What are Local, Renewable Power Sources?

[Halcyan2]

In GS, before you get access to renewable power options (Hydroelectric, Geothermal, Solar, Wind), occasionally some cities have some innate renewable power sources.

Early on, it happened with two cities that had originally settled on resources (one on Quicksilver, one on Horses) but throughout the game I have seen this local, renewable power value fluctuate from 2 power, some have 4 power, some have 6 power. None of them have hydroelectric, geothermal, or any improvements that provide power.

What are the rules regarding this local renewable power and what determines their value? Thanks!

 

[Hans Castorp]

That sounds odd. They weren't coastal cities by any chance? Cardiff gives power to cities with harbour buildings.

 

[Halcyan2]

Good point. Some of them are coastal cities but not all of them. Though I think some of the non-coastal ones have harbors.

UPDATE: Yes, you are correct Hans. All that power was coming from Cardiff. Since I'm still new to GS, wasn't as familiar with the newer city states. Thanks for pointing that out!