CO2 Storage Capacity Research Articles

Assessing the potential for CO2 storage in saline aquifers in Brazil: Challenges and Opportunities

AbstractThis study underscores the critical role of carbon capture and storage (CCS) in mitigating greenhouse gas emissions and addresses the potential for CCS projects in saline aquifers in Brazil, one of the world's largest carbon emitters. The country's ability to adopt CCS is significantly influenced by the availability of data related to regional CO2 storage potential and identifying suitable geological framework for CO2 injection. While oil and gas reservoirs have traditionally been prioritized, saline aquifers represent an underexplored and potentially higher capacity storage option. Despite Brazil's 31 sedimentary basins, the data quantity and availability for these contexts remain insufficient for advanced studies on the geological storage of CO2 considering saline aquifers. An initial study was conducted indicating five potential targets in the Paraná and Potiguar Basins for geological storage in saline aquifers based on available public data, mainly drilling data. This review reveals substantial challenges related to the evaluation of Brazil's CO2 storage capacity, such as the lack of modern seismic studies, the absence of a regulatory framework for CO2 storage, and insufficient investment in new well exploration. These challenges necessitate multistakeholder collaboration, the development of a supportive regulatory environment, and investment in extensive site characterization campaigns. Addressing these barriers is fundamental to realizing the country's CCS potential and contributing to global decarbonization efforts. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

Decoding wettability in coal-water-CO2 system for enhanced sequestration security

The injection of CO2 into deep unminable coal seam is a most promising carbon storage method that can simultaneously achieve the dual objectives of mitigating CO2 emission and enhancing coalbed methane recovery. In this context, the wettability of the coal-water-CO2 system plays an important role in the CO2 injection rate, storage capacity, and sequestration security. However, the factors affecting wettability alternation in the coal-water-CO2 system are still unclear until now. In this study, the sessile drop method was used to measure the contact angle (CA) in the coal-water-CO2 system under different pressures (3 – 8 MPa) and temperatures of (40–70 °C) with four different rank coals. Results indicate that with increasing pressure, the CA shows a steady increase below 5 MPa followed by a rapid increase at 5 – 8 MPa. The CA decreases with increasing temperature and coal rank. The CA is negatively correlated with the mes- and macro-pores, but positively correlated with micropores. It was found that these relationships are attributed to the CO2 density and CO2 adsorption capacity of coal. As the CO2 density increases, the coal-CO2 interaction force intensifies, leading to a tendency towards CO2 wetting for the coal-water-CO2 system. The adsorption capacity illustrates the strength of the coal-CO2 interaction, where the affinity of polar adsorption sites for CO2 molecules exceeds that of nonpolar adsorption sites. Finally, we conducted a comprehensive assessment of the wettability of the coal-water-CO2 system as it varies with burial depth by developing an integrated model that considers four influential factors, including pressure, temperature, coal rank, and pore structure. The findings of this study can be utilized to determine the optimal CO2 injection pressure in CO2-ECBM projects and enhance sequestration safety.

CO2 dynamic mass balance of low permeability reservoir based on “four regions”

AbstractIn order to limit the increase in global average temperature to 1.5°C, it is necessary to reduce carbon dioxide (CO2) emissions by 45% by 2030. CO2 capture, utilization and storage (CCUS) is one of the effective ways to reduce CO2 emissions. Geological storage of CO2 provides a solution with the lowest economic cost and the fastest effect for reducing CO2 emissions. This article proposes a CO2 storage regional division method based on the characteristics of low‐permeability reservoirs in the Yanchang W oilfield in China. The storage space is divided into four regions: gas phase region, two‐phase or near‐miscible region, diffusion region, and oil phase region. As the displacement progresses, the volume of the gas phase region and the two‐phase or near‐miscible region gradually increases; the volume of the diffusion region first increases and then decreases. By calculating the storage capacity of each region separately, the total storage capacity is finally calculated. The impact of different pressures and injection rates on dynamic CO2 storage capacity was evaluated. The results show that pressure and injection rate are positively correlated with total storage capacity. When CO2 miscible conditions are reached, the increase in total storage capacity will significantly decrease. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

Semi-Analytical Reservoir Modeling of Non-Linear Gas Diffusion with Gas Desorption Applied to the Horn River Basin Shale Gas Play, British Columbia (Canada)

