But how big is the “net energy gain” anyway – and what does it mean for the fusion power plants of the future? Here’s what you need to know.
Existing nuclear power plants are working through fission — Breaking down heavy atoms to produce energy. In fission, a neutron collides with a heavy uranium atom, splitting it into lighter atoms while releasing a lot of heat and energy.
Fusion, on the other hand, works the other way around — it involves fusing two atoms (often two atoms of hydrogen) together to create a new element (often helium)., in the same way that stars generate energy. In the process, the two hydrogen atoms lose some mass, which is converted into energy according to Einstein’s famous equation E=mc². Because the speed of light is very, very fast – 300,000,000 meters per second – even a tiny loss of mass can result in a ton of energy.
What is “net energy gain” and how did researchers achieve it?
Up to this point, researchers have been able to successfully fuse two hydrogen atoms together, but the reaction has always cost more energy than they get back. The net energy gain – where they get more energy back than they expended in the reaction – has been the elusive holy grail of fusion research.
Now researchers at the National Ignition Facility at the Lawrence Livermore National Laboratory in California are to announce that they have made a net energy gain by bombarding hydrogen atoms with lasers. The 192 laser beams compress the hydrogen atoms to about 100 times the density of lead and heat them to about 100 million degrees Celsius. Due to the high density and temperature, the atoms fuse to form helium.
Other methods being explored include using magnets to confine superheated plasma.
“If that’s what we expect, it’s like the Kitty Hawk moment for the Wright brothers,” said Melanie Windridge, plasma physicist and CEO of Fusion Energy Insights. “It’s like the plane takes off.”
Does this mean that fusion power is ready for prime time?
no Scientists refer to the latest breakthrough as the “scientific net energy gain” – meaning that more energy was released from the reaction than was supplied by the laser. This is a huge milestone that has never been reached before.
But it’s just a net energy gain at the micro level. The lasers used in the Livermore lab are only about 1 percent efficient, according to Troy Carter, a plasma physicist at the University of California, Los Angeles. This means that the lasers require around 100 times more energy to operate than they can ultimately deliver to the hydrogen atoms.
So researchers have yet to reach “technical net energy gain,” or the point where the entire process requires less energy than is released by the reaction. They also need to figure out how to convert the emitted energy – currently in the form of kinetic energy from the helium nucleus and neutron – into a form usable for electricity. They could do that by turning it into heat and then heating up steam to turn a turbine and power a generator. This process also has efficiency limitations.
All of this means that the energy gain will likely have to be pushed much, much higher for fusion to actually be economically viable.
At the moment, researchers can only do the fusion reaction about once a day. In between, they must cool down the lasers and replace the fusion fuel target. An economically viable system would have to be able to do this several times per second, says Dennis Whyte, director of the Plasma Science and Fusion Center at MIT. “Once you have the scientific feasibility,” he said, “you have to figure out the technical feasibility.”
What are the advantages of the merger?
The possibilities of fusion are huge. The technology is much, much safer than nuclear power fission, since the fusion cannot produce runaway reactions. It also produces no radioactive by-products that need to be stored, or harmful carbon emissions; it simply creates inert helium and a neutron. And we probably won’t run out of fuel: the fuel for fusion is just heavy hydrogen atoms found in seawater.
When could fusion actually power our homes?
That’s the trillion dollar question. For decades scientists have joked that fusion is always 30 or 40 years away; Over the years, researchers have variously predicted that fusion devices will be operational in the 1990s, 2000s, 2010s, and 2020s. Current fusion experts argue that it’s not a matter of time, it’s a matter of will — if governments and private donors fund fusion aggressively, a prototype fusion power plant could be available in the 2030s.
“The schedule isn’t really a matter of time,” Carter said. “It’s a question of innovation and commitment.”
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