The ill-conceived energy bill recently passed by the House would require carbon dioxide emissions in the US to be reduced to about 2 tons per year per citizen by 2050. That is going to be a significant challenge since an adult person emits about 0.4 tons of CO2 per year just by breathing. If the person has a horse for transportation he will exceed his allotment, since the horse breaths out over 2 tons of CO2 per year. Many Democrats and environmentalists think that "renewable" energy can rather easily replace fossil fuel. In that they are totally mistaken, for reasons discussed here. The long range solution is a transition to nuclear power, probably initially thorium breeder reactors (for which there are centuries of fuel available), and ultimately to fusion power. There is plenty of fossil fuel available for making a smoother transition over a century than the abrupt transition that Obama envisions. (AGW is a red herring, of course, as is obvious if you listen carefully to Democrats, who clearly indicate that AGW is just an excuse for doing what they want to do. If that argument is inadequate for you, consider that they admit that their legislation is not going to reduce temperature according to their own analysis.)