> If you use Renewable Energy Sources, it may happen there will be no wind or no sun.

Yes, but this rarely happens, so any potential solution should be designed around it being idle 99% of the time.

> Those power plants have about 1h cold start.

Gas turbines can spin up significantly faster. However, the weather is quite predictable, so it is unlikely that this will be needed. Besides, battery storage is the perfect solution as an ultra-fast ramp-up holdover source until the turbines are at 100%.

> Hence, in order to have RES you need to emit CO2.

Or you equip the handful of gas turbines you use to make up for that 1% gap in renewables with carbon capture? It's not ideal, but it is very much doable.

> Simply use nuclear power plants and do not bother with RES

... and have your electricity be even more expensive?