The NRDC has a plan that would allow the EPA to regulate GHG emissions from existing power plants, without either capitulating to the power sector, or banning coal outright immediately (which would be politically… uh, difficult). The trick is to use fleet-based target, as we do with vehicle emissions standards. The natural (regulatory) unit is the state, so each state could have its own carbon intensity targets or degression pathway, tailored to its initial generation mix. The carbon intensity would decline over time, eventually squeezing coal out of the mix, and could allow energy efficiency improvements to count toward the goal, at least initially. It really amounts to a kind of back-door cap-and-trade for the power sector, and it can be implemented by Obama, all on his lonesome, without any help from the intransigent congress. The hard part here will be setting stringent enough long term targets. 40% reduction by 2025? 90% reduction by 2050?