The US Department of Energy announced Tuesday that scientists at a national lab — for the first time ever — have generated more energy from nuclear fusion than the process took to start.
Fusion, which powers stars like our sun, has the potential to create a massive amount of energy with precious little pollution, making it the holy grail of clean energy production.
“This is an announcement that has been decades in the making,” the DOE said in a statement on Twitter.
The agency said scientists at the Lawrence Livermore National Laboratory in California had made a significant leap in fusion research, generating a net gain in energy for the first time on Dec. 5.
“We have taken the first, tentative steps toward a clean energy source that could revolutionize the world,” said Jill Hruby, the DOE’s Under Secretary for Nuclear Security
“This is what it looks like for America to lead,” said Energy Secretary Jennifer Granholm. “And we’re just getting started.”
The lab — which is primarily tasked with nuclear weapons research — conducts fusion experiments in order to maintain and develop the US thermonuclear arsenal without the need for test detonations.
But that research also allows scientists to push the envelope in creating fusion energy.
In contrast to nuclear fission — the process of splitting atoms used in nuclear power plants and atomic bombs — fusion has radically less radioactive waste and no propensity for the kind of runaway chain reaction that leads to a fission meltdown.
But while scientists have created energy through fusion in the past — and fusion reactions play a role in the detonation of thermonuclear weapons — never before have the reactions generated more energy than they required to get started.
Nuclear fusion occurs when the nuclei of two atoms fuse together to create a larger atom, giving off massive amounts of energy in the process. It requires extreme heat — over 180 million degrees Fahrenheit — which has previously necessitated even more energy than the fusion process then creates.
Getting more energy out of the process than it creates, and doing so continuously, would make it self-sustaining.
Current nuclear fusion reactors typically use one of two methods to generate the kind of heat required: Magnetic confinement reactors use magnets in addition to ancillary heat sources to heat up and contain the hydrogen, while laser-based systems like the one at Lawrence Livermore hit the hydrogen with massive pulses of laser light.
Paz-Soldan, whose research has been conducted primarily with magnetic reactors, said the two differ most practically in how long the fusion reaction occurs.
While laser-based reactors have seemingly crossed the threshold into net-energy-gain territory, when lasers are used, “the fusion is happening in a small period of time,” Paz-Soldan said.
Magnetic reactors, in contrast, keep the fusion process going for longer, but require more energy and have yet to make more energy than they use.
The laser-based system at Lawrence Livermore, known as the National Ignition Facility, is the most powerful such system to date, focusing 192 beams on a given target. Its lasers are not capable of constantly firing — a prerequisite for scaling fusion reactors up into commercial power plants.
Scientists at the facility said Tuesday that they’d created 3.15 megajoules of energy from a 2.05 megajoule laser pulse. But that laser had taken some 300 megajoules of power to operate.
“There are very significant hurdles, not just in the science but in the technology. This is one ignition, one time,” said Dr. Kim Budil, the director of Lawrence Livermore National Lab.
In order to build a fusion power plant, she said, “You have to be able to produce many, many fusion events per minute.”
“The laser wasn’t designed to be efficient,” Mark Hermann, the lab’s deputy director for weapons physics said.
Budil said she estimated it could take several decades to design and build a viable power plant based on the success of the experiment, but that the timeline could be shorter if more resources were put into developing more efficient technologies.
Granholm and others said Tuesday that the White House has called for the creation of a viable fusion reactor within ten years’ time.
“If we want to get serious about [laser reactors] we need to invest in those technologies,” Tammy Ma, a plasma physicist at the lab, said in a technical panel after the announcement.
Closer to home, Carlos Paz-Soldan, a professor of applied physics at Columbia University, told The Post the experiment was “a significant milestone.”
“It shows that such a thing is physically possible,” he said.
Paz-Soldan, whose research has been conducted primarily with magnetic fusion reactors — not the laser-based system found at Lawrence Livermore — said the two differ most practically in how long the fusion reaction occurs.
While laser-based reactors have now crossed the threshold into net-energy-gain territory, when lasers are used, “the fusion is happening in a small period of time,” Paz-Soldan said.
Magnetic reactors, in contrast, keep the fusion process going for longer, but require more energy and have yet to make more energy than they use.
Private money has started to be invested in fusion power experiments — particularly with magnetic reactors. Backers say commercializing fusion could happen in a decade or more, generating virtually carbon-free electricity that could help fight climate change.
The value of fusion is in its cleanliness and relative safety. Using hydrogen as a fuel means its fusion byproduct is the relatively benign element helium. And unlike nuclear fission, there’s no chain reaction to lose control of, Paz-Soldan said.
“It’s not really the kind of reaction that runs away from you — we’ve been trying so hard just to get it started,” he said.
The panel at Lawrence Livermore said Tuesday that they hoped last week’s success would help move fusion forward, regardless of the method of ignition.
“Right now, fusion is so impactful and important for humankind that what we really want to do is maximize the potential pathways for success,” Ma said.
