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It was touted as a “major scientific breakthrough,” and apparently the rumors were true: On Tuesday, scientists at Lawrence Livermore National Laboratory announced that they had achieved the first net energy gain in a controlled fusion experiment.
“We’ve taken the first tentative steps towards a clean energy source that could revolutionize the world,” said Jill Hruby, director of the National Nuclear Security Administration, at a news conference on Tuesday.
The victory came courtesy of the National Ignition Facility at LLNL in San Francisco. This facility is trying to master nuclear fusion, a process that has long powered the sun and other stars to harness the enormous amount of energy released during the reaction because, as Hruby points out, all that energy is “clean.” energy.
However, despite decades of effort, these fusion experiments had one major snag: the amount of energy used to perform the fusion was much greater than the energy released. As part of the NIF mission, scientists have long hoped to achieve “ignition” where the energy output is “greater than or equal to the laser drive energy.”
Some experts were skeptical that even such an achievement was dubious. possible with fusion reactors currently in operation. But slowly, the NIF pushed forward. In August of last year, LLNL announced that it was approaching this threshold by producing about 1.3 megajoules (a measure of energy) versus a laser driver using 1.9 megajoules.
But LLNL’s scientists say they managed to cross the threshold on December 5.
They managed to fire.
All in all, this achievement is cause for celebration. It is the culmination of decades of scientific research and incremental progress. Demonstrating how this type of reactor works is a critical, albeit small, step. to be able toactually, generate energy.
“Achieving ignition in a controlled fusion experiment is an achievement after more than 60 years of global research, development, engineering and experimentation,” says Hruby. Said.
“This is a scientific milestone, but also an engineering marvel,” Arati Prabhakar, policy director for the White House Office of Science and Technology, said during the conference.
Still, a fully functional platform connected to the grid and used to power homes and businesses will likely be several decades away.
“It’s a pod that fires at the same time,” said LLNL director Kim Budil. “You have to do a lot of things to realize commercial fusion energy. You have to be able to generate many fusion ignition events per minute and you have to have a solid drive system to deliver it.”
So how did we get here? And what’s the future for fusion energy?
simulated stars
The physics underlying nuclear fusion has been well understood for almost a century.
Fusion is a reaction between the nuclei of atoms that occurs under extreme conditions, such as those found in stars. For example, about 75% of the sun is hydrogen, and these hydrogen atoms are squeezed together due to the heat and pressure that encompasses everything in its core, melting to form helium atoms.
If atoms had feelings, it would be easy to say that they didn’t particularly feel. like crushed together. Doing this takes a lot of energy. Stars are fusion powers; Gravity creates the perfect conditions for a self-sustaining fusion reaction, and they continue to burn until all their fuel – these atoms – is gone.
This idea forms the basis of fusion reactors.
Building a unit that can artificially recreate conditions inside the sun allows for an extremely green energy source. Fusion does not directly produce greenhouse gases such as carbon dioxide and methane that contribute to global warming.
And critically, a fusion reactor doesn’t have the disadvantages of nuclear power either. fission, fission of atoms used in nuclear bombs and reactors today.
In other words, a fusion power plant does not produce the radioactive waste associated with nuclear fission.
great fusion experiment
Taking up nearly three football fields in LLNL, NIF is the most powerful “inertial confinement fusion” experiment in the world.
In the center of the room is a target: a “hohlraum” or cylindrical device that houses a small capsule. The capsule, about the size of a peppercorn, is filled with isotopes of hydrogen, deuterium, and tritium, or DT fuel for short. NIF focuses all 192 lasers on the target, creating extreme heat that generates plasma and initiates an internal explosion. As a result, DT fuel is exposed to extreme temperatures and pressures by converting hydrogen isotopes into helium, and a result of the reaction is the release of a ton of extra energy and neutrons.
You can think of this experiment as simulating the conditions of a star.
The complicated part, though, is that the reaction requires a ton of energy to get started. More than 400 megajoules are needed to power the entire laser system used by NIF — but only a small percentage actually hit hohlraum with each firing of the beams. Previously, NIF was able to hit the target fairly consistently with about 2 megajoules from their laser.
