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Over the years, Carbon Capture and Sequestration (CCS) has been recognized as a crucial element in the toolkit of measures to combat climate change. At the European Union (EU) level, CCS plays a vital role in climate policy, particularly in reducing CO2 emissions from hard-to-abate industries. However, no comprehensive legal framework covers all stages of CCS. These stages include carbon capture techniques, transportation by ships or pipelines, injection, site closure, and post-closure management. Each of these stages is regulated by different legal frameworks that address various topics such as geoengineering, climate change, industrial activities, property, transportation, port operations, waste management, dumping, health, and the environment. Critical legal questions remain unanswered, such as who is liable for discharges in the marine environment during the transportation of CO2 by ships and for the long-term management of sub-seabed storage sites. As the transportation of CO2 by ships will likely have transboundary implications, we explore the legal possibilities, limitations and risks associated with exporting CO2 streams for sequestration under the sub-seabed. [ABSTRACT FROM AUTHOR]

The injection of CO2 into deep, unmineable coal seams is an effective strategy for reducing greenhouse gas emissions. At depths greater than 800 m, the carbon dioxide transitions to the supercritical state (Sc-CO2). This study investigated the complex interactions between Sc-CO2 and coal, which substantially affected the pore structure, mineralogy, and permeability of the coal. We used low-pressure nitrogen gas adsorption (LP-N2GA) to assess the impact of Sc-CO2 on the pore characteristics of the coal. X-ray diffraction (XRD) was also used to determine the causal factors. We performed comparative triaxial permeability tests before and after Sc-CO2 exposure to evaluate the changes in permeability for various coal types. Our findings suggested that Sc-CO2 exposure markedly increased the complexity of the coal pore structure, which in turn affects coal-rock permeability. Specifically, a 10-day exposure period resulted in considerable increases of 43.5% and 50.9% in the pore volume and the specific surface area, respectively, along with a slight increase of 0.01 nm in the average pore diameter. Furthermore, there were notable decreases in the contents of minerals such as kaolinite, calcite, and pyrite, with decreases of 1.5%, 2.8%, and 2.2%, respectively, whereas the quartz content increased by 3%, indicating that significant mineral dissolution influenced the pore structure. A significant positive correlation was observed between the loss of coal mass and the increase in permeability. The effects of Sc-CO2 were most pronounced in coals with low permeabilities, particularly during the initial phase of saturation. Subsequent saturation cycles and prolonged exposure resulted in a reduced rate for permeability enhancement, which eventually reached a plateau. This study underscores the critical role of Sc-CO2 in long-term geological CO2 storage and improved efficiency for coalbed methane production. [ABSTRACT FROM AUTHOR]

Addressing critical environmental challenges such as greenhouse gas emissions, global warming, and eutrophication demands urgent and innovative solutions. In recent years, microalgae have emerged as a promising avenue for addressing these pressing issues. In this study, the combination of dairy and municipal wastewater is proposed as a culture medium for cultivating microalgae strains capable of sequestering atmospheric CO2. Specifically, the growth of Chlorella vulgaris was investigated using Bold's basal medium, along with varying concentrations of municipal and dairy wastewater, both with and without CO2 supplementation, to assess their CO2 capture potential. Concurrently, the efficiency of chemical oxygen demand (COD), total nitrogen, potassium, and phosphate removal from the wastewater was evaluated. Additionally, the combination of wastewater media with CO2 supplementation yielded the highest CO2 uptake rates, indicating the feasibility of simultaneous CO2 capture during microalgae cultivation. Media composition with 25% municipal wastewater: 75% dairy wastewater supplemented with CO2 demonstrated superior COD elimination with a higher percentage of nutrient removal from wastewater compared to other wastewater proportions. The nutrient removal capacity of aforementioned media also comes in line with high CO2 sequestration rate (13.57 mg L−1 h−1). These findings underscore the potential of utilizing wastewater from diverse sources as a viable culture medium for microalgae cultivation, facilitating concurrent CO2 capture and wastewater treatment. [ABSTRACT FROM AUTHOR]

Learning operators with deep neural networks is an emerging paradigm for scientific computing. Deep Operator Network (DeepONet) is a modular operator learning framework that allows for flexibility in choosing the kind of neural network to be used in the trunk and/or branch of the DeepONet. This is beneficial as it has been shown many times that different types of problems require different kinds of network architectures for effective learning. In this work, we design an efficient neural operator based on the DeepONet architecture. We introduce U-Net enhanced DeepONet (U-DeepONet) for learning the solution operator of highly complex CO2-water two-phase flow in heterogeneous porous media. The U-DeepONet is more accurate in predicting gas saturation and pressure buildup than the state-of-the-art U-Net based Fourier Neural Operator (U-FNO) and the Fourier-enhanced Multiple-Input Operator (Fourier-MIONet) trained on the same dataset. Moreover, our U-DeepONet is significantly more efficient in training times than both the U-FNO (more than 18 times faster) and the Fourier-MIONet (more than 5 times faster), while consuming less computational resources. We also show that the U-DeepONet is more data efficient and better at generalization than both the U-FNO and the Fourier-MIONet. [ABSTRACT FROM AUTHOR]

The fast developing world is in search of measures to control the accumulation of unused by‐products and waste materials generated during the production of useful commodities. Accordingly, wastes from agro‐industrial sectors can form raw materials for the production of various resources that are extensively used in many areas such as gas sorption and energy production. In the present work, cashew nut shell liquid (CNSL), the vesicant liquid present in the outer shell of cashew seed, forms the source material for the synthesis of porous organic polymers for carbon dioxide capture. Herein, novel types of hypercrosslinked polymers (HCPs) are synthesized via a simple Friedel–Crafts reaction with CNSL as the starting material. Polymerization of natural CNSL with dimethoxymethane/bis‐(chloromethyl)‐biphenyl as external crosslinker provides products in quantitative yield. One of the synthesized HCP is tuned to attain the required high porosity by carbonization at elevated temperatures using an activator. Thus, activated carbon material prepared at 700°C is found to have a high surface area of 880 m2/g with a good carbon dioxide adsorption capacity of 14.72 wt%. These porous materials had moderate isosteric heat of adsorption (23–31 kJ/mol) with excellent recycling capability. [ABSTRACT FROM AUTHOR]

This study characterized the AA-01 depleted hydrocarbon reservoir in the KOKA field, Niger Delta, using a multidimensional approach. This investigation involved data validation analysis, evaluation of site suitability for CO2 storage, and compositional simulation of hydrocarbon components. The primary objective was to determine the initial components and behavior of the hydrocarbon system required to optimize the injection of CO2 and accompanying impurities, establishing a robust basis for subsequent sequestration efforts in the six wells in the depleted KOKA AA-01 reservoir. The process, simulated using industry software such as ECLIPSE, PVTi, SCAL, and Petrel, included a compositional fluid analysis to confirm the pressure volume temperature (PVT) hydrocarbon phases and components. This involved performing a material balance on the quality of the measured data and matching the initial reservoir pressure with the supplied data source. The compositional PVT analysis adopted the Peng–Robinson equation of state to model fluid flow in porous media and estimate the necessary number of phases and components to describe the system accurately. Results from this investigation indicate that the KOKA AA-01 reservoir is suitable for CO2 sequestration. This conclusion is based on the reservoir's good quality, evidenced by an average porosity of 0.21 and permeability of 1 111.0 mD, a measured lithological depth of 9 300 ft, and characteristic reservoir – seal properties correlated from well logs. The study confirmed that volumetric behavior predictions are directly linked to compositional behavior predictions, which are essential during reservoir initialization and data quality checks. Additionally, it highlighted that a safe design for CO2 storage relies on accurately representing multiphase behaviour across wide-ranging pressure–temperature–composition conditions. [ABSTRACT FROM AUTHOR]

