U.S. scientists reportedly have carried out the first nuclear fusion experiment to achieve a net energy gain. The Department of Energy (DOE) is expected to announce the breakthrough on Dec. 13, according to news reports late Sunday.

The nuclear power industry has pursued fusion technology for decades, with a renewed emphasis for those efforts in recent years as scientists have turned their attention to finding a zero-emission renewable energy source to replace fossil fuels. (Editor’s note: Click here to read the story of the official announcement.)

Industry experts have chased the promise of fusion since the 1950s, with research to replicate the nuclear reaction that creates energy on the sun. Fusion has been called the “holy grail” of energy, with billions of dollars spent worldwide by both governments and private enterprise to manufacture fusion equipment that could provide unlimited electricity with no carbon footprint.

A senior fusion scientist said to be familiar with the work at the Lawrence Livermore National Laboratory in California—where the milestone was reached—told The Washington Post: “To most of us, this was only a matter of time.”

The laboratory on Sunday did confirm that a successful experiment had recently occurred at its National Ignition Facility, saying in a statement, “Initial diagnostic data suggests another successful experiment at the National Ignition Facility. However, the exact yield is still being determined and we can’t confirm that it is over the threshold at this time. That analysis is in process, so publishing the information . . . before that process is complete would be inaccurate.”

Tuesday’s announcement likely will note that commercial use of fusion energy is probably still years away. U.S. and Biden administration officials, though, are expected to promote the news as positive for the government’s investment in research for new nuclear power technology.

Energy Secretary Set to Make Announcement

The news of a net energy gain from fusion was first reported Dec. 11 by the Financial Times, and then confirmed to other media by two people familiar with the research, who did not want to be named ahead of Tuesday’s official announcement. Energy Secretary Jennifer Granholm is expected to make the announcement at an event that has been billed as the unveiling of “a major scientific breakthrough.”

Nuclear fusion relies on smashing two atoms together at incredibly high speeds. The energy that comes from that process is transformed into electricity. It emits no carbon, and does not produce nuclear waste. Until now, researchers conducting fusion experiments have been unable to create a process that does not consume more energy than it produces.

Want to learn more about fusion technology? Check out this edition of The POWER Podcast, “Could Fusion Energy Transform the Power Industry By 2035?” Also read this POWER Interview with a leading researcher in the field and “Fusion Energy Is Coming, and Maybe Sooner Than You Think,” which touches on fusion basics, and goes into greater detail on other research that’s being done and some of the challenges to commercialization of fusion technology.

An official at the California lab said researchers continue to work on their analysis, and would not release any official information prior to Tuesday. The Financial Times reported that people with knowledge of the experiment said the fusion reaction produced about 2.5 megajoules of energy, an amount that was about 120% of the 2.1 megajoules of energy in the lasers.

The National Ignition Facility originally was designed primarily for testing of nuclear weapons through simulations, before being used for research into fusion energy. The facility last year became the closest in the world to reaching a net energy gain from fusion, producing 1.37 megajoules from a reaction, which the lab said was about 70% of the energy in the lasers on that occasion.

The National Ignition Facility at the Lawrence Livermore lab in California, which includes the target chamber shown here, is about the size of three football fields. Source: Lawrence Livermore National Laboratory

The challenge of commercializing fusion includes developing machinery that could affordably turn the fusion reaction into power that could be deployed to the grid. Scientists have said that building equipment large enough to create fusion power at scale requires materials that are difficult to produce. In addition, the fusion reaction creates neutrons that significantly stress equipment, and could potentially destroy that equipment.

The Biden administration, including Granholm and the DOE, have made nuclear power in general and research into fusion energy in particular a priority in their efforts to produce cleaner energy and combat climate change. Funding for nuclear power research is a major part of the Inflation Reduction Act signed by President Biden this summer.

— Darrell Proctor is a senior associate editor for POWER (@POWERmagazine).