Pub Date : 2025-12-15DOI: 10.1016/j.ccst.2025.100557
Yutong Ju , Ye Li , Xiangping Xian , Tiejun Liu
The valorization of recycled concrete fines (RCF) into reactive binders offers a sustainable solution for mitigating construction waste and carbon emissions. However, embedded sand particles hinder phase development during thermal activation. This study explores thermally activated sand-containing RCF by adjusting calcium-to-silicon ratio via limestone addition to produce reactivated cementitious materials (RCM). Carbonation-cured RCMs were analyzed for phase evolution, microstructure, and strength. Results showed that higher activation temperature with Ca addition enhanced sand reactivity and mineral formation, transitioning from α′H-C2S and β-C2S below 1000 °C to low-reactivity CS or C3S2 at 1200 °C. Carbonation curing of RCM activated at 1000 °C with 20 wt.% limestone addition yielded the highest mechanical performance by optimizing phase reactivity, carbonation efficiency, and pore refinement, while lower strengths in other groups stemmed from insufficient CaCO3 and silica gel. Life cycle assessment showed a 61 % CO2 reduction compared to Portland cement, which validates thermochemical tuning for closed-loop RCF recycling.
{"title":"Carbonation behavior of reactivated recycled concrete fines containing residual sand: Effects of Ca/Si ratio adjustment and activation temperature","authors":"Yutong Ju , Ye Li , Xiangping Xian , Tiejun Liu","doi":"10.1016/j.ccst.2025.100557","DOIUrl":"10.1016/j.ccst.2025.100557","url":null,"abstract":"<div><div>The valorization of recycled concrete fines (RCF) into reactive binders offers a sustainable solution for mitigating construction waste and carbon emissions. However, embedded sand particles hinder phase development during thermal activation. This study explores thermally activated sand-containing RCF by adjusting calcium-to-silicon ratio via limestone addition to produce reactivated cementitious materials (RCM). Carbonation-cured RCMs were analyzed for phase evolution, microstructure, and strength. Results showed that higher activation temperature with Ca addition enhanced sand reactivity and mineral formation, transitioning from α′<sub>H</sub>-C<sub>2</sub>S and β-C<sub>2</sub>S below 1000 °C to low-reactivity CS or C<sub>3</sub>S<sub>2</sub> at 1200 °C. Carbonation curing of RCM activated at 1000 °C with 20 wt.% limestone addition yielded the highest mechanical performance by optimizing phase reactivity, carbonation efficiency, and pore refinement, while lower strengths in other groups stemmed from insufficient CaCO<sub>3</sub> and silica gel. Life cycle assessment showed a 61 % CO<sub>2</sub> reduction compared to Portland cement, which validates thermochemical tuning for closed-loop RCF recycling.</div></div>","PeriodicalId":9387,"journal":{"name":"Carbon Capture Science & Technology","volume":"18 ","pages":"Article 100557"},"PeriodicalIF":0.0,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Integrated carbon capture and utilisation (ICCU) is a promising technology to mitigate the impact of carbon emissions, as it combines sorbent regeneration and CO2 utilisation. ICCU has been intensively studied for reverse water shift reaction (RWGS), methanation and dry methane reforming (DRM). However, ICCU-RWGS and ICCU-Methanation rely on hydrogen, which compromises economic viability and safety, and the complex synthesis of DFMs for ICCU-DRM, requiring promoters or multilayer structures. To enhance the practicality of ICCU technology, here we investigated carbon-based ICCU (C-ICCU), which utilises the reverse Boudouard reaction with carbon as the reducing agent. In this study, we explored the key operational factors influencing C-ICCU performance, specifically Ni loading, the Ni/graphite mass, and temperature. Our findings indicate that Ni/graphite is a highly effective catalyst for the in-situ conversion of CO2 to CO. Specifically, a Ni loading of 3 wt.% or higher achieved a CO2 conversion greater than 95% at 650°C. Furthermore, in-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) analysis revealed the synergistic interactions between graphite and nickel. Specifically, graphite promotes CO2 generation while nickel catalyses its subsequent conversion. Our research demonstrates that the C-ICCU mechanism is a complex synergistic process involving the dynamic evolution of surface species. This work offers a promising, safer, and potentially more economical pathway for industrial carbon capture and utilisation.
