So you enhance the already-existing continent-scale grid and import your power from an area a few thousand km/mi away which isn't both cloudy and windless at th

So you enhance the already-existing continent-scale grid and import your power from an area a few thousand km/mi away which isn't both cloudy and windless at the same time. Heck, there's probably plenty of opportunity for hydro storage in that range. If all else fails: power up the backup natural gas power plants for a couple of hours. We're trying to minimize CO2 emissions as quickly as possible, getting to 0% immediately isn't the goal. Run a carbon capture plant during times of energy excess to compensate if you feel like it.