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Geological disposal of CO2 after capturing the gas from large emitting sources is one of the safest and most prominent methods to eliminate CO2 from the atmosphere and mitigate climate change. The heterogeneities in porosity, permeability and capillary pressure in various underground formations impact gas distribution, affecting their storage capacity. Therefore, a numerical model is developed to study the plume migration under various physical heterogeneities by upscaling the variation in capillary pressure. Accordingly, homogeneous, heterogeneous and layered formations have been considered. The influence of capillary pressure and field-scale heterogeneities, such as porosity and permeability, is incorporated using the Leverett J function. The impact of variations in capillary pressure on gas migration is calibrated in different formations for ten years of injection. The analysis project that plume evolution in different formations highly deviates and a plume length of 3410 m is obtained for layered formation. A sensitivity analysis was conducted to understand the influence of interfacial tension in formations with differing heterogeneity. The change in interfacial tension impacts the average saturation of CO2, ranging from 0.287 to 0.155 in heterogeneous aquifers. The plume migration decreases in layered and increases in homogenous and heterogeneous media with decreased interfacial tension. [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]

CO2 curing of fresh concrete is one of the solutions allowing direct carbon sequestration within the construction industry. Additionally, it enhances the early mechanical performance when comparing to traditional hydration curing. Temperature of carbonation curing has pronounced impact on both reactions involved in hardening of Portland cement: carbonation and hydration. Both reactions are accelerated with rising temperature, while the formed products and resulting microstructure are altered. Higher curing temperature promotes the precipitation of silica gel and C-S-H phase with reduced Ca/Si ratio. Furthermore, alumina and sulfate distributions among the reaction products are different. Temperature of carbonation curing has a distinct impact on the cement paste hydration after carbonation curing. The high curing temperature results in a densification of the matrix which limits further reaction progress, compared to the samples cured at lower temperatures. During the post hydration, calcium deficient system changes into C-S-H phase with higher Ca/Si and eventually portlandite. [ABSTRACT FROM AUTHOR]

Pre-existing faults cross-cutting caprock formations constitute potential leakage pathways during geological CO2 sequestration. When the fault filling material is calcite-rich, dissolution of the fault minerals is expected to occur causing the mechanical weakening of the fault or, even worse, its reactivation. In turn, these chemical-mechanical processes influence the distribution of pore pressure in the vicinity of the fault. Hence, a fully coupled approach including the chemically-induced alteration is necessary while investigating fault's mechanical stability. In this paper, we present a simplified set of equations that allows the resolution of the coupled hydro-chemo-mechanical problem of reactive fluid flow inside a fault. Empirical relationships are used to describe the change of the fault's material mechanical properties with porosity. The derived model was used to simulate the evolution of the hydro-chemo-mechanical behavior of a fault following an expected leakage scenario during CO2 storage in the Dogger formation in the Paris Basin. The simulation results showed that under normal conditions, fault reactivation is unlikely to happen even in the long term (∼100 years). Nevertheless, the proposed model is capable of capturing the evolution of fault reactivation and has the potential to become a useful element of the toolbox for assessing the risks related to fault reactivation and leakage for CO2 storage projects. [ABSTRACT FROM AUTHOR]

Further understanding into the impacts of supercritical CO2 fluid exposure toward CO2 storage and coalbed methane (CH4) recovery is significant to evaluate validity, stability, and safety of CO2-ECBM. For purpose of addressing the potential impacts, the long-term static interactions between supercritical CO2 fluid and moisture-equilibrated coal matrices with various degrees of coalification were conducted at 318.15 K and 12.00 MPa for 240 days in this study. Furthermore, the changes of the physicochemical properties dominating adsorbability of moisture-equilibrated coals due to the exposure were revealed. Ultimately, the impacts of the exposure toward CH4 adsorbability of moisture-equilibrated coals were addressed. Results indicate that the long-term supercritical CO2 exposure induces complex effects typically including organic matter extraction, mineral dissolution and formation, and matrix swelling to the coals, thereby further reducing the micropores within pore diameter ranges of 0.38–0.71 nm and 0.74–0.90 nm of the low-rank moisture-equilibrated coals, and slightly increasing those of 0.40–0.70 nm and 0.75–0.90 nm of the high-rank moisture-equilibrated coal. Additionally, the complex effects reduce the mesopores with pore diameter less than 8.00 nm for all the coal samples. Moreover, the exposure alters the surface chemistry of the coals. Particularly, the exposure increases the oxygen-containing functional groups typically comprising C-O, C=O, and -COOH of the low-rank moisture-equilibrated coals by 25.32–27.16%, and weakens the graphitization of the high-rank coal by 34.00%. Moreover, the induced synergistic effects decrease the number of pores with diameter less than approximately 8.00 nm of all the moisture-equilibrated coals. Furthermore, the CO2 exposure significantly reduces CH4 adsorption capacity of the moisture-equilibrated coal matrices indicated by the decreasing amplitude in absolute adsorption amount of 6.20–18.00%. Overall, the long-term supercritical CO2 exposure could favor CH4 production during CO2-ECBM. Future study should focus on in-situ characterization and accurate quantitative analysis on extraction, mineral dissolution and formation, and matrix swelling due to CO2 exposure, and distinguishment in the contribution of these effects to pores and functional groups of coals. [ABSTRACT FROM AUTHOR]

In the context of geological CO2 sequestration projects, CO2/water/rock wettability directly affects the capacities of residual and structural trapping mechanisms. Therefore, presenting an accurate model that can simulate the wettability behavior of CO2/water/rock under different environmental conditions is necessary. In this study, a new model based on adaptive neuro-fuzzy interference system (ANFIS) was developed for estimation of CO2/water/quartz contact angle as a function of influencing parameters, such as pressure, temperature, salinity, and salt type. Results of the proposed model were compared to the actual data and it was found that the presented model has immense potential with high correlation coefficient (R2) of 0.991 and average absolute relative error (AARE) of 2.010 for predicting the CO2/water/quartz contact angle. Finally, a sensitivity analysis was performed on the influencing factors. Results of this analysis demonstrated that salinity and pressure have the highest impact on the wettability of CO2/water/quartz. [ABSTRACT FROM AUTHOR]