CO2–slickwater hybrid fracturing technology is an essential part of shale gas recovery and CO2 geo-storage. However, the exposure to supercritical CO2 (ScCO2) and slickwater can result in potential changes of the pore structures and surface wetting behavior, which affect the gas transportation and CO2 sequestration security in shale reservoirs. Therefore, in this paper, X-ray diffraction (XRD), low-pressure nitrogen gas adsorption (N2GA), mercury intrusion porosimetry (MIP), and fractal analysis were used to describe the pore characteristics of shale before and after ScCO2–slickwater coupling treatments. Shale's surface wettability was confirmed by contact angle measurements. After the ScCO2–slickwater treatments, the number of micropores (<3.5 nm) and mesopores (3.5–50 nm) increased, while that of macropores (>50 nm) declined based on the N2GA and MIP experiments. Combined with fractal analysis, we argue that the pore connectivity diminished and the pore structure became more complicated. By analyzing the results of XRD, shale pore changes occurring after the ScCO2–slickwater treatment can be explained by the adsorption of polyacrylamide (PAM). Contact angle measurement results showed that the shale's surface treated by ScCO2 and slickwater was more hydrophilic than that treated by ScCO2 and water, and indirectly prove our argument above. Hence, the coupling using effect of ScCO2 and slickwater can impair the negative effect of CO2 on the shale capillary force to improve shale gas productivity, but it can negatively affect the security of CO2 sequestration in shale reservoirs. [ABSTRACT FROM AUTHOR]

It is acknowledged that injecting CO2 into oil reservoirs and saline aquifers for storage is a practical and affordable method for CO2 sequestration. Most CO2 produced from industrial exhaust contains impurity gases such as H2S that might impact CO2 sequestration due to competitive adsorption. This study makes a commendable effort to explore the adsorption behavior of CO2/H2S mixtures in calcite slit nanopores. Grand Canonical Monte Carlo (GCMC) simulation is employed to reveal the adsorption of CO2, H2S as well as their binary mixtures in calcite nanopores. Results show that the increase in pressure and temperature can promote and inhibit the adsorption capacity of CO2 and H2S in calcite nanopores, respectively. CO2 exhibits stronger adsorption on calcite surface than H2S. Electrostatic energy plays the dominating role in the adsorption behavior. Electrostatic energy accounts for 97.11% of the CO2-calcite interaction energy and 56.33% of the H2S-calcite interaction energy at 10 MPa and 323.15K. The presence of H2S inhibits the CO2 adsorption in calcite nanopores due to competitive adsorption, and a higher mole fraction of H2S leads to less CO2 adsorption. The quantity of CO2 adsorbed is lessened by approximately 33% when the mole fraction of H2S reaches 0.25. CO2 molecules preferentially occupy the regions near the pore wall and H2S molecules tend to reside at the center of nanopore even when the molar ratio of CO2 is low, indicating that CO2 has an adsorption priority on the calcite surface over H2S. In addition, moisture can weaken the adsorption of both CO2 and H2S, while CO2 is more affected. More interestingly, we find that pure CO2 is more suitable to be sequestrated in the shallower formations, i.e., 500–1500m, whereas CO2 with H2S impurity should be settled in the deeper reservoirs. [ABSTRACT FROM AUTHOR]

Carbon capture, utilization, and storage supply chain is recently acknowledged as a crucial method to limit global warming. There is a notable desire to optimize supply chains simultaneously with respect to economic and environmental factors, and the development of a mathematical model integrating the life cycle assessment into source-sink matching is missing in the existing literature. The present work means to fill this gap by using a bi-objective mixed-integer linear programming problem. The case study for this research focuses on a real-life scenario in Germany where carbon dioxide is captured from flue gas and transported to be stored or/and used. The total profit and life cycle GHG reduction are maximized. The results show that the profit per unit of sequestered CO2 decreases from 2014 to −€332 as the rate of life cycle GHG reduction increases from −873 to 52 MtCO2eq/year. The findings from the model can provide valuable knowledge that can be utilized in various countries at different levels, such as at regional, state, and national levels. This knowledge can also assist decision-makers in selecting more sustainable solutions when designing carbon capture, utilization, and storage systems. [ABSTRACT FROM AUTHOR]

Depleted gas reservoirs with bottom water show significant potential for long-term CO2 storage. The residual gas influences mass-transfer dynamics, further affecting CO2 dissolution and convection in porous media. In this study, we conducted a series of numerical simulations to explore how residual-gas mixtures impact CO2 dissolution trapping. Moreover, we analyzed the CO2 dissolution rate at various stages and delineated the initiation and decline of convection in relation to gas composition, thereby quantifying the influence of residual-gas mixtures. The findings elucidate that the temporal evolution of the Sherwood number observed in the synthetic model incorporating CTZ closely parallels that of the single-phase model, but the order of magnitude is markedly higher. The introduction of CTZ serves to augment gravity-induced convection and expedites the dissolution of CO2, whereas the presence of residual-gas mixtures exerts a deleterious impact on mass transfer. The escalation of residual gas content concomitantly diminishes the partial pressure and solubility of CO2. Consequently, there is an alleviation of the concentration and density differentials between saturated water and fresh water, resulting in the attenuation of the driving force governing CO2 diffusion and convection. This leads to a substantial reduction in the rate of CO2 dissolution, primarily governed by gravity-induced fingering, thereby manifesting as a delay in the onset and decay time of convection, accompanied by a pronounced decrement in the maximum Sherwood number. In the field-scale simulation, the injected CO2 improves the reservoir pressure, further pushing more gas to the producers. However, due to the presence of CH4 in the post-injection process, the capacity for CO2 dissolution is reduced. [ABSTRACT FROM AUTHOR]

The induction of accelerated carbonation curing (ACC) as carbon capture, utilization, and sequestration (CCUS) technique helps in achieving the net zero target. ACC is one of the potential techniques to sequester the CO2 in concrete. However, the usage of ACC in reinforced concrete is still debatable. This paper investigates the effect of ACC on mechanical, permeation, mineralogy, hydration and microstructural characteristics of concrete with the long-term performance of reinforced concrete using linear polarization resistance (LPR) and carbonation depth. In order to study the effect of ACC duration on the properties of concrete, the specimen was subjected to 6, 12, and 24 hours (h) of carbonation curing. The results were compared with conventional water-curing specimens. ACC at 12 h provided the best results for tested properties. The results were varied by statistical analysis using ANOVA and stoichiometry. Based on the best 12-h duration, 2.13 kg of CO2 can be sequestered in 1 m3 (0.89 kg/t) of concrete. [ABSTRACT FROM AUTHOR]

The aim of this study is to examine the CO2 gas adsorption capability of coals from Sohagpur coalfield, India. Coal bed CO2 sequestration is a technique utilized to mitigate carbon dioxide emissions and improve global warming. Various factors, including pore structure, pore volume, mineral composition, moisture content, cleats, coal quality, pressure, and temperature, influence the adsorption of CO2 in coal seams. To conduct this investigation, multiple coal samples were collected from the study area and subjected to proximate analysis, ultimate analysis, scanning electron microscopy (SEM), Fourier transform-infrared (FT-IR), Brunauer – Emmett–Teller (BET), and measurement of CO2 adsorption rates on the coal samples. Samples were characterized based on their geochemical properties, then pore and fracture properties and maximum adsorption of CO2 gas were determined. The interrelationship between the genetic properties of coal with the adsorption rate of CO2 gas was established. These coals lie mesopore in category with the presence of fractures and hydrogen bonds. The result of BET and kinetics rate indicates that the adsorption of gas was unrestricted multilayer type, and the maximum adsorption of CO2 gas at 50 bar is 2.15 moles gas/kg sample, respectively. [ABSTRACT FROM AUTHOR]

