The paper discusses the possibility of using the reversible reaction CaCO3 ↔ CaO + CO2 for the cyclic capture and release of CO2 directly inside a fluidised bed combustor. This could lead to the lowering of CO2 emissions into the atmosphere, as part of an effort to mitigate the greenhouse effect associated with the rising atmospheric CO2 concentrations resulting from obtaining energy from burning fossil fuels.An enrichment coefficient E has been introduced and defined as a measure of the production of CO2 (on calcining CaCO3) or its removal (on carbonation of CaO) with respect to the level associated with fuel combustion alone. The observations made on the effect of introducing an additional external stream of CO2 on the efficiency of the chemical capture process have been described. Through an appropriate control of the temperature inside the reactor it is possible to change the value of E over the range [-0.8; 0.8]. This implies that up to about 80% of the CO2 derived from the fuel can be temporarily retained within the bed and released later, at a higher concentration. The proposed method of burning fuel in a chemically active fluidised bed could be an available method leading to CO2 isolation from the flue gases and leading to its eventual sequestration.