The best way to curb emissions IMHO is not by internalizing their costs, but by capping consumption before they emit (prevention).

According to the diagram below one-third of GHG emissions come from the transportation sector. Motor vehicle regulations can be modified, placing an upper limit on new production vehicle weight and horsepower, especially for non-freight vehicles. That would tie emissions increases in that sector more directly with how many cars are on the road (and therefore population), rather than how big a vehicle people can cruise around in. Per capita GHG emissions from the transportation sector should remain relatively constant thereafter. In fact this measure should also prevent any increase in foreign oil dependence, and provide a regulatory mechanism to reduce it in the future.

It's conceivable though that an emissions credit scheme is the only thing that would work to ensure that consumers are paying for the real cost of their electricity.