Sequestering CO2 in depleted oil reservoirs provides one of the most appealing measures to reduce greenhouse gases (GHG) concentration in the atmosphere. The remaining liquids after enhanced oil recovery (EOR) processes, including residual oil and remaining water, lead to the main challenges to this approach. How to effectively evacuate a depleted oil reservoir by recovering not only residual oil but also remaining water is a critical consideration for this type of CO2 sequestration. This paper presents conceptual investigations concerning the methods which effectively evacuate depleted oil reservoirs from both the displacement efficiency and the sweep efficiency points of view. To improve the displacement efficiency, surfactant slug and solvent slug injection was examined using a core scale numerical model. Investigations regarding improving sweep efficiency, such as horizontal well pattern infilling and foam injection, were carried out based on a typical row well pattern. Simulation results showed that surfactant slug which modified the relative permeability and capillary pressure remarkably reduced both residual oil saturation and remaining water saturation. A CO2 slug injected before surfactant slug can help improve the oil recovery. Solvent enriched CO2 slug also remarkably reduced the residual oil saturation to as low as 2%. Horizontal well pattern infilling had great advantage for thick or inclined reservoirs, and foam slug injection greatly improved CO2 storage capacity in thin reservoirs by improving the sweep efficiency. Maximum mobility reduction (MRF) is the most important parameter to maximize the storage capacity and the benefit. The variation of CO2 storage capacity along with CO2 slug size. Larger foam slug size will play a better storage performance. The conceptual simulation investigations confirmed that depleted oil reservoirs can be effectively evacuated for CO2 storage. Depleted oil reservoirs with maximum evacuation are the best candidates for CO2 sequestrations. [ABSTRACT FROM AUTHOR]

The urgent need to find mitigating pathways for limiting world CO2 emissions to net zero by 2050 has led to intense research on CO2 sequestration in deep saline reservoirs. This paper reviews key advancements in lab- and simulation-scale research on petrophysical, geochemical, and mineralogical changes during CO2–brine–rock interactions performed in the last 25 years. It delves into CO2 MPD (mineralization, precipitation, and dissolution) and explores alterations in petrophysical properties during core flooding and in static batch reactors. These properties include changes in wettability, CO2 and brine interfacial tension, diffusion, dispersion, CO2 storage capacity, and CO2 leakage in caprock and sedimentary rocks under reservoir conditions. The injection of supercritical CO2 into deep saline aquifers can lead to unforeseen geochemical and mineralogical changes, possibly jeopardizing the CCS (carbon capture and storage) process. There is a general lack of understanding of the reservoir's interaction with the CO2 phase at the pore/grain scale. This research addresses the gap in predicting the long-term changes of the CO2–brine–rock interaction using various geochemical reactive transport simulators. Péclet and Damköhler numbers can contribute to a better understanding of geochemical interactions and reactive transport processes. Additionally, the dielectric constant requires further investigation, particularly for pre- and post-CO2–brine–rock interactions. For comprehensive modeling of CO2 storage over various timescales, the geochemical modeling software called the Geochemist's Workbench was found to outperform others. Wettability alteration is another crucial aspect affecting CO2–brine–rock interactions under varying temperature, pressure, and salinity conditions, which is essential for ensuring long-term CO2 storage security and monitoring. Moreover, dual-energy CT scanning can provide deeper insights into geochemical interactions and their complexities. [ABSTRACT FROM AUTHOR]

In recent years, technical processes for the sequestration of CO2 through industrial waste mineral carbonation have been explored and developed. There is a large portfolio of carbon capture, utilisation, and storage (CCUS) techniques that have been employed in laboratories and at pilot scale. These include geological storage, ocean storage, and mineralisation by carbonate ores. In view of this, the main purpose of this research was to investigate and explore chemical variables, particularly ammonium salts as lixiviants for calcium mineral extraction from iron-making slag. The slag in use was acquired from a steel mill in the Vaal Triangle Region in Gauteng, South Africa. The experimental test work was conducted using different ammonium lixiviants, namely, NH4NO3, NH4Cl, and CH3COONH4, to understand the influence of anion type as well as possible differences in mechanisms of interactions. Lixiviant concentration as well as reaction time were varied in this research study. The three selected ammonium-based lixiviants showed different extents of calcium extraction owing to differences in the anion groups. NH4NO3, NH4Cl, and CH3COONH4 were found to be capable of dissolving 50% to 80% of the calcium from the selected slag for different molar concentrations. Anion type and leaching time also had significant influences on the leaching of calcium from the slag. Rapid pH degradation resulted in better calcium extraction capabilities. This work has shown that the selected ammonium salts have the potential to be lixiviants for calcium dissolution from iron-making blast furnace slags. These lixiviants would, therefore, be important to consider during calcium mineral carbonation for CO2 sequestration. [ABSTRACT FROM AUTHOR]

In recent years, the building industry has looked for technological ways to protect the environment and preserve natural resources. Since the COVID-19 epidemic, there has been a shortage of building materials, which has caused construction costs to go up. This has made it more important for sustainable development to be based on the principles of the circular economy. This gives an opportunity to utilise various reliable materials as substitutes, like construction and demolition (C&D) waste. (C&D) wastes are made up of a large chunk of all solid waste, which causes many environmental problems. The most important factor in the struggle against climate change is the reduction of CO2 emissions from the construction sector. At the same time, globally, climate change caused in part by carbon dioxide (CO2) emissions is an important problem that requires innovative carbon sequestration strategies. Because C&D waste is alkaline-rich (e.g., calcium hydroxide and calcium-silicate-hydrate (C-S-H)), it can be used to sequester CO2 by converting it into thermodynamically stable carbonates. Temperature, partial pressure of CO2, time, process route, humidity, and the water-to-solid ratio (w/s) can affect the CO2 sequestration over the C&D wastes. [ABSTRACT FROM AUTHOR]

In terms of the collaborative optimization of CO2 flooding for Enhanced Oil Recovery (EOR) and CO2 sequestration, previous studies have co-optimized both cumulative oil production and CO2 sequestration by various algorithms. However, these solutions fail to optimize the CO2 injection schemes for high-water cut oil reservoirs. This paper presents an optimization methodology for CO2 flooding and sequestration in high-water cut oil reservoirs. The production optimization was carried out by adjusting the injection and production rate. To solve the proposed objective functions, the simultaneous perturbation stochastic approximation (SPSA) algorithm is applied in this paper, and the CMG-GEM module is utilized to simulate the reservoir production performance. A typical high-water cut reservoir in the Shengli oilfield was used to verify the feasibility of the presented methodology. In this paper, the production performance and net present value (NPV) for continuous gas injection under different water cuts were analyzed. The optimal timing of transforming from water flooding to gas displacement for the high-water cut reservoir was optimized. In addition, the optimal water–gas ratios for Water-Alternating-Gas (WAG) flooding were determined. The sensitivity of NPV to gas injection price and carbon subsidy was analyzed. The results show that when the gas price is 0.178 $/m3 and the carbon subsidy is 0.0169 $/m3, the optimal timing of transforming from water flooding to gas injection should be earlier than the time when the water cut is 0.82. Through the combination of NPV, cumulative oil production rate, and CO2 sequestration volume for WAG flooding, the optimal WAG ratio should be 1:2. The presented method in this paper considers various economic indicators and can optimize CO2 flooding and sequestration in high-water cut oil reservoirs efficiently, which can provide some guidance for the design of CO2 flooding schemes in high-water cut oil reservoirs. [ABSTRACT FROM AUTHOR]

