Full-plant analysis of a PSA CO₂ capture unit integrated in coalfired power plants: Post- And pre-combustion scenarios

It is well proven that a general policy to address the worldwide issue of global warming cannot disregard Carbon dioxide Capture and Storage (CCS) in the portfolio of tools. Pressure Swing Adsorption (PSA) processes are believed to be a promising option for achieving more energy and cost-effective capture of CO₂ from large point sources, especially coal-fired power plants. Nevertheless, there is a gap in knowledge with respect to information and approaches for the integration of CO₂ capture using PSA in power plants. The main contribution of this work is to fill this gap, providing a plant-level comparison with other techniques of decarbonization (i.e., state-of-the-art absorption processes) in terms of CO₂ separation performance, energy efficiency and footprint of the technology. Full-plant analyzes were developed based on a dynamic computational model representing coal-fired power plants operating with a Pressure Swing Adsorption (PSA) cycle, both in a post- And pre-combustion configuration. The resulting plant performance is compared to that of absorption-based systems using the same reference power plant assumptions. The post-combustion scenario outputs reveal that the benchmark absorption process outperforms the PSA alternative. Even though the CO₂ separation requirements are met, the relatively large energy penalty and the very large footprint seem to highlight the current unsuitability of PSA for post-combustion CO₂ capture. Conversely, the pre-combustion scenario analysis shows the PSA process as a promising alternative. The performance, in terms of CO₂ separation, energy efficiency and footprint of the technology, results just slightly lower than that of a plant implementing absorption as a CO₂ capture method. However, the novelty of the analysis and the non-maturity of the technology in this application leaves the window open for future improvements.