Figure | The four primary separation mechanisms in DAC processes. (i) 'Absorption', which works by binding the CO 2 within a liquid; (ii) 'Adsorption', which works by binding the CO 2 to the surface of a solid; (iii) 'Membrane' that separates via different diffusion abilities; and (iv) 'Cryogenic' process that desublimates (phase change from gas directly to solid without an intermediate liquid phase) CO 2 based on the higher freezing point compared to other atmospheric gasses. The CO 2 produced from the main separation processes is directed for further conditioning and storage. In absorption and adsorption technologies different drivers for the regeneration of the material can be applied, including water (steam or humidity), electricity, and heat, which results in 11 DAC technology categories (see and DAC companies which are primarily focused on the production of e-fuels instead of generating negative emissions (e.g., Aircela, 91 Prometheus, 92 and RedoxNRG, Terraform Industries 94 ).