Flexibility in adsorption-based direct air capture: drivers, mechanisms, and research needs

Direct Air Capture (DAC) is key for net-zero goals, but its high energy demand and costs prevent large-scale deployment. Leveraging time-varying external drivers — renewables availability, electricity prices, ambient conditions, and downstream CO 2 demand — offers a promising pathway to improve its cost-effectiveness. We define flexibility in DAC as the ability to operate under time-varying boundary conditions while maintaining adequate performance. We distinguish between flexibility by design (inherent robustness) and flexibility by operation (dynamic adaptation). Focusing on adsorption-based DAC, we classify flexibility mechanisms into system-level and process-level approaches. Key needs include dynamic modeling, integration of temporal variability in experiments, and multi-scale frameworks linking process and systems.