If humanity survives for thousands more years, our primary energy source could very likely be nuclear fusion.
It’s clean, the fuel is inexhaustible and cheap and there’s no risk of a meltdown. It’s the power source of the stars — the whole cosmos, in fact. And we’re tantalizingly close to making it work. The downside is that the particular reactor now making the important breakthroughs in fusion is linked inextricably to nuclear weapons research.
That’s not necessarily a deal breaker, but it presents risks that the public should know about and weigh in on.