Direct air capture

Direct air capture (DAC) is the use of chemical or physical processes to extract carbon dioxide (CO2) directly from the ambient air. If the extracted CO2 is then sequestered in safe long-term storage, the overall process is called direct air carbon capture and sequestration (DACCS), achieving carbon dioxide removal. Systems that engage in such a process are referred to as negative emissions technologies (NET). DAC is in contrast to carbon capture and storage (CCS), which captures CO2 from point sources, such as a cement factory or a bioenergy plant. After the capture, DAC generates a concentrated stream of CO2 for sequestration or utilization. Carbon dioxide removal is achieved when ambient air makes contact with chemical media, typically an aqueous alkaline solvent or sorbents. These chemical media are subsequently stripped of CO2 through the application of energy (namely heat), resulting in a CO2 stream that can undergo dehydration and compression, while simultaneously regenerating the chemical media for reuse. DAC has yet to be integrated into emissions trading because, at over US$1000, the cost per ton of carbon dioxide is many times the carbon price. The current high cost of DAC is driven by the scale of deployment and energy factors. In 2025 DAC costs exceeded $1000 per tonne CO2. Some claim that for plant scales of 1 Mtpa (million tonnes per annum) and above, DAC cost could be reduced below $200 per tonne of atmospheric CO2 removed, but others dispute this. Future innovations may reduce the energy intensity of this process. DAC was suggested in 1999 and is still in development. Several commercial plants are planned or in operation in Europe and the US. Large-scale DAC deployment may be accelerated when connected with economical applications or policy incentives. In contrast to carbon capture and storage (CCS) which captures emissions from a...