In real life, over 50% of electricity production by burning fuel uses a so-called fluidized-bed burner. (And rest is mainly even more complicated things..)
Fluidized bed burners have 2 key characteristics, which, in my opinion, can be turned into nice tech mechanic:
- burns only pulverized fuel (usually coal)
- requires supply of air to keep dust in fluidized state
So, I suggest advanced (say Medium Voltage) version of generator inspired by Fluidized-bed burners.