There are many labs working on chemical looping combustion. Most have not gotten to "burning" coal yet. They are starting with natural gas to prove the process. Usually they will use two to three fluidized bed beds reactors to convert the fuel and oxygen (from the air) to CO2 and water. The trick, as I see it, is to find/develop, the oxygen carrier. Most so far have been Fe, Mn, or Cu based. Raw minerals have been tried for the carrier but they break down, both from attrition and from the chemical conversion of adding and losing the oxygen. You might get 20 loops out the material before you lose the material in the cyclone separators. They have also tried the putting the oxygen carrier on ceramic carriers. This seems to survive longer, but the cost is higher. The models I have seen suggest that if you need to sequester CO2 and you are burning coal this has real economic advantages over oxy-fuel combustion or integrated gasification combined cycle power systems. Then if you are going to move the CO2 any distance you will still need to clean up and dry the CO2 stream if you are going to pipeline it, but while we continue to use fossil fuels we need to be smart how we use it.