Basically I try to do something like the "Trading Posts grow into towns"-Mod for Civ5.
The concept is, that your tile improvements grow into better improvements if they are worked by a citizen.

For example a generator grows into a substation or whatever (+1 energy) and the substation grows into a power plant (removes all production and food from the tile, +1 energy for each prod/food removed). This should be done for all improvements (farm, mine, generator, academy, terrascape, manufactory)

The main problem is, that I'm no good modder and I have no plan if / how this is possible.

It would very nice if soebody helped me.

Feel free to submit your ideas how to do it.