Chemical absorption (Che) and calcium looping (CaL) have been recognized as the promising technologies for post-combustion CO2 capture (PCC) applied in fossil fuel power plants. However, there is a lack of understanding of how the energy integration affects the performance difference of the two separation technologies employed for the retrofitted coal-fired (CFPP) and natural gas combined cycle (NGCC) power plants. Thus, this study aims to provide a new perspective by investigating power generation fuel and heating fuel from energy conversion and transfer pathways. Results indicate that in the case of CFPP-PCCs, adopting the CaL technology can enhance the initial parameters of the steam cycle and reduce the heat transfer temperature difference for the utilization of heating fuel, where the heat transfer exergy destruction of heating fuel drops from 27.9 % to 15.1 % compared to the Che capture system. Conversely, for NGCC-PCCs, due to the superior performance of the combined cycle, the adoption of the CaL technology undermines the advantages of the heat transfer and power generation units, resulting in inferior performance compared to the Che capture system in most conditions. Results implicate that the degree of difference in energy conversion and transfer pathways between the power generation fuel and the heat supply fuel directly determines the performance of the capture system. Thus, concentration CO2 along with the efficient fuel conversion will be a promising direction for the innovation of capture technologies.
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