From what I can tell, the generators consume fuel proportional to the amount of power being drawn, so you can add more capacity without actually using all of that fuel. Currently, you can implement a "battery" by placing more generators than you can actually supply with a storage container to buffer your coal or fuel. Hope this helps. :)
Having worked for the org that manages the power grid in the Midwest, I can tell you this is much more realistic on the scale that the game uses than batteries are. The only real option we have for power storage is to pump water up a hill at surplus and let that water run generators at peak load. Its kind of cool but it takes up huge amounts of land. Battery tech is not a sustainable future. We're gonna have to find something better.
BTW, i think the devs want us to be upset about the smog we're pouring into this world. I'm interested to see what they put in the narrative about this. Do you think they'll have us destroy the world, or will the game represent a sped up evolution from leaves to nuclear and then beyond?
I love the idea of power switches! I hope they give us that.