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Continued increase in CO2 emissions has unquestionably led to rising global temperatures. To aid in themitigation of climate change new Negative Emission Technologies (NETs) have been proposed. CO2-sequestration by bio-enhanced silicate weathering is one such proposed NET that seeks to captureatmospheric CO2 by weathering silicate rocks. The research focuses on investigating whether the naturalprocess of weathering can be enhanced using biology. Previous studies have shown promising resultswhere microbes have increased the weathering rates of silicates.As such, this project aimed to investigate how the presence of citric acid affects the weathering rateof dunite. Furthermore, the study aimed to investigate how the process is affected by biological growth.The setup consisted of 50 g of dunite powder mixed with 1 M citric acid that was incubated for aboutthree months. Due to this extensive time-period, most of the analyses made were performed on anexperiment started in December of 2023. The following analyses consisted of Scanning ElectronMicroscopy (SEM) imaging, geochemical analyses such as pH, anions, organic carbon content, specificsurface area analyses (BET) and X-ray diffraction spectroscopy (XRD). The second part of this studyconsisted of starting up a new more extensive setup similar to the original one. Furthermore, the studyalso investigated the biological growth that could be seen on the original setup and how the weatheringrate was affected.The setup demonstrated a substantial increase in weathering rate in the presence of citric acid. Theanalyses also showed that the alkalinity had significantly increased during incubation, demonstratingthe method’s possible use in mitigating acidification as well as the CO2 emissions. Although the initialpH of the citric acid solution was low (pH 2), fungal growth became evident after a few weeks. Thisobservation holds promise for an efficient bio-enhanced silicate weathering experimental setup, as lowerpH levels are ass, Med de ökande koldioxidutsläppen ökar även de globala temperaturerna såväl som andraklimatförändringar. För att på ett snabbt men även rimligt sätt sänka CO2-utsläppen har så kalladeNegative Emission Technologies (NETs) lagts fram som en möjlig lösning. En sådan teknik ärkoldioxidinfångst med hjälp av accelererad silikatvittring, som bygger på att använda biologi för attpåskynda vittringsprocessen som naturligt tar upp CO2 från atmosfären. Tidigare studier har visat på attmikrober kan förbättra vittringen av silikater.Detta arbete hade som syfte att undersöka hur vittringen av dunitpulver påverkas av citronsyra.Utöver detta undersöktes även hur vittringen påverkas av mikrobiologisk tillväxt inom reaktorerna.Reaktorerna bestod av 50 g dunitpulver och 1 M citronsyra som fick inkuberas under ungefär tremånaders tid. På grund av denna tidsperiod utfördes majoriteten av analyserna på experiment somstartades i december 2023. Analyser som utfördes var bland annat svepelektronmikroskopering (SEM),geokemiska analyser såsom pH, anjoner, organiska syror, organiskt kol samt analys av specifik ytarea(BET) och röntgendiffraktion (XRD). Förutom analyser av det originella experimentet, startades ävenett nytt, utökat experiment liknande det första. En tredje del av denna studie bestod av att undersöka denbiologiska tillväxten inom reaktorerna och hur den har påverkat vittringen.Experimentet visade på en betydande ökning i vittringshastighet med citronsyra närvarande.Analyser visade också på en markant ökning i alkalinitet, vilket pekar på en möjlig användning avaccelererad silikatvittring för att motverka försurning så väl som CO2-utsläppen. Trots de låga pHnivåerna i början av experimentet (pH 2), fanns ingen antydan om att citronsyran påverkademöjligheterna för tillväxt av liv, vilket öppnar för möjligheten att påskynda vittringen ännu mer iexperiment för bio-accelererad silikatvittring. Slutsatsen för projektet blir att citronsyra kan användasför att accelerera silikatvittring, o

The cement industry accounts for 8% of global energy- and process-related greenhouse gas emissions. To achieve global net-zero emission targets by 2050, the need for commercially ready low-carbon construction materials is becoming increasingly urgent. The fixation of captured carbon dioxide in concrete through CO₂ sequestration is a crucial area of study to reduce concrete embodied carbon. This paper discusses the development of a low-carbon ready-mix concrete (RMC) with aqueous CO2 sequestration, and the synergy between carbon dioxide and other constituent materials. The effectiveness of this approach was evaluated through mineralogical composition analysis using TGA, and the mechanical and rheological properties of various concrete mixes were studied. Aqueous CO2 sequestration using carbonated mixing water can stably fix up to 0.84% of CO2 by weight of cement within the cement matrix as CaCO3. The poor workability and incompatibility with GGBS that results from this approach were addressed by the inclusion of RCA as an external source of alkalinity and lubrication. This mix of low-carbon RMC has similar strength and rheological properties to conventional RMC and achieved an embodied carbon reduction of approximately 47%.

The construction industry has been focused on sustainability, particularly with regards to reducing CO2 emissions and recycling construction and demolition (C&D) waste. This study focuses on the alternative technology adaptation of carbonized pavement compact production by using waste concrete powder (WCP) which can be a substitute material to concrete and also able to absorb CO2. While material scientists embraced and developed this technological application, the financial perspective for adopting this technology has yet to be properly addressed. This paper conducts a feasibility assessment, which includes technical, environmental, social, and financial factors, from different stakeholders' perspectives (government, construction contractors, and material manufacturers) to launch the production of carbonized pavement compact by utilizing WCP. The benefit-cost analysis underlies the Evolutionary Game Model functions' formulation, which emphasizes not only the obvious financial benefits from WCP or its carbonized compacts sale but the benefits from the absorption of CO2 during the compacts production and avoiding WCP disposal at a landfill. The results based on a Hong Kong case (typical multistorey apartment building) identify promising scenarios where a minimum of 2300t of WCP is required for stakeholder interest in recycling, and a WCP wholesale price of 150HKD/t is suitable for the C&D contractor to participate in the recycling market. The study also estimates a cost-effective selling price of finished carbonized WCP compacts, which is competitive with similar products on the market. Important insights are drawn to initiate the WCP market and consequently increase the sustainability of the C&D recycling market.

