Technology

I think people still don't understand what the problem is with fusion. The problem is not that it doesn't work, it will work, and soon. The problem is that everyone seems to think fusion means cheap limitless energy, and that couldn't be further from the truth. When fusion does finally work, it will be the most expensive form of energy available. That's going to be a gamebreaker, right out of the gate.

So far, the only method we know of to guarantee that your reactor will be energy positive is to make it truly enormous. Let me tell you, going truly enormous is not a good way to keep costs down. But let's say you just spent 8 years building a cutting edge fusion power plant and you want it to work smoothly. Well you better hire a large team of nuclear physics PHDs to keep that reactor working, they must be a dime a dozen, right? You'll need them for all the maintenance of your cutting edge reactor, get ready for those maintenance costs to mount up. And be prepared to continue paying for all your staff and facilities even while the reactor is (frequently) power down for maintenance.

Also, you do have an economical way to dispose of nuclear waste right? Because fusion reactors are probably going to generate a significant amount of nuclear waste... That's one of the side effects of actually turning the high energy particles released by the reactor into heat. Those free protons and neutrons get absorbed by a physical shield around the reactor called the blanket. That blanket becomes radioactive over time and needs to be replaced. Congratulations, your clean fusion energy is now producing radioactive waste, and your back to the exact same problems we have with fission.

My advice, keep using the nuclear energy we understand really well at this point, fission. Also, renewables and storage are already a cheaper solution to do exactly the same thing fusion will eventually do. I'm certain that fusion will be a fantastic technology for large spacecraft someday, but I make no promises it will ever become the first choice for general terrestrial power generation.