We know how to smooth out peaks in electricity production to provide a steady supply: (a) pumped storage, like the Falls of Cruachan station in Scotland and (b) using complementary sources which don't all peak at the same time (solar and wind, for example). We also know how to eliminate most of the world's energy demand: getting rid of the private car - entirely - would cut it by half.

A nuclear power station is basically a very large, expensive and poisonous battery. The energy costs involved in building it and disposing of it are comparable to the power it will generate during its life - and the energy used to do that is from fossil fuel, you don't get mains-electric bulldozers and cement-producing furnaces.

No nuclear power station has ever been decommissioned back to bare, usable earth. And no nuclear waste is in permanent storage anywhere.