But could that really happen? 

Well here is the radical (renewable energy) revolutionary reasoning behind that astounding claim of 100% rooftop solar in 20 years, hehey.

Without even desert solar installations or huge wind machines on prairies and offshore wind/wave power?  Yep, here's how.  With a little personal sacrifice from us it could. 

Conservation?  Potential savings, 40% of present energy use.

Surveys indicate around 50% of present power use could come from rooftop solar at the 10% efficiency calculated in this older data.

With concentrating solar PV/heat cogeneration 60% would be normal, higher could be acheived.

Storage would come from emergency backup batteries in homes and buildings.  More storage from heat/cold storage in building mass and heat stored in molten salt in factory roof mounted solar furnce systems.  I am including space over parking lots and outdoor factory sites in the calculation for the solar furnaces.

And the sides of buildings as well, with good solar exposure.

Over the next 20 years superconducting magnetic energy storage could be expanded, it is in operation in power grids already.

This energy revolution looks doable.