Integration of sCO2 Brayton Cycles With Carbon Capture Systems

Abstract Increasing global energy consumption and greater market penetration of intermittent energy sources require a baseline power source to enable renewable energies. Here, a case is made for pairing supercritical CO2 Brayton cycles with carbon capture to create low-emission, high-efficiency, combustion-based power generation systems. Pairing carbon capture and storage (CCS) systems with supercritical carbon dioxide (sCO2) Brayton cycles enables the reduction of greenhouse gas emissions in combustion systems, but with an associated energy cost. Three different representative models of CCS systems (oxyfuel combustion, amine scrubbing, and cryogenic carbon capture) are considered for pairing with an sCO2 Brayton cycle, each with assumed capture efficiency between 87% and 90%. Integrated models of supercritical CO2 Brayton cycles with CCS are used to predict the thermal efficiency of each combined system utilizing the process modeling software steamgen expert. The recompression sCO2 Brayton cycle exhibits thermal efficiencies in the range of 44–52%. When integrated with a cryogenic CCS system, the combined system demonstrated a nominal thermal efficiency of 39.1% with the potential to achieve 34–46%. Similarly, for oxyfuel combustion or amine scrubbing, the range of expected thermal efficiencies is 26–39% and 28–40%, respectively. The upper limits for these ranges represent a best-case scenario for aggressive operating conditions of the sCO2 Brayton cycle. CCS systems provide a CO2 source stream for operating the sCO2 Brayton cycle with other energy sources, including nuclear and solar. Additionally, the combined system has the potential to reach carbon negativity when paired with biomass combustion.