The future of clean energy? How nuclear fusion works

The reaction fuses two molecules of hydrogen isotopes to generate energy.

ByStephanie Ebbs and Katrina Stapleton
December 16, 2022, 4:36 PM

The Department of Energy announced a scientific breakthrough in nuclear fusion this week, marking a major step toward developing a new, sustainable form of energy that releases virtually no carbon dioxide or other types of air pollution.

Here's a look at exactly how that reaction works according to the U.S. Department of Energy and the Lawrence Livermore National Laboratory:

Nuclear Fusion Explainer
ABC News Photo Illustration, Energy.gov, Lawrence Livermore National Laboratory

The reaction itself was done on Dec. 5 at the National Ignition Facility, the world's largest laser system at the Lawrence Livermore National Laboratory. Scientists at the lab successfully generated a fusion reaction between two hydrogen atoms and maintained that reaction in a controlled setting, marking the potential to use such reactions to generate huge amounts of energy without burning fuels.

Nuclear Fusion Explainer
ABC News Photo Illustration, Energy.gov, Lawrence Livermore National Laboratory

The experiment pointed 192 lasers at a container holding a small pellet of fuel the size of a peppercorn, specifically made up of deuterium and tritium – both isotopes of hydrogen.

Nuclear Fusion Explainer
ABC News Photo Illustration, Energy.gov, Lawrence Livermore National Laboratory

Those lasers generated 2.05 megajoules of energy within that container that hit the fuel pellet and ignited the reaction, briefly heating it to over 3 million degrees Celsius - creating the conditions of a star – and generating 3.15 megajoules of energy.

Nuclear Fusion Explainer
ABC News Photo Illustration, Energy.gov, Lawrence Livermore National Laboratory

That increase is why the experiment is being called such a success because by generating more energy than they put in it proves the potential that this kind of reaction could be a source of power someday, if they can scale it up and make it more efficient outside of a lab setting.

Nuclear Fusion Explainer
ABC News Photo Illustration, Energy.gov, Lawrence Livermore National Laboratory

The announcement could mark a major step in creating a form of energy that would not release the gases that are warming the planet and contributing to climate change, but is still decades away from being ready for large-scale application.