In this study investigated the CO2 fixation efficiency and biomass productivity by green algae Chlorella vulgaris which is grown in various concentrations of dairy wastewater supplemented with CO2. The cultivation was carried out at 25°C for various CO2-Air ratios such as (5%, 10%, and 15%). Artificial light-enhancing photosynthesis in bench-scale batch cultures were carried out in suspension (Photobioreactor) and attached (algadisk) for the period of 2 weeks. The maximum carbon fixation efficiency of 87.67 mg/l/day in suspended culture and 88.5 mg/l/d in algadisk was obtained at 15% CO2-Air ratio in dairy wastewater without dilution. Usage of external nutrient supply was supplemented by the nutrient-rich wastewater, which also results in nutrient removal from the dairy wastewater. [ABSTRACT FROM AUTHOR]

Microbial fuel cell (MFC) provides a promising technology to handle two problems by decomposing organic waste and power generation which is economical and clean source of energy. However, use of platinum catalyst in the MFC is quite expensive and not economically suitable for real-time applications that needs to find an alternative. Hence, the main aim of the present research is to investigate the power generation and food processing wastewater treatment with two types of microalgae (Oscillatoria sp. and Scenedesmus sp.) as a biocathode in the MFC. The experimental results showed that the peak power density of 32.5 ± 0.5 and 28.5 ± 0.3 mW/m2 was obtained for Oscillatoria sp. and Scenedesmus sp., respectively. The MFC power generation was also investigated with respect to CO2 supply and light intensity, respectively. The results of this study indicated that the possibility of bioelectricity generation using algae as a biocatalyst for economic feasibility and allowing the development of energy efficient systems for wastewater treatment. [ABSTRACT FROM AUTHOR]

Accelerated carbonation curing (ACC) is one of the emerging techniques to sequester CO2 in concrete. The present study focuses on assessing the near surface properties of concrete subjected to ACC. Freshly cast concrete was subjected to ACC for a period of 6 hours after an initial preconditioning of 2 hours and was followed by water spray till 3 days. Thermogravimetric analysis (TGA) and X-Ray Diffraction (XRD) analysis revealed presence of CaCO3 and increased quantity of CSH gel in near surface of ACC concrete. The findings of XRD and TGA were also confirmed by Scanning Electron Microscopy which exhibited a densification of microstructure due to precipitation of CaCO3 in voids. Mechanical properties and permeation properties of both bulk concrete and near surface concrete were assessed and results were compared with traditional water curing. Compressive strength and abrasion resistance of concrete was found to increase by 30% at the age of 3 days in ACC concrete. Water absorption, sorptivity, chloride permeability and carbonation depth decreased in case of carbonation cured concrete, showing a reduction in permeability of concrete surface. The effect of ACC was more prominent on near surface properties than on bulk properties at later ages and the same were confirmed by performing analysis of variance. [ABSTRACT FROM AUTHOR]

Algae are not only a great source of natural bio energy but also they have the ability to capture CO2. ALGADISK refers to a biofilm reactor for algae biomass production that could compete with the current algae cultivation technologies, e.g., open-pond and tubular photo bioreactors. When algae-based biomass is grown on the surface attached biofilm as opposed to a suspended culture, then the biomass is concentrated and it can be more easily harvested. Automatic and continuous harvesting, increased efficiency and decreased water requirements indicate ALGADISK as a promising technology. Since it is in developing stage, it has its own disadvantages such as it is not recommended to operate in cold weather conditions. [ABSTRACT FROM AUTHOR]

In sequestration of CO2 in deep saline aquifers, the relative permeability of the immiscible fluids plays a crucial role in governing dissolution and capillary trapping mechanisms. Relative permeability is solely dependent on capillary pressure and saturation at that instant of time, whereas the capillary pressure dynamically changes during flow reversal resulting in the hysteresis behavior of the relative permeability curves. However, the conventionally used models equate relative permeability as an explicit function of saturation, neglecting the inherent physics that govern the immiscible displacement of fluids. On the other hand, upscaling the pore scale mechanisms, such as contact angle hysteresis and wettability characteristics, to Darcy scale remains complicated. In the present investigation, an attempt has been made in formulating a methodology to compute relative permeability of the phase fluids based on contact angle hysteresis. The relative permeability curves calculated using the present model have been compared with that computed using existing methodology present in the literature. It has been observed that the present relative permeability model effectively calculates the drainage and imbibition relative permeability of both the wetting and non-wetting phases in the porous system. [ABSTRACT FROM AUTHOR]

Gas hydrate-based technology is a promising method for solidifying and sequestrating of CO2 gas into stratum sediments to reduce anthropogenic CO2 emissions and realize the exploitation of natural gas hydrate in the permafrost regions. In order to clarify the formation characteristics of CO2 hydrate in the porous media under condition of below the freezing point, the experiments were conducted in the frozen quartz sands. And the formation rate, the conversion rate and the gas storage capacities for CO2 hydrate were investigated through experimental study in the porous media. The results showed that, under the same temperature and initial pressure conditions, the formation rate, the conversion rate, and the gas storage capacities of hydrate increased with the decrease of particle sizes of the frozen quartz sands. And the ice content of the frozen quartz sands played little influence on the formation rate and the conversion rate of hydrate at the same particle size. Furthermore, the average formation rate attained 0.000544 mol∙h−1 in porous media below the freezing point. The conversion rate of ice attained 70.14, 81.72, and 90.61% in the frozen quartz sands with particle sizes of 500, 380, and 250 μm, respectively. The results also illustrated that, the gas-storage capacity of hydrate achieved 127.58, 144.04, and 152.65 L/L in the corresponding porous media. These results are of significance for guiding capture and sequestration of CO2 gas in the form of gas hydrate in stratum sediments. [ABSTRACT FROM AUTHOR]

