US Energy Secretary Jennifer Granholm on Tuesday announced a “major scientific breakthrough” in the decades-long search for harnessing fusion, the energy that powers the sun and stars.
For the first time, researchers at Lawrence Livermore National Laboratory in California have produced more energy in a fusion reaction than was used to ignite it, called a net energy gain, the Energy Department said.
That success will pave the way for advancements in national defense and a clean power future, Granholm and other officials said.
“This is a landmark achievement for the researchers and staff at the National Ignition Facility who have dedicated their careers to making fusion ignition a reality, and this milestone will undoubtedly spur even more discoveries,” Granholm said at a news conference in Washington.
The fusion breakthrough “will go down in the history books,” she said.
While there are different ways to try to produce nuclear fusion — the same process that powers our sun and other stars — the lab used 192 lasers aimed at the inner wall of a cylinder that contained a small BB-sized capsule.
This generated X-rays from the wall that hit the capsule and the fusion fuel in the capsule was squeezed out. This fusion fuel remained hot, dense, and round long enough to ignite and produce more energy than the lasers required.
While the energy produced was small—about three megajoules, or enough to power a light bulb—it represents a historic first in the field of nuclear fusion.
Proponents of fusion hope it could one day produce nearly unlimited carbon-free energy, displacing fossil fuels and other traditional energy sources. Energy production that powers homes and businesses from fusion is still decades away. But the researchers said it was still a significant step.
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“It’s almost like it’s a launch weapon,” said Professor Dennis Whyte, director of the Center for Plasma Fusion and Science at the Massachusetts Institute of Technology and a leader in fusion research. “We should push to make fusion energy systems available to address climate change and energy security.”
Fusion difficult to control
Net energy gain has been an elusive goal because fusion occurs at such high temperatures and pressures that it is incredibly difficult to control.
Fusion works by pushing hydrogen atoms together with such force that they combine into helium, releasing enormous amounts of energy and heat. Unlike other nuclear reactions, it does not produce radioactive waste.
Billions of dollars and decades of work have gone into fusion research, which has produced exciting results – in fractions of a second. Previously, researchers at the National Ignition Facility, Lawrence Livermore Division, where the breakthrough occurred, used 192 lasers and temperatures several times higher than the center of the sun to create an extremely short fusion reaction.
Lasers focus a huge amount of heat on a small metal can. The result is a superheated plasma environment where fusion can occur.
A “significant milestone” but years of work remain
Riccardo Betti, a professor at the University of Rochester and an expert on laser fusion, said announcing that clean energy had been obtained from the fusion reaction would be significant. But he said the result would be a long way from generating sustainable electricity.
He likened the breakthrough to when people first learned that refining crude oil into gasoline and igniting it could cause an explosion.
“You still don’t have the engine and you still don’t have the tires,” said Betti. “You can’t say you have a car.
The net energy gain referred to the fusion reaction itself, not the total amount of energy needed to run the lasers and run the project. For fusion to be viable, it will need to produce significantly more power and for longer.
It is incredibly difficult to master the physics of stars. Whyte said it was challenging to reach this point because the fuel must be hotter than the center of the sun. Fuel doesn’t want to stay hot – it wants to escape and cool. Maintaining that is an incredible challenge, he said.
According to Jeremy Chittenden, a professor at Imperial College London who specializes in plasma physics, the net energy gain at the California lab is not a big surprise because it has already made progress.
“That doesn’t change the fact that this is a significant milestone,” he said.
Progress in fusion research requires enormous resources and effort. One approach turns hydrogen into plasma, an electrically charged gas that is then controlled by huge magnets. The method is being researched in France in a collaboration between 35 countries called the International Thermonuclear Experimental Reactor, as well as researchers from the Massachusetts Institute of Technology and a private company.
Last year, teams working on these projects on two continents announced significant progress in the vital magnets needed for their work.
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