But how big of a deal is “net energy gain” anyway – and what does it mean for the fusion power plants of the future? Here’s what you need to know.
It works through existing nuclear power plants fragmentation – splitting heavy atoms to create energy. During fission, a neutron collides with a heavy uranium atom, splitting it into lighter atoms and releasing a lot of heat and energy at the same time.
Fusion, on the other hand, works in the opposite way – it fuses two atoms (often two hydrogen atoms) together to form a new element (often helium)., just as stars create energy. In this process, the two hydrogen atoms lose a small amount of mass, which is converted into energy according to Einstein’s famous equation E=mc². Because the speed of light very, very fast — 300,000,000 meters per second — even a tiny amount of lost mass can result in a ton of energy.
What is a “net energy gain” and how did researchers achieve it?
Up until this point, researchers had been able to successfully combine two hydrogen atoms, but it always took more energy to carry out the reaction than to return it. Net energy gain—where they get back more energy than they use to create a reaction—has been the unlikely holy grail of fusion research.
Now, researchers at the National Ignition Facility at Lawrence Livermore National Laboratory in California are expected to announce a net energy gain by firing lasers at hydrogen atoms. 192 laser beams compress hydrogen atoms to about 100 times the density of lead and heat them to about 100 million degrees Celsius. The high density and temperature cause atoms to fuse into helium.
Other methods being explored include using magnets to confine the super-hot plasma.
“If it’s what we expect, it’s like a Kitty Hawk moment for the Wright brothers,” said Melanie Windridge, CEO of Plasma Physics and Fusion Energy Insights. “It’s like a plane taking off.”
Does this indicate that the fusion energy is ready for prime time?
No. The scientists call the current achievement “scientific net energy gain,” meaning that more energy came out of the reaction than the laser put in. This is a huge milestone that has never been achieved before.
But this is only a net energy gain at the micro level. According to Troy Carter, a plasma physicist at the University of California, Los Angeles, the lasers used at the Livermore lab are only 1 percent efficient. This means that lasers need about 100 times more energy to fire than they can deliver to hydrogen atoms.
So researchers will still have to arrive at an “engineering net energy gain,” or the point at which the entire process takes in less energy than is produced by the reaction. They will also need to figure out how to convert the extracted energy—currently in the form of kinetic energy from helium nuclei and neutrons—into a form that can be used for electricity. They could do this by converting it to heat, then heating the steam, turning a turbine and running a generator. This process also has efficiency limitations.
All of this means that the energy gains would need to be much, much higher for fusion to be truly commercially viable.
Currently, researchers can only perform one fusion reaction per day. In between, they must let the lasers cool down and replace the fusion fuel target. A commercially viable plant should be able to do this several times per secondsays Dennis White, director of the Center for Plasma Science and Fusion at MIT. “Once you have scientific viability,” he said, “you have to understand engineering viability.”
What are the benefits of fusion?
The possibilities of fusion are great. The technology is much, much safer than nuclear fragmentation, because the compound cannot produce runaway reactions. It also produces no radioactive byproducts or harmful carbon emissions that need to be stored; it simply produces inert helium and neutrons. No chance of running out of fuel: The fuel for fusion is simply the heavy hydrogen atoms found in seawater.
When can Fusion actually power our homes?
That’s the trillion dollar question. For decades, scientists joked that fusion was always 30 or 40 years away; Over the years, researchers have variously predicted that fusion plants will be operational in the 1990s, 2000s, 2010s, and 2020s. Current fusion experts argue that it’s not a matter of time, but of will—if governments and private donors aggressively finance fusion, they say, a prototype fusion power plant could be in place by the 2030s.
“The timeline isn’t really a matter of time,” Carter said. “It’s a matter of innovation and effort.”