In present investigation carried out large-scale treatment of tannery effluent by the cultivation of microalgae, Neochloris aquatica RDS02. The tannery effluent treatment revealed that significant reduction heavy metals were chromium-3.59, lead-2.85, nickel-1.9, cadmium-10.68, zinc-4.49, copper-0.95 and cobalt-1.86 mg/L on 15th day of treatment using N. aquatica RDS02. The microalgal biosorption capacity qmax rate was Cr-88.66, Pb-75.87, Ni-87.61, Cd-60.44, Co-52.86, Zn-84.90 and Cu-54.39, and isotherm model emphasized that the higher R2 value 0.99 by Langmuir and Freundlich kinetics model. The microalga utilized highest CO2 (90%) analyzed by CO2 biofixation and utilization kinetics, biomass (3.9 mg/mL), lipid (210 mg mL−1), carbohydrate (102.75 mg mL−1), biodiesel (4.9 mL g−1) and bioethanol (4.1 mL g−1). The microalgal-lipid content was analyzed through Nile red staining. Gas chromatography mass spectrometric (GCMS) analysis confirmed that the presence of a biodiesel and major fatty acid methyl ester (FAME) profiling viz., tridecanoic acid methyl ester, pentadecanoic acid methyl ester, octadecanoic acid methyl ester, myristic acid methyl ester, palmitic acid methyl ester and oleic acid methyl ester. Fourier transform infrared (FTIR) analysis confirmed that the presence of a functional groups viz., phenols, alcohols, alkynes, carboxylic acids, ketones, carbonyl and ester groups. The bioethanol production was confirmed by high-performance liquid chromatography (HPLC) analyze. [ABSTRACT FROM AUTHOR]

The CO2 stocks in roadside trees in Bilaspur, India, were estimated using a systematic sampling method on 30 sample plots. The sampling plots covered a total area of 3 ha. The region housed 438 trees of 37 species and 17 families, with an accumulated biomass of 101.44 t, 48.18 t of carbon and 176.64 t of CO2. Delonix regia had the largest amounts of species-specific biomass and CO2 stocks, followed by Tamarindus indica, Ficus religiosa, Albizia lebbeck and Ficus benghalensis. Azadirachta indica, Peltophorum pterocarpum, Samanea saman and Senna siamea had the highest numbers and relative abundances in roadside plantations. The 10 tree species that sequestered more than 80% of Bilaspur's CO2 were, in order of highest to lowest sequestration, Delonix regia, Samanea saman, Tamarindus indica, Azadirachta indica, Ficus religiosa, Peltophorum pterocarpum, Albizia lebbeck, Terminalia catappa, Ficus benghalensis and Terminalia arjuna. These tree species are therefore recommended for roadside plantations to sequester large amounts of CO2 from the city and contribute to offsetting warming and mitigating the impact of climate change. [ABSTRACT FROM AUTHOR]

Microalgae are the unicellular or multicellular photosynthetic microorganisms that can efficiently fix carbon dioxide (CO2) from various sources such as the environment, industrial flue gas, and some carbonate salts. In the present study, one green microalgal strain and a cyanobacterial consortium were used separately for the sequestration of CO2 at different pHs (7–11), at different initial concentrations of CO2 (5–20%), and at various inoculum sizes (5–12.5%). The maximum sequestration of CO2 was found to be 74.37 ± 0.49% and 71.12 ± 0.05% at 5% and 15% CO2 for green algae and cyanobacterial consortium. The biomass generated after sequestration of CO2 was utilized for the synthesis of biomolecules. [ABSTRACT FROM AUTHOR]

Prediction of adsorption equilibria of methane (CH4)/carbon dioxide (CO2) on coal at various feed gas composition is essential for the commercial development of primary and enhanced coalbed methane (ECBM) recovery by CO2 sequestration from coal reservoirs. In this article, an attempt is made to determine the adsorption equilibria of CH4 and CO2 mixture over a wide range of pressure and free gas compositions with the help of developed computational approach using the Ideal Adsorption Solution theory (IAST) for multicomponent adsorption. The advantage of the model is that it can predict the adsorption equilibrium of the mixture from the pure gas equilibrium data. Considering the complex adsorption during gas transportation and efficient gas injection modes at constant pressure or constant composition, the two different computational approaches were developed to solve the iterative calculation of IAST, i.e. constant mole fraction with variable pressure (P = 0 to 1000 psi) and constant pressure with mole fraction as a variable (y = 0 to 1). Individual adsorption isotherm of CH4 and CO2 for the two different sub-bituminous coal samples was determined up to a pressures of 1250 psi. Pure gas isotherms reveal that volume wise CO2 has 2.00 to 2.63 times more adsorption capacity than CH4 for the samples respectively. Computational model developed using ideal solution theory can predict the adsorbed gas volume at any pressure on the experimentally studied samples collected from Indian CBM fields. The developed computational code using MATLAB© software was validated using the binary adsorption data for the two coal samples from global CBM fields published in the literatures, with calculated error lying within the permissible limit. [ABSTRACT FROM AUTHOR]

The novel technology of biological carbon sequestration using microbial enzymes have numerous advantages over conventional sequestration strategies. In the present study, extracellular carbonic anhydrase (CA) producing bacteria were isolated from water samples in the Arabian Sea, India. A potential isolate, Bacillus safensis isolate AS-75 was identified based on 16S rDNA sequence analysis. The culture conditions suitable for CA production were 32 °C incubation temperature with 4% NaCl and 10 mM Zn supplementation. Experimental optimization of culture conditions enhanced enzyme activity to 265 U mL−1. CA specific gene was characterized and based on the analysis, the CA of B. safensis isolate AS-75 was a leucine (11.3%) with α-helices as the dominant component in its secondary structure. Based on soil microcosm studies, CA could sequester CO2 by 95.4% ± 0.11% in sterilized soil with enzyme microcosm. Hence, the application of enzyme was found to be more effective in removing CO2. [ABSTRACT FROM AUTHOR]

Thermodynamics of contact angle phenomena is strongly affected by the presence of thin liquid films. However, at present, studies for CO2/brine/mineral systems only consider the films apart from contact angles. In this paper, molecular dynamics (MD) simulations have been performed to simultaneously investigate the interrelationship between water film thicknesses and water contact angles. Two types of contact angles were considered namely Young's contact angle (no water film is present) and contact angle with film (a stable film is present). The results showed that as Young's contact angle increased, film thickness decreased which leading to increasing of contact angle with film. The effects of CO2-mineral pre-contact have also been investigated and it has been found that on mediate hydrophilic surfaces (Q3), water films were present when CO2 droplets were placed above the surfaces, however, water films were absent when CO2 droplets directly contact with the surfaces. This phenomenon implies that water films on mineral surfaces have a possibility to rupture and a film rupture mechanism for CO2 adhesion on hydrated mineral surfaces was proposed. These results may provide new information on interactions among CO2, water/brine and mineral to better understand the behaviour of CO2 during geologic sequestration. [ABSTRACT FROM AUTHOR]

