CNN –
For the first time, US scientists at the National Ignition Facility at the Lawrence Livermore National Laboratory in California have successfully produced a nuclear fusion reaction that resulted in a net energy gain, a source familiar with the matter confirmed to CNN project
The US Department of Energy is expected to officially announce the breakthrough on Tuesday.
The result of the experiment would be a massive step in a decades-long quest to unlock an infinite source of clean energy that could help end dependence on fossil fuels. Researchers have for decades tried to recreate nuclear fusion, replicating the fusion that powers the sun.
U.S. Energy Secretary Jennifer Granholm will make an announcement Tuesday about a “major scientific breakthrough,” the department announced Sunday. The development was first reported by the Financial Times.
Nuclear fusion occurs when two or more atoms fuse into one larger one, a process that generates a massive amount of energy in the form of heat. Unlike the nuclear fission that powers electricity around the world, it does not generate long-lived radioactive waste.
Scientists all over the world have been making progress towards the breakthrough, using different methods to try to achieve the same goal.
The National Ignition Facility project creates energy from nuclear fusion using what is known as “thermonuclear inertial fusion.” In practice, American scientists fire pellets containing a hydrogen fuel into an array of nearly 200 lasers, essentially creating a series of repeated, extremely rapid explosions at a rate of 50 times per second.
The energy collected from neutrons and alpha particles is extracted as heat, and this heat is the key to producing energy.
“They contain the fusion reaction by bombarding the outside with lasers,” Tony Roulstone, a fusion expert at the University of Cambridge’s Department of Engineering, told CNN. “They heat the outside; that creates a shock wave.”
While getting a net energy gain from nuclear fusion is huge, it’s happening on a much smaller scale than what’s needed to power power grids and heat buildings.
“It’s about what it takes to boil 10 kettles of water,” said Jeremy Chittenden, co-director of the Center for Inertial Fusion Studies at Imperial College London. “To make it a power plant, we need to get a higher energy gain; we need it to be substantially more.”
In the UK, scientists are working with a huge donut-shaped machine equipped with giant magnets called a tokamak to try to generate the same result.
After a small amount of fuel is injected into the tokamak, giant magnets are activated to create a plasma. The plasma must reach at least 150 million degrees Celsius, 10 times hotter than the core of the sun. This forces the fuel particles to coalesce into one. With nuclear fusion, the fused product has less mass than the original atoms. The missing mass becomes an enormous amount of energy.
The neutrons, which are able to escape from the plasma, collide with a “blanket” lining 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.
Last year, scientists working near Oxford were able to generate a record amount of sustained energy. It only lasted 5 seconds though.
Whether using magnets or shooting pellets with lasers, the result is the same: the sustained heat from the process of fusing atoms is the key to helping produce energy.
The big challenge in harnessing fusion energy is keeping it around long enough for it to power power grids and heating systems around the world.
Chittenden and Roulstone told CNN that scientists around the world must now work to dramatically scale up their fusion projects while also reducing the cost. Making it commercially viable will require years of further research.
“Right now we’re spending a lot of time and money on every experiment we do,” Chittenden said. “We have to reduce the cost by a huge factor.”
However, Chittenden called this new chapter in nuclear fusion “a real breakthrough moment that is tremendously exciting.”
Roulstone said there are many signs that more work needs to be done before fusion can generate electricity on a commercial scale.
“The counterargument is that this result is miles away from the actual energy gain needed for electricity production,” he said. “So we can say (that) it’s a success for science, but a long way from providing useful energy.”