This week’s publication highlights relate to direct air capture, biochar, forestation and enhanced rock weathering.
Amine Free Direct Air Capture Integrated with Buildings’ Cooling Systems in Humid Environments
Abstract
Direct air capture, among the negative emission technologies, is well positioned to reach climate goals. However, adsorption-based direct air capture system faces significant challenges in humid environments due to water-CO2 co-adsorption, which substantially increases thermal regeneration energy requirements and negatively impacts overall efficiency. To overcome this problem, this study presents novel direct air capture systems integrated with air handling units incorporating a silica gel wheel to dehumidify air before the adsorption process. Dehumidification of air by integrated silica gel wheel enhances the performance of physisorbents and chemisorbents such as NbOFFIVE, Zeolite-13X, SBA-15 functionalized with tetraethylenepentamine, SBA-15 functionalized with L-PEI, and Lewatit by reducing moisture, thereby improving CO2 capture efficiency in humid environments. After capture, saturated part of silica gel wheel meet the moisture-free airstream and regenerate the water without heating and raising the stream humidity approaching the desired indoor humidity levels. The findings presented are supported by both experimental work and mathematical models. This integration significantly reduces thermal regeneration energy requirements by 82 % for NbOFFIVE and 39 % for SBA-15 with tetraethylenepentamine compared to non - silica gel wheel configurations. Moreover, compared to operating direct air capture and heating, ventilation, and air conditioning systems separately, in which their combined thermal energy is 304.73 kWh/day, the integrated system consumes only 128.52 kWh/day of thermal energy, cutting total thermal energy use by 57.8 %. Even against heating, ventilation, and air conditioning system alone (149.08 kWh/day), it achieves a thermal energy saving of 13.8 %.
Abdellatif, Y. et al. (2026) Amine Free Direct Air Capture Integrated with Buildings’ Cooling Systems in Humid Environments 247 (120544) Energy and Conversion Management.
Read the full paper here: Amine Free Direct Air Capture Integrated with Buildings’ Cooling Systems in Humid Environments I Energy and Conversion Management.
Direct Air Capture: Recent Progress in Materials, Equipment, and Process Engineering
Abstract
The direct air capture (DAC) technology possesses transformative potential for achieving negative emissions. However, challenges such as massive energy consumption, low capture efficiency, and supply chain concerns have impeded their large-scale implementation. Process Systems Engineering (PSE) is expected to address these challenges and bridge existing gaps. This paper first conducts a bibliometric analysis of 1171 DAC-related research papers published between 2015 and 2025. We then classify recent representative DAC studies through the lens of PSE. Afterwards, we discuss the role of PSE methods and tools in material design, equipment retrofitting, process optimization, and system integration across molecular, unit, and process scales. Finally, we point out future research opportunities and challenges in cross-scale modeling and optimization, multisystem integration, and flexible design for varying DAC conditions.
Hu, Y. et al. (2025) Direct Air Capture: Recent Progress in Materials, Equipment, and Process Engineering 50 (101197) Current Opinion in Chemical Engineering.
Read the full paper here: Direct Air Capture: Recent Progress in Materials, Equipment, and Process Engineering I Current Opinion in Chemical Engineering.
Biochar from Pellets: Influence of Binders and Pyrolysis Temperature on Physical Properties of Pyrolyzed Pellets
Abstract
Pelletization of biomass materials enhances their density, making them suitable feedstocks for continuous pyrolysis reactors capable of co-processing diverse feedstocks in semi-homogeneous particles. The physical properties of resulting biochar are critical for evaluating its viability in storage, transportation, and automated handling systems, as well as final applications. This study investigates the effects of different biomass feedstocks and binders on the physical properties of biochar derived from pelletized biomass through slow pyrolysis at 550 °C and 700 °C. By incorporating spent coffee grounds and potato pulp as binders, we reveal a strong correlation between the bulk and particle densities of pyrolyzed pellets and their biomass precursors (R2 = 0.91 at 550 °C and R2 = 0.83 at 700 °C). This novel approach enables accurate estimations of biochar properties, essential for optimizing storage and transportation logistics in industrial applications. These insights offer significant promise for scalable biochar production, particularly from waste biomass in the circular economy context.
