(CNN) — For the first time in history, US scientists at the Lawrence Livermore National Laboratory’s National Ignition Facility in California have successfully produced a nuclear fusion reaction that has resulted in a net gain of energy, a source confirmed to CNN. familiar with the project.
The result of the experiment would be a giant step forward in the decades-long search for an infinite source of clean energy that could help end reliance on fossil fuels. Researchers have spent decades trying to recreate nuclear fusion, that is, reproduce the fusion that powers the Sun.
US Energy Secretary Jennifer Granholm will announce a “significant scientific breakthrough” on Tuesday, the Department announced Sunday.
Nuclear fusion occurs when two or more atoms fuse into a larger one, a process that generates an enormous amount of energy in the form of heat.
Scientists around the world have been working toward a breakthrough for decades, using different methods to try to achieve the same goal.
The NIF project creates energy from nuclear fusion through what is known as “inertial thermonuclear fusion.” In practice, US scientists fire pellets containing a hydrogen fuel into an array of nearly 200 lasers, essentially creating a series of extremely fast explosions repeated at a rate of 50 times per second.
The energy collected from neutrons and alpha particles is extracted as heat, and that heat is the key to producing energy.
“They contain the fusion reaction by bombarding the outside with lasers,” Tony Roulstone, a fusion expert at Cambridge University’s Department of Engineering, told CNN. “They heat up the outside; that creates a shock wave.”
While getting a net energy gain from nuclear fusion is a big thing, it’s happening on a much smaller scale than it takes to power electrical grids and heat buildings.
“It’s about what it takes to boil 10 kettles of water,” explains Jeremy Chittenden, co-director of the Center for the Study of Inertial Fusion at Imperial College London. “To turn that into a power plant, we need a higher energy gain – we need it to be substantially higher.”
In February, British scientists announced that they had more than doubled the previous record for generating and sustaining nuclear fusion.
In a huge donut-shaped machine called a tokamak, fitted with giant magnets, scientists working near Oxford managed to generate a record amount of sustained power. Even so, it only lasted 5 seconds.
The heat sustained by the process of fusing atoms is the key to helping produce energy.
As CNN reported earlier this year, the fusion process creates helium and neutrons, which are lighter in mass than the parts they’re originally made of.
The missing mass is then converted into an enormous amount of energy. The neutrons, which are able to escape from the plasma, strike a “blanket” that covers the walls of the tokamak, and their kinetic energy is transferred as heat. This heat can be used to heat water, create steam, and power turbines to generate power.
All this requires that the machine that generates the reaction be very hot. The plasma has to reach at least 150 million degrees Celsius, 10 times hotter than the core of the sun.
The big challenge in harnessing fusion power is sustaining it long enough to power electrical grids and heating systems around the world.