Now that is a post to summon Imp. Knoedel if there ever was one.
ROFL, looks like that.
In general clean power is just too good too early. No idea how to incentivize more historical reliance on fossil fuels though.
The following would be a plan to do just that, without changes on civics or the tech tree.
Per a new mechanic, cities consume 1 power per inhabitant. Power that is locally produced but not consumed by city inhabitants, flows into a national pool, is divided by half, then equally distributed to cities that don't have enough power yet.
Buildings that require power, are giving only 50% output when the power level of the city is above 80%. Having less than 80% power means a blackout, these buidlings stop working.
A coal plant gives 5 power output, +5 per available coal or oil.
A hydro plant gives 5 power output, +2 per worked watermill of the city.
A solar plant gives 5 power output, +5 for every desert tile in the city BFC.
A nuclear plant gives 0 power output, +10 power per available uranium.
All plant buildings can never produce more than 20 power. There can, however, be several plants per city.
For some small change: Windmills produce 1 power output when worked, +1 after invention of renewable energies.
Itaipu dam is turned into a national wonder with 100 power output (seriously, we had Assuan, Itaipu, Hoover, Three Gorges... this is a national wonder. Could have
national flavors.)
ITER reactor produces 200 power?