Industrial by-products have been used as an alternative raw material for the long-term storage of CO2 as a mineral carbonate with various polymorphs and properties. For example; desulfurization gypsum (DG) obtained from a power station has great potential due to its high CaO content. This study used a mineral carbonation process to produce CaCO3 particles (PCC) from DG wastes for fixation of CO2 The effects of solid-to-liquid ratio (1:13, 1:9, and 1:7) and hydroxide sources (NaOH, NH4OH) on properties of PCC were determined using XRD, SEM, FTIR, AAS, and wet chemical analyses. Calcite crystals were produced in all cases with the use of NaOH, whereas calcite crystals along with spherical vaterite crystals were observed in the presence of NH4+. This study suggested a good option due to not only fixation of CO2 but also production of PCC with a high purity. [ABSTRACT FROM AUTHOR]

The impact of indigenous microorganisms on the mineral corrosion and mineral trapping in the SO2 co-injected CO2-saline-sandstone interaction was investigated in this study by lab experiments under 55 °C, 15 M pa. The results verified that co-injection of SO2 resulted in a decrease in biomass and shifts in microbial communities within 90 days, but some microorganisms still could adapt to acidic, high-temperature, high-pressure, and high-salinity environments. Firmicutes and Proteobacteria remained dominant phylum, but phylum Proteobacteria showed better tolerance to the co-injection of SO2 in the initial period. In the SO2 co-injected CO2-saline-sandstone interaction under microbial mediation, acid-producing bacteria further promoted the corrosion of K-feldspar, albite, and clay minerals, meanwhile mobilizing more K+, Na+, Ca2+, Mg2+ into solution. The acidogenic effect may be linked to the dominant genus of Bacillus, Paenibacillus, Acinetobacter, Pseudomonas and Exiguobacterium. Co-injection of SO2 inhibited the carbonates capture, while microbial acid production further reduced the pH, further inhibiting carbonates capture. As a result, no secondary carbonate (e.g., calcite) was observed on a short time scale within 90 days. So, microbial acidogenic effect was not conducive to carbonates capture in short term. [ABSTRACT FROM AUTHOR]

This study investigated capillary-trapped CO2 depending on the consideration of hysteresis effect in relative permeability for various water-alternation-gas (WAG) operating conditions to ascertain the oil production process. From the simulation results of CO2 WAG flooding method, the trapped CO2 led to prevent water-flow, in which CO2 acts as a gas blocker near the well. It caused the injection pressure increase during water injection period. As the trapped CO2 in pores increased, the reservoir pressure was also increased and maintained above minimum miscibility pressure (MMP). Ultimately, it was concluded that the reservoir was kept under miscible conditions throughout WAG process, reducing residual oil and increasing oil recovery. [ABSTRACT FROM AUTHOR]

The Blue Lagoon is a geothermal aquifer with a diverse ecosystem located within the Reykjanes UNESCO Global Geopark on Iceland’s Reykjanes Peninsula. Blue Lagoon Ltd., which exploits the aquifer, isolated a strain of coccoid cyanobacteria Cyanobacterium aponinum (C. aponinum) from the geothermal fluid of the Blue Lagoon more than two decades ago. Since then Blue Lagoon Ltd. has cultivated it in a photobioreactor, for use as an active ingredient in its skin care products. Until recently, the cultivation of C. aponinum was achieved by feeding it on 99.99% (4N) bottled carbon dioxide (CO2). In this investigation, C. aponinum was cultivated using unmodified, non-condensable geothermal gas (geogas) emitted from a nearby geothermal powerplant as the feed-gas instead of the 4N-gas. The geogas contains roughly 90% vol CO2 and 2% vol hydrogen sulfide (H2S). A comparison of both CO2 sources was made. It was observed that the use of geogas did enhance the conversion efficiency. A 13 weeks’ average CO2 conversion efficiency of C. aponinum was 43% and 31% when fed on geogas and 4N-gas, respectively. Despite the high H2S concentration in the geogas, sulfur accumulation in the cultivated biomass was similar for both gas sources. Our results provide a model of a CO2 sequestration by photosynthetic conversion of otherwise unused geothermal emission gas into biomass. [ABSTRACT FROM AUTHOR]

To investigate the effects of sequestration condition on hydrogen bonds between mineral and water, molecular dynamics simulations have been performed. The simulations were conducted at conditions related with geologic sequestration sites: pressure (3.1–32.6 MPa), temperature (318 and 383 K), salinity (0–3 M), salt (NaCl and CaCl2) and silica surface models Q2(geminal), Q3(isolated) and amorphous Q3. The hydrogen bonds were classified into four types: silica–silica, silica–dissolved CO2, silica–water as donors and silica–water as acceptors. The mean numbers of hydrogen bonds for each type were analysed. The results show that: (1) silica surface silanol groups do not form H-bonds with dissolved CO2molecules in water (brine); (2) The mean number of hydrogen bonds between silanol groups follows the order: Q2> amorphous Q3> Q3; (3) The mean number of hydrogen bonds between silanol and water molecules follows the order: Q3> amorphous Q3> Q2. [ABSTRACT FROM AUTHOR]

