Preprint: outdoor moisture-driven pilot could deliver about 100 g of CO2 a day
What was demonstrated
A resin sorbent captured CO2 from ambient air, then released it into an alkaline aqueous medium when moistened. A small pilot-scale system, which the abstract says could deliver about 100 g of CO2 per day, was operated outdoors in a 4.2 m² raceway pond. A lab-scale system delivered about 1 g of CO2 per day in a laminar flow hood. The abstract does not state the outdoor test duration, location or humidity conditions.
Why it matters
The result shows that a sorbent can be cycled by moisture rather than by heat or vacuum, at a small pilot scale outdoors. If the sorbent can be made more water-repellent while keeping its CO2 binding capacity, this route could reduce the energy needed for direct air capture, as the authors estimate for an aspirational scenario.
Caveats
- The 100 g per day figure is from a small pilot in a 4.2 m² pond. It is far below the scale of any commercial direct air capture plant, and the abstract does not give test duration, location or humidity conditions.
- The sorbent takes up about 330 wt.% water in its packets, so water use is roughly 33 times the thermodynamic limit. The authors say future sorbents must become more hydrophobic while keeping or increasing their capacity for CO2.
- The up to 87% lower energy use is modelled for an aspirational sorbent with 4 mmol CO2 per gram and 50 wt.% water uptake. The cost estimates in the abstract are model results for a practical and an aspirational scenario, not measured costs.
Technology profiles
Sources
- preprint
Design and demonstration of a direct air capture system with moisture-driven CO2 delivery into aqueous medium
Justin Flory, et al.. arXiv, 4 Aug 2025.
Last reviewed 21 Oct 2026.