To form carbon dioxide, oxygen depleted air and hydrogen by burning coal.

A combination of two fluidized bed reactors and a third transfer line reactor are used; the first reactor 10 being supplied with coal particles and fluidized with high temperature steam; the second reactor 12 being fluidized with high temperature steam and the third reactor 14 being fluidized by compressed air. Solids circulated among these three reactors include calcium compounds (present as CaO, CaCO3, and mixtures thereof) and iron compounds (present as FeO, Fe2O3 and mixtures thereof). The coal is gasified by the steam in the presence of CaO to produce CaCO3 and hydrogen for use by a CO2 acceptor process. The carbon of the central fluidized bed reactor reacts with Fe2O3 in the third reactor and the temperature in the middle fluidized bed reactor is sufficiently high to decompose CaCO3 back into CaO.