Re: “It seems that every article I’ve read on fusion since I was a teenager has said we’re 20 years away from fusion.”
I agree.
Europe, Russia, and the USA have been doing commercial fusion research since at least 1960.
It would not surprise me if the world wide price tag for this technology has reached $100 billion.
If we had put that money into photovoltaic, battery, and hydrogen research instead, I think we might be at break even or better on those three technologies.
He proposed that it might be possible through a staging process similar to a thermonuclear weapon, where about 30-65% of the energy came from fusion and other 70 to 35% came from the fission used to initiate the staging reaction. Of course, that type of fusion wouldn't satisfy the Enviro-Nazis, and that kind of reactor -- to my knowledge, and I am no expert -- has never been significantly researched.
As for the other kind of fusion? "It might happen," he said, looking around the seminar room, "within the lifetimes of a few of the people in this room." I was then one of the youngest grads in the room, a 26 year old. 30+ years have passed since then. I believe Teller's prediction might have very well be too optimistic.