High Water Footprint. High water use is an obstacle for certain DAC approaches (e.g., absorption-based DAC technologies, humidity swing) or DACCS systems (depending on material synthesis procedure or CO 2 storage option). For example, technologies 1A and 1C require a great amount of make-up water (4.38 tonnes per tonne of CO 2 23 ) due to solvent volatility and/or water losses during process operation. Consequently, a 1MT DAC facility could require nearly 13,000 tonnes of make-up water a day in a dry region. Lack of geographical inventories and water risk assessments, including information on scarcity, is an obstacle for understanding and evaluating the scale and relevance of the potential environmental impacts related to water use. However, DACCS may rate favorably in terms of water usage compared to other CDR solutions, such as BECCS, where it may present an even higher burden for massive scale-up. Land Transformation and High Footprint. It is unclear how much land area DACCS installations require given that available data generally focuses on the DAC unit and not on the wider DACCS system (see Table ). The physical footprint depends not only on the removal efficiency of the DAC unit and its design characteristics, but also on DACCS system-level configuration and integration. For instance, if land requirements of energy production are taken into consideration, overall land use may be quite significant (e.g., use of photovoltaics to power DAC units). Also, due to an expected increase in population and the electrification of energy systems, it is likely that DACCS will compete with agriculture for land availability and with other industries on land transformation. If DACCS is integrated into existing industrial clusters, waste heat, if available from other industrial processes, can be used to support the DAC unit operation. It may also be possible to supply the CO 2 product stream into existing CCUS chains by integrating DACCS and CCUS. However, studies from such integrations are not currently unavailable.