This week’s publications cover a wide range of issues related to direct air capture, marine CDR and the use of biomass as a natural CDR method.
In Pursuit of Carbon Neutrality: Progresses and Innovations in Sorbents for Direct Air Capture of CO2
Abstract
Direct air capture (DAC) is of immense current interest, as a means to facilitate CO2 capture at low concentrations (~400 ppm) directly from the atmosphere, with the aim to address global warming caused by excessive anthropogenic CO2 production. Traditionally, DAC of CO2 has relied on amine scrubbing and metal carbonate /hydroxide solutions. However, recent years have seen notable progress in DAC sorbents, with key advancements aimed at improving efficiency, capacity, and regenerability while reducing energy consumption. This review delivers an exhaustive analysis of contemporary developments in DAC sorbents, addressing the innovations in material design and consequent performance enhancement. The limitations of the sorbents have also been discussed, with future perspectives for improving sustainable CO2 capture strategies. We anticipate that this overview will help lay the groundwork for further development and large scale implementation of sustainable sorbents and cutting-edge technologies towards attaining carbon neutrality.
Podder, S. et al. (2025) In Pursuit of Carbon Neutrality: Progresses and Innovations in Sorbents for Direct Air Capture of CO2. Chemistry A European Journal.
Read the full paper here: In Pursuit of Carbon Neutrality: Progresses and Innovations in Sorbents for Direct Air Capture of CO2. Chemistry A European Journal.
The Effect of Model Resolution on Air-Sea CO2 Equilibration Timescales
Abstract
Marine Carbon Dioxide Removal (mCDR) will likely play a role in aspirations to keep global warming below 2°C. mCDR methods create a deficit in dissolved inorganic carbon concentration (DIC), relative to the unperturbed counterfactual. This DIC deficit induces either an uptake of atmospheric CO2 or reduced CO2 outgassing into the atmosphere. The immediate climatic benefit of mCDR depends on air-sea CO2 equilibration before the DIC deficit in the surface ocean loses contact with the atmosphere through water mass subduction. Air-sea CO2 equilibration is governed by surface ocean dynamics and occurs over vast ocean regions, which are too large to constrain equilibration with current in situ observations. As such, numerical modeling is needed to evaluate spatial and temporal scales of air-sea CO2 equilibration. This study employs the ACCESS-OM2 model at three resolutions (0.1°, 0.25°, and 1°) to evaluate the dependency of simulated equilibration timescales on model resolution. Results indicate that model resolution has limited influence on equilibration timescales in the tropics but exerts a more significant effect in polar regions. However, the air-sea CO2 exchange locations may vary significantly with resolution within the same model, particularly in regions of high kinetic energy. We developed novel software to visualize the DIC deficit. The comparison of our results with simulations made with other ocean models further suggests that differences due to model resolution are smaller than differences between different models of similar resolutions. Our results are one step forward in evaluating the robustness of model-based assessments of air-sea CO2 equilibration timescales.
Xie, Y. et al. (2025) The Effect of Model Resolution on Air-Sea CO2 Equilibration Timescales. ESS Open Archive.
Read the full paper here: The Effect of Model Resolution on Air-Sea CO2 Equilibration Timescales. ESS Open Archive.
The Co-Benefits of Integrating Carbon Dioxide Removal in the Energy System: A Review from the Prism of Natural Climate Solutions
Abstract
Anthropogenic activities such as fossil fuel combustion and land use changes are increasing atmospheric CO2 concentrations, driving climate change. These emissions are distributed across three natural reservoirs: the atmosphere, land, and oceans. Climate change mitigation necessitates rapid reductions in greenhouse gas emissions and the removal of residual atmospheric CO2. However, among the solutions, Carbon Dioxide Removal (CDR) methods—especially Natural Climate Solutions (NCS)—are gaining attention. In this review, we explore how the energy system, a major contributor to climate change, can integrate these solutions. Thus, we present different CDR highlighting the role of NCS while determining their link to the energy system using biomass as renewable energy source through Bioenergy Carbon Capture and Storage. Hence, we schematized the pathways which depict their multiple roles like providing negative emissions A comparative evaluation of CDR methods identifies the affected components of ecosystems and energy systems. Additionally, this paper emphasizes that NCS not only eliminates carbon but also offers ecosystem benefits, such as enhanced biodiversity and agricultural productivity, while contributing to climate adaptation. The challenges, including land-use constraints and long-term sustainability, are underscored as critical to maximizing the effectiveness of CDR, which remains essential for achieving climate mitigation goals.
