re: #4 Okami

Well, as far as solar, as the largest electricity use is during the day it works out pretty well.

As for wind - yes intermittency is an issue, but that can be worked around.

In the ideal, coal wouldn’t supplement wind. Rather, one would have nuclear energy as a baseload (and for energy consumption intense industrial areas), with solar and wind supplying the rest.

The problem is what to do about transportation, which in the US nearly all is dependent upon liquid hydrocarbon fuels.