Le résidu de bauxite est un résidu minier alcalin produit pendant la production de l’alumine par le procédé Bayer. Ce résidu a été utilisé dans la carbonatation minérale afin de réduire les émissions de dioxyde de carbone à la sortie des cheminées des alumineries du Québec. Dans cette thèse, les carbonatations en phase aqueuse et solide ont été évaluées à température ambiante. Des tests en phase aqueuse ont été réalisés sur des suspensions avec 40, 50 et 60 % de densité de pulpe avec 10 % de CO₂ injecté à pression de 150 psi. La réaction par la voie gaz-solide a été priorisée et optimisée à l’égard de l’absorption et de la minéralisation du CO₂. L’humidité du résidu, le débit du gaz, la concentration du CO₂ et le temps de réaction ont été évalués sur la carbonatation du résidu de bauxite pur dans un lit fixe de capacité de 1,5 L. Par la suite, afin d’améliorer la capacité de séquestration de CO₂, des expériences ont été menées avec l’ajout d’amendements calciques : un sous-produit de désulfuration des gaz de Rio Tinto, nommé Chaux Hydratée Aqua-Catalysée (CHAC) et les Poussières de four à chaux (Lime Kiln Dust - LKD). Les ajouts ont été effectués pour apporter un équivalent de 10 % en CaO au résidu. Les résultats ont montré que la réaction en phase aqueuse n’était pas viable pour la séquestration du CO₂, car les ions carbonates formés lors de la dissolution du CO₂ ne pouvaient pas précipiter sans une surface de nucléation, en raison de la faible saturation de la solution. Ainsi, le résidu devrait être stocké dans les suspensions jusqu’à la précipitation des carbonates. La carbonatation par la voie gaz-solide élimine ce problème et améliore la séquestration du CO₂. Parmi les paramètres évalués, le seul avec un effet significatif sur la carbonatation gaz-solide du résidu pur était la teneur d’humidité du résidu, car la porosité et la diffusion du gaz en dépendent. L’humidité optimale était de 26 % et la capacité de séquestration obtenue était de 12,3 kg.t ⁻¹ de résidu

An abundant source of CH4 can be found in natural hydrate deposits. Recent demonstration of CH4 recovery from hydrates via CO2 exchange has revealed the potential as a fuel source that also provides a medium for carbon sequestration. It is vital to understand the structural and dynamic impacts of guest variation in CH4, CO2, and mixed hydrates and link the results to the stability of various deposits in nature, harvesting methane, and sequestering CO2. Molecular vibrations are examined in CH4, CO2, and mixed CH4-CO2 hydrates at 5 and 190 K and Xe hydrates for comparison. Inelastic neutron scattering (INS) is an ideal spectroscopy technique to observe the dynamic modes in the hydrate structure and enclathrated CH4, as it is extremely sensitive to 1H. The presence of CO2 in hydrates tightens the lattice. It introduces more active librational modes to the host lattice, while hindering the motion of CH4 in mixed CH4-CO2 hydrate at 5 K. At 190 K, a large broadening of the CH4 librational modes indicates disorder in the structure leading to dissociation.

In this study, we explored the capability of coda wave interferometry (CWI) for monitoring CO2 storage by estimating the seismic velocity changes caused by CO2 injection. Given that the CWI method is highly efficient, the primary aim of this study was to provide a quick detection tool for the long-term monitoring of CO2 storage safety. In particular, we looked at monitoring with a cross-well geometry. We also expected that CWI could help to reduce the inversion errors of existing methods. Time-lapse upgoing waves and downgoing waves from two-component datasets were utilized to efficiently monitor the area between the wells and provide a quick indication of possible CO2 leakage. The resulting mean velocity changes versus the depth indicated the depth where velocity changes occurred. Combining the upgoing and downgoing wavefields provided a more specific indication of the depth range for changes. The calculated velocity changes were determined using the time shift between the time-lapse wavefields caused by CO2 injection/leakage. Hence, the resulting velocity changes were closely related to the ratio of propagation path length through the CO2 injection/leakage layer over the length of the entire travel path. The results indicated that the noise level and repeatability of the time-lapse datasets significantly influenced the results generated using CWI. Therefore, denoising and time-lapse processing were very important for improving the detectability of any change. Applying CWI to time-lapse cross-well surveys can be an effective tool for monitoring CO2 in the subsurface at a relatively low computational cost. As a highly efficient monitoring method, it is sensitive to changes in the seismic response caused by velocity changes in the subsurface and provides additional constraints on the inversion results from conventional travel time tomography and full waveform inversion.

Mineral carbonation of construction and demolition waste is a viable alternative for the reduction of CO2 emissions from industry. Concrete and cement, together with ceramic blocks, are the primary sources of calcium for mineral carbonation in which CO2 is fixed in a stable and inert process. One type of concrete was selected from 5 for the carbonation tests. Crushed, separated into size fractions, moistened to 20% and tested at 10 bars of CO2 for 24 to 720h. Destruction of portlandite and ettringite phases was determined. Calcite precipitated as carbonate phase. Maximum carbonation was reached after 72h, fixing 6.5% of CO2., La carbonatación mineral de los residuos de construcción y demolición es una alternativa viable para la reducción de las emisiones de CO2 de la industria. El hormigón y el cemento, junto con los bloques de cerámica, son las principales fuentes de calcio para la carbonatación mineral en la que el CO2 se fija en un proceso estable e inerte. Se seleccionó un tipo de hormigón de entre 5 para las pruebas de carbonatación. Triturado, separado en fracciones de tamano, ˜ humedecido al 20% y probado a 10 bares de CO2 durante 24 a 720 horas. Se determinó la destrucción de las fases de portlanita y ettringita. La calcita se precipitó como fase de carbonato. La máxima carbonatación se alcanzó después de 72 horas, fijando el 6,5% de CO2.

The importance of trees for the environment focuses on the services they can offer, CO2 fixation being one of the most prominent. The objective of the research was to estimate the amount of carbon captured by the trees in the green areas of the Universidad Laica Eloy Alfaro de Manabí. For this purpose, an inventory of the tree stratum was carried out. All individuals with a diameter at 1.30 m (plus minus 5 cm) were recorded. Richness and abundance were evaluated, as well as dendometric variables (total height, trunk diameter). The carbon captured was calculated from the estimate of forest biomass. The wood density of the different species was obtained from various global forestry databases. 68 species and 1200 individuals were identified. The most abundant species was Azadirachta indica (37%). CO2 sequestration was 19 650.76 t. Although a significant amount of carbon is fixed, many specimens are in conflict with physical infrastructure, which requires their removal. It is recommended to design new green areas under strict quality standards, prioritizing native species., A importância das árvores para o ambiente centra-se nos serviços que podem oferecer, sendo a fixação de CO2 um dos mais destacados. O objetivo da pesquisa foi estimar a quantidade de carbono capturada pelas árvores nas áreas verdes da Universidad Laica Eloy Alfaro de Manabí. Para tanto, foi realizado um inventário do estrato arbóreo. Todos os indivíduos com diâmetro de 1.30 m (mais menos 5 cm) foram registrados. Foram avaliadas a riqueza e abundância, bem como as variáveis dendométricas (altura total, diâmetro do tronco). O carbono capturado foi calculado a partir da estimativa da biomassa florestal. A densidade da madeira das diferentes espécies foi obtida de vários bancos de dados florestais globais. 68 espécies e 1200 indivíduos foram identificados. A espécie mais abundante foi Azadirachta indica (37%). O sequestro de CO2 foi de 19 650.76 t. Embora uma quantidade significativa de carbono seja fixada, muitos espécimes estão em conflito com a infraestrutura física, o que exige sua remoção. Recomenda-se projetar novas áreas verdes sob rígidos padrões de qualidade, priorizando espécies nativas., La importancia de los árboles para el ambiente se centra en los servicios que pueden ofrecer, siendo el de fijación de CO2 uno de los más destacados. El objetivo de la investigación fue estimar la cantidad de carbono capturado por el arbolado de las áreas verdes de la Universidad Laica Eloy Alfaro de Manabí. Para este propósito se realizó un inventario del estrato arbóreo. Se registraron todos los individuos con diámetro de 1.30 m (más menos 5 cm). Se evaluó la riqueza y abundancia, además de variables dendométricas (altura total, diámetro del tronco). Se calculó el carbono capturado a partir de la estimación de biomasa forestal. La densidad de la madera de las distintas especies se obtuvo de varias bases de datos forestales mundiales. Se identificaron 68 especies y 1200 individuos. La especie más abundante fue Azadirachta indica (37%). El secuestro de CO2 fue de 19 650.76 t. A pesar de que se fija una importante cantidad de carbono, muchos ejemplares se encuentran en conflicto con infraestructura física, lo cual requiere la remoción de estos. Se recomienda diseñar nuevas áreas verdes bajo estrictas normas de calidad, priorizando especies nativas.

