This week’s publications highlight cover a wide range of issues related to direct air capture, ocean alkalinity enhancement, biochar and marine CDR.
Optimizing amine-based adsorbents for direct air capture: A comprehensive review of performance under diverse climatic conditions
Abstract
Since the Industrial Revolution, the rapid rise in greenhouse gas emissions has driven a concerning increase in atmospheric CO2 levels, resulting in global warming and climate-related crises. In response, direct air capture (DAC) technology has emerged as a crucial negative-emissions solution, uniquely positioned to directly remove CO2 from the atmosphere, beyond merely targeting industrial emissions. This review provides a comprehensive analysis of solid amine-based adsorbents for DAC, focusing on both performance optimization and economic viability—two essential factors for successful commercialization. A systematic classification of solid amine-based adsorbents is presented based on sorbent classes, amine types, and support materials including metal-organic frameworks (MOFs), silica, alumina, and covalent organic frameworks (COFs). Special emphasis is given to the performance of these adsorbents under varying environmental conditions, exploring humidity levels in the range of 0–100 % relative humidity and temperatures from −20 to 40 °C. By examining these factors, the review establishes regional optimization strategies to enhance the practical deployment of DAC technology worldwide. The insights provide key recommendations for optimizing DAC deployment in diverse climatic contexts and identify priority areas for further research and development to drive the technology forward.
Jin, Y. et al. (2025) Optimizing Amine-based Adsorbents for Direct Air Capture: A Comprehensive Review of Performance under Diverse Climatic Conditions 217 (115782) Renewable and Sustainable Energy Reviews.
Read the full paper here: Optimizing Amine-based Adsorbents for Direct Air Capture: A Comprehensive Review of Performance under Diverse Climatic Conditions I Renewable and Sustainable Energy Reviews.
Influence of Wave Action on Applications of Olivine-Based Ocean Alkalinity Enhancement on Sandy Beaches
Abstract
Ocean Alkalinity Enhancement (OAE) is an emerging carbon dioxide removal approach that aims to store additional atmospheric CO2 as (bi)carbonate in seawater. OAE can be realized through a variety of pathways, one of which is the dispersal of alkaline mineral sand on beaches where wave energy shall accelerate alkalinity formation. Here, we built a “Beach-Machine” to simulate a gradient of wave energy and test its effect on alkalinity formation by olivine, a widely considered mineral for OAE. We find that wave energy strongly (linearly) increases alkalinity formation from olivine when energy input is beyond a certain threshold. However, when olivine is mixed with organic-poor sand, energy input also increases the loss of alkalinity possibly by promoting precipitation reactions thereby canceling out the benefits of waves on alkalinity formation. Our experiments show that the effects of wave energy on OAE efficiency are dependent on the sediment where olivine-based OAE is applied.
England, P. and Bach, L. (2025) Influence of Wave Action on Applications of Olivine-Based Ocean Alkalinity Enhancement on Sandy Beaches 52 (8) Geophysical Research Letters.
Read the full paper here: Influence of Wave Action on Applications of Olivine-Based Ocean Alkalinity Enhancement on Sandy Beaches I Geophysical Research Letters.
