Clean up coal emissions and you end up with more -- and more toxic -- coal ash. You get cleaner air, but you get ash that can't be recycled (into, e.g., concrete). You breath free, but you've got arsenic and mercury leaching into your groundwater from coal-ash landfills.

Look at this vintage coal magic:

There are ways to remove the pollutants from emissions without making the ash unusable [for recycling]. But that equipment can be up to four times more expensive, adding millions of dollars to the cost of meeting EPA guidelines, [American Coal Ash Association executive director Dave] Goss said.

"The utility's primary goal is to provide cheap, dependable electricity for you, the consumer, connected to the grid," he said. "In order to do that and maintain compliance, sometimes the only thing they can do is make the ash unusable."

Once again we see it, what I'm now dubbing Dave's Second Law of Sustainability Politics:

Coal can be clean and cheap, but it can't be both at once.