Actually, conventional coal plants don't emit soot, and they don't emit flyash (unless there is a malfunction). Good combustion prevents soot, a precipitator or baghouse captures flyash, combustion control reduces NOx, a scrubber can remove sulphur, mercury, and nitrogen compounds. Conventional coal plants are really cleaner than the anti-coal people want to admit.
The term "clean coal" is typically used to mean newer design boilers where pollutants like sulphur are captured before they even enter the flue gas stream. There may still be flyash in a "clean coal" process like a CFB boiler. These type of boilers still require a baghouse or precipitator.
What the general public really means when they talk about "dirty coal" is the conventional plants of old, which burned coal without any controls at all. These do not exist anymore with maybe one or two exceptions. These days they have added CO2 as a pollutant from "dirty coal" to maintain the villainization as the emissions of coal plants continue to get cleaner. This is just BS.
Putting that in perspective - imagine the auto makers saying we will eliminate CO2 from your car's exhaust but it will take one out of every three gallons of gas you put in the tank to do it.
At the plant where I work we are spending 300+ million for additional pollution control and will end up putting less MW on the line.
Consumers don't have a clue about the costs about to hammer them.
Such a clean stack would ideally emit only CO2 and water as steam or vapor; mount an evaporator coil with cooled liquid circulating through it in this exit stream and drain the water to catch basins and pump the CO2 through pipes and eventually into underground storage caverns to await future consideration; a carbon dioxide bank, so to speak.
Now, there’s a job-building project worthy of any peacetime navy hull painting crew ever imagined.