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US achieves first-ever self-sustaining nuclear fusion reaction

Scientists from Lawrence Livermore National Laboratory used the world’s largest laser to create a fusion reaction that mimicked those that power the sun and the stars.

By Evan Halper


Joel Achenbach


Federal scientists announced Tuesday that they have created the first nuclear fusion reaction that generated more energy than it took to produce, a major advancement in the worldwide quest for a new source of abundant, clean energy.

Their findings were released after days of buzz among physicists and clean-power executives about the pending announcement and its implications for the energy landscape. The announcement took place in Washington, where Energy Secretary Jennifer Granholm hailed them as a major “breakthrough.”

“This is a landmark achievement,” Granholm said. “This milestone will undoubtedly spark even more discovery. … This is what it looks like for America to lead.”

Scientists from Lawrence Livermore National Laboratory used the world’s largest laser to create a fusion reaction that mimicked those that power the sun and the stars.

The Energy Department proclaimed the experiment successful because at the point of compression, where multiple lasers converged, more energy came out than went in. The experiment delivered 2.05 megajoules of energy to the target and resulted in 3.15 megajoules of fusion energy output, officials said. Basically, two in, three out.

That, however, did not account for the energy it took to create the lasers in the first place — what could be called the wall-socket energy needed for the experiment. Kim Budil, director of the Lawrence Livermore laboratory, described that at the news conference: “300 megajoules at the wall, two megajoules at the laser.”

The Biden administration is aggressively pushing investment in clean energy technologies that are still years away from practical deployment. Scientists caution that while fusion energy holds potential to provide around-the-clock electricity without the pollution or radioactive risks of traditional coal, gas and nuclear power plants, it would be a decade or even decades before any of it is brought to the grid, if it ever is.

The reaction that scientists produced at the National Ignition Facility at the Livermore lab required the firing of a laser so large it is housed in a football stadium complex, and was built only after massive cost overruns and years of delays.

Generating electricity from nuclear fusion would require such a reaction, called “ignition,” every second throughout the day. Getting there would be a monumental engineering feat, as just producing a fraction of a second of net energy gain creates so much stress on the costly machinery that the process tends to break it.

The nation’s fusion program was initially created with the goal of more efficient management of the U.S. nuclear weapons stockpile. Fusion reactions could be used to test those arms without the need for explosions, which create radioactive fallout.

Commercial fusion energy has been a fringe pursuit for years, amid disappointing results in national laboratories and constant threats that the funding for fusion experiments would be canceled.

“We had some rocky times,” said Rep. Zoe Lofgren, a Bay Area Democrat who fought multiple efforts to defund the National Ignition Facility. “To see they have achieved ignition is fabulous. It is a profound breakthrough that brings an enticing promise that we could produce a nonpolluting, basically limitless source of energy.”

Whether that promise will ever be fulfilled is hotly debated among scientists.

The National Ignition Facility work is “not aimed at fusion energy production but at understanding fusion explosions,” said Ian Hutchinson, a professor of nuclear science and engineering at MIT. “Useful energy production from miniature fusion explosions still faces enormous engineering challenges, and we don’t know if those challenges can be overcome.”


By Evan Halper

Evan Halper is a business reporter for The Washington Post, covering the energy transition. His work focuses on the tensions between energy demands and decarbonizing the economy. He came to The Post from the Los Angeles Times, where he spent two decades, most recently covering domestic policy and presidential politics from its Washington bureau. Twitter

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By Joel Achenbach

Joel Achenbach covers science and politics for the National desk. He has been a staff writer for The Post since 1990. Twitter

Washington Post

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