Power from underground coal fires?
In a lot of places there are underground coal fires which, unfortunately, are pretty much unstoppable. These coal fires release an enormous amount of CO2 in the air every day.
So instead of this heat and energy going completely to waste, maybe some of the energy could be harvested using geothermal like constructions.
At least it’ll be better then just letting the coal burn, not using the energy, and then burning some additional fossil fuels to generate energy we need.