Global warming is one of the most pressing environmental concerns which correlates strongly with anthropogenic CO2 emissions so that the CO2 decreasing strategies have been meaningful worldwide attention. As an option, natural gas hydrate reservoirs have steadily emerged as a potent source of energy which would simultaneously be the proper places for CO2 sequestration if the method of CO2/CH4 replacement could be developed. On the flip side, CO2 hydrates as safe and non-flammable solid compounds without an irreversible chemical reaction would contribute to different industrial processes if their approaches could be improved. Toward developing substantial applications of CO2 hydrates, laboratory experiments, process modelling, and molecular dynamics (MD) simulations can aid to understand their characteristics and mechanisms involved. Therefore, the current review has been organized in form of four distinct sections. The first part reviews the studies on sequestering CO2 into the natural gas hydrate reservoirs. The next section gives an overview of process flow diagrams of CO2 hydrate-based techniques in favour of CO2 Capture and Sequestration & Utilization (CCS&U). The third section summarizes the merits, flaws, and different effects of hydrate promoters as well as porous media on CO2 hydrate systems at macroscopic and mesoscopic levels, and also how these components can improve CO2 hydrate properties, progressing toward the more feasibility of CO2 hydrate industrial applications. The final sector recapitulates the MD frameworks of CO2 clathrate and semiclathrate hydrates in terms of new insights and research findings to elucidate the fundamental properties of CO2 hydrates at the molecular level.

The affinity of the basalt surfaces towards CO2, quantified as wettability functions, is one of the most important driving factors for CO2 trapping capacity and containment security. SiO2 is a minor constituent, often found in traces in the seawater and formation brine injected or reinjected into the sub-surface formations. This work, thus, evaluates the effect of nano-sized SiO2 (100, 1000, and 2000 mg. L−1) on the wettability of the basalt rock surface in the pressure range of 5-20 MPa. The results from brine/CO2/rock wettability measurements show that SiO2 nanoparticles turn the CO2-wet basalt surface to weakly water-wet upon aging with nanofluids. About 40% reduction in the measured brine contact angle takes place upon treatment of the rock sample with 1000 mg. L−1 nanoparticles. We hypothesize that this change in wettability may facilitate enhanced capillary or residual trapping of CO2 in the basalt formation having adequate porosity and permeability to enhance the basalt CO2 trapping capacity.

Wettability is one of the main parameters controlling CO2 injectivity and the movement of CO2 plume during geological CO2 sequestration. Despite significant research efforts, there is still a high uncertainty associated with the wettability of CO2/brine/rock systems and how they evolve with CO2 exposure. This study, therefore, aims to measure the contact angle of sandstone samples with varying clay content before and after laboratory core flooding at different reservoir pressures, of 10 MPa and 15 MPa, and a temperature of 323 K. The samples’ microstructural changes are also assessed to investigate any potential alteration in the samples’ structure due to carbonated water exposure. The results show that the advancing and receding contact angles increased with the increasing pressure for both the Berea and Bandera Gray samples. Moreover, the results indicate that Bandera Gray sandstone has a higher contact angle. The sandstones also turn slightly more hydrophobic after core flooding, indicating that the sandstones become more CO2-wet after CO2 injection. These results suggest that CO2 flooding leads to an increase in the CO2-wettability of sandstone, and thus an increase in vertical CO2 plume migration and solubility trapping, and a reduction in the residual trapping capacity, especially when extrapolated to more prolonged field-scale injection and exposure times.

Evaluation of seismic reflection data has identified the presence of fluid escape structures cross-cutting overburden stratigraphy within sedimentary basins globally. Seismically-imaged chimneys/pipes are considered to be possible pathways for fluid flow, which may hydraulically connect deeper strata to the seabed. The properties of fluid migration pathways through the overburden must be constrained to enable secure, long-term subsurface carbon dioxide (CO2) storage. We have investigated a site of natural active fluid escape in the North Sea, the Scanner pockmark complex, to determine the physical characteristics of focused fluid conduits, and how they control fluid flow. Here we show that a multi-scale, multi-disciplinary experimental approach is required for complete characterisation of fluid escape structures. Geophysical techniques are necessary to resolve fracture geometry and subsurface structure (e.g., multi-frequency seismics) and physical parameters of sediments (e.g., controlled source electromagnetics) across a wide range of length scales (m to km). At smaller (mm to cm) scales, sediment cores were sampled directly and their physical and chemical properties assessed using laboratory-based methods. Numerical modelling approaches bridge the resolution gap, though their validity is dependent on calibration and constraint from field and laboratory experimental data. Further, time-lapse seismic and acoustic methods capable of resolving temporal changes are key for determining fluid flux. Future optimisation of experiment resource use may be facilitated by the installation of permanent seabed infrastructure, and replacement of manual data processing with automated workflows. This study can be used to inform measurement, monitoring and verification workflows that will assist policymaking, regulation, and best practice for CO2 subsurface storage operations.

This study presents a robust optimization workflow to determine the optimal water alternating gas (WAG) process for CO2 sequestration in a heterogeneous fluvial sandstone reservoir. As depicted in this study, WAG injection could enhance CO2 residual and solubility trapping based on an integrated modeling workflow. First, continuous CO2 injection and WAG were compared to demonstrate the efficiency of the WAG process for CO2 trapping enhancement. To achieve this while highlighting the impact of reservoir heterogeneity, 200 geological realizations were generated considering a wide range of plausible geological conditions. The ranking of these realizations was performed by quantifying the CO2 cumulative injection (P10, P50, and P90 realizations) that represent the overall geological uncertainties. Then, an innovative robust workflow was used Artificial Intelligence optimizer to determine the optimal solution for CO2 trapping. For comparison, a nominal optimization workflow of P50 realization was also conducted. The proposed robust optimization workflow resulted in higher CO2 trapping than the nominal optimization workflow. Thus, this study demonstrates a fast and reliable workflow that can accurately represent for optimization the cycle length injection in the WAG process under geological uncertainties.

