A review of direct air capture (DAC): scaling up commercial technologies and innovating for the future

Direct air capture (DAC) can provide an impactful, engineered approach to combat climate change by removing carbon dioxide (CO 2 ) from the air. However, to meet climate goals, DAC needs to be scaled at a rapid rate. Current DAC approaches use engineered contactors filled with chemicals to repeatedly capture CO 2 from the air and release high purity CO 2 that can be stored or otherwise used. This review article focuses on two distinctive, commercial DAC processes to bind with CO 2 : solid sorbents and liquid solvents. We discuss the properties of solvents and sorbents, including mass transfer, heat transfer and chemical kinetics, as well as how these properties influence the design and cost of the DAC process. Further, we provide a novel overview of the considerations for deploying these DAC technologies, including concepts for learning-by-doing that may drive down costs and material requirements for scaling up DAC technologies.