Historic Breakthrough: Five Questions for Understanding the New Advance in Clean Energy

The breakthrough in the merger investigation announced Tuesday in Washington was decades away. For the first time, scientists have managed to engineer a reaction that produces more energy than it takes to ignite it.

Using powerful lasers to focus enormous energy into a miniature capsule the size of half a pellet, scientists at California’s Lawrence Livermore National Laboratory have unleashed a reaction that it produced about 1.5 times more energy than that contained in the light used to produce it.

We will still have to wait decades before fusion can one day be used – perhaps – to produce electricity in the real world. But the the merger prospects are attractive. If mastered, it could produce nearly unlimited, carbon-free energy to meet humanity’s electricity needs without raising global temperatures or making climate change worse.

At the presentation press conference in Washington, the scientists celebrated the breakthrough.

“This is great,” said Marvin “Marv” Adams, deputy administrator for defense programs at the National Nuclear Security Administration.

“Pressure was applied to the fusion fuel in the pod and fusion reactions began. All of this had already happened -a hundred times before-, but last week they first designed this experiment so that the fusion fuel would stay hot enough, dense enough and round enough to ignite long enough,” Adams said.

“And it produced more energy than the lasers had deposited,” he explained.

Here’s a look at what exactly nuclear fusion is and some of the difficulties to make it the cheap, carbon-free energy source scientists hope it will be.

What is Nuclear Fusion?

nuclear fusion reactions supply energy to the sun and other stars.

The reaction occurs when two light nuclei fuse to form a single heavier nucleus. Since the total mass of that single nucleus is less than the mass of the two original nuclei, the the residual mass is energy released in the process, according to the Department of Energy.

In the case of the Sun, its intense heat – millions of degrees Celsius – and the pressure exerted by its gravity allow atoms to fuse that would otherwise repel each other.

Scientists have long known how nuclear fusion works and have been trying to reproduce the process on Earth since the 1930s.

Current efforts are focused on fusion of a pair of hydrogen isotopes — deuterium and tritium — according to the Department of Energy, which says this particular combination releases “much more energy than most fusion reactions,” and requires less heat to make.

What value can it have?

Daniel Kammen, professor of energy and society at the University of California at Berkeley, said that nuclear fusion offers the possibility of get “practically unlimited” fuel. if the technology becomes commercially viable. The necessary elements are available in sea water.

It’s also a process that doesn’t produce radioactive waste from nuclear fission, Kammen said.

Crossing the line of net energy increment constitutes a important result, said Carolyn Kuranz, a professor at the University of Michigan and an experimental plasma physicist.

“Obviously now people are thinking, well, how can we go ten times or a hundred times? There is always some next stepKuranz added. ‘But I think it’s a clear line that, yes, we’ve achieved ignition in the lab.’

How are scientists trying to do this?

One way scientists have tried to recreate nuclear fusion involves what’s called a tokamak: a donut-shaped vacuum chamber that uses powerful magnets to convert the fuel into a superheated plasma (between 150 million and 300 million degrees Celsius) where melting can occur.

The Livermore lab uses a different technique, in which researchers fire a 192-beam laser at a small capsule filled with deuterium-tritium fuel. The lab reported that a test conducted in August 2021 yielded 1.35 megajoules of fusion energy, about 70% of the energy fired at the target.

Experts added that several subsequent experiments have shown decreasing resultsbut they believed they had identified ways to improve the quality of the fuel pod and the symmetry of the lasers.

Why is fusion so difficult?

It takes more than extreme heat and pressure. Accuracy is also required. Laser energy must be applied precisely to counteract the external force of the fusion fuel, according to Stephanie Diem, a professor of engineering physics at the University of Wisconsin-Madison.

And that’s just to prove that net increase in energy is possible. It is even more difficult to produce electricity in a power plant.

For example, lasers in the laboratory may only run a few times a day. To feasibly produce energy, they would have to be fired rapidly and the capsules would have to be inserted several times a minute or even faster, Kuranz explained.

Another challenge is to increase efficiencyexplained Jeremy Chittenden, a professor at Imperial College London who specializes in plasma physics. The lasers used at Livermore need a lot of electricity and researchers need to find a way to reproduce the results in a much more cost-effective way, he said.

Translation: Elisa Carnelli