An alternative to CO2 sequestration from industrial plants is to capture it directly from the environment. Ambient air is typically pushed by fans toward filters where CO2 is absorbed or adsorbed, then pure CO2 is released by heating the sorbent. Direct air capture (DAC) has the potential to achieve negative emissions if clean energy is used in the process without generating extra CO2. DAC plants are small and can be placed where needed, such as near carbon storage, use, or emission sites. DAC projects have recently been strongly supported by substantial funding, and 19 DAC plants have been established worldwide. Unfortunately, because of the very low CO2 concentration in the atmosphere (412 ppm), the theoretical energy required to capture one ton of CO2 from air is several times that of capturing it from power plant emissions, and the current cost of capture is higher than the price of CO2 so DAC is not profitable today.