..."renewable energy" is energy/mass density. This is in fact, why so called "renewable energy" was abandoned at the end of the 18th century, only to rear, in an insipid fashion, it's ugly head in the late 20th and early 21st century, at great cost to humanity.
The energy/mass density of nuclear fuels dwarfs dangerous fossil fuels.
At various points, this high energy to mass ratio has been problematic in the sense that materials science lagged behind physics. The step down from particles with kinetic energies at 100's of MeV to the temperatures associated with steam were challenging, but even with 50 year old technology, the process has been managed to the great benefit of the human race.
In recent years, however the developments in materials science have been mind boggling. Very high temperature ceramics, or semi-metallic ceramics like the "MAX" phases have shown the ultimate solution to these issues. An old guy like me can't read a materials science monograph these days without being struck with awe and wonder.
In addition, we've developed a number of very sophisticated cyclic chemical reactions, so called "chemical looping" and "hydrogen cycles, and hybrid hydrogen carbon dioxide cycles, all thermochemically driven. With hydrogen and carbon oxides, there are very few high volume production organic chemicals that cannot be made.
It is technically feasible for several billion people, perhaps not seven billion, but maybe three or four billion to live sustainably with uranium, thorium, plutonium, neptunium, americium and curium driven systems.
"Technically feasible" is very different from "easy" and even more different than "likely."
Unfortunately, such an outcome would take commitment, a scientifically and technically literate public, and a willingness to invest for the benefit of future generations. None of these factors right now outweigh the mass of fear and ignorance that pervades.
I think we should do away with fossil fuels because, well, they actually manage to be worse than wind and solar power, neither of which are sustainable, clean or, as we are finding out, very safe, owing to low mass density and distributed toxicology.
But we won't do away with fossil fuels, because we don't give a rat's ass about the future, and because ignorance, as has happened many times, usually the prelude to the worst times, has prevailed.
It's not a pretty scenario.
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