{"title":"Graphite–Ni synergy unlocks a hydrogen-free pathway for carbon based integrated CO₂ capture and utilisation (ICCU)","authors":"Junhan Lu, Xiaotong Zhao, Jia Hu, Bo Zong, Yuanyuan Wang, Chunfei Wu","doi":"10.1016/j.ccst.2025.100546","DOIUrl":"10.1016/j.ccst.2025.100546","url":null,"abstract":"<div><div>Integrated carbon capture and utilisation (ICCU) is a promising technology to mitigate the impact of carbon emissions, as it combines sorbent regeneration and CO<sub>2</sub> utilisation. ICCU has been intensively studied for reverse water shift reaction (RWGS), methanation and dry methane reforming (DRM). However, ICCU-RWGS and ICCU-Methanation rely on hydrogen, which compromises economic viability and safety, and the complex synthesis of DFMs for ICCU-DRM, requiring promoters or multilayer structures. To enhance the practicality of ICCU technology, here we investigated carbon-based ICCU (C-ICCU), which utilises the reverse Boudouard reaction with carbon as the reducing agent. In this study, we explored the key operational factors influencing C-ICCU performance, specifically Ni loading, the Ni/graphite mass, and temperature. Our findings indicate that Ni/graphite is a highly effective catalyst for the in-situ conversion of CO<sub>2</sub> to CO. Specifically, a Ni loading of 3 wt.% or higher achieved a CO<sub>2</sub> conversion greater than 95% at 650°C. Furthermore, in-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) analysis revealed the synergistic interactions between graphite and nickel. Specifically, graphite promotes CO<sub>2</sub> generation while nickel catalyses its subsequent conversion. Our research demonstrates that the C-ICCU mechanism is a complex synergistic process involving the dynamic evolution of surface species. This work offers a promising, safer, and potentially more economical pathway for industrial carbon capture and utilisation.</div></div>","PeriodicalId":9387,"journal":{"name":"Carbon Capture Science & Technology","volume":"17 ","pages":"Article 100546"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145680891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01DOI: 10.1016/j.ccst.2025.100551
Aaqib Ali , Arshad Raza , Mubashir Aziz , Mohamed Mahmoud , Umair Ali , Ammar Mohammed Alshammari
Accelerated soil carbonation (ASC) is a rapidly advancing carbon capture and storage technique which provides a dual benefit of permanent CO2 sequestration and geotechnical soil stabilization. This paper presents a comprehensive review of soil carbonation processes, emphasizing the mechanisms, quantification methods, and engineering performance improvements achieved through MgO and CaO-based binders and industrial by-products. The carbonation process transforms reactive oxides into stable carbonate minerals, enhancing soil strength, stiffness, and durability while reducing moisture content and porosity. A systematic analysis of the impact of carbonation on physical, chemical, mechanical, and microstructural behavior is presented, together with quantification approaches such as thermogravimetric analysis, calcimetry, and gas-balance techniques. The techno-economic evaluation highlights that optimized magnesia-lime-slag systems can offset up to 70 % of embodied emissions, offering a cost-effective and scalable pathway for carbon-negative ground improvement. Despite these advances, the field faces challenges related to reaction uniformity, long-term durability, and standardization of quantification and field protocols. The study identifies key research directions to establish ASC as a reliable, sustainable, and verifiable carbon sequestration strategy in geotechnical engineering.
