Between wind, solar, and storage, you would be hard pressed to “run out” of energy in a well designed system. Stating otherwise is nonsense.
The sun doesn't shine in a lot of places for less than 12 hours a day. In the winter, a lot of places have much less sunlight.
When men needed wind to sail the sea, there were situations when the wind didn't blow for weeks.
How much energy would your "well designed system" need to store and what is possible?
Yes, I read about that Tesla battery in Australia. Then I calculated how many Tesla walls a city like Munich would need to be able to survive for 1 week. I don't believe it is possible.
People rely on electric power. If the grid goes down in places like Germany like once every month, there would be uproar.
At least in Germany even large industrial energy consumers are for years now an active part of grid balancing. Either they can stop and resume production as needed or continuous processes serve a similar function as your base power plants. The silver bullet to get them there was money, it became financially viable and profitable and all of a sudden businesses jumped at the opportunity.
Disclaimer: Worked at two of these power hungry places and know of of another one making quite some money on the electricity exchanges by just timing his production runs properly.
Solar still works in cloudy weather, and you can compensate by building more than you typically need. You can transmit increasingly long distances. Here's a line working at 2300+km.
https://www.power-technology.com/features/featurethe-worlds-...
Most weather doesn't span 2300km in all directions so I think it's possible to handle most situations and fill in the gaps over time.
You can use a Tesla as home battery. Charge at work or home, or at a supercharger, power your house at night.
Sure there are edge cases like far north where you need coal or nuclear. But I'd bet the bulk of humankind can be supplied well given another 10/20 years of innovation.
Storage will happen, but it's a long way off.
Some questions that might be interesting: What is the current downtime of electricity. What would be the desired goal for the new mixed / renewable grid? Given existing patterns of wind and solar generation, how much storage needs to be installed to reach this goal? How much would this storage be expected to cost at today's prices, and then with projected future savings from scaling (this could be used as a higher bound)?
The reason "running out" might be a valid concern is that the power grid is currently reasonably robust. Turbines are massive, with a great deal of inertia, meaning that even if something drastic were to happen, they can often cope with spikes in load long enough for extra production to ramp up. Wind and solar less so. Batteries presumably would be pretty great for ramping up, assuming we get enough of them on the grid. But then the economics needs to take into account the price of not just the renewables, but also generation.