Coal-fired power plants are dirty. No question about that.

But in Sunday's paper, I wrote a story about the PSEG plant south of Trenton, which has installed $600 million in air pollution controls and reduced emissions by more than 90 percent.

(An interesting tidbit that didn't make it into the story: In 1960, when the plant was built, it cost $110 million.)

But other plants have not yet followed suit. And even among those that have -- like PSEG's plant -- all bets are off when it comes to regulating carbon dioxide emissions.

An Environmental Protection Agency hearing is being held in Philadelphia Tuesday to get public comment on regulations to reduce emissions of mercury and other hazardous air pollutants from coal.  Other rules to address other coal emissions are also in the works.

It would be easy for environmental advocates to say to forget coal. Build wind. Build solar. But in such a power-hungry nation as ours, how?

Natural gas burns cleaner, but what about the environmental effects of extracting it from geologic formations like the Marcellus shale? Are we doing it right? Can we do it right?

So what should we do about coal? Please weigh in by commenting below.