This research explores nanomaterials' potential in CO2 capture and storage, emphasizing their role in CO2 diffusion and interfacial tension. We aimed to develop eco-friendly nanomaterials and evaluate their impact on CO2 sequestration, considering factors like pressure, temperature, salinity, and nanoparticle concentration. The research involved experimental measurements of CO2 diffusion in brine solutions and brine-based nanofluids containing green silica NPs and SiO2/Xanthan nanocomposites. CO2 diffusion coefficients were determined through practical pressure decay measurements using the Sheikha method. These measurements were conducted within a Fluid EVAL (PVT) cell, allowing CO2 interaction with each solution. The results of the study revealed significant improvements in the carbon dioxide (CO2) diffusion coefficients and reductions in interfacial tension when utilizing water/silica nanofluids containing 0.5 wt.% and 0.1 wt.% concentrations, in comparison with a brine solution without nanoparticles (NPs) and with a high salt concentration (20 wt.% NaCl). The CO2 diffusion coefficient increased from 2.15E-09 to 4.01E-09 m2/s. An even more significant enhancement was observed with 0.1 wt.% SiO2 NPs, where the CO2 diffusion coefficient reached 4.87E-09 m2/s. In addition, CO2 interfacial tension reduced from 44.3517 to 1.0388 mN/m and 0.9098 mN/m, respectively. The general trend of the measured carbon dioxide diffusion coefficient aligned with increased pressure and temperature. Additionally, when considering the transition to a supercritical state, the findings highlighted consistent behavior, independent of variations in pressure and temperature. Conversely, the interfacial tension between CO2 and nanofluids decreased in response to heightened pressure and temperature. Moreover, an increase in salinity led to a rise in interfacial tension. In conclusion, heightened CO2 diffusion and reduced interfacial tension improve CO2 sequestration, enhancing CO2 transport, absorption, and storage efficiency for successful long-term CO2 storage. [ABSTRACT FROM AUTHOR]

Climate change necessitates urgent actions to mitigate carbon dioxide (CO2) emissions from fossil fuel-based energy generation. Among various strategies, the deployment of carbon capture and storage (CCS) solutions is critical for reducing emissions from point sources such as power plants and heavy industries. In this context, cryogenic carbon capture (CCC) via desublimation has emerged as a promising technology. While CCC offers high separation efficiency, minimal downstream compression work, and integration potential with existing industrial processes, challenges such as low operating temperatures and equipment costs persist. Ongoing research aims to address these hurdles in order to optimize the desublimation processes for widespread implementation. This review consolidates diverse works from the literature, providing insights into the strengths and limitations of CCC technology, including the latest pilot plant scale demonstrations. The transformative potential of CCC is first assessed on a theoretical basis, such as thermodynamic aspects and mass transfer phenomena. Then, recent advancements in the proposed process configurations are critically assessed and compared through key performance indicators. Furthermore, future research directions for this technology are clearly highlighted. [ABSTRACT FROM AUTHOR]

The properties of amorphous calcium carbonate (ACC) and its transformations to crystalline polymorphs are frequently studied in aqueous systems and in small quantities. In this study, synthetic calcium carbonate stones are created from bulk ACC and crystalline polymorphs, which were precipitated from gaseous CO2, at a gradient of end pH. Some of the ACCs hardened into stones which are durable against an abrasion and impact test, while some of the ACCs create fragile, friable stones. When ACCs which transform to durable stones and those which transform into fragile stones were subject to calorimetry, significant differences were observed. These stones, synthesized from gaseous CO2, can be used as a storage reservoir for utilized CO2 in construction and other infrastructure applications. [ABSTRACT FROM AUTHOR]

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Extralow-permeability reservoirs have emerged as a significant area of focus for CO2 geological sequestration due to their stable subterranean structure and expansive storage capacity, offering substantial potential in addressing global climate change. However, the full extent of CO2 geological sequestration potential within these extralow-permeability reservoirs remains largely unexplored. To address this gap, this paper utilizes the Shahejie Formation (Es1 member) of the Shuang 229 block in the Liaohe oilfield, Bohai Bay Basin, as a case study. This section is characterized by its abundant oil-gas reserves and serves as an exemplar for conducting experimental research on CO2 storage within extralow-permeability reservoirs. The results demonstrate that the reservoir lithology of the Es1 member is fine sandstone and siltstone, with high compositional and structural maturity. Moreover, the average porosity is 14.8%, the average permeability is 1.48 mD, and the coefficient of variation of the reservoir is approximately 0.5, which indicates a low- to extralow-permeability homogeneous reservoir. In addition, the overburden pressure is >2.0 MPa, the fault can withstand a maximum gas column height of >200 m, and the reservoir exhibits favorable overburden and fault sealing characteristics. Notably, stepwise increasing gas injection in the Shuang 229-36-62 well reveals that the injected liquid CO2 near the wellhead exhibits a relatively high density, close to 1.0 g/cm3, which gradually decreases to approximately 0.78 g/cm3 near a depth of 2000 m underground. The injected fluid changes into a supercritical state upon entering the formation, and the CO2 injection speed is optimal, at 0.08 HCPV/a. According to these findings, it is predicted that the highest burial CO2 volume via the injection of 1.5 HCPVs in the Wa 128 block area is 1.11 × 105 t/year, and the cumulative burial volume reaches approximately 2.16 × 106 t. This shows that the CO2 sequestration potential of extralow-permeability reservoirs is considerable, providing confidence for similar instances worldwide. [ABSTRACT FROM AUTHOR]

Increased CO2 emissions have resulted in extreme climatic variations and as the forecast is that the global temperature will hit its highest-ever level in the next five years. This comes at a time when there is an urgent need for effective and smooth means of reducing greenhouse gas emissions. Geological Sequestration of Carbon (GCS) is a new alternative: the effective and safe storage of CO2 underground. The most critical part of the process is the leakage assessment and geological formation safety as a long-term sink of CO2. Caprock is important in this process as an efficient long-time sequester for CO2, as it is more permeable to CO2 than geological reservoirs. Of all the other processes involved in trapping, the most effective in the immediate phase after the injection of CO2 is capillary trapping. The CO2 remains stored under the caprock until the critical pressure that initiates movement is achieved. Traditional methods, such as mercury intrusion porosimetry and core flooding experiments, do not tend to be replicated correctly in-situ and often complicate the process. Measurements made in such a manner usually overestimate threshold pressures for one of many reasons, be it late flow signal recognition in the low permeability of caprocks or incompletely saturated cores. For these purposes, in-situ-type novel equipment was developed for easy and direct capillary pressure measurement, core saturation, and effortless reproduction of in-situ conditions at higher pressures. This new technique measures the pressure in the outflow directly, so the values of threshold pressure it gives are very exact. [ABSTRACT FROM AUTHOR]

Agroforestry is an integrative farm management approach in which trees are deliberately integrated with other crops. Agroforestry systems can be effective if appropriate trees are chosen based on particular environmental and economic factors. However, it is crucial to identify suitable trees for agroforestry implementation (AI). The objective of the current study was to recognize the most suitable trees for AI in the agricultural lands of Nazar Kahrizi (NK) rural district of Hashtroud city, located in the northwest of Iran using a multi-dimensional approach. The study area was environmentally evaluated using ArcGIS, which led to the creation of 16 classes with different features. Then, based on the preference of 126 local farmers (from 26 villages of NK), 19 native trees were selected for AI assessment. These trees were evaluated and compared considering seven criteria (i.e., frostbite resistance, salinity resistance, sensitivity to drainage, storm resistance, drought resistance, preventing soil erosion, and economic benefits). Finally, a flexible multi-criteria decision analysis (MCDA) tool (PROMETHEE II) was applied to provide a complete ranking of preferred trees from the best to the worst for each class. The findings showed that the agricultural lands should be allocated for planting elaeagnus (about 79.6%, 27,446 ha), almond (13.5%, 4619 ha), quince (4.6%, 1573 ha), apple (1.8%, 635 ha), and walnuts (0.5%, 176 ha). Measurements showed that AI with the recommended trees in the study area will lead to CO2 sequestration of about 12.96 Mg yr−1. The approach used in this study provides a valuable resource for decision-making in AI evaluations and, therefore, contributes to preserving the lands from degradation and ensures sustainable AI. [ABSTRACT FROM AUTHOR]

