Fusion Breakthrough Raises Hopes for Clean Energy

For more than a decade, scientists have been pursuing fusion—the energy-producing nuclear reaction that powers the sun and other stars—as a source of clean energy. But for equally as long, they’ve faced a problem: Creating any fusion reaction has used more energy than it produces.

On Tuesday, however, researchers from the Lawrence Livermore National Laboratory (LLNL) in California announced that they have finally achieved the opposite result; they conducted the first experiment yielding more energy from a fusion reaction than the amount of energy put in.

“This milestone moves us one significant step closer to the possibility of zero-carbon abundant fusion energy powering our society,” U.S. Department of Energy Secretary Jennifer Granholm said during Tuesday’s announcement, per Matthew Daly, Michael Phillis, Jennifer McDermott and Maddie Burakoff of the Associated Press (AP).

“This is a monumental breakthrough,” Gilbert Collins, a physicist at the University of Rochester who formerly collaborated with LLNL but did not contribute to the new research, tells Science News’ James R. Riordon.

Fusion occurs when two atomic nuclei combine to form a new one. The resulting nucleus has less mass than the original two, because some of the mass is transformed into energy, per the New York Times’ Kenneth Chang.

At LLNL’s National Ignition Facility, lasers create heat and pressure that allows hydrogen isotopes to fuse, according to New Scientist’s Matthew Sparkes. In an experiment conducted December 5, the lasers blasted a tiny capsule made of diamond, causing it to vaporize in an instant. Within it were two frozen hydrogen isotopes, which fused together following the diamond’s obliteration. The lasers shot out 2.05 megajoules of light energy, and the resulting fusion produced around 3.15 megajoules of energy, per NPR’s Geoff Brumfiel.

The finding shows nuclear fusion’s potential as a power source, which would add another tool to our clean energy arsenal against climate change. But Tony Roulstone, a nuclear engineer at Cambridge University in England who was not involved in the new research, tells NPR that without a larger breakthrough, fusion will likely not be a major source of power production before the 2060s or 2070s. Scientists say we need to reach net zero emissions by 2050 to limit the worst effects of climate change.

Kimberly S. Budil, the director of LLNL, agrees that we are still a long way off from a fusion-powered future. “Probably, with concerted effort and investment, a few decades of research on the underlying technologies could put us in a position to build a power plant,” she said during Tuesday’s news conference, per the Times.

To produce the 2.05 megajoules of light that initiated the fusion reaction, the lasers needed more than 300 megajoules of power, Ryan McBride, a nuclear engineer at the University of Michigan, tells NPR. And though the experiment created more energy than those 2.05 megajoules, it was still a relatively small total. “It’s about what it takes to boil ten kettles of water,” Jeremy Chittenden, a plasma physicist at Imperial College London in England, tells CNN’s Ella Nilsen and René Marsh.

In order to produce a practical amount of energy, the lasers would need to blast thousands of beams of light per day, writes The Atlantic’s Charles Seife. But currently, the lasers can only shoot once in a span of several hours, as the equipment needs time to cool.

“At the moment, we’re spending a huge amount of time and money for every experiment we do,” Chittenden says to CNN.

Moreover, the facility used to carry out the experiment was the size of three football fields, and any future fusion power plant would need to be smaller and cheaper, writes the Times. To be practical, a plant would need to produce 30 to 100 times more energy than the laser inputs, but this experiment gained just 1.5 times as much, per the Times. All told, “we don’t really know what the power plant would look like,” Roulstone tells NPR.

But the breakthrough has laid the groundwork for future developments that could, ideally, solve some of these issues, scientists say. “We now have a laboratory system that we can use as a compass for how to make progress very rapidly,” Collins tells Science News.

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Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next.