Abstract: A gasifier 10 includes a first chemical process loop 12 having an exothermic oxidizer reactor 14 and an endothermic reducer reactor 16. CaS is oxidized in air in the oxidizer reactor 14 to form hot CaSO4 which is discharged to the reducer reactor 16. Hot CaSO4 and carbonaceous fuel received in the reducer reactor 16 undergo an endothermic reaction utilizing the heat content of the CaSO4, the carbonaceous fuel stripping the oxygen from the CaSO4 to form CaS and a CO rich syngas. The CaS is discharged to the oxidizer reactor 14 and the syngas is discharged to a second chemical process loop 52. The second chemical process loop 52 has a water-gas shift reactor 54 and a calciner 42. The CO of the syngas reacts with gaseous H2O in the shift reactor 54 to produce H2 and CO2. The CO2 is captured by CaO to form hot CaCO3 in an exothermic reaction.