In the beginning of the game factorio, and probably lots of other games like it, everything you build is the "burner" version because those are the first things

In the beginning of the game factorio, and probably lots of other games like it, everything you build is the "burner" version because those are the first things you have available. You build them and feed them with coal to make them work. They produce lots of pollution and the bugs attack you for it. You don't use them forever; you quickly upgrade to electric/non-burner stuff, but you still have to use the burner stuff to build the more advanced electric structures. Once you have enough, you replace all the burner stuff and maybe keep some around as some kind of fallback. We're still building the necessary non-burner stuff, and the reality is that we'll probably have to use more coal than we thought for a little while longer. But I just don't see that as an issue, I see it as an annoying transition phase as we build out the new technology we're steadily unlocking.