Adsorbed gas may account for a significant part of the gas resources in shale gas and coalbed methane plays. Understanding gas sorption behaviors and integrating gas desorption into analytical reservoir modeling and an associated transient performance analysis are important for evaluating a system’s gas desorption ability and further analyzing its CO2 injectability, utilization, and storage capacity. However, gas desorption, along with other pressure-dominated gas properties, increases a system’s non-linearity in theoretical studies. Few studies on analytical modeling have integrated the gas desorption feature into a non-linear system and validated the model’s accuracy. In this study, the desorbed gas due to pressure decay was treated as an additional source/sink term in the source-and-sink function methods. This method was combined with the integral image method in a semi-analytical manner to determine the amount of gas desorption. Fundamental reservoir and gas properties from the Horn River Basin shale gas play were chosen to evaluate the methodology and the performance of the associated production well. The results were compared with the commercial fine-gridding numerical simulation software, and good matches were achieved. The results showed that the desorbed gas released from rock will supply free-gas flow when the pressure significantly decreases due to gas production. The production wellbore pressure can be maintained at a higher level, and the production rate was higher than in cases where gas desorption was not considered, depending on the operating conditions.

Comparative Study of CO2 Storage Capacity Estimation in Depleted Oil & Gas Reservoir: A Case Study in Vermillion Basin Gulf of Mexico

CO2 emissions rates have seen an exponential growth from the 19th century up till date, if no drastic measures and plans are implemented to prevent this exponential growth the consequence will be devastating. The notion of achieving net-zero greenhouse gas emissions gained prominence through the Paris Agreement, a groundbreaking accord reached at the United Nations Climate Change Conference. This agreement was devised to mitigate the impact of greenhouse gas emissions. To execute the net-zero CO2 emission plan, the USDOE has set a new goal to remove gigatons of carbon dioxide (CO2 ) from the atmosphere and durably store it for less than $100/ton of net CO2 -equivalent. Making such a goal a reality requires an accurate estimation of CO2 storage capacity for the successful implementation of Carbon Capture and Storage (CCS) technologies, and the assessment of the impact of CCS to the reduction of CO2 emissions. Hence this paper serves as a template for accurately estimating CO2 storage capacity in depleted saturated oil reservoirs with initial gas cap using three approaches: Volumetric, Production and Correlation-based methods and compares the accuracy of the estimates. A case study was conducted on a depleted VR273_Q combination sand in the Vermillion Basin, Gulf of Mexico (GOM). The deterministic and stochastic (P50) CO2 storage capacity estimates from the Volume-based method are 1.21 million tonnes (Mt) and 1.23 Mt respectively, while the deterministic CO2 storage capacity estimates from the Production and Correlationbased method are 1.32 Mt and 1.41 Mt respectively. All three approaches showed similar results, with little deviations attributed to petrophysical uncertainties arising from data gaps i.e., absence of well logs to key wells. However, these uncertainties are captured by Stochastic (P90) CO2 storage capacity estimates of 1.47 Mt from the Volume-based method. Although the Correlation-based approach slightly overestimates the CO2 storage capacity, it can be used as a starting point for quick estimation as it only requires production data which are readily available on various databases for GOM. Finally, through this paper, opportunities for concerned agencies to make well-informed energy-related policies and business decisions are made possible.

Bridging Housing and Climate Needs: Bamboo Construction in the Philippines

The Philippines faces a significant shortage of affordable housing, and with the growing urgency brought by climate change, there is a pressing need for more sustainable and affordable building solutions. One promising option is cement bamboo frame buildings, which blend traditional bamboo building methods with modern materials. This approach is already being implemented in social housing projects in the Philippines. Dynamic lifecycle assessment (DLCA) calculations show that these bamboo buildings can effectively reduce overall CO2 emissions. Before a building’s end of life, biogenic effects offset approximately 43% of its total production emissions, while the temporary carbon storage afforded by these biogenic materials further reduces total emissions by 14%. In comparison to concrete brick buildings, bamboo constructions reduce emissions by 70%. Transforming an unmanaged bamboo plantation into a managed plantation can potentially triple the capacity for long-term CO2 storage in biogenic materials and further reduce net emissions by replacing concrete with bamboo as the main construction material. Thus, bamboo construction offers a potent, economically viable carbon offsetting strategy for social housing projects.