Marine microalgae sequester large quantities of inorganic compounds by way of photosynthesis. Therefore, phytoplankton has a considerable environmental impact as it contributes to counter-balancing anthropogenic releases of CO2. However, open questions remain regarding interactions between microalgae and their environment in particular the inorganic compounds which cells consume as nutrients. On the other hand, Michaelis-Menten (MM) kinetics links environmental chemistry and microbiology as it concurrently explains the cells' uptake of nutrients and utilization for cell production. Thereby, cells modify the chemical composition of their growing environment, which in turn is hypothesized to impact the cells' sequestration capabilities. However, the system of ordinary differential equations (ODEs) that represents MM cannot be solved without further considerations, as it contains unknown physiological parameters. These parameters though are of central interest, as they describe the cells' compound uptake in a certain chemical environment. Innovations in chemometrics are presented that derive values for these parameters as a function of the cells' nutrient availability. For this purpose, the MM ODE system has been merged into nonlinear least-square regression in lieu of a fit function. By this approach, it is demonstrated that microalgae's nutrient uptake is indeed driven by chemical conditions in their growing environment. These results are also indicative that the chemical conditions in a microscopic vicinity of the cells are relevant rather than nutrient concentrations on a culture level. These proof-of-principle results underline that for an accurate assessment of such chemically active samples, it is necessary to consider both the cells and their chemical environment. [ABSTRACT FROM AUTHOR]

Global warming due to the emission of carbon dioxide (CO2) gas, by the anthropogenic sources is a great threat to the environment. A part of this gas is absorbed by soil bacteria as well as aquatic bacteria and it is converted into insoluble calcium carbonate (CaCO3) or calcite. Increased calcite concentration in water and agricultural land creates many problems to the human. In this investigation, an attempt has been made to carry out some experiments to isolate some bacteria from cow dung, which have both calcite solubilization and urease activities. Isolated bacteria solubilize calcite due to the secretion of citric acid, oxalic acid and sanazine pigment. All bacterial isolates were identified by 16S rRNA gene sequencing and the phylogenetic relationship among them was also studied using MEGA 6 software. [ABSTRACT FROM AUTHOR]

An integrated model is proposed for simultaneous study of CO2-flood enhanced oil recovery and sequestration in both technical and economic points of view. Based on this model, Green Balance software is developed for quick estimation of performance and profitability of CO2-flood enhanced oil recovery and carbon capture and storage projects. This software benefits users to do sensitivity analyses in extended times, easily and quickly. Several sensitivity analyses were done and effects of reservoir parameters and economic expenditures and taxes were studied. Among all affecting parameters, the role of tax per CO2emission is the most important one. The use of adjusted tax, scaled for each project’s operational expenditures, is recommended. These regulations can make small carbon capture and storage projects, like large projects, profitable and more attractive to investors. [ABSTRACT FROM PUBLISHER]

The prospect of unconventional oil development has long been coming to offset the rapid decline of conventional crude. And looking ahead, the worry is already turning away from the onshore exploitation to the challenging offshore environment, with the question being whether the emerging technology can overcome the challenges of deep-water heavy oil production. In economics terms, the immiscible process shows a negative return, a longer payback time, and a low net present value. With an increased revenue through increased production, there is a degree of strong, dynamic, and appealing prospect to any future heavy oil development using miscible process. [ABSTRACT FROM AUTHOR]

The significance of Joule-Thomson effect in petroleum industry applications has extensively been documented in the literature. In the first part of an extensive literature survey conducted on the significance of Joule-Thomson effect in petroleum fields Yadali Jamaloei and Asghari, 2015, this effect was presented in well testing, in multilateral/slanted wells, in drilling/completion/production operations, and in hydrate formation. In this article, the second part of this comprehensive review is presented, which consists of Joule-Thomson effect in CO2injection into depleted natural gas reservoirs, in prediction of wellbore temperature profiles, and the influence of thermal stresses resulting from this effect on the wellbore stability. It is expected that this article will serve as a reference tool for the engineers interested in the Joule-Thomson effect in petroleum fields. [ABSTRACT FROM AUTHOR]

The significance of Joule-Thomson effect—occurring in throttling-type processes, such as adiabatic flow—in downstream and upstream petroleum industry applications cannot be overemphasized. In this article, the first part of a comprehensive review of this effect in oil and gas field applications is presented. For space reasons, the second part of the review will be presented in a second article. The first part of this review, which is the subject of the present work, includes the Joule-Thomson effect in well testing in oil and gas fields, in applications regarding the horizontal/multilateral/slanted wells, and in drilling, completion, production testing, and monitoring. In addition, challenges of the hydrate formation associated with Joule-Thomson cooling effect are discussed. It is expected that this article would serve as a helpful reference tool for the engineers interested in the Joule-Thomson effect in oil/gas field applications. [ABSTRACT FROM PUBLISHER]

In the present study, we focus on the phase properties of CO2–brine systems in geologic media. Molecular dynamics simulation methods were used to investigate the ion hydration and hydrogen bond structure in CO2–brine and brine solutions at temperatures and pressures for CO2sequestration. By comparing the results of CO2–brine solutions with those of brine solutions, the effects of solvated CO2were analysed and discussed. [ABSTRACT FROM PUBLISHER]

The mineral carbonation method is still a challenge in practical application owing to: (1) slow reaction kinetics, (2) high reaction temperature, and (3) continuous mineral consumption. These constraints stem from the mode of supplying alkaline earth metals through mineral acidification and dissolution. Here, we attempt to mineralize gaseous carbon dioxide into calcium carbonate, using a cation exchange reaction of vermiculite (a species of expandable clay minerals). The mineralization is operated by draining NaCl solution through vermiculite powders and continuously dropping into the pool of NaOH solution with CO2gas injected. The mineralization temperature is regulated here at 293 and 333 K for 15 min. As a result of characterization, using an X-ray powder diffractometer and a scanning electron microscopy, two types of pure CaCO3polymorphs (vaterite and calcite) are identified as main reaction products. Their abundance and morphology are heavily dependent on the mineralization temperature. Noticeably, spindle-shaped vaterite, which is quite different from a typical vaterite morphology (polycrystalline spherulite), forms predominantly at 333 K (∼98 wt%). [ABSTRACT FROM PUBLISHER]

The use of carbon dioxide (CO2) in enhanced oil recovery is a mature well-practiced technology; however, enhancing gas recovery (EGR) through the injection of CO2is yet to be tested in the field. Depleted natural gas or gas condensate reservoirs are becoming important targets for CO2injection. The study of injection of CO2for EGR needs accurate fluid modeling of CO2behavior in the gas reservoir conditions; especially the interaction of CO2and reservoir fluid should be taken into account to obtain the best conditions for injection (Oldenburg and Benson, 2001). The purpose of this study is to evaluate the efficiency of CO2injection in one of Iranian gas condensate reservoirs by modeling of reservoir fluid properties and different behaviors of its mixture with CO2to have a proper estimation of injection condition and possibility of problems such as gravity segregation, viscous fingering, and liquid drop out at reservoir conditions. PVTi module of Eclipse software was used to perform modeling based on laboratory pressure-volume-temperature analysis of well number X of one of Iranian gas condensate reservoirs. [ABSTRACT FROM PUBLISHER]

