I'm kinda assuming that it has to be economicly via to count, but even if not, I'm not sure how you could make coal safe. You'd have to lock up the carbon dioxide in a form as stable as the coal you're burning. What would that form be? Calcium carbonate?
rex, that's true for any carbon based fuel - as long as we're burning carbon (to heat water, to generate steam, to spin turbines, to spin generators, to make electricity) that's gonna be an issue - whether it's coal, or fracked natural gas, or oil, or biomass
ideally, the best form to put it into would be one that had demand - can you imagine re-engineering the world of plastics manufacture to make it economically viable with CO2 as the primary feedstock? :think:
and as far as calcium carbonate goes, you're talking about cement and gravel, both of which have demand
but where are you planning to source the calcium from?