You really dont, you just need to burn fuel to fill in for gaps caused by weather, that become increasingly less frequent the more wind and solar is oversupplied. And oversupply is not a big problem - it can be easily curtailed. The optimal amount of renewables supply to build is over the level where they regularly exceed demand - and that is the stage where big batteries become very economical to build.
Carbon neutral fuel-wise, biofuels and electrically generated fuels are very viable future options.
Storage doesn't become more of a problem with more wind and solar - it becomes more of an opportunity to further reduce fuel consumption.
Storage is not a problem now - economic solutions exist already to build it where it is valuable. Its just not needed much yet.
That suggests that we'd need to keep most of the existing infrastructure for power generation and also replicate its capacity with wind and solar plants.
That sounds both expensive and inefficient.
> Storage is not a problem now - economic solutions exist already to build it where it is valuable. Its just not needed much yet.
Nuclear has actually proven that it can work at the scale we need it (~20% of actual power generation from memory). Renewables and storage have not. So this is an argument of hypotheticals vs actuals. The burden of evidence on the hypothetical solution is a bit higher than an assertion that it'll work.
The only grid-level storage solutions that actually store energy (not just modulate grid supply short-term) is big hydroelectric dams which are not one size fits all solutions.
Meanwhile the nuclear power station we started building ten years ago is contributing 0%.
Its efficient to use existing plant for as long as it is useful. The main expense of running most of it is fuel - and the cost of that in legacy terms and in CO2 is slashed by 'replicating' its capacity with wind/solar.
Currently when we add wind and solar capacity almost their entire output replaces fuel burn. When in a handful of years wind and solar have replaced 30-40% of demand supply, about 10-20% of their output may possibly be getting rejected. That makes wind/solar maximally 10-20% more expensive than what they would be with full storage and use. Hydro, batteries and long distance transmission is already economically viable in certain situations. Hydrogen synthesis will become increasingly economically viable, with carbon pricing and development. There are technologies existing which are ready to reduce waste supply from wind/solar as it arises. But even without them a potential overhead of 10-20% cost wont stop more wind/solar getting built, because its already currently cheaper than fuel burning -without carbon pricing and has been getting more efficient year on year, with no end in sight.
This actual economic performance contrasts with new nuclears promises which are in truth in their final throws, completely outperformed already by the alternatives which have been developed. Investment in Nuclear is no real threat to wind and solar anymore, the arguments seem to persist only to delay overall action on policy transition. New nuclear plants may or may not get built, wind and solar IS getting built and its variable nature will make nuclear supply uneconomic - there's no sense in financing plants on the basis of supplying constant power, when a huge competitor supplies much much cheaper power 75% of the time, and encourages hydro, biofuels and maybe cheap storage to fill in its gaps. Nuclear is not going to be economical for that, and that is the opportunity which is being created by wind and solar manufacturers and installers, as we hash over this outdated debate.
By the way, your point 4 for nuclear power doesn't hold ground. If you have lots of nuclear power plants, then you're going to not use (waste) a percentage of the power you produce at night by burning fissile material. But if you don't have any nuclear power plants, then 100% of the potential energy from fissile material that is available on Earth is going to be "wasted" (ie, not used).