Costs are lower in the long run, especially when considering lower system costs - the power grid has to be much more capable and more complex with variable generation from solar and wind, plus these energy sources always need a stable backup (like nuclear)
I was looking for inspiration on requirements engineering practices beyond arc42 & friends that are compatible with (or can be explained to deciders in) larger organisations, and found the Nasa process ideas (expectations - "conops" - requirements) surprisingly flexible
There is lots of potential, but as we see in Germany, a glass ceiling for solar and wind power exists where backup is needed - when there is little wind for only one hour at night, you still need another controllable source of energy with an output that does not vary by weather. Few are available with low CO2, such as hydro, nuclear, geothermal
Wind power is intermittent in most regions in Europe, without expensive storage it just extends the lifetime of coal plants that are then used as an indefinite "backup".
We need to get back to the building times of the 80s in Sweden for nuclear. The korean nuclear plants have the fastest building time these days after the chinese, so no surprise they will be building the new ones in Poland
Combinations of solar, wind, batteries, and (crucially) some e-fuel like hydrogen enables a 100% RE grid to work even in Europe, at a cost that new construction nuclear will have trouble matching. Europe, particularly eastern Europe, is one of the last places nuclear makes any sense, but even that is an expiring refuge as renewables and storage continue to improve in the face of massive demand driving them down experience curves.
Complexoty causes high system costs at scale for energy grids with a large amount of intermittent renewables. Adding more stable adjustable sources like nuclear, hydro or geothermal will become more attractive than creating wildly intricate "smart grid" architecture. Just produce more power when needed instead of costly redistribution and storage.
Costs are lower in the long run, especially when considering lower system costs - the power grid has to be much more capable and more complex with variable generation from solar and wind, plus these energy sources always need a stable backup (like nuclear)