brief, not the kind of continuous process that power plants typically use. And for now, at least, those pellets are expensive and time-consuming to make.

• Magnetic confinement: The more widely used method employs powerful magnetic fields to contain plasma, an electrically charged superheated gas, so that it can sustain a fusion reaction. It requires temperatures far hotter than the sun, in the range of 150 million C (270 million F). Most efforts use a Soviet-era design known as a tokamak, which features a supercooled, donut-shaped chamber to hold the plasma, or a variant known as a stellarator.

• Other alternatives: Startups are pursuing hybrid technologies or their own unique ideas. One of the best-funded companies, California’s TAE Technologies, uses accelerators to suffuse plasma with high-energy particles, making it easier to manage.

4. What are the hurdles?

Fusion produces no high-level nuclear waste like the spent fuel rods from fission, the atom-splitting alternative form of atomic power that’s been used in commercial reactors since the 1950s and powered the original atomic bombs. Still, fusion research needs to surmount technical challenges such as how to develop materials that can withstand the bombardment of atomic particles within a machine. It’s also not clear how the energy produced will be harnessed and converted into electricity.

5. Who are the players?

There are three distinct groups: national initiatives, a pack of almost three dozen private startups and the 35-nation, $25 billion International Thermonuclear Experimental Reactor, or ITER. The international collaboration — the biggest research project in history — has been laboring on a gigantic demonstration machine in France since 2010. It’s a project on the scale of the space race, when the US and the former Soviet Union competed to build huge rockets. The most prominent backers of startups include Amazon founder Jeff Bezos, Microsoft founder Bill Gates and Palantir’s Peter Thiel. There’s a view that the push for fusion will generate scientific advances even if the core technology needs decades to pan out.

6. What would signal progress?

Magnetic confinement projects have yet to demonstrate net energy gain, and ITER’s tokamak won’t begin operations until 2025 at the earliest. Commonwealth Fusion Systems plans to fire up its own machine in Massachusetts in 2025.

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