Why fusion could be a clean energy breakthrough

The major advances in fusion research announced Tuesday in Washington would be decades away, with scientists for the first time able to engineer a reaction that produced more force than was used to ignite it.

Using powerful lasers to focus massive energy on a BB-sized miniature capsule, scientists at Lawrence Livermore National Laboratory in California started a reaction that produced about 1.5 times more energy than the light used to produce it. .

There are still decades to wait before fusion can one day – perhaps – be used to produce electricity in the real world. But the promise of fusion is enticing. If harnessed, it could produce nearly unlimited, carbon-free energy to meet humanity’s electricity needs without raising global temperatures and exacerbating climate change.

At the press conference in Washington, the scientists celebrated.

“So this is pretty cool,” said Marvin “Marv” Adams, the National Nuclear Security Administration’s deputy administrator for defense programs.

“Fusion fuel was pressed into the capsule, fusion reactions started. All this had happened before — 100 times before — but last week, for the first time, they designed this experiment so that the fusion fuel stays hot enough, dense enough and round enough long enough to ignite,” Adams said. “And it produced more energy than the lasers had deposited.”

Here’s a look at exactly what nuclear fusion is, and some of the difficulties of converting it into the low-cost and carbon-free source of energy that scientists hope it can be.


Look up and it’s happening right above you – nuclear fusion reactions power the sun and other stars.

The reaction takes place when two light nuclei fuse into a single heavier nucleus. Because the total mass of that single nucleus is less than the mass of the two original nuclei, the remaining mass is energy released in the process, according to the Department of Energy.

In the case of the sun, the intense heat — millions of degrees Celsius — and the pressure exerted by gravity cause atoms that would otherwise repel each other to fuse together.

Scientists have long understood how nuclear fusion works and have tried to replicate the process on Earth as far back as the 1930s. Current efforts focus on fusing a pair of hydrogen isotopes — deuterium and tritium — according to the Department of Energy, which says a particular combination releases “much more energy than most fusion reactions” and requires less heat to do so.


Daniel Kammen, a professor of energy and society at the University of California at Berkeley, said nuclear fusion offers the possibility of “basically unlimited” fuel if the technology can be made commercially viable. The necessary elements are available in seawater.

It’s also a process that doesn’t produce the radioactive waste of nuclear fission, Kammen said.

Breaking the net energy gain mark is a major achievement, said Carolyn Kuranz, a University of Michigan professor and experimental plasma physicist.

“Of course now people think, well, how do we go to 10 times more or 100 times more? There’s always a next step,’ Kuranz said. “But I think that’s a clear line of, yes, we achieved inflammation in the lab.”


One way scientists have tried to replicate nuclear fusion is a so-called tokamak – a doughnut-shaped vacuum chamber that uses powerful magnets to convert fuel into a superheated plasma (between 150 million and 300 million degrees Celsius) where fusion can take place.

The Livermore lab uses a different technique, in which researchers fire a 192-beam laser at a small capsule filled with deuterium-tritium fuel. The lab reported that a test in August 2021 yielded 1.35 megajoules of fusion energy – about 70% of the energy fired at the target. The lab said several subsequent experiments showed diminishing results, but researchers thought they had found ways to improve the quality of the fuel capsule and the symmetry of the lasers.


It takes more than extreme heat and pressure. It also takes precision. The lasers’ energy must be precisely applied to counteract the outward force of the fusion fuel, according to Stephanie Diem, a professor of engineering physics at the University of Wisconsin-Madison.

And that’s just to prove that net energy gains are possible. It is even more difficult to generate electricity in a power plant.

For example, the lab’s lasers can only fire a few times a day. To produce viable energy, they would have to fire rapidly and insert capsules several times per minute, or even faster, Kuranz said.

Another challenge is to increase efficiency, said Jeremy Chittenden, a professor at Imperial College London who specializes in plasma physics. The lasers used at Livermore require a lot of electrical energy, and researchers need to find a way to reproduce their results in a much more cost-effective way, he said.


Associated Press reporter Maddie Burakoff contributed to this report.


The Associated Press’ climate and environmental coverage is supported by several private foundations. Read more about AP’s climate initiative here. The AP is solely responsible for all content.

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