(90d) A Dynamic Framework for Developing Integrated CO2 Capture, Utilization and Storage System Toward Large-Scale Removal of CO2 Emissions

CO₂ capture and utilization/storage (CCU/S) have been identified as necessary technologies for reducing greenhouse gas (CO₂ equivalent) emissions. CCS can contribute to remove large CO₂ amount, but needs high cost-expenses for CO₂ capture, liquefaction, transport, and injection. CCU can create some added values but requires large energy consumption while reducing only modest CO₂ emission amount. Thus, large-scale implementation of either CCU or CCS faces some technical and economic challenges. These issues have fueled increasing interest in integrating CCU and CCS for abating large-scale CO₂ sources economically.

In this study, we proposed a dynamic framework for developing integrated CO₂ capture, utilization and storage systems, contributing to mitigate large-scale CO₂ emission sources. The framework includes four main modules:

• Input data platform contains basic data required for evaluating economic benefit and CO₂ emission reduction (i.e., market price and life cycle CO₂ emissions).
• Process data platform contains mass and heat balance data of the CCUS processes. These are obtained via rigorous process design and simulation.
• Multi-criteria evaluation model includes two evaluation indicators: net present value (NPV) and potential CO₂ reduction (PCR). Here, NPV and PCR are modelled as functions of the amounts of CO₂ stored/utilized.
• Optimization solver, What’s Best (an add-in to Excel), optimizes the NPV and PCR functions by finding optimal CO₂ amounts for storage and each utilization pathway.

Based on the framework, a CCUS superstructure producing methane and methanol was developed. The resilience of NPV and PCR optimization results is examined, considering dynamic change of different external factors (hydrogen source supplied for methane and methanol production and its availability, and carbon tax rate).

The results show that different CCUS configurations can be output, depending on the changing of the external factors. Under a carbon tax rate of $250/ton CO₂, if grey hydrogen is used, CO₂ geological storage alone is the most profitable configuration. However, if green hydrogen with a reduced cost of $2/kg is used, integrating CO₂ geological storage with methane production is necessary to attain high economic benefit and net CO₂ reduction. If the same kind of green hydrogen is used under a carbon tax rate lower than $250/ton CO₂, integrating methane and methanol production processes is the best strategy for reducing economic loss.

Based on the proposed framework, the potential prices of purchasing hydrogen and selling the CCU products can also be estimated, providing direct insight into economic competitiveness of CCUS systems. Therefore, besides supporting different stakeholders to make decisions in developing optimal CCUS systems, the results obtained in this study can also be considered as a foundation for advancing production technologies and supply chain of hydrogen.