This is a picture of the Mojave Generating Station, near Laughlin, Nevada. As you can see, there is absolutely no pollution coming out the the smokestack... The reason you don't see anything, however, is because this coal fired power plant has been shut down.
The owners of this plant would rather shut it down than upgrade the pollution control equipment. Here's an indicator of what they really think about “clean” coal.
Of course, the power companies didn't actually shut it down on their own. They were forced to – after they lied in 1999 that they would put on the equipment... and after 6 years, still hadn't.
What? The coal industry lied!!! Need I be more sarcastic?
(Side note: This plant was one of the dirtiest emitters of mercury in the country. But the pollution control equipment wouldn't really have helped that.)
Ironically, in a way, I somewhat agree with the coal fired power industry. I feel that the pollution control equipment would been more or less a waste of money. All it would have done is transfer the pollution problem to the ground. Since it's physically impossible to make these poisons disappear with scrubber technology, all they would have accomplished would have been to keep them out of the air and concentrate them in a sludge pond.
Will sludge ponds leak? Absolutely. There is no such thing as a perfect container – and sludge ponds are far from perfect. 75% of US coal fired power plants use unlined, unmonitored landfills and surface impoundments.
The Mojave Generating Station may be shut down (for now), but the poisons it released will be here for us to deal with for a very long time... You can see this plant's sludge ponds in the picture (but you can see they're actual size much better on Google Earth). And, just in case you hadn't noticed, those “surface impoundments” (sludge ponds) are less than a mile from the Colorado River.