According to news reports from National Geographic and The MVEye, a U.S. lab has successfully sparked a fusion reaction that released more energy than went into it. For more than 60 years, scientists have pursued one of the toughest physics challenges ever conceived: harnessing nuclear fusion, the power source of the stars, to generate abundant clean energy here on Earth. Today, researchers announced a milestone in this effort. For the first time, a fusion reactor has produced more energy than was used to trigger the reaction.

On December 5, an array of lasers at the National Ignition Facility (NIF), part of the Lawrence Livermore National Laboratory in California, fired 2.05 megajoules of energy at a tiny cylinder holding a pellet of frozen deuterium and tritium, heavier forms of hydrogen. The pellet compressed and generated temperatures and pressures intense enough to cause the hydrogen inside it to fuse. In a tiny blaze lasting less than a billionth of a second, the fusing atomic nuclei released 3.15 megajoules of energy—about 50 percent more than had been used to heat the pellet.

Though the conflagration ended in an instant, its significance will endure. Fusion researchers have long sought to achieve net energy gain, which is called scientific breakeven. “Simply put, this is one of the most impressive scientific feats of the 21st century,” U.S. Energy Secretary Jennifer Granholm said at a Washington, D.C. media briefing.

In reaching scientific breakeven, NIF has shown that it can achieve “ignition”: a state of matter that can readily sustain a fusion reaction. Being able to study the conditions of ignition in detail will be “a game-changer for the entire field of thermonuclear fusion,” says Johan Frenje, an MIT plasma physicist whose laboratory contributed to NIF’s record-breaking run.

The achievement does not mean that fusion is now a viable power source. While NIF’s reaction produced more energy than the reactor used to heat up the atomic nuclei, it didn’t generate more than the reactor’s total energy use. According to Kim Budil, director of Lawrence Livermore National Laboratory, the lasers required 300 megajoules of energy to produce about 2 megajoules’ worth of beam energy. “I don’t want to give you the sense that we’re going to plug the NIF into the grid—that’s not how this works,” Budil added. “It’s a fundamental building block.”

Even so, after decades of trying, scientists have taken a major step toward fusion power. “It looks like science fiction, but they did it, and it’s fantastic what they’ve done,” says Ambrogio Fasoli, a fusion physicist at the Swiss Federal Institute of Technology in Lausanne.

The dream of a fusion power plant

For all of NIF’s success, commercializing this style of fusion reactor wouldn’t be easy. Betti, the University of Rochester physicist, says that such a reactor would need to generate 50 to 100 times more energy than its lasers emit to cover its own energy use and put power into the grid. It’d also have to vaporize 10 capsules a second, every second, for long periods of time. Right now, fuel capsules are extremely expensive to make, and they rely on tritium, a short-lived radioactive isotope of hydrogen that future reactors would have to make on-site.

But most of these challenges aren’t unique to NIF, and the world’s many fusion labs and companies are chipping away at them. Last year the Joint European Torus (JET), an experimental reactor in Culham, England, set a record for the most fusion energy ever released during a single experimental run. Construction on JET’s successor—a huge international experiment known as ITER—is underway in France. And private companies in the United States and United Kingdom have built next-generation superconducting magnets, which could help create smaller, more powerful kinds of reactors.

It’s hard to say when, or even if, this work will yield a new energy future. But fusion researchers see the technology as an incredible tool for humankind whenever it’s ready—whether that’s 20, 50, or 100 years from now.

“When people say fusion is very complex, it’s true, but when people say that fusion is too complex, it’s not,” Fasoli says. “We know how to do complex things … Going to the moon is not simple. Achieving this result in fusion, it’s not simple. And we’ve demonstrated we can do it.”

News and image sourced from nationalgeographic.com and photography credited to Damien Jemison, Lawrence Livermore National Laboratory. The fusion record was achieved at the National Ignition Facility at California's Lawrence Livermore National Laboratory, which ignites fusion fuel with an array of 192 lasers. These lasers reach high energies thanks in part to devices called preamplifiers (seen in the image).