Overview

A lab has successfully sparked a fusion reaction that released more energy than went into it. The experiment crossed a long-awaited milestone in reproducing the power of the Sun in a laboratory; however, there are some significant obstacles that scientists still need to overcome.

The science and other stuff to know

Scientists have for decades talked about how fusion, the nuclear reaction that powers the stars, could generate bountiful clean energy here on Earth. And since the 1940s, researchers from all over the globe have been trying to harness this power, the toughest physics challenges ever conceived, without much success, until now.

Scientists at the National Ignition Facility (NIF), a part of Lawrence Livermore National Laboratory in California, have announced that they managed to control a fusion reaction that produced more energy than it took to start the reaction.

In the experiment, researchers fired 2.05 megajoules of laser light at a tiny cylinder holding a pellet of frozen deuterium and tritium, the heavier forms of hydrogen. The pellet then compressed and generated temperatures and pressures intense enough to cause the hydrogen to fuse.

In a brief moment lasting less than 100 trillionths of a second, the fusing atomic nuclei released about 3.15 megajoules of fusion energy. This was approximately 50 percent more energy than had been used to heat the pellet.

So what?

The achievement raises hopes for the development of clean fusion energy in the future.

“This is a momentous result in this quest, arguably one of the most important steps forward ever taken. For the first time, we have evidence of a fusion reaction producing a sizable amount of excess energy,” Gianluca Sarri, a physics professor at Queen’s University Belfast who was not involved in the experiment, told Live Science. “So far, there were questions and doubts even on the feasibility of a proof-of-principle experiment of this kind. These have now been dissipated, injecting so much optimism and energy to push this forward and solve the technical issues still remaining.”

Fusion energy would be essentially an emissions-free power source, and it would help reduce the need for power plants using fossil fuels, which pump billions of tons of planet-warming carbon dioxide into the atmosphere every year.

What’s next?

This groundbreaking achievement, however, doesn’t mean fusion is now a viable power source. While NIF’s reaction produced more energy than the reactor used to heat the atomic nuclei, it did not generate more than the reactor’s total energy use. The lasers required 300 megajoules of energy to produce about 2 megajoules’ worth of beam energy.

“The net energy gain is with respect to the energy in the light that was shined on the target, not with respect to the energy that went into making that light,” said University of Rochester physicist Riccardo Betti, who also wasn’t involved with the research. “Now it’s up to the scientists and engineers to see if we can turn these physics principles into useful energy.”