Reservoir simulation is traditionally based on the assumption that water is an inert phase, while hydrocarbon components split into oil and gas phases. This approach is usually reasonable when modeling conventional hydrocarbon recovery, but specific applications may require accounting for mass exchange between the water and hydrocarbon phases. We here present the extension of our Graphics Processing Units (GPUs) compositional reservoir simulator (Esler et al. SPE J. 27(01), 597–612, 2021) to support gas-water equilibrium. Specifically, the Søreide and Whitson equation of state (EoS) (Søreide and Whitson Fluid Phase Equilib. 77, 217–240, 1992) was implemented to compute mutual solubilities of hydrocarbon/brine mixtures. The impact of salinity on phase equilibrium is accounted for, with salt being treated as an active tracer. The simulator uses a mass-variables formulation, meaning that little modifications to the construction of transport equations and Jacobian assembly was required; most of the required code changes are localized in the EoS module for the computation of component fugacities, and phase properties such as partial molar fractions and partial molar volumes. Treating salt as an active tracer instead of defining a further pseudo-component has an important advantage with the Søreide and Whitson EoS. If salinity changes as in water vaporization processes, our choice ensures that flash iterations can still be cast as a Gibbs Minimization problem with salinity being a constant parameter. On the contrary, salinity would change as flash iterations progress, jeopardizing the thermodynamic consistency of the phase equilibria. The overall reservoir simulation system of equations is still accurate to first order in time, at the cost of possibly slight volume imbalances at the end of converged timesteps. In this paper, we focused on CO 2 sequestration in saline aquifers, where solubility trapping is a key mechanism. The accuracy of our implementation with respect to conventional CPU ones is first demonstrated on a synthetic box model. We then select an open-access aquifer model (Gassnova 2016) to illustrate its applicability in an industrial setting. Finally, we show how being able to seamlessly run high resolution models allows for modeling of convective mixing. A key conclusion of this work is that the extreme performance of GPU-based reservoir simulation naturally transfers to new fields of study, which is critical when modeling saline aquifers whose extent is an order of magnitude larger than that of typical oil and gas fields. [ABSTRACT FROM AUTHOR]

Objective Fracture systems in shale reservoirs have an important impact on CH4 production and CO2 sequestration, and different geological characteristics of reservoirs have their corresponding optimal fracturing schemes. The study aims to investigate the effect of artificial fracture parameters on CO2 sequestration and CH4 production of Yanchang formation shale reservoirs in Ordos Basin. Methods Based on the geological conditions of shale reservoirs of Yanchang formation in Ordos Basin, a dual-porosity, dual- permeability homogeneous model was established to analyze the effects of artificial fracture half-lengths, fracture width, fracture height, fracture spacing, and the number of fractures on CO2 sequestration and CH4 production in CO2-ESGR. Results The results showed that fracture half-length fracture width and fracture height were positively correlated with CO2 sequestration and CH4 production, among which fracture width had the greatest influence. When the fracture width increased from 5 mm to 25 mm. CO2 sequestration increased by 112.69% and CH4 production increased by 87.11% at most. Both fracture interval and fracture number increased CO2 sequestration and CH4 production. However, when the horizontal well length was the same, the increasing of fracture number had a far greater impact on CO2 sequestration and CH4 production than that of fracture interval. When the number of fracture increased from 2 to 6. CO2 sequestration increased by 151. 92% and CH4 production increased by 137. 81% at most. Conclusions During the development process, strategically enhancing the half-length, height, width and quantity of artificial fractures can facilitate efficient sequestration of CO2 and extraction of CH4. [ABSTRACT FROM AUTHOR]

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The technique of Enhanced Gas Recovery by CO2 injection (CO2-EGR) into shale reservoirs has brought increasing attention in the recent decade. CO2-EGR is a complex geophysical process that is controlled by several parameters of shale properties and engineering design. Nevertheless, more challenges arise when simulating and predicting CO2/CH4 displacement within the complex pore systems of shales. Therefore, the petroleum industry is in need of developing a cost-effective tool/approach to evaluate the potential of applying CO2 injection to shale reservoirs. In recent years, machine learning applications have gained enormous interest due to their high-speed performance in handling complex data and efficiently solving practical problems. Thus, this work proposes a solution by developing a supervised machine learning (ML) based model to preliminary evaluate CO2-EGR efficiency. Data used for this work was drawn across a wide range of simulation sensitivity studies and experimental investigations. In this work, linear regression and artificial neural networks (ANNs) implementations were considered for predicting the incremental enhanced CH4. Based on the model performance in training and validation sets, our accuracy comparison showed that (ANNs) algorithms gave 15% higher accuracy in predicting the enhanced CH4 compared to the linear regression model. To ensure the model is more generalizable, the size of hidden layers of ANNs was adjusted to improve the generalization ability of ANNs model. Among ANNs models presented, ANNs of 100 hidden layer size gave the best predictive performance with the coefficient of determination (R2) of 0.78 compared to the linear regression model with R2 of 0.68. Our developed MLbased model presents a powerful, reliable and cost-effective tool which can accurately predict the incremental enhanced CH4 by CO2 injection in shale gas reservoirs. [ABSTRACT FROM AUTHOR]

Occurrences of natural magnesium alumina silicate hydrate (M-(A)-S-H) cement are present in Feragen and Leka, in eastern and western Trøndelag Norway, respectively. Both occurrences are in the subarctic climate zone and form in glacial till and moraine material deposited on ultramafic rock during the Weichselian glaciation. Weathering of serpentinized peridotite dissolves brucite and results in an alkaline fluid with a relatively high pH which subsequently reacts with the felsic minerals of the till (quartz, plagioclase, K-feldspar) to form a cement consisting of an amorphous material or a mixture of nanocrystalline Mg-rich phyllosilicates, including illite. The presence of plagioclase in the till results in the enrichment of alumina in the cement, i.e., forms M-A-S-H instead of the M-S-H cement. Dissolution of quartz results in numerous etch pits and negative quartz crystals filled with M-A-S-H cement. Where the quartz dissolution is faster than the cement precipitation, a honeycomb-like texture is formed. Compositionally, the cemented till (tillite) contains more MgO and has a higher loss of ignition than the till, suggesting that the cement is formed by a MgO fluid that previously reacted with the peridotite. The M-(A)-S-H cemented till represents a new type of duricrust, coined magsilcrete. The study of natural Mg cement provides information on peridotites as a Mg source for Mg cement and as a feedstock for CO2 sequestration. [ABSTRACT FROM AUTHOR]

Water-quenched copper-nickel metallurgical slag enriched with olivine minerals exhibits promising potential for the production of CO2-mineralized cementitious materials. In this work, copper-nickel slag-based cementitious material (CNCM) was synthesized by using different chemical activation methods to enhance its hydration reactivity and CO2 mineralization capacity. Different water curing ages and carbonation conditions were explored related to their carbonation and mechanical properties development. Meanwhile, thermogravimetry differential scanning calorimetry and X-ray diffraction methods were applied to evaluate the CO2 adsorption amount and carbonation products of CNCM. Microstructure development of carbonated CNCM blocks was examined by backscattered electron imaging (BSE) with energy-dispersive X-ray spectrometry. Results showed that among the studied samples, the CNCM sample that was subjected to water curing for 3 d exhibited the highest CO2 sequestration amount of 8.51wt% at 80°C and 72 h while presenting the compressive strength of 39.07 MPa. This result indicated that 1 t of this CNCM can sequester 85.1 kg of CO2 and exhibit high compressive strength. Although the addition of citric acid did not improve strength development, it was beneficial to increase the CO2 diffusion and adsorption amount under the same carbonation conditions from BSE results. This work provides guidance for synthesizing CO2-mineralized cementitious materials using large amounts of metallurgical slags containing olivine minerals. [ABSTRACT FROM AUTHOR]

