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The Department of Energy announced Tuesday morning that Lawrence Livermore National Laboratory has produced a nuclear fusion reaction that creates a net energy gain.
“This is one of the most impressive scientific feats of the 21st century,” Secretary of Energy Jennifer Granholm said at a press conference. “Today we tell the world that America has achieved a major scientific breakthrough, one that happened because we invested in our research and our national labs.”
In an experiment last week, using a process called inertial confinement fusion, in which a pellet of hydrogen plasma is bombarded by the world’s biggest laser, researchers at the lab in Livermore, Calif., were able to produce more energy than they put into the laser, the first time this has ever been achieved.
Nuclear fusion is the reaction in which two light atomic nuclei combine to form a single heavier one and release massive amounts of energy — the same energy that is used in thermonuclear weapons. Harnessing it for civilian energy has been a goal of researchers in several countries for half a century or more.
“It's a scientific milestone, but it's also an engineering marvel beyond belief,” said Arati Prabhakar, policy director of the White House Office of Science and Technology.
Granholm and other officials noted the potential implications for combating climate change: that nuclear fusion could provide electricity that produces no greenhouse gases or the radioactive waste generated by existing nuclear reactors, which use fission, the splitting of atoms of uranium.
“This milestone moves us one significant step closer to the possibility of zero-carbon abundant energy powering our society,” Granholm said.
“We have taken the first tentative steps towards a clean energy source that could revolutionize the world,” said Jill Hruby, undersecretary of energy for nuclear security and administrator of the National Nuclear Security Administration.
They also readily conceded that being able to apply this technology to the power sector is a long way off. For one thing, the net energy gain does not include all the electricity that went into the larger project, quite apart from the specific energy input in the laser.
“We got out 3.15 megajoules; we input 2.05 megajoules in the laser,” said Mark Herrmann, the Livermore laboratory’s program director for weapon physics and design, in an expert panel discussion that followed the announcement. “That’s never been done before in any fusion laboratory anywhere in the world.”
But, he added, the output was about 1% of the electricity used.
“I want to be clear — ultimately this experiment drew about 300 megajoules from the grid,” Herrmann said. “The laser wasn’t designed to be efficient. This laser was designed to give us as much juice as possible to make these incredible conditions happen in the laboratory. There are many, many steps that would have to be made to get to inertial fusion as an energy source.”
In other words, massive increases in the efficiency of the process would be needed to make it effective as a source of energy. Other technological challenges remain. The National Academy of Engineering has noted that “building full-scale fusion-generating facilities will require engineering advances to meet all of these challenges, including better superconducting magnets and advanced vacuum systems."
In anticipation of Tuesday’s announcement, climate experts expressed excitement about the breakthrough, but many cautioned that using nuclear fusion to power the U.S. economy is a long way off, if it ever comes to fruition.
“We shouldn't kid ourselves: Fusion as a source of electricity is a really, really hard problem,” Matthew McKinzie, a nuclear physicist with the Natural Resources Defense Council, told Yahoo News on Monday.
When asked by a reporter on Tuesday about the timeline for deploying commercial-scale nuclear fusion, Livermore's director, Kim Budil, said it would take “probably decades” of additional research and development from both the public and private sectors.
“I don't want to give you a sense that we're going to plug the [National Ignition Facility] into the grid,” Budil said. “That's not how this works. But this is the first building block.”