Given the homogeneous atmospheric CO 2 concentration levels around the world, DAC facilities can be deployed in locations that provide abundant cheap and carbon-free energy and/or that are close to pipeline infrastructure, underground storage, or utilization facilities for reducing the CO 2 transportation cost 3. Direct Air Capture (DAC), despite being at an early stage of development, is gaining increasing attention and recognized as a promising climate change mitigation strategy 1. Most IPCC emission scenarios overshoot the carbon budget at first and then remove excess carbon via Carbon Dioxide Removal (CDR) technologies, i.e., intentional efforts to remove CO 2 from the atmosphere and store it on land or in the oceans on the order of 200–1200 Gt CO 2 toward the year 2100 2.ĬDR strategies include the enhancement of natural above- and belowground carbon sinks in plants, rock formations, and soils as well as scalable engineering solutions designed to sequester, store, or utilize concentrated atmospheric CO 2. The remaining global carbon budget of 420–1170 gigatonnes (Gt) CO 2 is expected to be depleted in 10–30 years under present annual emission rates and projected Nationally Determined Contributions (NDCs) 2. DAC deployment aids the achievement of long-term climate targets, its environmental and climate performance however depend on sectoral mitigation actions, and thus should not suggest a relaxation of sectoral decarbonization targets.Ĭlimate change mitigation scenarios used by the Intergovernmental Panel on Climate Change (IPCC) 1 suggest that a rapid decarbonization in energy and material related services is likely to be insufficient to keep global mean temperature increase well below 2 ☌ by the end of the 21st century. DAC exhibits regional environmental impact variations, highlighting the importance of smart siting related to energy system planning and integration. These increases can be reduced by improvements in DAC material and energy use efficiencies. Decarbonizing the electricity sector improves the sequestration efficiency, but also increases the terrestrial ecotoxicity and metal depletion levels per tonne of CO 2 sequestered via DAC.
DIRECT AIR CAPTURE SERIES
Performing a prospective life cycle assessment for two promising technologies in a series of climate change mitigation scenarios, we find that electricity sector decarbonization and DAC technology improvements are both indispensable to avoid environmental problem-shifting. Direct air capture (DAC) is critical for achieving stringent climate targets, yet the environmental implications of its large-scale deployment have not been evaluated in this context.
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