Distribution of the adsorbed density of supercritical CO2 onto the anthracite and its implication for CO2 geologic storage in deep coal

CO2 geological storage in deep coal has been a research hotspot in carbon capture and storage under the background of carbon neutrality. Understanding supercritical CO2 adsorption onto coals has been significant for accurately evaluating deep coal's CO2 geological storage capacity and further determining the deployment of a CO2-ECBM project. The supercritical CO2 adsorption experiments on dry Qinshui anthracite coal were conducted. The adsorbed CO2 density and average number of adsorbed molecule layers were calculated. The effects of temperature, pressure, and pore size on the density of the adsorbed phase were discussed using the simplified local density (SLD) adsorption model, and the distribution of adsorbed CO2 on the coal surface was disclosed. Finally, the modified method for calculating CO2 geological storage in coal was proposed. The results show that: (1) The average adsorbed density of supercritical CO2 onto the anthracite at the experimental temperatures ranged from 1.073 to 1.088 g/cm3, and the average number of adsorbed molecular layer ranged from 1.15 to 1.26, indicating the coexistence of micropore filling and multilayer adsorption. (2) The SLD theory demonstrated that the distribution of the adsorbed CO2 density is jointly controlled by temperature, pressure, pore size, and CO2 phase. The supercritical CO2 can form a second layer of adsorbed molecules. The minimum pore size to keep the adsorbed CO2 density unchanged on the pore wall is around 0.82 nm for subcritical CO2 and 3 nm for supercritical CO2. (3) The real average adsorbed CO2 density is always lower than that of the first adsorbed molecular layer and the density under extreme pressure. There are four different distributions of free and adsorbed CO2 on the surface of the coal with the changes in temperature and pressure, consisting of subcritical, gas-like supercritical, liquid-like supercritical, and extreme states. (4) The modified method of CO2 storage capacity for coal, based on excess adsorption and equivalent free CO2 in the total pore, avoids the error caused by the uncertainty of adsorbed CO2 density and free space volume. It is recommended that this method should be preferentially adopted during the selection of the potential target area for CO2 geological storage in deep coal. The study aims to provide a new idea for the mechanism of supercritical CO2 adsorption on coal and the assessment of supercritical CO2 geologic storage capacity in deep coal.

Optimization of Injection Rate for CO2 Geological Storage Based on Differential Evolution

CO2 geological storage is one of the important means to reduce carbon emission and greenhouse effect, and it is an emerging field of earth science research. The selection of the injection rate has an important impact on the CO2 storage capacity, and it is limited by the injection time and construction conditions, thus the selection of the injection rate is a complex optimization problem. In this paper, the optimal injection site calculated based on dynamic planning is used for injection simulation, based on which the carbon sequestration injection rate optimization problem is transformed into a differential evolution problem, and the problem is optimized by different differential methods. For the Utsira block in the Sleipner project in Norway. On this basis, the effect of injection rate on storage capacity and leakage is researched, and numerical simulations under different injection rates are designed. Thus, it provides theoretical guidance for the selection of injection rate in CO2 geological storage.

Amino acid-assisted effect on hydrate-based CO2 storage in porous media with brine.

CO2 storage as hydrates in porous media is a promising method for storing carbon dioxide (CO2). However, the sluggish formation kinetics of hydrates urge the need to focus on the use of additives (promoters) to accelerate hydrate kinetics. This study investigates the effect of amino acid solutions in brine on CO2 hydrate formation and dissociation kinetics in quartz sand particles QS-2 (0.6-0.8 mm) with 38% porosity. The amino acids l-methionine (l-meth), l-isoleucine (l-iso), and l-threonine (l-threo) were studied at 0.2 wt% using an autoclave hydrate reactor at 4 MPa and 274.15 K in the presence and absence of salt (3.3 wt% NaCl) in 100% water saturation. The hydrate dissociation kinetics was studied at a temperature of 277.15 K. These conditions represent the normal seabed temperature range in Malaysia and hence were used for testing CO2 hydrate formation and dissociation kinetics in quartz sand in this study. Further, CO2 hydrate formation and dissociation experiments were conducted with sodium dodecyl sulphate (SDS) and brine systems as standards for comparison. The findings reveal the best kinetics for l-meth exhibiting the highest CO2 hydrate storage capacity. l-meth recorded a gas-to-hydrate conversion ratio of about 93% at 0.2 wt% in quartz sand with brine. Moreover, l-meth exhibited the lowest hydrate dissociation rate compared to l-iso and l-threo systems, thereby enhancing CO2 hydrate stability in quartz sand. Comparatively, l-meth enhanced the storage capacity by 36% and reduced the induction time by more than 50% compared to conventional promoter SDS in quartz sand with brine, suggesting it to be favorable for CO2 storage applications. CO2 hydrate nucleation time was predicted in quartz sand with and without the best-studied amino acid l-meth system with high prediction accuracy and an absolute average deviation of 2.4 hours. The findings of this study substantiate the influence of amino acids in promoting the storage capacity of CO2 in sediments as hydrates.