Percolation experiments, using columns filled with alternating layers of hydrated Portland cement and crushed sedimentary rocks, were conducted at PCO2 = 10 bar and 60 °C. Limestone, sandstone and marl were representative of reservoir and cap rocks for a geologic CO2 storage site. The injected solution was at equilibrium with gypsum and equilibrated with the CO2. The main reactions were the dissolution of the calcite that constitutes the rocks and the hydrotalcite and portlandite of the Portland cement. The resulting porewaters were supersaturated with respect to aragonite and gypsum, leading to their precipitation. 2D reactive transport simulations successfully reproduced the experimental aqueous chemistry changes caused by the major dissolution of calcite, portlandite and hydrotalcite together with the precipitation of aragonite, dolomite (cement carbonation), gypsum and alunite. Porosity increased to different extents in both cement and rock. Cement degradation was noticeable in all the cases, but even more in the sandstone experiment.

To limit the effect of global warming society needs clean energy sources and to reduce emissions of greenhouse gases into the atmosphere. By combining carbon capture and storage technologies together with geothermal power production it is possible to gain fossil free energy while potentially storing CO2 at the same time. Furthermore, it would be possible to reduce the emissions from geothermal sites with high greenhouse gas content in the groundwater by recirculating the retrieved fluid. Many uncertainties remain however about this type of adaptation. To study this, this master thesis investigated how a geothermal system would be effected by comparing a water injection with 10 % CO2 to a pure water injection. A 2D model over a 1000 m times 1000 m horizontal fracture zone with two boreholes spaced 500 m apart and a injection rate of 1 kg/s was simulated using the iTOUGH2 software with the ECO2N module, designed for numerical simulations regarding geohydrological systems. In addition to comparing the two injection scenarios stated above, the effects of changing the injection rate, CO2 concentration in the injection fluid, permeability and surrounding pressure as well as introducing salinity and having an initial CO2 saturated liquid phase were investigated as well. It was concluded that using CO2 in the injection fluid does allow for a large greenhouse gas sequestration while slightly increasing the heat production, but the system experienced a significant pressure increase while doing so. It was suggested that further investigations regarding adjustments of injection rate and concentration of CO2 was to be performed to find an optimal injection strategy, and to study the impact of different salinity concentrations in both the fracture zone and the injection fluid., För att begränsa konsekvenserna av den globala uppvärmningen behöver dagens samhällen tillgång på fossilfri energi och reducera utsläppen av växthusgaser. Genom att kombinera koldioxidlagringsteknik och geotermisk elproduktion är det möjligt att få utsläppsfri energi samtidigt som det lagras CO2. Vidare finns möjligheten att återcirkulera den upphämtade vätskan för geotermiska kraftverk i områden med högt växthusgasinnehåll i grundvattnet, för att på så vis minska utsläppen från dessa kraftverk. Emellertid så återstår det många osäkerheter kring den här typen av implementation. För att undersöka detta har ett geotermiskt system studerats hur det skulle påverkas av att använda en vatteninjektion med 10 % CO2 i jämförelse mot rent vatten. En 2D modell över en 1000 m x 1000 m horisontell sprickzon med två borrhål 500 m ifrån varandra och en injektionshastighet på 1 kg/s simulerades med modulen ECO2N till mjukvaran iTOUGH2, en mjukvara som är speciellt designat för att numeriskt simulera geohydrologiska system. Förutom att jämföra de två injektionsscenariorna ovan så undersöktes även hur skillnader i injektionshastigheten, injektionskoncentrationen av CO2, permeabiliteten och sprickzonens tryck samt införandet av salinitet och en initialt CO2 mättad vätskefas påverkade resultatet. Slutsatsen blev att genom att använda CO2 i injektionsflödet så möjliggörs en stor lagring av CO2 samtidigt som värmeproduktionen ökar något, men med en stor tryckökning i sprickzonen som följd. Det rekommenderades att göra flera undersökningar på justeringar av injektionshastigheten och CO2 koncentrationen för att hitta en optimal injektionsstrategi, samt att studera hur olika salthalter i både sprickzonen och i injektionsfluiden skulle påverka resultatet.

Human activities from overpopulation to pollution are drastically increasing the global temperature and causing fundamental changes in the Earth. The primary reason for this phenomenon is the greenhouse gas effect that primarily comes from the destruction of the forest cover and conventional energy production. This would cause extreme weather conditions, consequently imperilling the natural habitats, ecosystems and all the Earth’s activities. Emission of an enormous amount of anthropogenic carbon dioxide (CO2) has become the primary reason for global warming; so, it is vital to advance towards novel techniques to alleviate the issue. Within a portfolio of options, CO2 sequestration has gained growing attention – aimed at carbon capture and storage in geological formations. In this context, CO2 sequestration in coal reservoirs is identified as an effective method, because the process is associated with enhanced coalbed methane (ECBM) extraction – that further offsets the cost of CO2 storage in coal reservoirs. The successful implementation of the process would certainly lead to a pollution-free world and ultimately a better future, through the mitigation of the greenhouse gas effect. Although the fundamental physics of CO2 sequestration have been evolved over several decades, there are some grey areas and unexplored aspects, that need further improvement through investigations. For instance, the injection of CO2 into coal affects its structural properties, and consequently, the efficiency of the sequestration process as well as the long-term integrity of the reservoir. The coal-CO2 interaction is a complicated physico-chemical and thermodynamic process that depends on multiple parameters, which in turn makes the evaluations quite challenging. A deep understanding of the structural alterations, in terms of coal hydro-mechanical properties, is thus essential to optimize the process, while minimizing the reservoir damage. Considering the above aspects, this research aim

La transcription des symboles et des caractères spéciaux utilisés dans la version originale de ce résumé n’a pas été possible en raison de limitations techniques. La version correcte de ce résumé peut être lue en PDF. Au cours des dernières années, différentes méthodes de séquestration du CO2 ont été proposées. Parmi elles, la carbonatation minérale permet de faire réagir le CO2 et un cation métallique, principalement fer (Fe), magnésium (Mg) et calcium (Ca) pour former des carbonates stables. Dans la région de Sept-Îles au Québec, le projet Mine Arnaud prévoit l’exploitation d’un gisement d’apatite et entrainera la production de résidus miniers principalement composés de fayalite. Ces résidus, riches en fer (23 % Fe2O3) ont un potentiel d'utilisation pour la carbonatation minérale. Ce projet propose d’évaluer le potentiel de séquestration en CO2 de résidus de fayalite pour le traitement des gaz de combustion des industries proches de la mine (ArcelorMittal et Aluminerie Alouette). Cette approche de carbonatation minérale a été réalisée par voie aqueuse avec une étape de lixiviation préalable du Fe. Le Fe est ensuite complexé avec du 2,2’-bipyiridine avant d’être précipité sous forme de carbonates (FeCO3). L’approche développée a permis la séquestration du CO2 et la formation de carbonates de Fe pur à 71 %. L'optimisation des paramètres dans un scénario de recirculation a montré une capacité de lixiviation du Fe de 38 % par rapport au résidu initial, ainsi qu'un taux d'élimination du CO2 de 57 % dans des conditions de réaction douces (pH 12, 80 ºC, 10 % volume de CO2, pression atmosphérique, 2 heures de réaction) avec une efficacité globale de 24 % (0,13 g CO2 enlevée/g résidu). La possible valorisation des produits, ainsi que les faibles émissions générées sont optimistes pour une future industrialisation. La thèse se compose principalement de deux parties. La première consiste en une synthèse de l'étude, présentant le contexte par une revue bibliographique, présen

