(Photo: National Nuclear Security Administration/Flickr)

There are 22 nuclear power reactors operating at five power plants in Canada. All of them, along with every single other nuclear power plant in the world, operates using a process called nuclear fission: breaking down the nucleus of a heavy atom like uranium or plutonium into lighter ones, and releasing a ton of energy in the process. But nuclear fusion — squashing together two or more atoms to form a new one — has been something of a holy grail for nuclear scientists, who've been trying to come up with a practical large-scale way of accomplishing the process since the 1950s.

Now a lab in the U.S. has passed a major hurdle in the race to harness the power of nuclear fusion, according to the BBC. For the first time in history, researchers have managed to release more energy from a fusion reaction than was absorbed by the fuel that's used in the process.

The National Ignition Facility, based in Livermore, California, employs the world's most powerful laser to jump-start their fusion reaction. Using 192 beams of light, they heat and compress a tiny pellet of hydrogen fuel until it's so hot that fusion reactions take place. Meanwhile in France, another research team announced earlier today that they were able to fuse a boron atom with a hydrogen nucleus using another very powerful laser and proton beams.

Despite these milestones, the BBC says, we're still well short of the dream of cheap, wide-scale nuclear fusion. For starters, the laser process used at the National Ignition Facility still takes a little more energy than it produces due to inefficiencies in the system. But it's still a major step forward in fulfilling the dream of cheap, abundant and low-waste energy that science fiction writers have been exploring for decades.

Via BBC