Source-sink matching and cost analysis of offshore carbon capture, utilization, and storage in China

Carbon Capture, Utilization, and Storage (CCUS) is an indispensable technology to achieve carbon neutrality in China, but confined by technology and economy, the offshore CCUS in China is still in the planning stage and has not yet reached the desired scale. Offshore source-sink matching and cost analysis of CCUS is the premise and basis of offshore CCUS deployment. Thus, based on the CO2 storage potential of offshore sedimentary basins in China, this paper conducts the offshore source-sink matching and cost analysis of CCUS in China under different constraints. The result showed that: ⅰ) the CO2 storage capacity of China's offshore sedimentary basins is estimated to be 767.3 Gt, which is enough to meet approximately 200 years of coal power CO2 emissions in China. ⅱ) the CO2 storage potential could reach 721.9 Mt/a by source-sink matching under different constraints. ⅲ) early opportunities for offshore CCUS would be in the Bohai Bay and Pearl River Mouth Basin, considering the compensation effect of CO2-EOR. ⅳ) combined with the CCUS cost and emission reduction in China under different time nodes, it is inferred that deploying offshore CCUS in China between 2030 and 2040 commercially will be advantageous.

Numerical simulation study of CO2 storage capacity in Deep Saline aquifers

The storage of supercritical CO2 in deep saline aquifers is essential for reducing carbon emissions, and the selection of an appropriate reservoir is a primary consideration for carbon sequestration. To investigate the impact of reservoir physical properties on the CO2 storage capacity of saline aquifers, this study establishes a numerical simulation model of CO2 storage in deep saline aquifers and utilizes the MRST toolbox to solve it by the finite volume method. The research thoroughly analyzes the influence of reservoir physical properties on the CO2 migration process and CO2 storage capacity of the saline aquifer layer. The results show that prolonged CO2 injection involves a process of initially suppressing pressure and subsequently slowly diffusing it to the surroundings. Furthermore, the physical properties of the reservoir and the reservoir pressure significantly influence CO2 burial in deep saline aquifers. Higher reservoir permeability and deeper burial depth result in enhanced CO2 storage and faster CO2 plume migration. However, the porosity and temperature of the reservoir have a negligible impact on CO2 storage. Our research work provides a precise understanding of selecting suitable layers for CO2 storage in deep saline aquifers, offering strong support for early predictions of carbon capture, utilization, and storage (CCUS).

Experimental and modeling study of CO2 solubility in formation brines at in-situ conditions

The dissolution of CO2 into formation brine, one of the dominant trapping mechanisms for geological carbon storage (GCS) in deep saline aquifers, has been widely investigated. Most experimental and modeling studies focused on the CO2 solubility in synthetic brines. However, rare studies have been performed to investigate CO2 solubility in real formation brines, especially when ion-ion interactions were considered. In this work, the CO2 solubility of seventy formation brines from major basins in China including the Junggar basin, Ordos basin, and North and South Songliao basin was measured at in-situ pressure and temperature conditions. Experimental results show that CO2 solubility has a strong relationship with pressure and total dissolved solids (TDS), while the relationship between solubility and temperature is weak. Three solubility regions were classified in terms of depth. In Regions I and III, CO2 solubility increases with depth and is independent with depth in Region II. However, the effect of salinity on CO2 solubility was observed in all regions. Additionally, a modified Duan's model used for a mixed-salt system was proposed using dataset from this study and literature. Comparisons with Duan's model for CO2 solubility in mixed-salt systems show the average absolute relative deviation equals 5.14%, which reveals a clear improvement in the modified model. In addition, the validation of the model was performed, and results show that the average absolute relative deviation before and after improvement are 12.10% and 5.11%, respectively, indicating the high accuracy of the improved model. Overall, this research improves the understanding of CO2 solubility in real formation brines and illustrates the efficiency and accuracy of the modified model, which is crucial for the evaluation of the CO2 storage capacity, fate of CO2 over storage site life for commercial GCS projects.