High-pressure experiments were performed to investigate the effectiveness, rate and mechanism of carbonation of serpentinites by a carbon-saturated COH fluid at 1 5-2 5 GPa and 375-700 °C. This allows a better understanding of the fate and redistribution of slab-derived carbonic fluids when they react with the partially hydrated mantle within and above the subducting slab under pressure and temperature conditions corresponding to the forearc mantle. Interactions between carbon-saturated CO2-H2O-CH4 fluids and serpentinite were investigated using natural serpentinite cylinders with natural grain sizes and shapes in piston-cylinder experiments. The volatile composition of post-run fluids was quantified by gas chromatography. Solid phases were examined by Raman spectroscopy, electron microscopy and laser ablation inductively coupled plasma mass spectrometry. Textures, porosity and phase abundances of recovered rock cores were visualized and quantified by three-dimensional, high-resolution computed tomography. We find that carbonation of serpentinites is efficient at sequestering CO2 from the interacting fluid into newly formed magnesite. Time-series experiments demonstrate that carbonation is completed within ∼96 h at 2 GPa and 600 °C. With decreasing CO2,aq antigorite is replaced first by magnesite quartz followed by magnesite talc chlorite in distinct, metasomatic fronts. Above antigorite stability magnesite enstatite talc chlorite occur additionally. The formation of fluid-permeable reaction zones enhances the reaction rate and efficiency of carbonation. Carbonation probably occurs via an interface-coupled replacement process, whereby interconnected porosity is present within reaction zones after the experiment. Consequently, carbonation of serpentinites is self-promoting and efficient even if fluid flow is channelized into veins. We conclude that significant amounts of carbonates may accumulate, over time, in the hydrated forearc mantle.

Carbon capture and sequestration (CCS) is an engineering-based approach for mitigating excess anthropogenic CO2 emissions. Deep brine aquifers and basalt reservoirs have shown outstanding performance in CO2 storage based on their global widespread distribution and large storage capacity. Capillary trapping and mineral trapping are the two dominant mechanisms controlling the distribution, migration, and transportation of CO2 in deep brine aquifers and basalt reservoirs. Understanding the behavior of CO2 in a storage reservoir under realistic conditions is important for risk management and storage efficiency improvement. As a result, numerical simulations have been implemented to understand the relationship between fluid properties and multi-phase fluid dynamics. However, the physics-based simulations that focus on the uncertainties of fluid flow dynamics are complicated and computationally expensive. Machine learning method provides immense potential for improving computational efficiency for subsurface simulations, particularly in the context of parametric sensitivity. This work focuses on parametric uncertainty associated with multi-phase fluid dynamics that govern geologic CO2 storage. The effects of this uncertainty are interrogated through ensemble simulation methods that implement both physics-based and machine learning modeling strategies. This dissertation is a culmination of three projects: (1) a parametric analysis of capillary pressure variability effects on CO2 migration, (2) a reactive transport simulation in a basalt fracture system investigating the effects of carbon mineralization on CO2 migration, and (3) a parametric analysis based on machine learning methods of simultaneous effects of capillary pressure and relative permeability on CO2 migration.

This work aims to shed light on the yet unanswered question regarding the limited carbonation yield of activatedlizardite via direct carbonation. Two amorphous Mg-rich silicate phases were identified upon activation. A rapid and complete carbonation of a highly reactive amorphous silicate phase was observed under moderately low pressure and temperature conditions (50-120 °C, 6 bar). Carbonation of this phase yielded to the formation of carbonates and a Si-rich passivating phase. On the other hand, the other amorphous silicate phase remained unaltered upon carbonation, fixing a significant amount of Mg within its disordered structure. The presence of poorly reactive intermediate Mg-rich silicate and Si-rich phases might be responsible for the yet unanswered relatively low carbonation efficiencies obtained via direct carbonation of activated lizardite. These limiting factors are considered to reduce the carbonation yield significantly more than the nucleation of forsterite during thermal activation. Analogous experiments carried with different meta-serpentines yielded the formation of distinct carbonate phases. The different distribution of highly and poorly-reactive amorphous phases among the different activated materials might have played an important role in the accelerated formation of magnesite (which was observed to occur once hydromagnesite formation reached a steady state) and the transformation of nesquehonite to dypingite-like phases., This work has been partially funded by the Government of Catalonia through the FI-2017 program for the recruitment of early-stage researchers (K.R.). Contract number: 2017 FI_B00129 (K.R.). Authors are grateful to Prof. Joaquín Proenza (Universitat de Barcelona) who kindly provided the samples studied in this research. The authors gratefully acknowledge Prof. Alissa Park and Mr. Guanhi Rim for insightful discussions. Technical assistance in sample characterization of the reaction products by Drs. Trifon Trifonov and Montserrat Domínguez-Escalante, from the Barcelona Research Center in Multiscale Science and Engineering. Drs Jorge Molinero and Andrés Idiart from Amphos21 Consulting S.L. España are gratefully acknowledged for their collaboration in the framework of the InnoEnergy PhD mobility program funding to A.C., Peer Reviewed, Postprint (author's final draft)

Blue Carbon (BC) strategy refers to the approaches that mitigate and adapt to climate change through the conservation and restoration of seagrass, saltmarsh and mangrove ecosystems and, in some BC programs, also through the expansion of seaweed aquaculture. The major losses of coastal habitats in combination with the commitments of China under the Paris Agreement provide unique opportunity and necessity to develop a strong Chinese BC program. Here, we (1) characterize China's BC habitats, examine their changes since 1950 along with the drivers of changes; (2) consider the expansion of seaweed aquaculture and how this may be managed to become an emerging BC resource in China, along with the engineering solutions required to enhance its potential; and (3) provide the rationale and elements for BC program in China. We find China currently has 1326–2149 km2 wild and 2–15 km2 created mangrove, saltmarsh and seagrass habitats, while 9236–10059 km2 (77–87%) has been lost since 1950, mainly due to land reclamation. The current area of farmed seaweed habitat is 1252–1265 km2, which is close to the area of wild mangrove, saltmarsh and seagrass habitats. We conclude that BC strategies have potentials yet to be fully developed in China, particularly through climate change adaptation benefits such as coastal protection and eco-environmental co-benefits of seaweed farming such as habitat creation for fish and other biota, alleviation of eutrophication, hypoxia and acidification, and the generation of direct and value added products with lower environmental impact relative to land-based production. On this basis, we provide a roadmap for BC strategies adjusted to the unique characteristics and capacities of China.

