Abstract
This study evaluates two integrated pathways for synthetic natural gas (SNG) production via direct air capture (DAC) and utilisation: Dual-Function Material (DFM) technology and Temperature-Vacuum Swing Adsorption (TVSA) combined with a Sabatier reactor. DFM technology, which combines CO₂ capture and methanation in a single unit, is compared against the more established TVSA-Sabatier process regarding techno-economic feasibility. Superstructure optimisation is employed to assess the performance of these two pathways across various upstream and downstream operating units and to examine the impact of different design factors on economic outcomes. For a capturing scenario of 10,000 tCO2/year, results indicate that DFM technology presents promise, reaching an estimated cost of $740/tCO2 (assuming a 7% interest rate) under optimal conditions, comparable to the TVSA-Sabatier pathway. Sensitivity analysis underscores the importance of interest rates, energy prices, and carbon credits, highlighting the potential of policy support in facilitating DFM technology. Comparative findings suggest that DFM can potentially reduce equipment complexity and energy use through in situ heat integration however, it requires further thermo-kinetic analysis and experimental validation. Future research is needed on kinetic modelling of DFM's and advancements are also required in material adsorption performance, more cost-effective catalyst alternatives, and addressing limitations related to pressure drop in further process intensification efforts. This study offers a comprehensive benchmark for DAC-to-SNG processes, indicating that while DFM technology demonstrates potential for streamlined operations and cost savings, targeted advancements are essential for commercial viability, contributing critical insights to sustainable carbon capture and utilisation strategies.