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Saline aquifer rocks exhibit significant spatial randomness due to geological sedimentation processes. To address the issue of the heterogeneity of rock formations in numerical simulations, it is common practice to homogenize rock layers with similar lithologies. However, the acceptability of the errors generated during homogenized computations is a major concern and should be investigated. Therefore, to study the influence of heterogeneity at the storage site on the CO2 migration behavior, the Monte Carlo simulation–random finite element method (MCS‐RFEM) was combined with a CO2 two‐phase flow model to compare the effects of the coefficient of variation (Cv) and correlation length (λx) of random reservoir permeability fields on the migration distance and extent of CO2 storage under the same mean conditions. The results showed that higher Cv and λx values significantly reduced the CO2 migration distance while increasing the spread extent. Compared to the homogeneous model, at a λx value of 100 m, the CO2 migration distance decreased by 5.05%, while the profile sweep area increased by 6.20%. Concurrently, with increasing Cv, the area with a CO2 volume fraction higher than 0.75 decreased by 20.22%, while an increase in λx resulted in a 42.35% increase in the area with a CO2 volume fraction higher than 0.75. Therefore, reservoirs with high Cv and low λx values are more suitable for safely storing CO2. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Geologic carbon sequestration requires CO2 injection into the storage formation at high‐injecting pressure. Such high pressure could induce choked flow accompanying huge variations in thermodynamic properties of CO2 at a converging‐diverging (CD) fractures in the storage formation. In this study, high‐velocity CO2 transport through CD fractures was investigated to quantify the effect of fracture morphology on occurrence of both choked flow and shockwave that constrain the mass flow rate of fluid. In addition, variations in thermodynamic CO2 properties including Mach Number (Ma), defined by the ratio of fluid velocity to sound speed, and shock properties were investigated. The morphological characteristics of CD fractures were determined by nine properties, such as throat diameter, throat length, inlet diameter, outlet diameter, throat diameters of two‐connected CD fractures, fracture wall curvature, roughness amplitude, and frequency. As a result, the throat diameter crucially affected choked flow occurrence and maximum Ma. When the inlet and outlet diameters varied, the profiles for Ma variation were consistent in the converging and diverging segments, respectively. In addition, regardless of change in the throat length, the position of maximum Ma was nearly constant with showing the position length ratio of 0.13–0.14. However, roughness of fracture wall significantly influenced the Ma variation and occurrence of shock. In particular, backflows segregated from the main CO2 flow were observed near the wall roughness. Plain Language Summary: Choked flow is a fluid‐mechanical process that restricts the mass flow rate of fluid and it can be occurred when fluid velocity overcomes its sound speed. When CO2 is injected into the targeted geologic formation, choked flow can occur due to highly pressurized flow within the fractures located near the CO2 injection well. Once choked flow occurred, the shock, which accompanies substantial changes in the thermodynamic properties of CO2, follows in the fractures. In the study, choked flow is generated within the converging‐diverging (CD) fracture which serves as a pathway of injected CO2, and its cross‐sectional area decreases and increases again after the "throat." We assumed that the CD fractures have various morphologic properties and analyzed the relationship between the fracture morphology and shock properties. The results highlighted that the throat diameter and fracture roughness mainly affected choked flow occurrence and shock properties. Findings here are applicable to other site‐specific studies, such as volcanoes, geysers, geothermal fields, and underground hydrogen storage sites where highly compressed fluid often migrates through subsurface fractures or any types of geologic conduits. Key Points: CO2 flow within the fracture was simulated to evaluate the effect of fracture morphology on choked flow and shock generationMorphologic properties including throat diameter and length, inlet and outlet diameter, number of throats, and wall roughness were variedThroat diameter influenced the Mach number (Ma); a complicated trend of Ma and backflow were observed owing to wall roughness [ABSTRACT FROM AUTHOR]

Climate change is rapidly exacerbating and adding to major-to-existential issues associated with freshwater availability and utilization. The massive, thus far untapped saline/salt water/ocean—wastelands/deserts—Halophytes resources nexus can, at scale and profitably, provide major climate change mitigation and greatly alleviate most extant freshwater issues. Approaches include ocean fertilization and saline/seawater agriculture on deserts and wastelands to sequester massive amounts of CO2 and methane and for food, freeing up some 70% of the freshwater now utilized by current agriculture for direct human use. This also enables the production of huge amounts of biofuels and biomass-based chemical feedstock employing the massive capacity of cheap saline/seawater and cheap deserts and wastelands. Overall, saline/seawater can, uniquely, at the scale of the climate and freshwater issues, without desalinization, profitably, utilizing extant technologies, some 40% of the land that is deserts/wastelands, and the 97% of the water that is saline/seawater rapidly, seriously, address land, freshwater, food, energy, and climate. [ABSTRACT FROM AUTHOR]

The presence of solvent impurities can significantly impact the corrosion performance of stainless steel when exposed to CO2-saturated NaCl (Sodium Chloride) solutions. Solvent impurities, originating from various sources, may introduce chemical changes that interact with the metal surface and alter its corrosion resistance. Under simulated flow circumstances, the corrosion performance of stainless steels in the presence of contaminants such Monoethyleneglycol (MEG) and oxygen in a CO2 environment was investigated. Utilizing a rotating cage, the corrosion performance of stainless steel was assessed, and mass loss measurements were used to calculate the corrosion rates. According to the experimental findings, the oxygenated MEG exhibits a very low rate of corrosion. SEM and EDX surface analysis techniques were utilized to examine the corrosion product that had developed on the metal surface. [ABSTRACT FROM AUTHOR]

It is a challenge to make thorough but efficient experimental designs for the coupled mineral dissolution and precipitation studies in a multi-mineral system, because it is difficult to speculate the best experimental duration, optimal sampling schedule, effects of different experimental conditions, and how to maximize the experimental outputs prior to the actual experiments. Geochemical modeling is an efficient and effective tool to assist the experimental design by virtually running all scenarios of interest for the studied system and predicting the experimental outcomes. Here we demonstrated an example of geochemical modeling assisted experimental design of coupled labradorite dissolution and calcite and clayey mineral precipitation using multiple isotope tracers. In this study, labradorite (plagioclase) was chosen as the reactant because it is both a major component and one of the most reactive minerals in basalt. Following our isotope doping studies of single minerals in the last ten years, initial solutions in the simulations were doped with multiple isotopes (e.g., Ca and Si). Geochemical modeling results show that the use of isotope tracers gives us orders of magnitude more sensitivity than the conventional method based on concentrations and allows us to decouple dissolution and precipitation reactions at near-equilibrium condition. The simulations suggest that the precise unidirectional dissolution rates can inform us which rate laws plagioclase dissolution has followed. Calcite precipitation occurred at near-equilibrium and the multiple isotope tracer experiments would provide near-equilibrium precipitation rates, which was a challenge for the conventional concentration-based experiments. In addition, whether the precipitation of clayey phases is the rate-limiting step in some multi-mineral systems will be revealed. Overall, the modeling results of multi-mineral reaction kinetics will improve the understanding of the coupled dissolution–precipitation in the multi-mineral systems and the quality of geochemical modeling prediction of CO2 removal and storage efficacy in the basalt systems. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years, a new class of highly crystalline advanced permeable materials covalent‐organic frameworks (COFs) have garnered a great deal of attention thanks to their remarkable properties, such as their large surface area, highly ordered pores and channels, and controllable crystalline structures. The lower physical stability and electrical conductivity, however, prevent them from being widely used in applications like photocatalytic activities and innovative energy storage and conversion devices. For this reason, many studies have focused on finding ways to improve upon these interesting materials while also minimizing their drawbacks. This review article begins with a brief introduction to the history and major milestones of COFs development before moving on to a comprehensive exploration of the various synthesis methods and recent successes and signposts of their potential applications in carbon dioxide (CO2) sequestration, supercapacitors (SCs), lithium‐ion batteries (LIBs), and hydrogen production (H2‐energy). In conclusion, the difficulties and potential of future developing with highly efficient COFs ideas for photocatalytic as well as electrochemical energy storage applications are highlighted. [ABSTRACT FROM AUTHOR]

