I'm gonna call "citation needed" on this one. The clean coal part, specifically. Reasons: Technically, it should be possible to filter out uranium. Thorium, to

I'm gonna call "citation needed" on this one. The clean coal part, specifically. Reasons: Technically, it should be possible to filter out uranium. Thorium, too. Both are heavy enough, it should be possible to centrifuge them out of just about any mixture, unless the compounds they're in are too tightly bound with lighter molecules by intermolecular forces. Even then, I would expect them to find their way "down", even if they had to drag some of the nonradioactive portion with them. The amount of energy you get out of the coal or the uranium is a function of not only the amount of energy in each, but their relative quantity, as well. If there's not enough uranium present to extract a significant portion, I'd have to wonder if there's really enough to put out as much energy as the coal's total output. Taking it a little further, if there isn't enough to extract, is there really enough to pose a significant health risk? We're exposed to a certain amount of background radiation on a daily basis already. How much more does the uranium in coal add to this? Again, I'm tempted to doubt it's significant, if there's not enough to be extracted. So, do we have reliable numbers on this?