Reading their analysis of nuclear power (which is, by the by, about as renewable as solar power; we'll run out of fissionables around the time the Sun goes out), I'm not seeing any reason you couldn't run things just on that if you solved the political problems.
Unless I'm missing something (always a possibility, of course) their later comparisons are all to a "green stack" that doesn't include nuclear.
Yes, you're right, my mistake. I expressed myself wrong (thought one think, wrote another...). We can live on renewables + nuclear (if we get there, which would be a monumental task - both politically and in terms of building necessary infrastructure, not to mention electrifying pretty much everything that now burns fuel), but definitely not on renewables alone. And this transition needs to be started ASAP.
The final comparisons of stacks were against electrified and reduced consumption (author started by pointing out how to reduce overall energy use to little more than 50% of the base value). There are many easy tricks that can help with this reduction - like better home insulation, keeping heating few degrees lower, using heat pumps for air conditioning, etc. - that don't mean one has to live without hot water & computers. But people need to start implementing those measures if we are to have any chance in transitioning to a sustainable energy economy.
Sure. Efficiency is important, not to mention cheaper in the long run. And if nothing else, we should at least be saving the hydrocarbons for industrial chemistry where they're actually hard to replace.
Convincing people to pay for the switchover is going to be a long, slow process though. And in most cases it boils down to major building renovation; people are famously reluctant to try that sort of thing.
Unless I'm missing something (always a possibility, of course) their later comparisons are all to a "green stack" that doesn't include nuclear.