Experimental work on the carbonation of brucite has been carried out in the temperature and pressure ranges of 50-120 °C and 1-10 bar respectively, using concentrated CO2 and simulated flue gas. At 120 °C hydro- magnesite and trace amounts of magnesite were identified. Highly to semi-ordered dypingite like-phases and nesquehonite, coexisting with a possibly amorphous carbonate phase, were identified at 50 °C. The dehydration temperatures and chemical composition of these amorphous phases are very close to those of crystalline, stoi- chiometric nesquehonite. This probably amorphous phase nourishes the late formation of dypingite. This latter mineral gradually undergoes a cell shrinkage due to the partial loss of molecular waters, becoming structurally more ordered as the carbonation reaction proceeds. It remains unclear whether nesquehonite formed directly from brucite or from the crystallization of an amorphous precursor. However, nesquehonite is precursor of dypingite and/or the possibly amorphous phase. Only crystalline carbonate phases were observed at 120 °C. Concentrated CO2 experiments yielded the highest amounts (up to 37 wt.%) of CO2 sequestered at 10 bar and 16 h of reaction, reaching an almost complete carbonation of brucite (> 98 %). On the other hand, flue gas experiments results showed higher amounts of CO2 sequestered per unit of CO2 partial pressure than with concentrated CO2., Peer Reviewed, Postprint (author's final draft)

Quantifying the dynamics of sequestered CO2 plumes is critical for safe long-term storage, providing guidance on plume extent, and detecting stratigraphic seal failure. However, existing seismic monitoring methods based on wave reflection or transmission probe a limited rock volume and their sensitivity decreases as CO2 saturation increases, decreasing their utility in quantitative plume mass estimation. Here we show that seismic scattering coda waves, acquired during continuous borehole monitoring, are able to illuminate details of the CO2 plume during a 74-h CO2 injection experiment at the Frio-II well Dayton, TX. Our study reveals a continuous velocity reduction during the dynamic injection of CO2, a result that augments and dramatically improves upon prior analyses based on P-wave arrival times. We show that velocity reduction is nonlinearly correlated with the injected cumulative CO2 mass and attribute this correlation to the fact that coda waves repeatedly sample the heterogeneous distribution of cumulative CO2 in the reservoir zone. Lastly, because our approach does not depend on P-wave arrival times or require well-constrained wave reflections it can be used with many source-receiver geometries including those external to the reservoir, which reduces the risk introduced by in-reservoir monitoring wells. Our results provide an approach for quantitative CO2 monitoring and plume evolution that increases safety and long-term planning for CO2 injection and storage.

The cement and concrete industry stand for approximately 8% of the global CO2 emissions. The demand of concrete and cement is expected to increase rapidly with the growing world population and increased urbanization. This makes it of the utmost importance for the industry to try to mitigate its emissions. One way to reduce the industry’s environmental impact is by mineral carbonation curing through which CO2 can be sequestered in the concrete. This investigation studied the CO2 uptake of wollastonite (CaSiO3) which can be used for mineral carbonation. The CO2 uptake of different brands of wollastonite powders for different temperatures, pressures and water to solid ratios were tested through carbonation, and the samples were then analyzed through XRD, SEM and particle size analysis. The results showed large differences in CO2 uptake between the brands of wollastonite powders. They also indicate that lower temperatures lead to higher CO2 uptake but also possibly slow down the reaction rate and that higher CO2 pressures seem to increase CO2 uptake though the effect is small. There was significant variation of the effects of the water to solid ratios on CO2 uptake between the tested brands. The morphology of the powders also seemed to be of little relevance as an amorphous and crystalline powder were the two best performing powders, similarly particle size is not indicated by the result to have a large effect on CO2 uptake, though further studies are required to fully determine the effect of the morphology and particle size., Cement- och betongindustrin står för cirka 8% av de globala koldioxidutsläppen. Efterfrågan på betong och cement förväntas öka snabbt med den växande världsbefolkningen och ökad urbanisering. Detta tyder på hur viktigt det är för industrin att minska sina utsläpp. Ett sätt att minska industrins miljöpåverkan är genom härdning av betongen via mineral karbonatisering, en process som binder in koldioxid i betong. I detta arbete studerades koldioxidupptagningen av mineralen wollastonit (CaSiO3) som kan användas för mineral karbonatisering. Olika märken av wollastonitpulvers koldioxidupptag vid olika temperaturer, koldioxidtryck och vattenhalter testades genom karbonatisering och proverna analyserades därefter genom XRD-analys, SEM-analys och partikelstorleksanalys. Resultaten visade stora skillnader i koldioxidupptagning mellan varumärkena av wollastonitpulver. De visar även att lägre temperaturer leder till högre upptag av koldioxid, men att reaktionshastigheten potentiellt saktar ner vid låga temperaturer. Högre koldioxidtryck verkar öka koldioxidupptagningen men effekten är liten. Det fanns signifikant variation av effekterna av vattenhalterna på koldioxidupptagning mellan de testade varumärkena. Pulvrens morfologi verkade inte ha en stor effekt då ett av de två bäst presterande pulvren var amorft och det andra kristallint. På samma sett verkade partikelstorleken inte ha en stor påverkan på koldioxidupptaget men ytterligare studier krävs för att fullständigt kunna bestämma effekten av morfologin och partikelstorleken.

Using a first-principle methodology, we investigate the stable structures of the nonreactive and reactive clusters formed between Zn2+–triazoles ([Zn2+-Tz]) clusters and CO2 and/or H2O. In sum, we characterized two modes of bonding of [Zn2+-Tz] with CO2/H2O: the interaction is established through (i) a covalent bond between Zn2+ of [Zn2+-Tz] and oxygen atoms of CO2 or H2O and (ii) hydrogen bonds through N–H or C–H of [Zn2+-Tz] and oxygen atoms of H2O or CO2, N–H···O. We also identified intramolecular proton transfer processes induced by complexation. Indeed, water drastically changes the shape of the energy profiles of the tautomeric phenomena through strong lowering of the potential barriers to tautomerism. The comparison to [Zn2+-Im] subunits formed with Zn2+ and imidazole shows that the efficiency of Tz-based compounds for CO2 capture and uptake is due to the incorporation of more accessible nitrogen donor sites in Tzs compared to imidazoles. Since [Zn2+-Tz] clusters are subunits of an organometallic nanoporous materials and Zn–proteins, our data are useful for deriving force fields for macromolecular simulations of these materials. Our work also suggests the consideration of traces of water to better model the CO2 sequestration and reactivity on macromolecular entities such as pores or active sites.

