Exergoeconomic analysis of a conditioning system for captured CO₂: Costs of physical and chemical exergy

To keep the rise in global temperature below 1.5 °C, global greenhouse gas emissions should be reduced to net zero in 2050. Carbon Capture, Utilisation, and Storage (CCUS) is expected to play an important role in reducing emissions from the energy and industrial sectors. One important step of the CCUS value chain is the conditioning process, where the captured CO₂ is liquefied and purified before transportation. The conditioning process can be divided into several subprocesses, most of which contribute to both liquefaction and purification. Therefore, it is not straightforward to determine the costs associated with removing different types of impurities. In this study, the costs of achieving changes in the physical and chemical exergy are analysed through an exergoeconomic analysis. A detailed thermodynamic model and an economic analysis considering both capital investment and operational expenses were made. The overall costs of the system were found to be 25 C (tCO₂)⁻¹, of which 20 % were associated with reaching the correct quality of CO2. The majority of these costs were related to the removal of water (16 % of total costs) while the direct costs of imposing constraints to incondensable gases for the given inlet composition were of minor significance (4 % of total costs). The results expand the knowledge of the economic effects from requirements downstream of the CCUS value chain.