Zap Energy’s reactor managed to reach a temperature of up to 37 million degrees Celsius earlier this month. This puts it in a special list of a handful of competitors who have also succeeded in this so far.
What is nuclear fusion?
Nuclear fusion fuses the nuclei of atoms, the tiny particles that make up everything in the universe, together. This happens at an extremely high temperature and pressure. The process takes place continuously in stars: the intense heat of the sun fuses hydrogen atoms into helium, releasing a lot of energy. The sun uses that energy to burn. If nuclear fusion can take place in a reactor, it could be a source of infinite clean energy.
If you want to know more about nuclear fusion, read this overview article.
Tokamak or stellarator
The two nuclear fusion techniques you hear about most are tokamak reactors (such as the world’s largest in Japan) and stellarators (such as this German-Belgian variant). Both methods use a strong magnetic field to keep a plasma (an extremely hot gas cloud) in the air so that it does not touch the reactor wall. Zap Energy, on the other hand, uses a Z-pinch method. This technology does not use ‘expensive and complex superconducting magnets and powerful lasers’, the company claims.
Clash and melt
Zap is the first to inject gas into a reactor. A burst of energy ionizes this gas into plasma. This plasma carries an electrical charge ten times as high as a bolt of lightning. Compressing and heating this plasma, which consists of the fuels deuterium and tritium, causes nuclei to collide and fuse. This process releases heat and electricity.
Z-pinch nuclear fusion was experimented with as early as the 1950s. The problem was that the plasma cooled too quickly, so fusion only took place on a very small scale. Zap Energy says it has solved this problem with a process it calls sheared-flow stabilization.
The results of Zap Energy were published in the scientific journal American Physical Review Letters. The company operates from Seattle and is a spin-off of a US government research institute. Zap Energy previously received investments from Bill Gates innovation fund Breakthrough Energy Ventures. It also received $160 million from Shell Ventures.
Plasma physics
“The dynamics are a beautiful balancing act in plasma physics,” explains Ben Levitt, vice president of R&D at Zap Energy. “As we climb to higher and higher plasma currents, we optimize the ‘sweet spot’ where the temperature, density and lifetime of the Z-pinch come together to form a stable, high-performance melt plasma.”
Ultimately, Zap Energy wants to build small nuclear fusion reactors of about 3 by 3 meters. These reactors should be able to produce enough electricity for a small city. It is unclear when we will see the first working reactor. Zap Energy is currently silent about the timeline and the next steps to be taken.
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