During the past decade, carbon capture, utilization, and storage (CCUS) has gained considerable recognition as a viable option to mitigate carbon dioxide (CO2) emissions. This process involves capturing CO2 at emission sources such as power plants, refineries, and processing plants, and safely and permanently storing it in underground geologic formations. Many CO2 injection tests have been successfully conducted to assess the storage potential of CO2 in saline formations, oil and natural gas reservoirs, organic-rich shales, and unmineable coal reservoirs. Coal seams are an attractive reservoir for CO2 storage due to coal's large capacity to store gas within its microporous structure, as well as its ability to preferentially adsorb CO2 over naturally occurring methane resulting in enhanced coalbed methane (ECBM) recovery. A small-scale CO2 injection test was conducted in Southwest Virginia to assess the storage and ECBM recovery potential of CO2 in a coalbed methane reservoir. The goal of this test was to inject up to 20,000 tons of CO2 into a stacked coal reservoir of approximately 15-20 coal seams. Phase I of the injection test was conducted from July 2, 2015 to April 15, 2016 when a total of 10,601 tons of CO2 were injected. Phase II of the injection was conducted from December 14, 2016 to January 30, 2017 when an additional 2,662 tons of CO2 were injected, for a total of 13,263 total tons of CO2 injected. A customized monitoring, verification, and accounting (MVA) plan was created to monitor CO2 injection activities, including surface, near-surface, and subsurface technologies. As part of this MVA plan, chemical tracers were used as a tool to help track CO2 plume migration within the reservoir and determine interwell connectivity. The work presented in this dissertation will discuss the development and implementation of chemical tracers as a monitoring tool, detail wellbore-scale tests performed to characterize CO2 breakthrough and interwell connectivity, and pre

Sustainable source of energy is the emergent necessity for the near future which comes from the simultaneous two issues: The growing request for energy and the necessity to strictly limit and control carbon emissions with warning on global warming. Although there are very terrible statistics of CO2 emission worldwide (110 billion metric tonnes in 2010 with estimated 140 billion metric tonnes by 2035), there are also hopes in that the plants and biomasses may sequester more than 260 Giga tonnes of CO2 annually. Interestingly, approximately 183 Giga tons of CO2 are annually fixed through microalgae to produce about 100 Giga tons of its biomass. These are other great motivations to invest in microalgae-based technologies such as microbial fuel cell (MFC) which are the cells to produce power from simultaneous CO2 sequestration and wastewater treatment. In this chapter, we present an overview of the current status together with the future prospects on the fuel cells based on biomass. Additionally, the necessities for scaling up the MFCs have been discussed. The main motivation for research and developments in this field is highlighted to develop green energy and technology for environmental protection. Specifically, latest researches and achievements in MFC technology are presented. The main constituents of MFC, i.e. anodes, cathodes, substrates, and microorganisms are discussed with the latest researches and developments. As a rule of thumb, for scale-up purposes, there is a threshold volumetric power density of 1 kWm-3, maintaining of which as the lab-scale one is challengeable. However, there are suggestions such as optimizing some key factors, such as and appropriately spacing the electrodes with the specific surface area. In this regard, three-dimensional electrodes with highly surface area for enhanced microbial attachment and anodic performance such as tenuous graphite rods have been introduced.

The stationary points for the reaction between the CO and nine different phosphatranes molecules have been characterized by means of MP2 computational methods. Two minima structures have been located: a pnicogen bonded complex where one of the oxygen atoms of CO acts as electron donor and an adduct that presents a covalent P−C linkage. The corresponding transition state structure linking the two minima has also been characterized. In gas phase, the pnicogen bonded complex is more stable than the corresponding adduct except in one case. In contrast, the inclusion of the solvent effect (toluene and THF), reverts the stability, being in all cases the different adducts more stable than the pnicogen bonded complexes. The electronic properties of the systems have been analysed with the Quantum Theory of Atoms in Molecules (QTAIM) and Electron Density Shift (EDS) methods.

The injection of CO2 at the Ketzin pilot site commenced in June 2008 and was terminated in August 2013 after 67 kT had been injected into a saline formation at a depth of 630-650 m. As part of the site monitoring program, four 3D surface seismic surveys have been acquired to date, one baseline and three repeats, of which two were conducted during the injection period, and one during the post-injection phase. The surveys have provided the most comprehensive images of the spreading CO2 plume within the reservoir layer. Both petrophysical experiments on core samples from the Ketzin reservoir and spectral decomposition of the 3D time-lapse seismic data show that the reservoir pore pressure change due to CO2 injection has a rather minor impact on the seismic amplitudes. Therefore, the observed amplitude anomaly is interpreted to be mainly due to CO2 saturation. In this study, amplitude versus offset analysis has been applied to investigate the amplitude versus offset response from the top of the sandstone reservoir during the injection and post-injection phases, and utilize it to obtain a more quantitative assessment of the CO2 gaseous saturation changes. Based on the amplitude versus offset modelling, a prominent decrease in the intercept values imaged at the top of the reservoir around the injection well is indeed associated solely with the CO2 saturation increase. Any change in the gradient values, which would, in case it was positive, be the only signature induced by the reservoir pressure variations, has not been observed. The amplitude versus offset intercept change is, therefore, entirely ascribed to CO2 saturation and used for its quantitative assessment. The estimated CO2 saturation values around the injection area in the range of 40%-60% are similar to those obtained earlier from pulsed neutron-gamma logging. The highest values of 80% are found in the second seismic repeat in close vicinity to the injection and observation wells.

The injection of CO2 at the Ketzin pilot CO2 storage site started in June 2008 and ended in August 2013. During the 62 months of injection, a total amount of about 67 kt of CO2 was injected into a saline aquifer. A third repeat 3D seismic survey, serving as the first post-injection survey was acquired in 2015, aiming to investigate the recent movement of the injected CO2. Consistent with the previous two time-lapse surveys, a predominantly WNW migration of the gaseous CO2 plume in the up-dip direction within the reservoir is inferred in this first post-injection survey. No systematic anomalies are detected through the reservoir overburden. The extent of the CO2 plume west of the injection site is almost identical to that found in the 2012 second repeat survey (after injection of 61 kt), however there is a significant decrease in its size east of the injection site. Assessment of the CO2 plume distribution suggests that the decrease in the size of the anomaly may be due to multiple factors, such as limited vertical resolution, CO2 dissolution and CO2 diffusion, in addition to the effects of ambient noise. 4D seismic modelling based on dynamic flow simulations indicates that a dynamic balance between the newly injected CO2 after the second repeat survey and the CO2 being dissolved and diffused was reached by the time of the first post-injection survey. Considering the considerable uncertainties in CO2 mass estimation, both patchy and non-patchy saturation models for the Ketzin site were taken into consideration.

Carbon monolithic adsorbents exhibiting a hierarchical pore structure are produced via a synthesis route based on the stabilization of liquid foams followed by a carbonization step. The macro-microporous structure is achieved by the incorporation of microporous, biomass-derived activated carbon particles in the liquid foam enclosed by a cationic surfactant as stabilizer. This method yields crack-free monoliths (solid foams) with a compressive strength of the order of 20 kPa. The microstructure and the textural properties of the final solid foams have been investigated by means of Scanning Electron Microscopy (SEM) and gas adsorption. The behavior as selective CO2 adsorbents at 25 °C has been evaluated using breakthrough experiments under simulated post-combustion conditions (16% V/V CO2/N2), resulting in a selectivity factor of 13 over N2. The hierarchical pore structure of the monoliths allows a rapid transport of the gas mixture through the macropores with no appreciable pressure drop, retaining more than 90 % of the adsorption capacity (∼ 0.868 mmol/g) after several adsorption/desorption cycles. Moreover, the monolith has shown a CO2 uptake capacity of 2.62 mmol/g under static condition at 1 bar and 25 °C. This study provides guidelines for the design of carbon-based foams decorated with carbon particles, which have morphological and textural properties that can be carefully selected for any gas-selective capture application.