{"title":"Advanced soil carbonation strategies: insights into quantification, performance, and scalable carbon capture","authors":"Aaqib Ali , Arshad Raza , Mubashir Aziz , Mohamed Mahmoud , Umair Ali , Ammar Mohammed Alshammari","doi":"10.1016/j.ccst.2025.100551","DOIUrl":"10.1016/j.ccst.2025.100551","url":null,"abstract":"<div><div>Accelerated soil carbonation (ASC) is a rapidly advancing carbon capture and storage technique which provides a dual benefit of permanent CO<sub>2</sub> sequestration and geotechnical soil stabilization. This paper presents a comprehensive review of soil carbonation processes, emphasizing the mechanisms, quantification methods, and engineering performance improvements achieved through MgO and CaO-based binders and industrial by-products. The carbonation process transforms reactive oxides into stable carbonate minerals, enhancing soil strength, stiffness, and durability while reducing moisture content and porosity. A systematic analysis of the impact of carbonation on physical, chemical, mechanical, and microstructural behavior is presented, together with quantification approaches such as thermogravimetric analysis, calcimetry, and gas-balance techniques. The techno-economic evaluation highlights that optimized magnesia-lime-slag systems can offset up to 70 % of embodied emissions, offering a cost-effective and scalable pathway for carbon-negative ground improvement. Despite these advances, the field faces challenges related to reaction uniformity, long-term durability, and standardization of quantification and field protocols. The study identifies key research directions to establish ASC as a reliable, sustainable, and verifiable carbon sequestration strategy in geotechnical engineering.</div></div>","PeriodicalId":9387,"journal":{"name":"Carbon Capture Science & Technology","volume":"17 ","pages":"Article 100551"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145680888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01DOI: 10.1016/j.ccst.2025.100539
Haydn Barros, Richard Harvey, Hannah Cheales-Norman, Chris Dimopoulos, Rod Robinson
Degradation products of sorbent amines used in Post Combustion CO2 Capture (PCC) (amines, nitrosamines, etc.) are potentially emitted to the atmosphere, impacting health and the environment. This paper proposes and validates for the first time a manual stack sampling method for monitoring nitrosamine emissions, using a purpose-built test bench and simulating nitrosamine sampling through monitoring tests under controlled conditions mimicking those of a PCC plant. The method uses isokinetic sampling (due to the presence of water droplets in the PCC flue gas), a combination of liquid sampling (three impingers in series) and dry sampling cartridges. Collected samples were refrigerated and send to for laboratory analysis (using a Gas Chromatography - Thermal Energy Analyser). In terms of the recovered mass of the target analytes, the method was successfully validated for the five more volatile compounds (NDMA, NMEA, NDEA, NDPA, and NPIP), while the three less volatile nitrosamine’s (NDBA, NPYR, and NMOR) had recoveries of 75–80 %. However, based on the same experimental data but using the criterion of recovering in the last impinger <5 % of the total (for each species), only the linear nitrosamines with medium volatility failed, NDPA and NDBA, capturing 11 and 22 % respectively. As expected, these last two nitrosamines were also found in sizeable amounts in the back-end cartridge, demonstrating significant breakthrough from all the impingers. In spite of the general good recovery of the method for volatile nitrosamines, the results for some of the semi-volatile species show that is advisable to enhance the method to achieve a recovery closer to 100 % for all the nitrosamines. Two simple proposals to achieve that goal are discussed. The sampling recovery depends on the volatility and chemical structure of the specific nitrosamines. The conclusions presented here could be carefully extrapolated to other species with similar volatilities and structures, but not to low volatile nitrosamines which will require different sample media to be sampled, for that reason they are outside of the scope of this work.
{"title":"Volatile nitrosamine manual stack monitoring method: sampling validation and performance assessment on stack simulated conditions","authors":"Haydn Barros, Richard Harvey, Hannah Cheales-Norman, Chris Dimopoulos, Rod Robinson","doi":"10.1016/j.ccst.2025.100539","DOIUrl":"10.1016/j.ccst.2025.100539","url":null,"abstract":"<div><div>Degradation products of sorbent amines used in Post Combustion CO<sub>2</sub> Capture (PCC) (amines, nitrosamines, etc.) are potentially emitted to the atmosphere, impacting health and the environment. This paper proposes and validates for the first time a manual stack sampling method for monitoring nitrosamine emissions, using a purpose-built test bench and simulating nitrosamine sampling through monitoring tests under controlled conditions mimicking those of a PCC plant. The method uses isokinetic sampling (due to the presence of water droplets in the PCC flue gas), a combination of liquid sampling (three impingers in series) and dry sampling cartridges. Collected samples were refrigerated and send to for laboratory analysis (using a Gas Chromatography - Thermal Energy Analyser). In terms of the recovered mass of the target analytes, the method was successfully validated for the five more volatile compounds (NDMA, NMEA, NDEA, NDPA, and NPIP), while the three less volatile nitrosamine’s (NDBA, NPYR, and NMOR) had recoveries of 75–80 %. However, based on the same experimental data but using the criterion of recovering in the last impinger <5 % of the total (for each species), only the linear nitrosamines with medium volatility failed, NDPA and NDBA, capturing 11 and 22 % respectively. As expected, these last two nitrosamines were also found in sizeable amounts in the back-end cartridge, demonstrating significant breakthrough from all the impingers. In spite of the general good recovery of the method for volatile nitrosamines, the results for some of the semi-volatile species show that is advisable to enhance the method to achieve a recovery closer to 100 % for all the nitrosamines. Two simple proposals to achieve that goal are discussed. The sampling recovery depends on the volatility and chemical structure of the specific nitrosamines. The conclusions presented here could be carefully extrapolated to other species with similar volatilities and structures, but not to low volatile nitrosamines which will require different sample media to be sampled, for that reason they are outside of the scope of this work.</div></div>","PeriodicalId":9387,"journal":{"name":"Carbon Capture Science & Technology","volume":"17 ","pages":"Article 100539"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145614607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01DOI: 10.1016/j.ccst.2025.100543
