This week’s publication highlights cover topics related to direct air capture, enhanced rock weathering and biochar.
Deactivation and Mitigation Strategies of Dual Function Materials for Integrated CO2 Capture and Utilization under Direct Air Capture and Realistic Flue Gas Conditions
Abstract
Integrated CO2 capture and utilization (ICCU) using dual-function materials (DFMs) has emerged as a promising strategy for scalable carbon emission mitigation from both atmospheric air and large stationary sources. However, the practical deployment of ICCU technique faces a critical challenge: the progressive deactivation of DFMs under realistic direct air capture (DAC) or flue gas conditions. Oxidative species (O2, H2O), acidic impurities (SO2, NOx), and particulate matter in industrial flue gas can induce oxidation, sintering, and poisoning of active sites, significantly diminishing the cyclic performance of alkaline-based DFMs. This review systematically examines the oxidation behavior and resulting performance decay of Ru- and Ni-based DFMs under DAC and flue gas environments. The stability of these DFMs in complex atmospheres containing multiple impurities are critically assessed, with particular emphasis on elucidating the underlying deactivation mechanisms. To address these challenges, a range of mitigation strategies are discussed, including doping with platinum group metals (PGMs), promotion with transition metals and oxides, physical separation via adjacent bed configuration to combat oxidative deactivation. Additionally, approaches such as self-regeneration activation and washing, incorporating sacrificial components, and process optimization are explored for their efficacy in counteracting poisoning by acidic impurities. By providing a detailed overview of deactivation pathways and state-of-the-art of combating approaches, this review serves as an essential guide for developing durable DFMs and advancing ICCU toward industrial implementation.
Guo, Y. et al. (2025) Deactivation and Mitigation Strategies of Dual Function Materials for Integrated CO2 Capture and Utilization under Direct Air Capture and Realistic Flue Gas Conditions 525 (170401) Chemical Engineering Journal.
Read the full paper here: Deactivation and Mitigation Strategies of Dual Function Materials for Integrated CO2 Capture and Utilization under Direct Air Capture and Realistic Flue Gas Conditions I Chemical Engineering Journal.
Techno-Economic Assessment of Coupling Direct Air Capture with Formic Acid Value Chain in Buildings under Different Scenarios
Abstract
Carbon capture and utilization (CCU) is emerging as a promising pathway that could play a key role in enhancing the sustainability of buildings. However, the energy performance and economic feasibility of this route under different conditions remain uncertain. To address this research gap, this study provides a techno-economic assessment of a novel CCU value chain within buildings, consisting of capturing indoor CO2 via a direct air capture (DAC) system and converting the captured CO2 into formic acid (FA) through an electrochemical CO2 reduction reaction (ECO2RR). The produced FA is designed to be sold to the market or converted into electricity using direct formic acid fuel cells (DFAFCs) as an electricity backup solution. The energy and cost efficiencies of this value chain are evaluated under ten distinct scenarios, considering varying levels of energy needs, carbon tax, capital and operating costs, as well as electricity and FA market prices. The results show that DAC has great potential in improving indoor air quality, but the energy requirements are 21–27% higher than conventional controlled ventilation, resulting in levelized costs of DAC of 56–259 $/tCO2, depending on the considered scenarios. Furthermore, it is observed that the ECO2RR is the costliest step in the studied value chain with a levelized cost of FA of 1.01–1.26 $/kgFA. In contrast, the conversion of produced FA into electricity via DFAFCs results in a levelized cost of electricity of 1.38–2.10 $/kWh, requiring innovation in DFAFC technology for widespread deployment in buildings. In this vein, implementing a carbon tax, providing clean and affordable energy, and lowering the overall cost of the investigated CCU chain demonstrate promising results for enhancing its economic viability. These outcomes can be used by investors, urban planners, and building owners as a guide to determine the conditions under which the explored value chain will be economically viable.
Elaouzy, Y. et al. (2025) Techno-Economic Assessment of Coupling Direct Air Capture with Formic Acid Value Chain in Buildings under Different Scenarios 343 (120257) Energy Conversion and Management.
Read the full paper here: Techno-Economic Assessment of Coupling Direct Air Capture with Formic Acid Value Chain in Buildings under Different Scenarios I Energy Conversion and Management.