Yildiz, M. et al. (2025) Biochar from Pellets: Influence of Binders and Pyrolysis Temperature on Physical Properties of Pyrolyzed Pellets 43 (e01328) Sustainable Materials and Technologies.
Read the full paper here: Biochar from Pellets: Influence of Binders and Pyrolysis Temperature on Physical Properties of Pyrolyzed Pellets I Sustainable Materials and Technologies.
Non-Negligible Large Impact of Potential Forestation on Livestock Production in China:
Abstract
Forestation projects have been identified as an important component of climate mitigation strategy to reduce greenhouse gas emissions worldwide. However, most previous studies ignore the impacts of potential forestation projects on livestock production, which is crucial to the livelihoods of local people. In this study, we identified potential forestation areas in China by integrating random forest regression model and LPJ-GUESS model. The impacts of potential forestation on carbon storage and pasture-based livestock production were then analyzed. The results showed that China has a potential forestation area of 43.2 million hectares, accounting for about 19.6 % of the country’s forest area as reported in the 9th National Forest Inventory. If all these regions are reforested, China’s forest cover will increase to 27.4 %. Furthermore, 1.58 Pg C of new above- and below-ground carbon would be sequestered, about an increase of 17.2 % of current forest carbon storage. However, the potential forestation may result in a significant negative impact on existing pastures and the amount of livestock. It can reduce 4.7 % of beef, and 0.8 % of mutton products from China’s livestock sector each year. These significant declines will result in a huge gap in China’s livestock products supply, posing a serious threat to food security and the livelihoods of many people. Our findings highlight that potential forestation projects should further consider a reasonable pasture protection strategy to balance the potential carbon sequestration and the socio-economic benefits of livestock production.
Wu, C. et al. (2025) Non-Negligible Large Impact of Potential Forestation on Livestock Production in China:4 (6) Geography and Sustainability.
Read the full paper here: Non-Negligible Large Impact of Potential Forestation on Livestock Production in China I Geography and Sustainability.
The Effects of Enhanced Rock Weathering on Soil Respiration was Modulated by Understory Removal in a Subtropical Fir Plantation
Abstract
Enhanced rock weathering (ERW) involving the modification of soils with crushed silicate rock is proposed an efficient CO2 removal technology. However, a comprehensive understanding of the influence of silicate rock application on soil respiration (Rs), especially under different silvicultural regimes, is still lacking, limiting our awareness of the potential for ERW to remove CO2. In this study, a wollastonite addition (WA) experiment was conducted in a Chinese fir plantation with or without understory removal (UR). The Rs and its heterotrophic (Rh) and autotrophic (Ra) components were measured for each treatment over a two-year period. Results showed that WA significantly increased Rs and Ra by 16.1 % and 51.8 %, respectively, but had no effect on Rh. Soil pH value was markedly increased by WA by 12.5 %, from 4.40 to 4.95, on average. The concentrations of available Si and exchangeable Ca and Mg increased but that of exchangeable Al decreased after WA. It seems that WA has provided the plants with higher nutrient availability and lower aluminum toxicity, thereby benefiting root activity. This pattern was evidenced by the positive correlations between Ra and soil pH value, exchangeable Ca and available Si concentration, as well as by the negative correlation between Ra and exchangeable Al concentration. Moreover, the effect of WA on Rs was interactively regulated by UR, leading to a weaker WA effect at understory-free stands. This study highlighted that the increase in soil CO2 efflux by WA should be taken into consideration while assessing the CO2 removal potential from ERW.
Li, R. et al. (2025) The Effects of Enhanced Rock Weathering on Soil Respiration was Modulated by Understory Removal in a Subtropical Fir Plantation 375 (110876) Agricultural and Forest Meteorology.
Read the full paper here: The Effects of Enhanced Rock Weathering on Soil Respiration was Modulated by Understory Removal in a Subtropical Fir Plantation I Agricultural and Forest Meteorology.