Zhaoxi Dong , Yurong Liu , Feihu Ma , Honghai Ma , Xin Peng , Weimin Zhong , Feng Qian
Energy storage technology is essential for addressing the intermittency of renewable energy, particularly wind power. Diabatic compressed air energy storage (DCAES) technology is relatively mature, however, it suffers from the drawback of greenhouse gas (GHG) emissions caused by fuel combustion. In this study, an integrated system that combines post-combustion carbon capture (PCC) with DCAES is proposed to decrease GHG emissions without purchasing outsource steam. A case study over a typical 24-hour period shows that the integrated system can ensure the stability of the power output from wind power to the grid during peak electricity usage period. The integration of PCC reduces the power output of DCAES during the discharge phase by 23.6 %, while the levelized cost of electricity rises from 55.63 $/MWh to 88.77 $/MWh. Otherwise, PCC subsystem contributes 12.7 % of the whole exergy destruction of the integrated system. These indicates that the cost of the PCC integration is acceptable from the thermodynamic and economic standing. Whereas, when wind power is used as the charging source, PCC integration can reduce life cycle GHG emissions by 66.9 % of the output electricity and the effect of GHG emission reduction is affected by region. This work provides valuable insights into achieving low-carbon operation of DCAES systems.
{"title":"Integrating diabatic CAES with post-combustion capture to mitigate combustion emissions: case study and regional sensitivity","authors":"Zhaoxi Dong , Yurong Liu , Feihu Ma , Honghai Ma , Xin Peng , Weimin Zhong , Feng Qian","doi":"10.1016/j.ccst.2025.100543","DOIUrl":"10.1016/j.ccst.2025.100543","url":null,"abstract":"<div><div>Energy storage technology is essential for addressing the intermittency of renewable energy, particularly wind power. Diabatic compressed air energy storage (DCAES) technology is relatively mature, however, it suffers from the drawback of greenhouse gas (GHG) emissions caused by fuel combustion. In this study, an integrated system that combines post-combustion carbon capture (PCC) with DCAES is proposed to decrease GHG emissions without purchasing outsource steam. A case study over a typical 24-hour period shows that the integrated system can ensure the stability of the power output from wind power to the grid during peak electricity usage period. The integration of PCC reduces the power output of DCAES during the discharge phase by 23.6 %, while the levelized cost of electricity rises from 55.63 $/MWh to 88.77 $/MWh. Otherwise, PCC subsystem contributes 12.7 % of the whole exergy destruction of the integrated system. These indicates that the cost of the PCC integration is acceptable from the thermodynamic and economic standing. Whereas, when wind power is used as the charging source, PCC integration can reduce life cycle GHG emissions by 66.9 % of the output electricity and the effect of GHG emission reduction is affected by region. This work provides valuable insights into achieving low-carbon operation of DCAES systems.</div></div>","PeriodicalId":9387,"journal":{"name":"Carbon Capture Science & Technology","volume":"17 ","pages":"Article 100543"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145614608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01DOI: 10.1016/j.ccst.2025.100545
Esmaeel Eftekharian , Ali Kiani , Vassili Kitsios , Ashok K. Luhar , Paul Feron , Aaron W. Thornton , Kathryn M. Emmerson
The removal of carbon dioxide (CO2) from the atmosphere using direct air capture (DAC) is crucial in achieving the net-zero emissions target and combating global warming. We develop a new numerical model that predicts the performance of DAC units under representative atmospheric flow conditions which captures the interaction between these units and the instantaneous flow fields. A new boundary condition for the CO2 concentration associated with the CO2-depleted exit plume was developed. This boundary condition dynamically calculates the time-varying fraction of CO2 removed from the air (capture rate) and the total mass of CO2 captured by the system per unit time (capture amount). We have also conducted experiments in a lab-scale DAC unit at different inlet air velocities. The experiment showed that both the CO2 capture rate and the capture amount depend on the unit’s inlet airflow velocity. Specifically, the CO2 capture rate decreases with an increase in unit inlet airflow velocity, while the CO2 capture amount increases. These data were used to validate our computational fluid dynamics analysis using a large eddy simulation (LES) approach. After validating the new boundary condition model with experimental data in still air, the LES simulations were extended to include the interaction of atmospheric boundary layer wind with individual DAC units. The CO2 capture rate and capture amount are almost constant in still air, whilst they strongly fluctuate for wind speeds above 7 m/s. The amplitude of these fluctuations grows with increasing wind velocity. The LES results showed that when the wind velocity increased, both the CO2 capture rate and the overall mean CO2 capture amount of an individual DAC unit were reduced. In strong winds of 9 m/s, the total CO2 mass removal was reduced by up to 7.5 % ± 6.5 % over one year. The new boundary condition model can more accurately predict the overall CO2 capture characteristics of large-scale DAC plants in complex real environmental conditions.