Three Years of Field Trials Indicate a Sustained Enhanced Rock Weathering Signal with Limited CO2 Removal
Abstract
Enhanced rock weathering (ERW) is a CO2 removal technology that involves spreading finely ground silicate rock on fields. The chemical weathering of this rock powder removes atmospheric CO2 in the form of bicarbonate ions and secondary carbonates. Despite some promising theoretical simulations and laboratory findings, results from field trials that evaluate the ERW’s impact on soil biogeochemistry and CO2 removal are still scarce. This study investigated the impact of basaltic rock powder applied at the equivalent rate of 20 t per hectare (2 kg m–2) in three temperate vineyard fields in Switzerland over 1000 days. Analyses of soil pore water revealed that most standard ERW monitoring proxies (pH, electrical conductivity, total dissolved inorganic carbon, calcium, and magnesium concentrations) did not increase significantly. By contrast, sodium concentration in soil pore water was on average 3-fold higher in the rock powder-treated plots, indicating active mineral dissolution. Integrating the pore water results with model analyses, we estimated that the average CO2 removal rate was 100 ± 30 kg CO2 ha–1 yr–1, which is 10 to 30 times lower than the upper rates reported in some previous modeling and experimental studies. Future work is now needed to improve our understanding of ERW’s CO2 removal potential and soil contamination under a variety of soils, rock feedstocks, and climate conditions.
Dupla, X. et al. (2025) Three Years of Field Trials Indicate a Sustained Enhanced Rock Weathering Signal with Limited CO2 Removal. Environmental Science & Technology.
Read the full paper here: Three Years of Field Trials Indicate a Sustained Enhanced Rock Weathering Signal with Limited CO2 Removal I Environmental Science & Technology.
Impact of Basalt Application on Soil Chemical Properties and Elemental Uptake by Paddy Rice through Enhanced Rock Weathering
Abstract
Enhanced Rock Weathering (ERW) is a negative emission technology in which crushed rock powder is applied to cropland to sequestrate carbon by enhancing chemical weathering of silicate minerals. It is a co-benefit approach to promote crop growth by supplying elements (silicon (Si), calcium (Ca), magnesium (Mg), etc.) from weathering rock as well. In this study, we cultivated paddy rice for 99 days in a pot experiment with Gray Lowland soil (pH = 6.19) with six application rates of basalt equivalent to 0, 5, 10, 20, 50, 100 t ha−1. We investigated the change of soil chemical properties and elemental uptake in rice. Then, we calculated the release of Si, Ca, Mg, potassium (K), and sodium (Na) from the basalt, and carbon balance between before planting and after harvest in the whole system including soil and plant. The application of the basalt increased the total amount of soil available Si and exchangeable Mg and Na in the pot as well as the uptake of Si and Na in rice (p < 0.05). There was no significant difference in arsenic, cadmium, chromium, copper, and nickel concentrations in rice grain among the application rates of the basalt. The release of Si, Mg, and Na from the basalt increased corresponding to the application rate of the basalt, suggesting that the applied basalt was weathered during cultivation, though increased carbon sequestration by the basalt weathering was not detected in 99 days of this experiment. We clearly demonstrated that basalt powder got weathered and released Si, Mg, and Na in paddy field condition and additional Si enhanced paddy rice growth.
Uchibayashi, H. (2025) Impact of Basalt Application on Soil Chemical Properties and Elemental Uptake by Paddy Rice through Enhanced Rock Weathering 71 (4) Soil Science and Plant Nutrition.
Read the full paper here: Impact of Basalt Application on Soil Chemical Properties and Elemental Uptake by Paddy Rice through Enhanced Rock Weathering I Soil Science and Plant Nutrition.
Developing a Framework towards Global Biochar Supply Chains to Optimize Regional Production Cost
Abstract
The expansion of carbon dioxide removal (CDR) strategies is essential to achieve the climate targets. Among emerging CDR technologies, biochar holds particular promise due to its stable carbon storage and multiple co-benefits. While previous studies have examined the global potentials of biochar production, comprehensive assessments that include cost structures and spatial variability remain limited. This study addresses this gap and presents a comprehensive that integrates geospatial machine learning with techno-economic analysis to estimate region-specific biochar production costs at a global level. The derived approach estimates the biomass yields of various lignocellulosic biomass sources using an XGBoost machine learning model trained on climate and soil data. Roadside production costs are then calculated based on resource input parameters, followed by transport cost estimations using spatial distance metrics. Finally, pyrolysis costs are included to derive the total production cost of biochar per ton across regions globally. The results show substantial regional variation, with total production costs ranging from 113 to over 1500 €/ton. Sub-Saharan Africa, Latin America, and South Asia demonstrate the lowest median costs, below 300 €/ton, primarily due to low labor and biomass costs. Eucalyptus emerges as the most cost-efficient biomass provided it is cultivated. While the Kontiki flame curtain kilns are more cost efficient in low-income regions, advanced-technology plants become competitive in industrialized areas, especially when district heat is considered. These insights are crucial for guiding investments and policies that aim to expand biochar use as a viable and cost-effective CDR pathway.
Kern, J. et al. (2025) Developing a Framework towards Global Biochar Supply Chains to Optimize Regional Production Cost 40 (104658) Environmental Technology & Innovation.
Read the full paper here: Developing a Framework towards Global Biochar Supply Chains to Optimize Regional Production Cost I Environmental Technology & Innovation.