Editing IPCC:AR6/WGI/Chapter-5 (section)

===== 5.6.2.2.4 Chemical CDR methods =====

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Direct air carbon capture with carbon storage (DACCS) is a combination of two techniques, direct capture of CO <sub>2</sub> from ambient air (DAC) and carbon storage. DAC entails contacting the air, capturing the CO <sub>2</sub> on a liquid solvent or solid sorbent, and regenerating the solvent or sorbent. Different DAC methods have been proposed, which differ by the chemical process used to capture the CO <sub>2</sub> and to recover it from the sorbent or solvent ( [[#NASEM--2019|NASEM, 2019]] ). The captured CO <sub>2</sub> may be either stored geologically as a high-pressure gas or sequestered by a mineral carbonation process. Storage is potentially permanent in both pressurised gas and mineral form ( [[#Fuss--2018|Fuss et al., 2018]] ). DACCS has significant requirements of energy and, (depending on the type of technology), water and materials ( [[#Smith--2016|Smith et al., 2016]] ; [[#NASEM--2019|NASEM, 2019]] ). Compared to other CDR methods, it has a small land footprint ( [[#Smith--2016|Smith et al., 2016]] ; [[#NASEM--2019|NASEM, 2019]] ). Side effects of DACCS include CO <sub>2</sub> -depleted air leaving the air contactor, which could have adverse effects on crop and ecosystem productivity, and VOC emissions ( [[#NASEM--2019|NASEM, 2019]] ). Additional risks and side effects are related to the high pressure at which CO <sub>2</sub> is stored in geologic formations ( [[#Fuss--2018|Fuss et al., 2018]] ). DACCS is assessed in detail in WGIII Chapter 12.

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