{"title":"Prediction of CO2 capture performance of a direct air capture unit under representative atmospheric flow conditions using large eddy simulation","authors":"Esmaeel Eftekharian , Ali Kiani , Vassili Kitsios , Ashok K. Luhar , Paul Feron , Aaron W. Thornton , Kathryn M. Emmerson","doi":"10.1016/j.ccst.2025.100545","DOIUrl":"10.1016/j.ccst.2025.100545","url":null,"abstract":"<div><div>The removal of carbon dioxide (CO<sub>2</sub>) from the atmosphere using direct air capture (DAC) is crucial in achieving the net-zero emissions target and combating global warming. We develop a new numerical model that predicts the performance of DAC units under representative atmospheric flow conditions which captures the interaction between these units and the instantaneous flow fields. A new boundary condition for the CO<sub>2</sub> concentration associated with the CO<sub>2</sub>-depleted exit plume was developed. This boundary condition dynamically calculates the time-varying fraction of CO<sub>2</sub> removed from the air (capture rate) and the total mass of CO<sub>2</sub> captured by the system per unit time (capture amount). We have also conducted experiments in a lab-scale DAC unit at different inlet air velocities. The experiment showed that both the CO<sub>2</sub> capture rate and the capture amount depend on the unit’s inlet airflow velocity. Specifically, the CO<sub>2</sub> capture rate decreases with an increase in unit inlet airflow velocity, while the CO<sub>2</sub> capture amount increases. These data were used to validate our computational fluid dynamics analysis using a large eddy simulation (LES) approach. After validating the new boundary condition model with experimental data in still air, the LES simulations were extended to include the interaction of atmospheric boundary layer wind with individual DAC units. The CO<sub>2</sub> capture rate and capture amount are almost constant in still air, whilst they strongly fluctuate for wind speeds above 7 m/s. The amplitude of these fluctuations grows with increasing wind velocity. The LES results showed that when the wind velocity increased, both the CO<sub>2</sub> capture rate and the overall mean CO<sub>2</sub> capture amount of an individual DAC unit were reduced. In strong winds of 9 m/s, the total CO<sub>2</sub> mass removal was reduced by up to 7.5 % ± 6.5 % over one year. The new boundary condition model can more accurately predict the overall CO<sub>2</sub> capture characteristics of large-scale DAC plants in complex real environmental conditions.</div></div>","PeriodicalId":9387,"journal":{"name":"Carbon Capture Science & Technology","volume":"17 ","pages":"Article 100545"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145614610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-29DOI: 10.1016/j.ccst.2025.100550
A. Lieber , C. Morrow , J. Stabile , K. Hornbostel
Carbon dioxide removal (CDR) methods that remove CO2 gas from the air and ocean are an essential long-term strategy to complement point source carbon capture. Many CDR methods have been proposed in recent years, and this review organizes and assesses these methods to aid researchers and decision-makers in accelerating development and deployment of CDR. This review organizes CDR methods into four categories: 1) marine/biological, 2) marine/nonbiological, 3) terrestrial/biological, and 4) terrestrial/nonbiological. For each of these categories, the fundamental mechanisms governing CO2 separation are explained, and key CDR methods within each category are discussed. This review also provides a comparison of the four categorical CDR methods based on cost, scalability and carbon storage duration. The infrastructure needs of each CDR category are then covered, and a quantitative study is performed to estimate the costs of moving seawater vs. air to remove CO2. Finally, the operational footprints of various CDR approaches are compared on a 1 Mt/y capture scale. Overall, this review examines the pros and cons of each CDR method to aid decision-makers in selecting the CDR approach that works best within their given constraints.
