I think it's a very debatable question we can EVER replace the current volume of energy consumption from oil, gas and coal with renewable energy.
No, it's not debatable at all. WE CAN'T. Alternatives can NEVER fully replace what fossil fuels have provided for us energy-wise.
What we call "civilization" will be turned inside-out (with lovely accompanying disease, war, die-off, environmental disaster, et al). If there are enough humans (and know-how) after all that is over, renewables may provide SOME energy for the new, localized societies that emerge.
But that's on the other side of The Collapse. . .if we are fortunate.
That's why it frustrates me so to hear so many talk about a slow and/or "manageable" decline. It's not just about fossil fuels. It's about the environment. It's about global warming and climate change. It's about a world-wide socioeconomic house of cards on the verge of collapse. It's about power politics uber alles--including war and pestilence. It's about SO MANY things, all piling up to hit (and, indeed, has started to hit) at the same time. Slow? Manageable? HA!
This is The Big Bubble--and when it pops, it's over.
Decades to go. Time to build, to plan. It'll all work out. And hunger will be eradicated by mining all the green cheese on the moon!
The human race may wake up. But it ain't coffee they'll be smelling.
Happy New Year. Really. Treat every day as a precious possession--while you still can. Cuz dusk is here, and full dark is approaching. Better learn how to have night vision. It might also help to pray to God, whoever you perceive him/her/it to be.
Most of all, don't YOU people go to sleep, too! We've GOT to stay awake; it's our best chance.