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Direct harvesting is not possible with the fusion reactions we are currently working on. The products are electrically neutral, so the only way to harvest the e
by alextingle 5y ago
Direct harvesting is not possible with the fusion reactions we are currently working on. The products are electrically neutral, so the only way to harvest the energy is as heat.
Helium-3 fusion produces charged particles, which it might be possible to directly harvest as electricity. The He3 fusion reaction has a high activation energy, which is currently unachievable, and there is no Helium-3 on Earth. We'd have to get it from space, somehow. (The movie "Moon" was set on a Helium-3 mining outpost on the Moon.)
- DennisP 5y agoConveniently, pure deuterium fusion (D-D) is easier than D-He3 fusion, and the output of D-D fusion is half He3, and half tritium which decays to He3 with a 12-year half-life. So if we can get net power from He3, we can make He3 from deuterium and generate energy in the process. D-D fusion does produce neutrons but they're much lower energy than D-T neutrons. Fusion startup Helion is working on a hybrid D-D/D-He3 reactor, saying the combination will produce only 6% of its energy as neutron radiation, low enough so they can do direct conversion. They've built half a dozen reactors, and now they're working on a seventh that they'll use for a net power attempt around 2025. They recently had a fundraising round led by Sam Altman, and raised $500M with another $1.7 billion of commitments based on milestones. https://techcrunch.com/2021/11/05/helion-series-e/ https://techcrunch.com/2021/11/05/helion-series-e/
- ksec 5y agoSounds too good to be true? 2024 commercialisation, size of shipping container and direct to electricity generation? Surely we are missing something in this discussions?
- DennisP 5y agoWell, it still might not work. But we probably have a lot of technologies today that seemed too good to be true, shortly before they turned real. A couple other fusion companies think they can achieve net power at least, around the same time.
- ncmncm 5y agoThere is no usefully available Helium-3 on the moon, either. The only practical source known is decay of tritium, which must itself be synthesized by nuclear reaction, and is, for military use. Another choice is fusion of ordinary hydrogen, usually labeled "p" for the proton, with boron, B, thus "pB". But that is even harder to achieve. Still, it is being worked on. There is no route to commercially viable fusion extracting heat from Tokamak reactors, as any such reactor would need to be enormously bigger and much more expensive to operate than the same-rated fission reactor, which is not today competitive, and gets less so all the time. Some people hope that something can be learned from Tokamak work that might be applicable to potentially practical designs, but the money is all going to Tokamak, while the others mostly go begging.
- gpm 5y ago> Direct harvesting is not possible with the fusion reactions we are currently working on Depends on which company you're talking about. Helion, for a coutner example, is directly harvesting energy out of plasma.