{"title":"A Comparative Review of terrestrial and marine carbon dioxide removal (CDR) methods","authors":"A. Lieber , C. Morrow , J. Stabile , K. Hornbostel","doi":"10.1016/j.ccst.2025.100550","DOIUrl":"10.1016/j.ccst.2025.100550","url":null,"abstract":"<div><div>Carbon dioxide removal (CDR) methods that remove CO<sub>2</sub> gas from the air and ocean are an essential long-term strategy to complement point source carbon capture. Many CDR methods have been proposed in recent years, and this review organizes and assesses these methods to aid researchers and decision-makers in accelerating development and deployment of CDR. This review organizes CDR methods into four categories: 1) marine/biological, 2) marine/nonbiological, 3) terrestrial/biological, and 4) terrestrial/nonbiological. For each of these categories, the fundamental mechanisms governing CO<sub>2</sub> separation are explained, and key CDR methods within each category are discussed. This review also provides a comparison of the four categorical CDR methods based on cost, scalability and carbon storage duration. The infrastructure needs of each CDR category are then covered, and a quantitative study is performed to estimate the costs of moving seawater vs. air to remove CO<sub>2</sub>. Finally, the operational footprints of various CDR approaches are compared on a 1 Mt/y capture scale. Overall, this review examines the pros and cons of each CDR method to aid decision-makers in selecting the CDR approach that works best within their given constraints.</div></div>","PeriodicalId":9387,"journal":{"name":"Carbon Capture Science & Technology","volume":"18 ","pages":"Article 100550"},"PeriodicalIF":0.0,"publicationDate":"2025-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The conversion of carbon dioxide (CO2) into valuable solid carbon materials presents a promising approach for carbon utilization and climate change mitigation. This review systematically evaluates six major carbon allotropes: graphene, carbon nanotubes (CNTs), carbon nanofibers (CNFs), fullerenes, diamonds, and porous carbon, with a focus on synthesis methods, operating conditions, and industrial feasibility. Among these, CNTs and CNFs show the highest potential, especially when produced via molten carbonate electrolysis or the Solar Thermal Electrochemical Process (STEP), which operate at approximately 750–770 °C and near-atmospheric pressure. These methods have demonstrated high carbon conversion efficiencies and significantly lower estimated production costs compared to conventional CVD techniques, due to their simpler operation and lower material costs. Graphene, although high in quality, requires approximately 1000 °C and expensive catalysts, making it less scalable. Fullerenes (C60) and diamonds have very low yields (<1 %) and require extreme pressures (up to 1000 atm), limiting their industrial use. Porous carbons, synthesized electrochemically or by metal/inorganic reduction at 500–850 °C, show promise for supercapacitors and adsorption, with yields up to 55.3 wt % and built-in doping capabilities. Metal-mediated methods using Mg, Zn, and NaBH4 offer simplicity, moderate conditions, and tunable structures, while new hybrid approaches provide synergistic benefits. Overall, molten salt electrochemical methods are highly promising candidates for scalable and energy-efficient processes, supporting CO2 valorization in sustainable carbon material production.