Chlela, S. et al. (2025) The Co-Benefits of Integrating Carbon Dioxide Removal in the Energy System: A Review from the Prism of Natural Climate Solutions. 976 (179271) Science of the Total Environment.
Read the full paper here: The Co-Benefits of Integrating Carbon Dioxide Removal in the Energy System: A Review from the Prism of Natural Climate Solutions. Science of the Total Environment.
In-Situ Engineering of Amine-Functionalized Layered Double Hydroxide Nanosheets for Highly Enhanced Efficiency in Direct Air Capture of CO2
Abstract
The development of amine-functionalized adsorbents represents a significant advancement in direct air capture (DAC) technologies for carbon dioxide (CO2) mitigation. Layered double hydroxides (LDHs) offer numerous benefits for DAC applications, including abundant adsorption sites, cost-effectiveness, and alkali resistance, making them ideal for amine loading. However, the conventional impregnation method (C-Im) leads to reduced surface area and platelet aggregation, impeding amine uniform dispersion. This study introduces a novel aqueous miscible organic solvent impregnation method (A-Im) for the in-situ loading of three alkyl primary diamines onto magnesium (Mg) and aluminum (Al)-based LDHs. CO2 adsorption isotherms demonstrated that the amine-functionalized LDHs synthesized via A-Im (LDH-A-AM) significantly outperformed C-Im counterparts (LDH-C-AM), with LDH-A-EDA achieving the highest CO2 adsorption capacity of 0.80 mmol/g at 0.4 mbar and 2.71 mmol/g at 1.0 bar, representing 40 and 8.7 times higher capacities, respectively, than that of LDH-C without amine. Adsorption kinetic studies revealed a rapid adsorption rate of 0.052 mmol/(g·min) and an impressive regeneration performance of 86 % after 10 cycles. Under humid conditions, CO2 breakthrough experiments demonstrated that LDH-A-EDA possessed enhanced CO2 adsorption capacities across varying relative humidity (0–75 %). The DAC mechanism elucidated that LDH-A-AM adsorbed CO2 via both physisorption and chemisorption by enhanced –OH and –NH2 sites. These findings position LDHs as effective carriers for amines, advancing CO2 capture technologies and contributing to sustainable climate solutions.
Jin, Y. et al. (2025) In-Situ Engineering of Amine-Functionalized Layered Double Hydroxide Nanosheets for Highly Enhanced Efficiency in Direct Air Capture of CO2. 367 Separation and Purification Technology 132882.
Read the full paper here: In-Situ Engineering of Amine-Functionalized Layered Double Hydroxide Nanosheets for Highly Enhanced Efficiency in Direct Air Capture of CO2. Separation and Purification Technology.
Connecting Material Characteristics with System Properties for Membrane-Based Direct Air Capture (m-DAC) Using Process Operability and Inverse Design Approaches
Abstract
This paper presents a process modeling approach for a two-staged membrane-based direct air capture (m-DAC) process, considering material characteristics, membrane separation, and system properties. m-DAC is a negative emissions technology for capturing dilute CO2 from air. Its continuous and modular nature could reduce economic challenges compared to sorption-based processes, which require costly regeneration. Facilitated transport membranes, with specialized CO2 carriers, offer higher performance than traditional sorption-diffusion membranes. Their key properties-the CO2 apparent diffusion coefficient (𝐷CO2 DCO2) and equilibrium constant (Keq)-determine membrane separation properties such as CO2 permeance and CO2/N2 selectivity. This work maps these inputs to feasible output spaces such as for CO2 recovery, purity, and capture cost. Additionally, inverse design is used to determine the required membrane properties for target system outcomes. Overall, this study provides a framework for membrane researchers to design cost-effective, scalable m-DAC solutions.
Gama, V. et al. (2025) Connecting Material Characteristics with System Properties for Membrane-Based Direct Air Capture (m-DAC) Using Process Operability and Inverse Design Approaches. Industrial & Engineering Chemistry Research.
Read the full paper here: Connecting Material Characteristics with System Properties for Membrane-Based Direct Air Capture (m-DAC) Using Process Operability and Inverse Design Approaches. Industrial & Engineering Chemistry Research.