The experiment did not generate more energy than the lasers supplied – a threshold known as “ignition” – but did result in the release of more energy than was absorbed by the fuel, BBC News reported.

The experiment is described as the most important achievement in recent years in the drive for nuclear fusion, according to the report, a process touted as having the potential to provide almost limitless supplies of clean, safe and sustainable energy without the downsides of nuclear power produced by fission.

Today’s nuclear power plants produce energy by splitting apart the heavy atoms of uranium fuel – fission – while fusion reactors fuse together atoms.

Unlike nuclear-fission power plants, fusion reactors do not produce high-level radioactive waste.

The initiative is being led by the US Department of Energy’s Lawrence Livermore National Laboratory and includes partners from the University of Rochester’s Laboratory for Laser Energetics, General Atomics, Los Alamos National Laboratory, Sandia National Laboratory, and the Massachusetts Institute of Technology.

The report of the success comes on the heels of a review article in the US scientific journal Physics of Plasmas explaining that the project is bringing nuclear fusion closer to reality.

One major hurdle on the path to that goal is “the premature breaking apart of the capsule” containing two hydrogen isotopes, John Edwards, NIF associate director for inertial confinement fusion and high-energy-density science, said in a press release last month.

The energy from the lasers implodes the capsule “to temperatures and pressures similar to those found at the center of the sun,” according to the press release.