Generalized penalties and standard efficiencies of carbon capture and storage processes

Any possible sustainable way to meet climate targets relies on carbon capture and storage (CCS). Many literature works focus on the comparison between CCS approaches and technologies, also utilizing thermodynamic analysis to evaluate the inefficiencies of the processes, to understand and locate the additional consumption of primary energy, and, eventually, to provide a rigorous instrument for comparison. In this article, we provide a comprehensive assessment of the energy consumption and exergy destruction in CCS and propose a general and novel methodology that allows to unify the various available approaches. According to our calculations, the lowest energy and fuel penalties can be achieved with precombustion capture schemes. The minimum values found are around 8% to 9% for energy penalty, very close to the minimum achievable penalty of 3%. In addition, this results into a fuel penalty of 10% against the thermodynamic limit of 3.5% to 4%. The postcombustion scheme shows slightly worse performance that can be improved with mechanical energy-driven processes (such as cryogenic separation or adsorption process) that, if optimized, can reach a work of separation quite below 1 MJ/kg CO₂. The methodology and results can be useful for engineers as well as for decision-makers to evaluate the optimal technological pathways of decarbonization.