{"title":"A comprehensive review on the conversion of CO2 into solid carbon materials","authors":"Bentolhoda Chenarani, Ahad Ghaemi, Alireza Hemmati","doi":"10.1016/j.ccst.2025.100547","DOIUrl":"10.1016/j.ccst.2025.100547","url":null,"abstract":"<div><div>The conversion of carbon dioxide (CO<sub>2</sub>) into valuable solid carbon materials presents a promising approach for carbon utilization and climate change mitigation. This review systematically evaluates six major carbon allotropes: graphene, carbon nanotubes (CNTs), carbon nanofibers (CNFs), fullerenes, diamonds, and porous carbon, with a focus on synthesis methods, operating conditions, and industrial feasibility. Among these, CNTs and CNFs show the highest potential, especially when produced via molten carbonate electrolysis or the Solar Thermal Electrochemical Process (STEP), which operate at approximately 750–770 °C and near-atmospheric pressure. These methods have demonstrated high carbon conversion efficiencies and significantly lower estimated production costs compared to conventional CVD techniques, due to their simpler operation and lower material costs. Graphene, although high in quality, requires approximately 1000 °C and expensive catalysts, making it less scalable. Fullerenes (C<sub>60</sub>) and diamonds have very low yields (<1 %) and require extreme pressures (up to 1000 atm), limiting their industrial use. Porous carbons, synthesized electrochemically or by metal/inorganic reduction at 500–850 °C, show promise for supercapacitors and adsorption, with yields up to 55.3 wt % and built-in doping capabilities. Metal-mediated methods using Mg, Zn, and NaBH<sub>4</sub> offer simplicity, moderate conditions, and tunable structures, while new hybrid approaches provide synergistic benefits. Overall, molten salt electrochemical methods are highly promising candidates for scalable and energy-efficient processes, supporting CO<sub>2</sub> valorization in sustainable carbon material production.</div></div>","PeriodicalId":9387,"journal":{"name":"Carbon Capture Science & Technology","volume":"18 ","pages":"Article 100547"},"PeriodicalIF":0.0,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145683712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A system for synthesizing methanol (MeOH) from carbon dioxide (CO2) in the air as a feedstock using electrical energy was developed to open a new avenue for atmospheric carbon capture and utilization. This system integrates three processes: direct air capture (DAC), direct carbonate reduction (DCR), and MeOH synthesis (MeS). A mixture of potassium carbonate and potassium bicarbonate aqueous solutions captures CO2 from the air as carbonate ions. Carbonate ions in the solution are directly reduced electrolytically to carbon monoxide (CO) using a nanoporous gold electrocatalyst. The produced CO is subsequently reduced electrolytically to MeOH using a cobalt phthalocyanine/carbon nanotube electrocatalyst. The system operated stably for 1.5 h, showing continuous CO2 capture and MeOH synthesis. This demonstrates the feasibility of the DAC-DCR-MeS integrated system operating under ordinary temperature and pressure conditions throughout all the steps. A notable feature of no need for high temperature or high pressure makes the system compatible with time-varying renewable energies including solar energy, which are essential for reducing net CO2 emissions.
{"title":"Continuous electrolytic methanol synthesis from air-captured CO2 at ordinary temperature and pressure","authors":"Yoshiyuki Sakamoto , Yuna Takeno , Yusaku F. Nishimura , Yohsuke Mizutani , Shintaro Mizuno , Ryo Hishinuma , Kazumasa Okamura , Yasuhiko Takeda , Tsuyoshi Hamaguchi , Masaoki Iwasaki","doi":"10.1016/j.ccst.2025.100552","DOIUrl":"10.1016/j.ccst.2025.100552","url":null,"abstract":"<div><div>A system for synthesizing methanol (MeOH) from carbon dioxide (CO<sub>2</sub>) in the air as a feedstock using electrical energy was developed to open a new avenue for atmospheric carbon capture and utilization. This system integrates three processes: direct air capture (DAC), direct carbonate reduction (DCR), and MeOH synthesis (MeS). A mixture of potassium carbonate and potassium bicarbonate aqueous solutions captures CO<sub>2</sub> from the air as carbonate ions. Carbonate ions in the solution are directly reduced electrolytically to carbon monoxide (CO) using a nanoporous gold electrocatalyst. The produced CO is subsequently reduced electrolytically to MeOH using a cobalt phthalocyanine/carbon nanotube electrocatalyst. The system operated stably for 1.5 h, showing continuous CO<sub>2</sub> capture and MeOH synthesis. This demonstrates the feasibility of the DAC-DCR-MeS integrated system operating under ordinary temperature and pressure conditions throughout all the steps. A notable feature of no need for high temperature or high pressure makes the system compatible with time-varying renewable energies including solar energy, which are essential for reducing net CO<sub>2</sub> emissions.</div></div>","PeriodicalId":9387,"journal":{"name":"Carbon Capture Science & Technology","volume":"18 ","pages":"Article 100552"},"PeriodicalIF":0.0,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145652006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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