Effect of ScCO2-H2O treatment duration on the microscopic structure of coal reservoirs: Implications for CO2 geological sequestration in coal

The microstructure of coal reservoirs, especially the pore structure, alters as a result of physicochemical reactions between the CO2 acidic fluid and coals. However, it is still unclear what controls this process and how the pore structure properties of coal alter by the action of CO2 acid fluids change over time. The objective of this study is to identify the underlying mechanism by analyzing the changes in the mineral composition, surface roughness, as well as micropore and mesopore structure of anthracite and bituminous coal when exposed to supercritical CO2 (ScCO2)-H2O. The results indicate that coal reservoirs primarily undergo processes of adsorption expansion and mineral dissolution/precipitation. Among these, adsorption expansion concluded or weakened after 7 days, with mineral precipitation gradually becoming the dominant factor, which results in more secure geological CO2 storage (GCS). Furthermore, comparative analysis of anthracite and bituminous coal with untreated and long-term treatment demonstrates that anthracite exhibits higher CO2 storage capacity and greater wettability. Consequently, anthracite is more suitable as a target reservoir for GCS compared to bituminous coal. These results, therefore, offer a theoretical foundation and a guide for choosing GCS sites in deep un-minable coal seams.

Post-combustion CO2 capture via the hydrate formation at the gas-liquid-solid interface induced by the non-surfactant graphene oxide

CO2 capture is currently the most effective way to reduce global carbon emissions, which leads to the emergence of novel gas hydrate method. In this work, the significant role of graphene oxide (GO) in enhancing the dynamic behaviors of post-combustion CO2 capture via the hydrate formation was investigated. Firstly, at the gas-liquid interface, the induction of GO increased the amount of gas transfer, and shortened the induction time for the hydrate nucleation at the heterogeneous nucleation sites provided by GO, which attracted CO2 molecules assembling on the GO layer to participate in the hydrate nucleation based on the molecular dynamics (MD) simulations. More importantly, the hydrate growth rate was nearly doubled in 0.05 wt% GO and 4 mol% tetrahydrofuran (THF) mixed accelerators than that in pure THF and sodium dodecyl sulfate (SDS) mixed systems, which greatly boosted the gas storage capacity of CO2 in the form of compact solid hydrates. Consequently, CO2 separation efficiency achieved up to 76 % in the GO based accelerators, enhanced by 23.2 % compared to that in pure THF and the SDS mixed systems. The present study could provide insights into the development of new type of nanomaterial accelerators for CO2 capture via the gas hydrate method.

A Case Study on the CO2 Sequestration in Shenhua Block Reservoir: The Impacts of Injection Rates and Modes

Carbon capture and storage (CCS) is the most promising method of curbing atmospheric carbon dioxide levels from 2020 to 2050. Accurate predictions of geology and sealing capabilities play a key role in the safe execution of CCS projects. However, popular forecasting methods often oversimplify the process and fail to guide actual CCS projects in the right direction. This study takes a specific block in Shenhua, China as an example. The relative permeability of CO2 and brine is measured experimentally, and a multi-field coupling CO2 storage prediction model is constructed, focusing on analyzing the sealing ability of the block from the perspective of injection modes. The results show that when injected at a constant speed, the average formation pressure and wellbore pressure are positively correlated with the CO2 injection rate and time; when the injection rate is 0.5 kg/s for 50 years, the average formation pressure increases by 38% and the wellbore pressure increases by 68%. For different injection modes, the average formation pressures of various injection methods are similar during injection. Among them, the pressure increases around the well in the decreasing injection mode is the smallest. The CO2 concentration around the wellbore is the largest, and the CO2 diffusion range continues to expand with injection time. In summary, formation pressure increases with the increase in injection rate and injection time, and the decreasing injection mode has the least impact on the increase in formation pressure. The CO2 concentration is the largest around the well, and the CO2 concentration gradually decreases. The conclusion helps determine the geological carrying capacity of injection volumes and provides insights into the selection of more appropriate injection modes. Accurate predictions of CO2 storage capacity are critical to ensuring project safety and monitoring potentially hazardous sites based on reservoir characteristics.