Under the dual-carbon target, CO2 mineralization through solid wastes presents a mutually beneficial approach for permanent carbon emission reduction at a low material cost, while also enabling the resource utilization of these wastes. However, despite its potential, a comprehensive understanding about the effect of industrial solid waste properties and operating parameters on the carbonation process, and the mechanism of direct aqueous carbonation is still lacking. A series of experiments were conducted to compare the carbonation performance of fly ash, steel slag, and carbide slag. Subsequently, CO2 mineralization by carbide slag was systematically studied under various operating parameters due to its high CO2 sequestration capacity. Results showed the reactivity of CaO and Ca(OH)2 was higher than that of CaO·SiO2 and 2CaO·SiO2. Carbide slag demonstrated a sequestration capacity of 610.8 g CO2/kg and carbonation efficiency ζCa of 62.04% under the conditions of 65 °C, 1.5 MPa initial CO2 pressure, 15 mL/g liquid-to-solid ratio, and 200 r/min stirring speed. Moreover, the formation of carbonates was confirmed through XRD, SEM-EDS, TG, and FTIR. A mechanism analysis revealed that initially, the rate of the carbonation process was primarily controlled by the mass transfer of CO2 in the gas–liquid interface. However, the rate-determining step gradually shifted to the mass transfer of Ca2+ in the solid–liquid interface as the reaction time increased. This study lays the foundation for the large-scale implementation of CO2 sequestration through carbide slag carbonation. [ABSTRACT FROM AUTHOR]

The carbonation of industrial calcium-rich byproducts such as steel slag demonstrates significant potential for CO2 sequestration. This technique aids in reducing carbon emissions while also promoting waste recycling. Despite its advantages, gaps remain in the understanding of how steel slag characteristics and operational parameters influence the carbonation process, as well as the underlying mechanism of direct aqueous carbonation. We evaluated the carbonation performance of three types of steel slag at temperatures below 100 °C. The slag with the highest CO2 sequestration capacity was chosen for a systematic evaluation of the effects of operating conditions on carbonation efficiency. Thermodynamic analysis indicated that the reactivity of CaO and Ca(OH)2 with CO2 exceeded that of CaO·SiO2 and 2CaO·SiO2. Under conditions of 85 °C, a particle size less than 75 μm, an initial CO2 pressure of 0.5 MPa, a liquid-to-solid ratio of 5 mL/g, and a stirring speed of 200 rpm, the steel slag achieved a sequestration capacity (K) of 283.5 g(CO2)/kg and a carbonation efficiency (ζCa) of 51.61%. Characterization of the slag before and after carbonation using X-ray diffraction, SEM-EDS, thermogravimetric analysis, and Fourier transform infrared spectrometry confirmed the formation of new carbonates. Mechanistic analysis revealed that the rate-limiting step initially involved the mass transfer of CO2, transitioning to Ca2+ mass transfer as time progressed. Our research provides a viable technique for CO2 capture and a beneficial approach for reutilizing waste steel slag. Furthermore, solid residues after capturing CO2 have the potential for conversion into carbon-negative building materials, offering a sustainable strategy for steel companies and other enterprises with high carbon emissions. [ABSTRACT FROM AUTHOR]

Basaltic rocks, owing to their vast geological presence, have been identified as potential reservoirs for carbon dioxide (CO2) sequestration. Their inherent attributes, namely, a pronounced mineral trapping capability, distinct structural intricacies, and a potential storage capacity surpassing 100Gt, earmark them as prime candidates for CO2 storage. However, knowledge gaps exist in understanding the modifications in the petrophysical and mechanical characteristics of these rocks post-CO2 sequestration. Comprehending these CO2-induced petrophysico-mechanical alterations is crucial for assessing their potential for long-term carbon mineralization-based storage. Thus, this study provides a critical review of key parameters that can induce post-CO2 injection changes in the mechanical and petrophysical properties of basaltic rocks. Also, the implications of these changes for long-term CO2 storage efficiency in Basaltic rocks are succinctly presented. Findings from this review work show that the mineralogical composition of basaltic rocks can alter the petrophysical and mechanical behaviors during CO2 injection. The reaction processes tend to enhance CO2 storage and mineralization via an increase in the porosity of the basaltic tuff, which was caused mainly by their dissolution. Laboratory simulations of CO2 storage in basaltic rocks had revealed that when the experiment was run for a longer length of time, the distribution/concentration of reaction minerals, reaction rates of the minerals, and/or permeability development of the rock matrix either decreased, increased, or remained the same. Furthermore, the strength indices for all types of basalts demonstrate that as exposure duration increases, the material strength steadily decreases. Core experiments and laboratory simulations have revealed that permeability increased at a higher flow rate and decreased at a lower flow rate. This is because a higher flow rate (increased injection pressure) will yield more pore spaces. Also, precipitation of carbonate minerals is favored under alkaline conditions since this condition necessitates increased production of divalent cations. Understanding these changes is essential since they can be detrimental to the immediate environment of the storage site, especially when there is CO2 leakage and consequent contact with freshwater resources. Similarly, we highlighted how several reports have correlated the occurrence of low-scale seismic events bounding the storage sites, to CO2 storage. Lastly, based on the reviews synthesized, we recommend promising directions to provide more profound insights into CO2 storage in basaltic rocks. [ABSTRACT FROM AUTHOR]

Capturing and storing CO2 (CCS) was once regarded as a significant, urgent, and necessary option for reducing the emissions of CO2 from coal and oil and gas industries and mitigating the serious impacts of CO2 on the atmosphere and the environment. This recognition came about as a result of extensive research conducted in the past. The CCS cycle comes to a close with the last phase of CO2 storage, which is accomplished primarily by the adsorption of CO2 in the ocean and injection of CO2 subsurface reservoir formation, in addition to the formation of limestone via the process of CO2 reactivity with reservoir formation minerals through injectivities. CCS is the last stage in the carbon capture and storage (CCS) cycle and is accomplished chiefly via oceanic and subterranean geological sequestration, as well as mineral carbonation. The injection of supercritical CO2 into geological formations disrupts the sub-surface's existing physical and chemical conditions; changes can occur in the pore fluid pressure, temperature state, chemical reactivity, and stress distribution of the reservoir rock. This paper aims at advancing our current knowledge in CO2 injection and storage systems, particularly CO2 storage methods and the challenges encountered during the implementation of each method and analyses on how key uncertainties in CCS can be reduced. CCS sites are essentially unified systems; yet, given the scientific context, these storage systems are typically split during scientific investigations based on the physics and spatial scales involved. Separating the physics by using the chosen system as a boundary condition is a strategy that works effectively for a wide variety of physical applications. Unfortunately, the separation technique does not accurately capture the behaviour of the larger important system in the case of water and gas flow in porous media. This is due to the complexity of geological subsurface systems, which prevents the approach from being able to effectively capture the behaviour of the larger relevant system. This consequently gives rise to different CCS technology with different applications, costs and social and environmental impacts. The findings of this study can help improve the ability to select a suitable CCS application method and can further improve the efficiency of greenhouse gas emissions and their environmental impact, promoting the process sustainability and helping to tackle some of the most important issues that human being is currently accounting global climate change. Though this technology has already had large-scale development for the last decade, some issues and uncertainties are identified. Special attention was focused on the basic findings achieved in CO2 storage operational projects to date. The study has demonstrated that though a number of CCS technologies have been researched and implemented to date, choosing a suitable and acceptable CCS technology is still daunting in terms of its technological application, cost effectiveness and socio-environmental acceptance. [ABSTRACT FROM AUTHOR]

