I don’t know if it’s all fusion reactors but General Fusion breeds tritium by surrounding the plasma with moving liquid lithium which breeds tritium and helium and they send the tritium back in. Seems sustainable.

I don’t know why their plan is to just vent helium given the shortage although I imagine that’s a second order problem they can solve later.

Thorium is something that is literally a waste product that falls out of refining of rare metals. And natural Uranium is also available in waste quantities. Without even trying we would have enough for the whole world.

And then compare to that the very complex and expensive process of process of breeding tritium.

How does that make any sense?

Sure, fusion is about 3 order of magnitude denser, but fission is already incredibly dense. The increase density doesn't really benefit you in any practical way unless maybe if you are trying to do interstellar flight or something.

Is there really enough lithium in the world to supply fusion reactors while also meeting the demand for its use in batteries over the next 1000 years? It will be interesting to see what the actual long term consequences are for building fusion reactors, as humans are notoriously bad at predicting what unforeseen circumstances arise from new technologies.

Maybe the Belters will mine lithium from asteroids and send them back to earth in exchange for air and water...

Fusion uses 6Li, which is only a minor fraction of natural lithium. The 7Li (93% of the element) can be used in batteries just fine.

At one point back in the 1960s some physicists were trying to make a neutron detector using lithium, and it wouldn't work. They eventually discovered the lithium they had purchased from a chemical supply company was nearly pure 7Li. It had been sold back into the chemical market from the waste stream of the government's lithium enrichment facility.