Study on accelerating activation of recycled hardened concrete powder based on microbial induced calcium precipitation

The CO2 atmosphere in the flue gas of cement kiln was simulated in this paper, and different methods were used to activate the RHCP with particle size < 75 µm under normal temperature and pressure. The effects of different activation methods were studied, and the mechanism of CO2 storage was clarified. On the basis of concrete carbonization curing, a new technology based on MICP was proposed. During the activation of RHCP, a Bacillus strain capable of secreting carbonic anhydrase was introduced into the CO2 carbonization system of RHCP. Carbonic anhydrase could accelerate the capture and conversion of CO2 into bicarbonate ions and carbonate ions. Calcite-type CaCO3 and amorphous silica gel were formed by the reaction of CO2 with active components in RHCP. Finally, the generated product filled the pores to make the microstructure of the slurry denser, and CO2 was also permanently sealed. The results showed that the MM-RHCP not only improved the activity index of the mortar, but also improved the potential for storing CO2 in RHCP. Through FT-IR, XRD, SEM-EDS, TGA and nitrogen adsorption pore size analysis, it was further proved that the use of microbial mineralized RHCP could accelerate the formation of CaCO3, ettringite and SiO2·n H2O. In addition, the CO2 storage capacity of MM-RHCP was greater than that of DC-RHCP and LP-RHCP. The RHCP after mineralization treatment could replace cement as mineral admixture, and this technology realized the resource utilization of solid waste. At the same time, CO2 was permanently fixed in RHCP. Therefore, it provided a new way for deep carbon sequestration in the cement industry.

Novel vermiculite/tannic acid composite aerogels with outstanding CO2 storage via enhanced gas hydrate formation

Gas hydrate-based CO2 storage, using only water cages, provides an environmentally friendly and energy-efficient solution to reduce greenhouse gas emissions. However, the sluggish formation kinetics of gas hydrate is hindered by the limited reaction interfaces, thereby impeding the practical utilization of hydrate-based greenhouse gas storage. Herein, we reported a novel strategy to fabricate natural vermiculite and tannic acid composite aerogels as the effective substrates for boosting CO2 hydrate formation. The results show that the formation kinetics of CO2 hydrate in the aerogels exhibits composition dependence and an outstanding CO2 storage capacity of 130.1 v/v (corresponding to 0.114 mol CO2/mol water). Inverse gas chromatography was used to analyze the surface energy and its components of the aerogels. Raman spectra and nuclear magnetic resonance were used to unravel the water molecule assembly and states. The CO2 uptake capacity can be further improved by compressing the aerogel to 75 % of the original volume, showing an impressive storage capacity of 146.8 v/v. The as-made aerogels demonstrated outstanding cycle stability and short induction time for CO2 hydrate formation. The results of this study pave the way for designing effective CO2 hydrate promoters and facilitating promising CO2 capture and storage technologies via gas hydrate.

Numerical analysis of temperature effect on CO2 storage capacity and CH4 production capacity during the CO2-ECBM process

Temperature is a key factor affecting the CO2 injection efficiency and CH4 production efficiency, so it is of great significance to clarify the evolution diagram of temperature change during the CO2-ECBM process. In this study, the crushed soft coal seam with low permeability in Huainan coalfield was taken as the research object. Firstly, the fully coupled mathematical models of CO2-ECBM process were constructed, and the influence of temperature field on CO2-ECBM process was emphasized. Secondly, the evolution law of CO2-ECBM process at different time was revealed. Then, the effects of injection temperature and initial temperature on the CO2-ECBM process were analyzed. Finally, the evolution mechanism of reservoir temperature during the CO2-ECBM process was illustrated, and the effect of temperature on temperature field of CO2-ECBM process was further illustrated. The results show that the longer the displacement time, the CH4 concentration gradually decreased, and the CO2 concentration gradually increased. The area where the temperature changes are more concentrated focuses on the vicinity of CO2 injection well, which are mainly determined by the dominant reaction of adsorption and desorption reactions of binary gas. Reservoir temperature and permeability are positively and negatively correlated with injection temperature, respectively. Both CO2 storage capacity and CH4 production capacity increase with the increase of injection temperature, and the sensitivity of CO2 storage capacity to temperature was greater than that of CH4 production capacity. With the increase of displacement time and injection volume, the effective displacement radius increases, but the increment of influencing radius gradually decreases. The lower the initial temperature of coal reservoir, the larger the influencing radius, and which increases with the increase of displacement time. CO2 storage capacity and CH4 production capacity decrease with the increase of initial temperature. Young's modulus and Poisson's ratio can effectively change the reservoir strength. CO2 storage capacity and CH4 production capacity decrease with the increase of Young's modulus, and increase with the increase of Poisson's ratio. This study can support the engineering landing of CO2-ECBM technology in crushed soft coal seam with low permeability, and promote the realization of China's “Dual Carbon” strategic goal.