CO2sequestration during cold heavy oil production using captured carbon dioxide was investigated using REVEAL of Petroleum Experts. The results indicated that the CO2release was influenced by the production phases. The prediction showed high CO2retention in the first few years post start-up, followed by a gradual decline toward 16.5% post peak production. The recovery rate was strongly influenced by the reservoir characteristics, such as fluid properties, permeability, aquifer, and well completion. Horizontal wells provided better performance than vertical wells. The CO2utilization and retention per barrel of heavy oil increased as the CO2injection pressure increased. [ABSTRACT FROM AUTHOR]

The Jurassic-aged Precipice Sandstone and Hutton Sandstone in the Surat Basin (Queensland) are potential targets for CO2sequestration that exhibit considerably different mineralogies. Hyperspectral logging was complemented with petrographic studies to reveal core-scale mineralogical distributions. Scanning electron microscopy and X-ray diffraction analyses of the bulk rock composition and clay (< 2 μm) fraction provided an adjunct to mineral identification. The Precipice Sandstone is interpreted to be geochemically poorly reactive with a clean, quartzose mineralogy dominated by quartz and kaolinitic clays. These clays coat grains and partially fill pores, having formed from the extensive leaching of unstable feldspars and lithics, and are commonly associated with Fe-oxide/hydroxide. The mineralogy of the Evergreen Formation is geochemically reactive and contains significant feldspar, smectite, chlorite, carbonate and kaolinite, and should therefore serve as an effective intraformational seal. Low permeability in the Evergreen Formation is attributed to extensive porosity loss following burial compaction, which is evident from the formation of pressure-dissolution features and a lithic-derived clay-rich pseudo matrix in several samples. The Hutton Sandstone is a heterogeneous potential reservoir, with geochemically reactive intervals containing smectite, chlorite and Fe–Mn–Mg–Ca carbonates, in addition to feldspars and lithics. Variable clay matrix content, porosity and locally significant cementation within the Hutton Sandstone indicate a mineralogically heterogeneous unit that could have the capacity to buffer emplaced CO2. This potentially provides an additional vertical component of capture and storage to the potential reservoir system, in addition to the traditional regional seal provided by the Evergreen Formation. [ABSTRACT FROM PUBLISHER]

Digital core analysis at multiple scales incorporating X-ray micro-computed tomography (μCT) imaging in different states in 3D, and registration of 2D SEM and SEM–energy-dispersive X-ray spectra (EDS) images into the 3D tomograms, offers an extensive and unique toolbox for characterising potential CO2reservoir and seal candidates. μCT imaging allows the calculation of connected porosity, and subsequently properties such as permeability, formation factor, Archie's cementation component, drainage capillary pressure, and Swi can be determined digitally and pore-throat network models can be generated. Sub-micron scale features in the 3D image can be directly correlated with high-resolution scanning electron microscope (SEM) images using 2D-to-3D image registration. Additionally, thein situmineralogy can be quantified by using an automated mineral and petrological analysis (SEM–EDS) system. The mineralogy determined in 2D by SEM–EDS can then be interpolated into the 3D image block for the direct identification of minerals with contrasting X-ray attenuation. The 3D data can be readily displayed using 3D visualisations that show the pore connectivity, 3D mineralogy, geological structures, and incorporating the pore-throat network model, SEM, and 2Din situmineral map. Additionally the porosity and flow pathways of a potential seal rock can be characterised at the nanoscale (pores 10–30 nm) using focussed ion beam SEM (FIBSEM) imaging. The behaviour of the potential reservoir and seal rocks during interaction with supercritical CO2and water can be directly investigated by coupling digital core analysis with a high-pressure cell. Multiple images can be collected of the same plug before, during and after interaction with CO2and water to directly characterise in 3D the CO2trapping, and changes to the pore/throat geometries and mineralogy owing to interactions with the CO2. [ABSTRACT FROM PUBLISHER]

The purification, immobilization, and characterization of carbonic anhydrase (CA) secreted by Bacillus subtilis VSG-4 isolated from tropical soil have been investigated in this work. Carbonic anhydrase was purified using ammonium sulfate precipitation, Sephadex-G-75 column chromatography, and DEAE-cellulose chromatography, achieving a 24.6-fold purification. The apparent molecular mass of purified CA obtained by SDS-PAGE was found to be 37 kD. The purified CA was entrapped within a chitosan–alginate polyelectrolyte complex (C-A PEC) hydrogel for potential use as an immobilized enzyme. The optimum pH and temperature for both free and immobilized enzymes were 8.2 and 37°C, respectively. The immobilized enzyme had a much higher storage stability than the free enzyme. Certain metal ions, namely, Co2+, Cu2+, and Fe3+, increased the enzyme activity, whereas CA activity was inhibited by Pb2+, Hg2+, ethylenediamine tetraacetic acid (EDTA), 5,5′-dithiobis-(2-nitrobenzoic acid (DTNB), and acetazolamide. Free and immobilized CAs were tested further for the targeted application of the carbonation reaction to convert CO2 to CaCO3. The maximum CO2 sequestration potential was achieved with immobilized CA (480 mg CaCO3/mg protein). These properties suggest that immobilized VSG-4 carbonic anhydrase has the potential to be used for biomimetic CO2 sequestration. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) sequestration in deep, unmineable coal seams provides a promising opportunity for the reduction of anthropogenic greenhouse gas emissions. However, little is known about optimal design features of the required in-ground infrastructure. Here, we report on a numerical study investigating the influence of the number of injection (and production) wells and their arrangement on the CO2 storage capacity of a coal-seam reservoir. The results of the modelling reveal a decline in injection rates and practical storage capacities with continued CO2 injection. This is related to coal matrix swelling (and associated permeability decrease) caused by adsorption of injected CO2 on coal, coupled with increasing reservoir pore pressures during injection, which reduce the pressure gradient from well to reservoir and thus the impetus for flow. Modelling carried out for scenarios with multiple wells showed an increase in storage capacity for the two-well scenario but a reduction in storage capacity for the three- and four-well models. This was related to the relative timing of interaction between zones of influence (swollen, high-pore-pressure zones) for neighboring injection wells and their limitations on additional CO2 injection. Models incorporating a distal water-production well demonstrated that reduction in pore pressures by water production can help increase injection rates and practical storage capacities. However, modelling showed that if the production well is placed too close to the injection well, methane accumulating in the vicinity of the production well can mix with injected CO2, causing significant changes in CO2 densities, pore pressures, and thus storage capacities. The results of the modelling confirm the influence of well arrangement on coal-seam CO2 storage capacity. [ABSTRACT FROM AUTHOR]

