Trend AnalysisOther Sciences
Direct Air Capture: Can We Vacuum CO₂ from the Atmosphere at Scale?
Direct Air Capture removes CO₂ directly from ambient air—but at current costs of $400-1000/ton, it is far from economically viable at climate-relevant scale. Recent advances in polymer sorbents, 3D-printed contactors, and warehouse-scale automation are pushing costs down, but significant gaps remain.
By Sean K.S. Shin
This blog summarizes research trends based on published paper abstracts. Specific numbers or findings may contain inaccuracies. For scholarly rigor, always consult the original papers cited in each post.
To limit warming to 1.5°C, the IPCC estimates that 5-16 billion tons of CO₂ must be removed from the atmosphere annually by 2050—in addition to rapid emissions reductions. Direct Air Capture (DAC), which uses chemical processes to extract CO₂ directly from ambient air, is one of the few technologies that can in principle achieve this at any location, regardless of emission source. But current DAC costs ($400-1000 per ton of CO₂) and energy requirements make it far from economically viable at climate-relevant scale. The research frontier is cost reduction—through better sorbents, more efficient contactors, and smarter engineering.
The Research Landscape
Kim, Holmes, and Wang (2025), with 16 citations in Advanced Functional Materials, present a materials engineering advance: 3D-printed polymer-sorbent contactors with complex geometries that improve heat and mass transfer rates while minimizing pressure drops.
The innovation is the contactor geometry. Traditional DAC contactors use packed beds or honeycombs—simple geometries that are easy to manufacture but suboptimal for gas-solid contact. Kim et al. use triply periodic minimal surfaces (TPMS)—complex, mathematically defined geometries that maximize surface area while maintaining open channels for airflow. These geometries cannot be manufactured by conventional methods but can be 3D-printed using a novel templated phase inversion process.
Performance results: TPMS contactors achieve 30-50% higher CO₂ capture rates per unit volume compared to conventional honeycomb geometries, while maintaining acceptable pressure drops. If this translates to full-scale systems, it could reduce the physical footprint and capital cost of DAC installations.
Membrane Adsorbents
Tran, Singh, and Cheng (2024), with 13 citations in ACS Applied Materials & Interfaces, develop highly porous membrane adsorbents comprising branched polyethyleneimine (PEI) on porous polymer supports. The key advantage is manufacturability: membranes can be produced in roll-to-roll processes at industrial scale, unlike many specialized sorbents that require batch synthesis.
Performance: CO₂ sorption capacity of ~2.2 mmol/g under ambient conditions—competitive with the best solid sorbents reported in the literature. The membranes maintain capacity over 100+ adsorption-desorption cycles with minimal degradation, addressing the durability concern that has limited other sorbent approaches.
Warehouse-Scale Automation
McQueen and Drennan (2024), with 7 citations, take an engineering systems approach. Rather than developing novel sorbents, they propose using existing materials (calcium carbonate/lime) with existing automation technology (warehouse robotics) to build scalable, low-cost DAC systems.
Their approach works by: spreading thin layers of calcium carbonate on trays → exposing trays to ambient air for CO₂ absorption → collecting trays using warehouse robots → heating the calcium carbonate to release pure CO₂. The process is simple—limestone weathering accelerated by engineering—and the automation technology is mature and commercially available.
The estimated cost is $50-200/ton CO₂, depending on energy source and system scale—substantially lower than current DAC systems. The trade-off is slower capture kinetics (the process takes days rather than hours per cycle) and larger land footprint.
Polymer Sorbent Overview
Shokrollahzadeh Behbahani and Green (2025), with 2 citations, review the broader landscape of polymeric materials for DAC, categorizing them as:
- Amine-functionalized polymers: Currently the most studied. Strong CO₂ affinity but susceptible to degradation in humid conditions.
- Ionic liquid-based polymers: Stable and selective but expensive.
- Bio-inspired polymers: Mimicking carbonic anhydrase enzyme for CO₂ hydration. Promising but early-stage.