Carbon capture from biomass flue gases for CO2 enrichment in greenhouses

Heating and CO2 enrichment systems can improve yields in intensive greenhouse agriculture Combining both techniques, which are currently applied commercially, can potentially enhance their effect. The CO2 must be separated from the other noxious gases present (such as CO, NOX, and SO2) to avoid them becoming part of the supply. The CO2 is then provided to the greenhouse on demand in the same way as the heating. In this work, we show that an improved food productivity of a pilot-scale greenhouse system combined with CO2 capture by adsorption using activated carbon and heating with alternative fuel. The proposed system's overall performance was evaluated and optimized. The best values were 46.7 g/kg of CO2 storage capacity on the adsorbent bed, 99.99 % removal rate harmful gases from the gas supplied to the greenhouse, CO2 levels of 1851.0 ± 262.8 mg/Nm3 of the CO2 levels in the greenhouse, and an enrichment time of 2.18 ± 0.92 h/day. The system's effective performance over extended periods (November–February) was confirmed and the productivity of a crop species (tomato) was compared to a control, showing an increment of 18 %. The results indicate that this is a valuable option for increasing the crop yield. By integrating this combined system with advanced climate control strategies, it is possible to maximize the CO2 provided per day, leading to higher yields. The system proved to be stable under real pilot-scale conditions over winter periods (four months).

Experimental Study on CO2 Geochemical Reaction Characteristics in Marine Weakly Consolidated Sandstone Saline Aquifers

Geological storage is one of the most important measures to reduce carbon emissions. The newly developed oilfield A in the Pearl River Mouth Basin of the South China Sea is associated with a large amount of CO2 with a purity of up to 95%. Two weakly consolidated sandstone saline aquifers located above the oil reservoir can be used for CO2 storage, but the CO2 geochemical reaction characteristics in the aquifers should be investigated clearly, which may cause significant damage to the physical properties of the reservoirs and caprocks of the aquifers. In this paper, static CO2 geochemical reaction experiments and rock thin section identifications were carried out using drill cuttings and sidewall cores, respectively. A numerical simulation was conducted according to the reactor conditions to explore the equilibrium state of the CO2 geochemical reaction. Through these studies, the characteristics of the geochemical reaction, its impact on the physical properties of the formation, and the CO2 storage potential by mineral trapping in the target aquifers were revealed. The results show that the two saline aquifers have similar physical properties. The reservoirs are mostly made up of fine-to-medium-grained sandstones as quartz arenite with a considerable amount of feldspar, which can provide favorable pore space for CO2 storage, while the caprocks are fine-grained felsic sedimentary rocks that can have a good sealing effect. However, both the reservoirs and caprocks contain a certain amount of carbonate and clay minerals. Mineral dissolution dominates in the CO2 geochemical reaction process, and more Ca2+ and Mg2+ is released into the formation water. The theoretical maximum CO2 mineral trapping capacity in the aquifers is 0.023–0.0538 mol/100 g rock, but due to the dynamic equilibrium of the geochemical reaction, the amount of mineralized CO2 in most of the rock samples is negative, and the average utilization factor is only −55.43%. As a result, the contribution of mineral trapping to the CO2 storage capacity takes −0.32%, which can be ignored. In the future, it is necessary to conduct detailed research to reveal the effect of a CO2 geochemical reaction on storage safety, especially in offshore weakly consolidated sandstone saline aquifers, which could be important sites for large-scale CO2 storage in China.