Global warming is caused by the increasing concentration of carbon dioxide in the atmosphere. Our society is therefore forced to drastically reduce carbon dioxide emissions. As this is unlikely to be sufficient, also negative emission technologies (NET) will play an important role in limiting the temperature rise. Direct air capture (DAC) is a NET technology that directly captures carbon dioxide from the atmosphere. DAC systems are based on the processes of absorption or adsorption, followed by its desorption. Carbon dioxide is chemically or physically (depending on the used technology) bound to the sorbent. This is followed by the regeneration of the sorbent, which is achieved by supplying energy and releasing almost completely pure carbon dioxide. The gas obtained in this way can be used as for example in the production of synthetic fuels, sparkling drinks, in the synthesis processes of various chemicals and in the extraction of oil or natural gas. Another options to remove carbon dioxide from air is its the storage of carbon dioxide in rocks.
DAC is a young technology and is therefore still at the beginning of its development. The main problem are the high operational costs mainly due to the large amount of energy required to regenerate the sorbent. This is the main reason, why the future of DAC technologies is still uncertain. Nevertheless, significant technical improvements can be expected in the coming decades.
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