But is it sustainable? Heavy thick smog (indicating the prominent use of coal to generate power) are certainly a negative signal when we have much better power sources.
Of course it is, (sustainable that is), it is just more expensive. I don't believe there is anything currently cheaper than a pouring fresh out of the mine coal, down a chute into a burner, which is making steam to drive a turbine. And there are a number of plants in China that seem to be just that.
You can pre-process the coal (remove impurities, create more uniform pellets, etc) to reduce random by products, and you can post process the exhaust plume through particulate and catalyzing filters to remove pollution by products. Much like a modern automobile a modern coal plant does all of that and more.
The down side is that it is more expensive to build, and to operate, and to fuel. Which is why generally government regulations are used to enforce it.
