Many of these dirty electric plants have avoided pollution controls for decades.

The plan also calls for the repowering of old and dirty plants to stop pollution in urban neighborhoods.

As utilities bought more power from the independents, they generated less from their own older, dirtier plants.

Over the long run, such savings could mean less pollution, because the dirtiest plants could be used less or not at all.

Competitors also argued that it protected older, dirtier plants, while preventing cleaner ones from being built.

That could leave some of the dirtiest plants completely undisturbed for the next 14 years.

Instead of building new, cleaner plants, many companies simply patched and upgraded their old, dirty plants.

A dirty plant can buy pollution rights from a clean plant, for example.

But dirtier coal-fired plants want to avoid carbon dioxide controls as long as possible.

"The only general exception to this would be if relatively dirty coal-fired plants are used, relatively near to cities."