- Polymer supports: Providing mechanical structure for active sorbents (as in Tran et al.'s membrane approach).
Critical Analysis: Claims and Evidence
<
| Claim | Evidence | Verdict |
|---|
| TPMS geometries improve capture rates by 30-50% | Kim et al.'s 3D-printing experiments | ✅ Supported — at lab scale |
| Roll-to-roll membrane sorbents are durable over 100+ cycles | Tran et al.'s cycling experiments | ✅ Supported |
| Warehouse-automation DAC can reach $50-200/ton | McQueen & Drennan's engineering estimates | ⚠️ Uncertain — estimates, not demonstrated at scale |
| Polymer sorbents offer a scalable path to low-cost DAC | Shokrollahzadeh Behbahani & Green's review | ⚠️ Uncertain — promising materials; scale-up challenges remain |
Open Questions
Energy source: DAC requires significant energy for sorbent regeneration. If that energy comes from fossil fuels, the net carbon removal is reduced. Coupling DAC with renewable energy is essential but adds cost and complexity.
What to do with the CO₂: Captured CO₂ must be permanently stored (geological sequestration) or utilized (converted to fuels, materials, or chemicals). The storage/utilization infrastructure is as important as the capture technology.
Market development: At current costs, DAC relies on voluntary carbon markets and government subsidies. When will costs decrease enough for market-driven deployment?
Land and water use: Large-scale DAC requires substantial land (for contactors) and potentially water (for some sorbent processes). How should this be managed in land- and water-scarce regions?What This Means for Your Research
For chemical engineers, the contactor geometry (Kim et al.) and membrane manufacturing (Tran et al.) advances represent the most actionable near-term cost reduction pathways. For climate policy researchers, the cost range ($50-1000/ton depending on approach) determines where DAC fits in the portfolio of climate solutions.
Explore related work through ORAA ResearchBrain.
To limit warming to 1.5°C, the IPCC estimates that 5-16 billion tons of CO₂ must be removed from the atmosphere annually by 2050—in addition to rapid emissions reductions. Direct Air Capture (DAC), which uses chemical processes to extract CO₂ directly from ambient air, is one of the few technologies that can in principle achieve this at any location, regardless of emission source. But current DAC costs ($400-1000 per ton of CO₂) and energy requirements make it far from economically viable at climate-relevant scale. The research frontier is cost reduction—through better sorbents, more efficient contactors, and smarter engineering.
The Research Landscape
3D-Printed Sorbent Contactors
Kim, Holmes, and Wang (2025), with 16 citations in Advanced Functional Materials, present a materials engineering advance: 3D-printed polymer-sorbent contactors with complex geometries that improve heat and mass transfer rates while minimizing pressure drops.
The innovation is the contactor geometry. Traditional DAC contactors use packed beds or honeycombs—simple geometries that are easy to manufacture but suboptimal for gas-solid contact. Kim et al. use triply periodic minimal surfaces (TPMS)—complex, mathematically defined geometries that maximize surface area while maintaining open channels for airflow. These geometries cannot be manufactured by conventional methods but can be 3D-printed using a novel templated phase inversion process.
Performance results: TPMS contactors achieve 30-50% higher CO₂ capture rates per unit volume compared to conventional honeycomb geometries, while maintaining acceptable pressure drops. If this translates to full-scale systems, it could reduce the physical footprint and capital cost of DAC installations.
Membrane Adsorbents
Tran, Singh, and Cheng (2024), with 13 citations in ACS Applied Materials & Interfaces, develop highly porous membrane adsorbents comprising branched polyethyleneimine (PEI) on porous polymer supports. The key advantage is manufacturability: membranes can be produced in roll-to-roll processes at industrial scale, unlike many specialized sorbents that require batch synthesis.
Performance: CO₂ sorption capacity of ~2.2 mmol/g under ambient conditions—competitive with the best solid sorbents reported in the literature. The membranes maintain capacity over 100+ adsorption-desorption cycles with minimal degradation, addressing the durability concern that has limited other sorbent approaches.
