A Pinch-Based Approach for Targeting Carbon Capture, Utilization, and Storage Systems

Carbon capture and storage (CCS) reduces carbon dioxide (CO2) emissions by sequestration of captured CO2 for long-term storage whereas carbon capture and utilization (CCU) offers resource conservation benefits by displacing the need for extracted CO2 from natural sources. The integration of these two results in a carbon capture, utilization, and storage (CCUS) system, which either uses CO2 for profitable applications or stores it in the reservoirs. One of the key problems in CCS systems is to optimally match the sources (e.g., CO2 captured from fossil-fueled power plants) and the sinks (e.g., available geological reservoirs for storing the captured CO2). In practice, the geological storage sites may be available at different times and have limitations on the maximum CO2 storage capacity and the injectivity rate, subject to other geological characteristics. This work proposes an improved pinch analysis-based methodology by simultaneously considering the injectivity constraints Is and variable availability of all sources and sinks. Two types of CO2 storage are considered in this work, that is, sinks with fixed life and sinks with fixed capacity. A new CCUS Mapping Diagram is presented to show the capture of CO2 to the individual sinks. Four illustrative examples demonstrate the applicability of the proposed methodology to the CCUS systems in which purity is not a constraint in CO2 utilization. In some cases, the improved methodology overcomes the pitfall of the previous method by identifying rigorous CCUS targets.