Ocean alkalinity enhancement in a coastal channel: simulating localised dispersion, carbon sequestration and ecosystem impact
Abstract
Ocean Alkalinity Enhancement (OAE) is a proposed marine carbon dioxide removal (mCDR) method that has the potential to sequester CO2 at the gigaton scale. Alkaline substances are added to the surface ocean to strengthen the air-sea pCO2 gradient and induce carbon transfer into the ocean or reduce its outgassing. While global and regional models show that OAE effectively sequesters CO2, their coarse resolution makes them inappropriate for investigating local environmental impacts and sequestration efficiency. Here, we simulate local (200 m horizontal resolution) OAE scenarios at a location where an OAE field trial is planned (Woodbridge, Tasmania) to investigate how simulations can guide the local design of OAE. Our simulations show the importance of seasonality where surface alkalinity retention, plume sizes and carbon sequestration efficiency are primarily controlled by surface stratification with wind stress and tidal currents playing a secondary role. Seasonal stratification variability modulates sequestration efficiency (ΔDIC/ΔTA) within the domain with summer values of 0.6 ± 0.1, and winter values of 0.46 ± 0.11, and no significant differences being driven by wind stress or current strength (p >0.05). In these the simulations, we show a linear scaling between the OAE injection rate and pH change at the addition location and the far field, which allows the injection rate to be modified to meet key environmental targets, for example not exceeding Australian pH guidelines (ΔpH > 0.2). We identify that pH changes return to baseline through mixing, dilution, and carbon uptake. OAE is a multi-scale problem where the impacts and efficiency encompasses the local to global scale responses. The use of local scale modelling (particularly for monitoring, reporting, and verification) is critical to enabling the future deployment of OAE for mCDR, and will need to be coupled to regional and global models to advance OAE safety, efficacy, and use.
Anderson, H. J. et al. (2025) Ocean alkalinity enhancement in a coastal channel: simulating localised dispersion, carbon sequestration and ecosystem impact. 7 (4) Environmental Research Communications.
Read the full paper here: Ocean alkalinity enhancement in a coastal channel: simulating localised dispersion, carbon sequestration and ecosystem impact I Environmental Research Communications.
Biochar as a Potential Nutrient Carrier for Agricultural Applications
Abstract
The maintenance of an adequate amount of organic matter in soil and a dynamic biogeochemical cycle of essential nutrients are key components of sustainable soil management. Biochar is a carbonized biomass derived from various feedstock materials, including wood and crop residues, manures, biosolids and animal carcasses. Biochar has been used for more than two decades as a soil amendment to improve soil physicochemical conditions and mitigate soil contamination. Nutrient-enriched biochar-based fertilizers (NEBBF) can be prepared using various nutrient enrichment procedures and have the potential to increase soil fertility and crop productivity. The application of NEBBF, which is a carbon-based nutrient source, has been shown to enhance microbial activity, thereby increasing the efficiency of nutrient use compared to conventional non-carbon-based synthetic fertilizers. This review identified key research gaps and discussed the importance and necessity of biochar as a nutrient carrier in agriculture.
Sharma, S. et al. (2025) Biochar as a Potential Nutrient Carrier for Agricultural Applications. 19 (11) Current Pollution Reports.
Read the full paper here: Biochar as a Potential Nutrient Carrier for Agricultural Applications I Current Pollution Reports.
Community perspectives on marine carbon dioxide removal and ocean alkalinity enhancement: A future scenario approach
Abstract
Minimal empirical work to date explores community perceptions of ocean alkalinity enhancement (OAE), an approach to carbon dioxide removal that is beginning to see initial field trials. Here, we explore community perceptions of OAE at a location of particular interest for ongoing and future OAE research and deployment: the Olympic Peninsula, a region in the Pacific Northwest of the US. Drawing on two workshops that make use of a future scenario approach with 38 community members, we find that views on OAE extended well beyond ecological impacts—instead orienting to specific political economic arrangements and multiple dimensions of environmental justice. Specifically, participants expressed a preference for configurations of OAE that involve the use of existing infrastructure and minimal ‘industrialization’ of coastlines, integration of established sectors and materials via ‘coupled’ models, and community or Tribal ownership models. Participants also emphasized the importance to them of different OAE configurations’ possible distributions of social benefits and burdens. Preferences were not, however, fixed or immutable: participants expressed tensions in thinking in regard to issues of climate urgency and possible deployment scales and locations. These reflections—a result of the scenario method we employed—highlight the importance of engagement approaches that encourage participants to contemplate the diverse contexts and systems in which OAE might be deployed.
Nawaz, S. and Belotti, G. (2025) Community perspectives on marine carbon dioxide removal and ocean alkalinity enhancement: A future scenario approach 125 (104080) Energy Research & Social Science.
Read the full paper here: Community perspectives on marine carbon dioxide removal and ocean alkalinity enhancement: A future scenario approach I Energy Research & Social Science.