But something changed during a study on December 5.
“Last week, for the first time, they designed this experiment so that fusion fuel stays hot enough, dense enough, and round enough for it to ignite long enough,” said Marv Adams, NNSA’s deputy executive director, during the conference. “And it produced more energy than the lasers could accumulate.”
More specifically, the scientists at NIF started a fusion reaction using about 3 megajoules of energy to power the lasers and were able to get about 2 megajoules out. According to the ignition definition used by the NIF, the benchmark was passed during this one short shot.
You can also see that the energy gain in the fusion reaction is represented by the variable Q.
Like ignition, the Q value can mean different things for different experiments. But here he means the energy coming out of the capsule versus the energy input from the lasers. If Q = 1, the scientists say they’ve reached the “breakeven” point, where the energy in is equal to the energy out.
For context, the Q of this run was around 1.5.
In the grand scheme of things, the energy created by this Q value is just enough to boil water in a kettle.
“The calculation of energy gain takes into account only the energy hitting the target, [very large] The energy consumption that goes into supporting infrastructure,” said Patrick Burr, a nuclear engineer at the University of New South Wales.
NIF isn’t the only facility chasing fusion, and inertial confinement isn’t the only way to start the process. “The more common approach is magnetically confined fusion,” said Richard Garrett, senior advisor for strategic projects at the Australian Nuclear Science and Technology Organization. These reactors use magnetic fields to control the fusion reaction in a gas, typically in a giant, hollow ring reactor known as a tokamak.
The density of these devices is much lower than NIF’s pellets, so temperatures need to be raised above 100 million degrees. Garrett said he doesn’t expect the NIF result to speed up tokamak fusion programs because basically the two processes work quite differently.
However, significant advances are also being made in magnetically confined fusion. For example, a tokamak is used in the ITER experiment under construction in France and is expected to begin testing in the next decade. They have lofty goals aimed at gaining a Q greater than: 10 and develop commercial fusion by 2050.
The future of fusion
The experiment at NIF may be transformative for research, but it will not immediately turn into a fusion energy revolution. This is not a power-generating experiment. This is a proof of concept.
This is particularly notable today, where fusion has been touted as a way to combat the climate crisis and reduce dependence on fossil fuels, or as an ointment to the world’s energy problems. Building and using fusion energy to power homes and businesses – conservatively for decades – and inherently tied to technological advances and investment in alternative energy sources is still a long way off.
When it is turned on, approximately 2.5 megajoules of energy is produced. Total Of course, it is not efficient if the input from the laser system is well above 400 megajoules. And as far as the NIF experiment was concerned, that was a short shot.
Looking further, continuous, reliable, long pulses will be required if this is to be sustainable enough to power water heaters, homes or entire cities.
“Fusion power … is unlikely to save us from climate change,” said physicist Ken Baldwin of the Australian National University. Fusion power will probably be a little late if we are to prevent the largest increases in global average temperature.
Other investments will come from private companies looking to operate tokamak fusion reactors over the next few years. For example, Tokamak Energy in the UK is building a global tokamak reactor and aims to reach breakeven point by the middle of this decade.
Then there’s Commonwealth Fusion Systems out of MIT, which hopes to generate around 400 megawatts of power to power tens of thousands of homes by the 2030s. Modern nuclear power plants can produce almost three times as much.
And as CNET editor Stephen Shankland points out in a recent article, fusion reactors will also need to compete against solar and wind power – so even despite today’s illuminating findings, fusion energy is well established in the experimental phase of existence.
But now we can turn our eyes to the future.
It may not prevent the worst of climate change, but when harnessed to its full potential, it can provide an almost unlimited source of energy for future generations. It’s one thing to think about the future of Earth’s energy and how it’s going to be used, but our eyes may wander even further into horizons – deep space travel could use fusion reactors that launch us far beyond our sun’s gravity. what helps teach us about fusion reactions and interstellar space.
Maybe then we would remember December 5, 2022 as the first small step towards places we once only dared to dream of.
