U.S. officials on Tuesday formally announced that government scientists at Lawrence Livermore National Laboratory’s National Ignition Facility had for the first time created a nuclear fusion reaction that produced more energy that it had consumed. Nuclear fusion is often called the “holy grail” of clean energy.

This fusion ignition is “one of the most impressive scientific feats of the 21st century,” Energy Secretary Jennifer Granholm said in Washington. “Ignition allows us to replicate for the first time certain conditions that are found only in the stars and the sun,” and “this milestone moves us one significant step closer” to having zero-carbon fusion energy “powering our society.”

To create nuclear fusion — essentially creating a miniature star by fusing two hydrogen atoms together to create helium and energy — the Lawrence Livermore scientists pointed 192 lasers at a small container holding a pellet of deuterium-tritium fuel smaller than a peppercorn. They fired 2.05 megajoules of energy at the capsule, and the reaction returned 3.15 megajouls, or about 1.5 times more energy. 

Astrophysicist Paul Sutter explained the process in greater detail on NBC News.

The Biden administration has an aspirational goal of a viable fusion power plant within a decade. But most scientists say commercial fusion power is decades away, at best, given the technical and logistical challenges of scaling up laboratory fusion and making it sufficiently cost- and energy-efficient. 

Kim Budil, director of the Livermore Lab, said “very significant hurdles” remain before nuclear fusion is ready for commercial use, but she now believes it’s just “a few decades” away, not 50 or 60 years, as previously expected. 

“The old joke among physicists is: Fusion is 20 years off, and it always will be,” PBS science correspondent Miles O’Brien noted on PBS NewsHour. Stephen Dean, president of Fusion Power Associates, said China, Britain, and the European Union are “way ahead” of the U.S., mostly using strong magnets to create fusion instead of lasers.

Steven Cowley, director of the Department of Energy’s Princeton Plasma Physics Laboratory, told The Washington Post he’s not sure if the magnetic fusion technique his lab uses or Lawrence Livermore’s laser fusion will win, but “fusion is so important we should have at least two technologies vying for completion. One of them is going to end up the airplane, and one of them is going to end up the Hindenburg.”

“Fusion is the most disruptive energy source we can ever make,” Dennis Whyte, director of the MIT Plasma Science & Fusion Center, told the Post. “The fuel is inexhaustible. It is inherently safe and provides on-demand energy that is adaptable to our needs. On paper, it can supply our energy demands forever. Not many things look like that in the energy landscape.”