Sequestration of CO2 in enhanced oil recovery applications has been widely recognized as one of the favorite techniques for reducing emissions of CO2 into the atmosphere in response to global climate change. This technique provides lower costs for CO2 sequestration by means of higher incremental oil recoveries. There are some key parameters, when considering a field for the CO2 displacement. Oil reservoirs are screened out according to oil gravity, reservoir temperature and pressure, minimum miscibility pressure, and remaining oil saturation. Throughout this study, the CO2-Prophet tool is utilized in order to assess suitability of Bati Raman and Çamurlu crude oil fields for CO2-enhanced oil recovery application. In the second part of the study, the Kinder Morgan Scoping economic model is used to see economic consequences of the project. Although the °API gravity and minimum miscibility pressure for these fields do not meet the required criteria for the miscible flood, due to importance of CO2 sequestration and absence of appropriate fields for CO2-enhanced oil recovery implementation in Turkey, these fields can be considered for CO2-enhanced oil recovery applications as long as the project is economically feasible. [ABSTRACT FROM PUBLISHER]

This article presents the numerical modeling study to investigate the effect of CO2 sequestration in deep saline aquifer at Gorae V structure, Korea. This structure includes the Donghae-1 gas field, which is the only one producing in Korea. A simulation for 20 years of injection and 1,000 years of monitoring was conducted by using generalized equation-of-state model compositional reservoir simulator (GEM), which can simulate the flow of the CO2-water mixture to verify major trap mechanisms and sequestration characteristics in this system. By a number of simulations in reservoir conditions, the 3,000 ton/day of optimum injection rate was obtained within the limits of the rock fracturing pressure. As a result of simulation, since most of injected CO2 rises by a buoyancy and moves horizontally by the effect of cap rock, the radius of CO2 flowed out in the top layer is larger than bottom layer. Also, the change of dominant trap mechanism among structural, solubility, and residual trapping mechanism with time was examined. As residual gas saturation increases, the contact area between CO2 and formation water decreases. Thus, the quantity sequestrated by a solubility trap is reduced, and a greater amount of gas remains in the grid block. Also, gas saturation in some block was decreased below residual gas saturation due to the continuous dissolution and the formation water, accordingly, the formation water which its density was increased than surrounding blocks, sank to lower part of structure. [ABSTRACT FROM AUTHOR]

The analytical and numerical modeling of CO2 sequestration in deep saline aquifers having different rock and fluid properties was studied under diffusion and convection mechanisms. In a diffusion dominated system, an aquifer with 100 m thickness was saturated with CO2 after 10,000,000 years. It was much earlier in a convective dominant system. In the diffusion process, the dissolution of CO2 in aquifer increased with porosity increase; however, in a convection dominant process dissolution of CO2 in aquifer decreased with porosity increase. The increase in permeability accelerated the dissolution of CO2 in aquifer significantly, which was due to increasing velocity. The dissolution process in the aquifer was realized faster for the aquifers with lower dispersivity. The results of convective dominant mechanism in aquifers with 1 md and 10 md permeability values were close to that of the diffusion dominated system. For the aquifer having permeability higher than 10 md, the convection mechanism began to dominate gradually and it became a fully convection dominated system for 50 md and higher permeability values. These results were also verified with calculated Rayleigh numbers. [ABSTRACT FROM AUTHOR]

Recently, there is a growing interest the in oil industry to utilize carbon dioxide (CO2) to enhance oil production from mature reservoirs. Conversely, there is a rising global attention to reduce CO2 emissions from burning fossil fuels due to environmental concerns. Synchronization between these two objectives is promising through CO2 Capture and Storage (CCS) projects where CO2 is captured from large emission sources and then storedin safe geological structures. Economical evaluation of CO2-EOR projects is a crucial measure in order to ensure a project's viability. In this study, an efficient model was developed to predict the economics of CO2-EOR projects. The developed model consists of five modules that are linked together to allow for fast prediction of CO2-EOR economics. The model was used to predict the economics of a case study where CO2-EOR application is considered for a Middle Eastern reservoir. Moreover, the case study was subjected to sensitivity analyses to evaluate the effects of several parameters on the various economical components of CO2-EOR projects. [ABSTRACT FROM AUTHOR]

The gas-induced swelling behavior of coal is important when considering CO2 sequestration into coal seams or enhanced coalbed methane applications, but coals may also swell in the presence of moisture, or shrink on drying. In this paper we examine the moisture-swelling properties of coals from Australia and elsewhere. Results on the moisture uptake and corresponding swelling measurements are presented for 15 coals of various ranks (sub-bituminous and bituminous) at 22°C and atmospheric pressure. Measurements were made by exposing sample blocks of coal (nominally 30 × 10 × 10 mm) to relative humidities ranging from 0% to 97%. A selection of coals was also fully saturated in water. Moisture uptake at 97% relative humidity (RH) ranged from about 2.5% to more than 16% db. Maximum linear strain associated with the moisture sorption (measured at 97% RH) varied from about 0.2% to 1.3%, with lower rank coals showing the most swelling. In all cases, swelling was greater in the direction perpendicular to the bedding plane. These results correspond to volumetric swelling of about 0.5% to around 5%. Although exhibiting significant expansion, all of the samples returned to their original dimensions upon drying. Volumetric moisture sorption and the amount of swelling induced were found to be strongly correlated by a single linear expression that held for all of the coals examined. It was further found that the volume of the water adsorbed was linearly related to the pore space within the coal, however, at 97% relative humidity, only about 60% of the available pore space is occupied by water. Exposure to liquid water allowed the pores to completely fill; although for the lowest rank coals, the volume of water absorbed appeared to be slightly more than the corresponding pore volume. Despite the additional water uptake, immersion in water did not produce further swelling beyond that induced at 97% relative humidity. [ABSTRACT FROM AUTHOR]

