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Comment by jmyeet

11 hours ago

Fusion, I hate to say it, is a pipe dream. Why? Because any fusion reactor loses a ton of energy to fast neutrons, which have the added negative of destroying the reactor. So-called aneutronic fusion (eg using He3) isn't zero neutrons. It's just fewer neutrons.

Stars don't have this problem because they're very large so there's only so far neutrons can go.

This is such a weird thing to assume is just impossible in physics, I don't quite know how to respond other than "yes, there are many unsolved problems in every energy sector, which is why it's an open question where we go from here"

  • I've heard every counterargument a million times at this point. And they fall into one of two buckets:

    1. Stars do it. Yes. But stars also have size and gravity, something no nuclear plant will ever have; and

    2. "People once said X was impossible" ie the Galileo Gambit. Just because Galileo was mocked for his heliocentric model but was later proven right does not mean everything is possible.

    Thing is, I'm not even talking about physics. I'm talking about engineering. Something not only has to be possible but it has to be technically viable and sufficiently cheap. Put it this way: would you pay $60 billion for a 1GW power reactor with a lifespan of 30 years and an annual maintenance cost of $2B? Even if the fuel was completely free the wholesale cost per MWh would be ~$600. Nobody would build that.

    Fusion research has been going on for decades and the best we've done thus far is fire a laser for about a second to induce a fusion reaction and also spend billions building magnets to try and contain a turbulent fluid at 100 million degrees, which, again, will do nothing about the neutrons that will destroy that vessel.

    The joke is that fusion is always 50 years away and always will be. If you're an optimist it's always 30 years away and always will be.