Direct Air Capture (DAC) removes carbon dioxide (CO2) directly from the air around us. While there are many approaches to DAC, most follow this two-step formula:
Step 1: ambient air flows through building-like structures where CO2 sticks to specially formulated chemicals or surfaces.
Step 2: the trapped CO2 is released by applying heat or electricity in a controlled way. The end result is a separated stream of CO2 that can be compressed and sent to storage, keeping it out of the atmosphere for many years to come.
What are the benefits of DAC?
DAC has almost unlimited potential to remove carbon from the atmosphere. It doesn’t need to be placed on arable land so it won’t take up valuable land required for crops and other nature-based solutions, like planting trees. DAC is a pathway to durable carbon removal, meaning that when designed properly it will keep CO2 out of the atmosphere for a very long time. DAC has a much lower land footprint than some other solutions, meaning it takes up less space. And DAC has the potential to be a strong local economic driver, bringing permanent, good-paying jobs to the area.
What are the risks with DAC?
Some fear that DAC, and carbon dioxide removal in general, enables us to continue emitting without concern (like exercising to justify that ice cream sundae). Use of bulk chemicals for CO2 removal could present an environmental hazard risk at the site or along upstream or downstream transport of materials and spent reagents. The same risk applies to transporting CO2 to storage when co-location is not possible. While land intensity remains lower than other solutions, the scale of DAC required for our climate goals will still require vast amounts of land use. These impacts will need to be carefully examined and DAC siting should adhere to best practices regarding community engagement and avoiding environmental disruption.
Where can I learn more?
For a more technical overview, check out our quick primer.
For more information on DAC and other carbon removal technologies, check out our CDR primer.
For a general review of DAC and responsible scaling, check out or work with WRI or this paper from our group.
Our group at Penn is developing spatial analyses to identify areas suitable for DAC deployment in an environmentally just way. If you are interested in learning more about it, or our research in general, please contact ceclab@seas.upenn.edu