CO2 emissions originated from industrial sources can be captured, transported, and stored in depleted gas/oil fields and deep saline aquifers. The transport mechanisms, occurred during CO2 sequestration in deep saline aquifers, are examined in this study. After injecting CO2 until the tolerable pressure for the aquifer is reached, the wells are closed and CO2 is deposited as free gas and soluble gas in water under the sealing rock. During injection and waiting periods, the concentration profile of CO2 within the aquifer is formed by diffusion and convection mechanisms. The Rayleigh number and mixing zone length concepts are used for investigating the effect of reservoir properties, such as dispersivity, permeability, porosity, and others on the aforementioned mechanisms. The results of convective dominant mechanism in aquifers with 1 md and 10 md permeability values are so near in that diffusion-dominated system. After 10 md, the convection mechanism begins to dominate gradually and it becomes totally convection dominated for 50 md and higher permeability values. These results are also verified by the Rayleigh number and mixing zone lengths. [ABSTRACT FROM AUTHOR]

CO2 can be sequestered in coal seams considering the environmental issues. By means of injecting CO2 into the coal seams, both sequestration of CO2 and the enhanced recovery of methane inside the coal seam can be realized. One-dimensional simulation regarding the binary CO2/CH4 flow in a coal seam core was studied by using an analytical solution method. The simulation results were compared with experimental data by matching the effluent concentrations of CO2 and CH4. The transport parameters such as longitudinal dispersion coefficient, retardation factor, and distribution coefficient were determined. It was seen that the amount of CO2 captured inside the coal sample during binary displacement was much lower than the maximum adsorption capacity of the coal at the same pressure. Then the transport behavior of CO2 and CH4 inside the coal seam was simulated. The results of analytical solution were in good agreement with the measured ones within the acceptable error range. [ABSTRACT FROM AUTHOR]

Geologic storage of CO2 in depleted oil reservoirs is considered to be an effective approach for both facilitating GHG sequestration and enhancing oil recovery. However, as a potential problem in the long run, risks associated with geological storage of CO2, such as leakage to the groundwater and atmosphere, might pose significant threats to local communities and surrounding environment. Identification and evaluation of such risks are essential for the long-term management of CO2 storage. Doing so requires a set of advanced technologies in order to well understand the long-range transportation of CO2 and its impact mechanisms. This study developed an integrated decision support framework for the Weyburn Field. This system included modules of data management, inexact hybrid numerical simulation, optimization for CO2 EOR processes, hybrid fuzzy-stochastic risk assessment, and post-modeling analysis. A user-friendly interface was designed through visual language programming. Such an effort would provide project managers with a collection of measures for analyzing and visualizing operations and development of different applicable technologies. Valuable information can be provided to EOR project operators about what might be required for new projects or project expansions and how to go about gathering and using the data they will need. [ABSTRACT FROM AUTHOR]

Carbon dioxide gas, a greenhouse gas (GHG), is released in the atmosphere by combustion of solid waste, wood, and fossil fuels for energy generation. Due to conspicuous absence of CO2 sequestration studies for Alaska, the study of CO2 sequestration options on North Slope has a very important role to play. The screening of the oil reservoirs to evaluate the technical feasibility with respect to their CO2-EOR potential was performed by calculating the rank of the oil reservoirs with parametric approach. CMG-WinProp® simulator was used to predict phase behavior for CO2 injection in viscous oil by tuning the equation-of-state. [ABSTRACT FROM AUTHOR]

The capacity of particles of CaO, produced by calcining limestone, to reactively absorb CO2, degrades with the number of cycles of carbonation and calcination. A novel method of reactivating the stone in humid, ambient air is described. Typically, a calcined limestone has a carrying capacity for CO2 which falls from ∼79% (on the basis of moles of CO2 per mole of CaO) to only about 20–30% after 30 cycles of regeneration and reuse. This new technique enables the carrying capacity to be restored to ∼55%, thereby improving the economics of sequestrating CO2 using a calcium-based sorbent. [ABSTRACT FROM AUTHOR]

This paper briefly discusses the following main issues: The future of the hydrogen economy. Thermo-chemistry of hydrogen production for different techniques of autothermal operation for different feedstocks. Improvement of the hydrogen yield and minimization of reformer size by contining fast fluidization with hydrogen and oxygen membranes and with in-situ CO2 sequestration. Efficient production of hydrogen using a novel membrane-circulating fluidized-bed autothermal reformer. Preliminary investigation of the economics of hydrogen production using these novel technologies. Novel gasification process for the direct production of hydrogen from biomass. It is shown that a hydrogen economy is not a myth as some people advocate, and that with well-directed research it will represent a bright future for humanity to utilize a clean, everlasting fuel that is also free of deadly conflicts for the control of energy sources. It is also shown that efficient autothermal production of hydrogen using novel reformer configurations and a wide range of feedstock is a very promising route for achieving a successful hydrogen economy. A novel process for the production of hydrogen from different renewable biomass sources is presented and discussed. The process combines the principles of pyrolysis with the simultaneous use of catalysts, membranes and in-situ CO2 sequestration to produce pure hydrogen directly from the unit. [ABSTRACT FROM AUTHOR]

Environmental protection is a critical issue worldwide at the current time. In particular, CO 2 emissions are now considered to be one of the major pollutants contributing to global warming. The aim of this concise review is to provide a clear picture of the present development of various capture technologies and available technology options. In addition, this article attempts to examine recent advances in research and developments for CO 2 storage and sequestration. Finally, the article also looks at opportunities and challenges based on cost and engineering economics of CO 2 capture and sequestration. [ABSTRACT FROM AUTHOR]