New Zealand is almost entirely run on renewables. Iceland is 100%. Sweden is almost there. The UK and Germany are close behind. This is totally doable with renewables. No need for waste that is radioactive for hundreds of thousands of years.
Wind, solar and geothermal should be able to fill the gap, but this technology takes time to devleop and deploy. Nuclear's been around since the 1960s, and it works. If we need 20-40 years to switch to fully-renewable energy, nuclear could get us there.
The missing piece seems to be network level storage so usage times can be decoupled from generation times.
There is also the problem that hydro is not recognised as renewable. At least as far as carbon credits go. NZ landed in hot water after that was announced. We expected to come out in a good position on carbon trading, that was not the case.