Warehouse-Scale Automation
McQueen and Drennan (2024), with 7 citations, take an engineering systems approach. Rather than developing novel sorbents, they propose using existing materials (calcium carbonate/lime) with existing automation technology (warehouse robotics) to build scalable, low-cost DAC systems.
Their approach works by: spreading thin layers of calcium carbonate on trays → exposing trays to ambient air for CO₂ absorption → collecting trays using warehouse robots → heating the calcium carbonate to release pure CO₂. The process is simple—limestone weathering accelerated by engineering—and the automation technology is mature and commercially available.
The estimated cost is $50-200/ton CO₂, depending on energy source and system scale—substantially lower than current DAC systems. The trade-off is slower capture kinetics (the process takes days rather than hours per cycle) and larger land footprint.
Polymer Sorbent Overview
Shokrollahzadeh Behbahani and Green (2025), with 2 citations, review the broader landscape of polymeric materials for DAC, categorizing them as:
- Amine-functionalized polymers: Currently the most studied. Strong CO₂ affinity but susceptible to degradation in humid conditions.
- Ionic liquid-based polymers: Stable and selective but expensive.
- Bio-inspired polymers: Mimicking carbonic anhydrase enzyme for CO₂ hydration. Promising but early-stage.
- Polymer supports: Providing mechanical structure for active sorbents (as in Tran et al.'s membrane approach).
Critical Analysis: Claims and Evidence
<
| Claim | Evidence | Verdict |
|---|
| TPMS geometries improve capture rates by 30-50% | Kim et al.'s 3D-printing experiments | ✅ Supported — at lab scale |
| Roll-to-roll membrane sorbents are durable over 100+ cycles | Tran et al.'s cycling experiments | ✅ Supported |
| Warehouse-automation DAC can reach $50-200/ton | McQueen & Drennan's engineering estimates | ⚠️ Uncertain — estimates, not demonstrated at scale |
| Polymer sorbents offer a scalable path to low-cost DAC | Shokrollahzadeh Behbahani & Green's review | ⚠️ Uncertain — promising materials; scale-up challenges remain |
Open Questions
Energy source: DAC requires significant energy for sorbent regeneration. If that energy comes from fossil fuels, the net carbon removal is reduced. Coupling DAC with renewable energy is essential but adds cost and complexity.
What to do with the CO₂: Captured CO₂ must be permanently stored (geological sequestration) or utilized (converted to fuels, materials, or chemicals). The storage/utilization infrastructure is as important as the capture technology.
Market development: At current costs, DAC relies on voluntary carbon markets and government subsidies. When will costs decrease enough for market-driven deployment?
Land and water use: Large-scale DAC requires substantial land (for contactors) and potentially water (for some sorbent processes). How should this be managed in land- and water-scarce regions?What This Means for Your Research
For chemical engineers, the contactor geometry (Kim et al.) and membrane manufacturing (Tran et al.) advances represent the most actionable near-term cost reduction pathways. For climate policy researchers, the cost range ($50-1000/ton depending on approach) determines where DAC fits in the portfolio of climate solutions.
Explore related work through ORAA ResearchBrain.
References (4)
[1] Kim, S.-Y., Holmes, H.E., & Wang, Y. (2025). Polymer-Sorbent Direct Air Capture Contactors with Complex Geometries 3D-Printed via Templated Phase Inversion. Advanced Functional Materials.
[2] Tran, T.N., Singh, S., & Cheng, S. (2024). Scalable and Highly Porous Membrane Adsorbents for Direct Air Capture of CO2. ACS Applied Materials & Interfaces.
[3] McQueen, N. & Drennan, D. (2024). The use of warehouse automation technology for scalable and low-cost direct air capture. Frontiers in Climate.
[4] Shokrollahzadeh Behbahani, H. & Green, M.D. (2025). Polymers in direct air capture: a mini review. Polymer International.