The present study investigates the role of varying subglacial drainage distribution, discharge patterns and reactive mineralogy in switching the chemical weathering mechanism and altering CO2 drawdown in distinct hydromicroclimate. Catchments with less glacierized area (Stok and Phutse in cold-arid zones) bestow high (ablation/accumulation)area ratio and large spatial extent of channelized subglacial conduits and, thus permit high specific discharge. Conversely, Chhota Shigri (CS) acquires large glacierized portion covered under accumulation zone. The low (ablation/accumulation)area ratio promotes the development of lesser channelized and more distributed subglacial drainage, allowing low specific discharge in CS basin. As a consequence of distinct drainage characteristics, carbonation reaction processed through atmospheric CO2 and calcite dissolution becomes the locus of solute generation in Phutse and Stok. Correspondingly, carbonate weathering mediated CO2 drawdown override and remains on the higher side than silicate weathering and thus makes the system potential sink to atmospheric CO2. Meltwater draining in Phutse and Stok shows neutral pH, low sulphate mass fractionation (SMF) and low pCO2. In contrary, Chhota Shigri augments predominant sulphide oxidation and carbonation via atmospheric CO2 as a major source of H+ for chemical weathering during low and high ablation seasons, respectively. Elevated role of sulphide oxidation in chemical weathering promotes high SMF, high pCO2 and lowered alkalinity during low ablation, which may act as a source of atmospheric CO2 in Chhota Shigri. [ABSTRACT FROM AUTHOR]

To limit global temperature rise to below 2°C, we need to radically and rapidly change the way we build and use materials, since construction is responsible for 20‐40% of industrial CO2 emissions. Magnesium carbonate‐based cements have the potential to become a major carbon sink in construction industry, as CO2 will not be emitted during their production, but CO2 will rather be bound during hardening. Two different reaction mechanisms lead to setting and hardening of such HMC cements: i) hydration of MgO‐Mg‐carbonate, also in blends with silica and other mineral additions, in the presence of water or salt solutions (such as sodium bicarbonate solution) at ambient conditions or ii) carbonation hardening of MgO‐based systems at increased CO2 partial pressure and/or at increased temperatures. However, the utilization of hydrated magnesium carbonate and magnesium silicate cements is currently hampered by the lack of systematic experiments and of fundamental understanding of the factors affecting the hardening process, mechanical properties, long‐term behavior and durability. In particular, the role of temperature, relative humidity and addition of supplementary cementitious materials and/or industrial by‐products has not been systematically investigated. We need knowledge both on the practical side through systematic experiments with pastes, mortars and concretes as well as on a fundamental level through solubility and sorption experiments and thermodynamic modelling. In addition, reaction kinetics need to be optimized as well as the early formation of the preferred phases (stability enhancement) to develop efficient HMC cements for construction. Due to the socio‐economic relevance of cement and concrete, the impact of such "carbon"‐negative cements may go beyond a purely scientific one and lead to technological breakthroughs to the benefit of environment and society. [ABSTRACT FROM AUTHOR]

After the national "30.60" carbon peaking and carbon neutrality goals were proposed, Yulin City in Shaanxi Province, an important energy base in China, came under intense pressure to reduce emissions because of its rich fossil energy reserves and large number of coal chemical and coalfired power plant enterprises. As a result, it urgently needs to switch from high emission to low carbon. In this paper a four-dimensional seismic forward modeling is established to prove that the geological conditions of the area are suitable for CO2 geological storage and CO2 can be monitored in this area. Then the CO2 emissions of major industrial parks and counties in Shaanxi Province were summarized the Yulin City's current CO2 capture, utilization, and storage (CCUS) industrial chain was organized. Last but not least, the following recommendations were made for the development of the CCUS cluster in Yulin: (1) Yulin is appropriate for large-scale CO2 capturing activities due to its highly concentrated emissions and matured CO2 capturing technology. (2) Since the cost of transporting CO2 to its storage location by tank truck is significant, it is suggested that a pipeline be constructed to transport the gas in order to reduce costs. (3) Despite the promise of CO2-EOR (CO2-enhanced oil recovery) in Yulin, geological storage in a deep saline aquifer close by is now the preferred method due to the emission source's distance from the oilfield. (4) Two CO2 geological storage demonstration projects in Yulin City are still centered on oil displacement at the moment. It is necessary to conduct surveillance research on the volume of CO2 storage and use the CCUS method to define the accounting boundary. Yulin's geological sequestration of CO2 is now too small to satisfy the urgent requirement for significant emission reductions. It is vital to draw lessons from industrialized nations' experience, establish scientific research institutions for CO2 geological sequestration, and then design innovative and motivating policies in technology, supply chains, and commercial models that can extend the CCUS scale. [ABSTRACT FROM AUTHOR]

Sequestration of CO2 in unworkable coal seams is one of the most promising carbon reduction strategies. The mobility of CO2 in coal reservoirs is closely related to permeability, especially in low-permeability reservoirs. To this end, a method of reconstructing 3D pore-fracture networks by combining nuclear magnetic resonance and CT was proposed; and the relationship between the structural characteristics of 3D micron pore-fracture networks and permeability was studied. It was found that the average pore–throat diameter was positively correlated with permeability (R2 = 0.84) among the parameters reflecting the complexity of the pore-fracture networks, which plays a vital role in the permeability of micron pore-fractures. Subsequently, skeleton deformation and permeability evolution of 3D micron pore-fracture networks under high-pressure CO2 was studied using COMSOL software, and a permeability evolution model was established based on the structural characteristics. To evaluate the reliability of the model, it was verified to experimental results, resulting in an excellent linear positive correlation between theoretical and experimental permeability (R2 = 0.999). This showed that the permeability evolution model is instructive for engineering. In addition, the adsorption-induced strain swelling, slippage effects and fractures have a crucial effect on the permeability of coal, which is necessary for predicting reservoir permeability. [ABSTRACT FROM AUTHOR]

This paper reports for the first time the use and application of a novel technique in the characterization of mineral carbonation reaction and CO2 sequestration in soil stabilization using flow meters. Soils based on SiO2 with two different sizes were tested. Lime (Ca(OH)2) was used as the reactant. Instant CO2 flow rate (L/min), total CO2 volume (L), temperature (°C), and absolute pressure (kPa) were monitored and recorded for 1 h by flow meters connected to the mold inlet and outlet. It was determined that the mineral carbonation reaction started in the first seconds and ended before the 5th minute. The mineral carbonation is a short-term and potential reaction, and it is not a time-dependent reaction. It is separated from other carbonation reactions with these characteristics. The highest CO2 captured value was obtained in the soil mixed with 5% lime, where fines were not used. The second highest CO2 captured value was obtained in soil mixed with 1% lime, where fines were not used. CO2 captured with 1% lime is more than CO2 captured with 5% lime in the soil containing fines. Accordingly, 1–5% lime can be used in soil carbonation studies. According to the soil properties, the highest CO2 captured and the CO2 efficiency was achieved with the use of 6–7% water by weight. [ABSTRACT FROM AUTHOR]

Human survival is threatened by the rapid climate change due to global warming caused by the increase in CO2 emissions since the Second Industrial Revolution. This study developed a secondary cement product production technology by replacing cement, a conventional binder, with calcium silicate cement (CSC), i.e., CO2 reactive hardening cement, to reduce CO2 emissions and utilize CO2 from the cement industry, which emits CO2 in large quantities. Results showed that the carbonation depth, compressive strength increase rate, and CO2 sequestration rate increased as the CSC content increased, suggesting that CSC can be applied as a secondary cement product. [ABSTRACT FROM AUTHOR]

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