La transcription des symboles et des caractères spéciaux utilisés dans la version originale de ce résumé n’a pas été possible en raison de limitations techniques. La version correcte de ce résumé peut être lue en PDF. La carbonatation minérale est une technologie qui permet de réduire les émissions de CO2 des grands émetteurs de gaz à effet de serre. Cette méthode se distingue des technologies de séquestration géologique et océanique par son efficacité et sa sécurité environnementale. Son avantage est la production de carbonates stables qui ne présentent pas de risque de relargage de CO2 dans l’atmosphère. De plus, les matières premières employées dans le procédé sont des rejets industriels non valorisés jusqu’à présent, comme les gaz des cheminés et des résidus miniers riches en silicates métalliques. Toutefois, la validation du procédé de carbonatation en phase aqueuse est encore un défi à son application à grande échelle dû à l’énergie associée au prétraitement des matières premières et à sa cinétique lente de précipitation des carbonates. Ce projet vise optimiser la précipitation des carbonates de magnésium. L’objectif est d’évaluer la cinétique de précipitation des carbonates de magnésium afin de réduire le temps de précipitation tout en gardant un bon rendement. Pour cela, une gamme de paramètres influençant la formation des carbonates a été évaluée en fonction du temps et de la température de la réaction. La vitesse d’agitation, l’utilisation de semences (cristaux de carbonate), l’emploi d’une atmosphère de CO2 et l’effet de la concentration des espèces dissoutes ont été évalués sur la précipitation des carbonates à l’aide d’une solution synthétique de MgCl2 et de NaHCO3. Ensuite, les conditions optimales ont été validées dans un procédé de carbonatation minérale. La température, suivie par la sursaturation de la solution ont été validées comme étant les paramètres les plus importants permettant d’accélérer la cinétique de précipitation. Les expériences menée

Two experimental small-scale cells have been constructed in the field to better understand passive mineral carbonation under natural atmospheric conditions in the ultramafic milling wastes of Thetford Mines (Québec, Canada). The magnesium-rich milling wastes mainly consist of poorly sorted grains and fibers of lizardite and chrysotile, with smaller amounts of antigorite, brucite and magnetite. These wastes could serve as significant and long-term CO2 sinks but the mechanisms and rates of mineral carbonation are not well understood. In this paper, the design of the experimental cells along with observations on gas composition, gas pressure, soil temperature, volumetric water content and mineral composition are presented with the objective to better understand the mineral carbonation processes under natural conditions and to propose a conceptual model for mineral carbonation at the field cell scale. Low CO2 concentrations (5–50 ppm) measured in the experimental cells and the presence of hydromagnesite suggest that natural and passive mineral carbonation is a significant process occurring in the magnesium-rich wastes (4 kg/m3/year of sequestrated CO2). In the proposed conceptual model, atmospheric CO2 (∼400 ppm) dissolves in the hygroscopic water of the piles, where weathering of magnesium silicates forms magnesium carbonates. Water saturation in the cells is relatively stable over time and varies between 0.4 and 0.65, which is higher than optimal saturation values proposed in the literature, reducing CO2 transport in the unsaturated zone. Gas-phase CO2 concentrations along with gas flow rate measurements in the cells suggest that the reaction is most active close to the surface and that diffusion of CO2 is the dominant transport mechanism in the wastes. Although the carbonation reaction is exothermic, no evidence of thermal convection has been observed in the experimental cells. This conceptual model will serve to support a reactive transport model in order to quantif

Natural weathering of ultramafic rocks in mine tailings captures atmospheric CO2 through the formation of magnesium carbonates. The Dumont Nickel Project (DNP) is of particular interest as it will generate 1.7 Gt of ultramafic residues. A field experiment has been conducted at the DNP site in order to understand the process of natural CO2 sequestration. Two experimental cells were built using waste rock and mineral processing tailings and were instrumented with gas sampling ports and probes to monitor water saturation and suction. A decrease of the interstitial gas-phase CO2 concentration in both cells, from atmospheric values (∼390 ppmv) near the surface to ∼100 ppmv near the bottom, reflects active CO2 consumption by the residues. The total carbon content of the weathered DNP mine waste ranges from 0.2 wt% to 6.5 wt% C. Hydrotalcites supergroup minerals (pyroaurite-3R, brugnatellite, pyroaurite 2-H), aragonite, nesquehonite, dypingite and hydromagnesite were absent from the unweathered residues and precipitated in the cells during passive mineral carbonation. In situ measurements using Wavelength-Scanned Cavity Ring Down Spectroscopy reveal an increase of δ13C(air) from −8‰ near the surface of the cells to ∼2‰ near the bottom that is correlated with the decrease in CO2 concentration. This trend is explained by kinetic carbon isotope fractionation during dissolution of atmospheric CO2 in interstitial water (ΔDIC-CO2 = −11.2‰). Secondary carbonates, precipitated from the interstitial water, are characterized by a moderately high δ18O and low δ13C. These isotopic compositions of the carbonates are consistent with precipitation in an evaporative environment where the kinetic carbon fractionation during atmospheric CO2 dissolution produces interstitial water depleted in 13C. Moreover, isotopic compositions of hydrotalcite supergroup minerals and other carbonate minerals are consistent with modern precipitation from the weathering of mining residue. These observations d

An effective and safe operation for sequestration of CO2 in coal seams requires a clear understanding of injection-induced coupled hydromechanical processes such as the evolution of pore pressure, permeability, and induced caprock deformation. In this study, CO2 injection into coal seams was studied using a coupled flow-deformation model with a new stress-dependent porosity and permeability model that considers CO2-induced coal softening. Based on triaxial compression tests of coal samples extracted from the site of the first series of enhanced coalbed methane field tests in China, a softening phenomenon that a substantial (one-order-of-magnitude) decrease of Young's modulus and an increase of Poisson's ratio with adsorbed CO2 content was observed. Such softening was considered in the numerical simulation through an exponential relation between elastic properties (Young's modulus and Poisson's ratio) and CO2 pressure considering that CO2 content is proportional to the CO2 pressure. The results of the numerical simulation show that the softening of the coal strongly affects the CO2 sequestration performance, first by impeding injectivity and stored volume (cumulative injection) during the first week of injection, and thereafter by softening mediated rebound in permeability that tends to increase injectivity and storage over the longer term. A sensitivity study shows that stronger CO2-induced coal softening and higher CO2 injection pressure contribute synergistically to increase a significant increase of CO2 injectivity and adsorption, but also result in larger caprock deformations and uplift. Overall, the study demonstrates the importance of considering the CO2-induced softening when analyzing the performance and environmental impact of CO2-sequestration operations in unminable coal seams. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.

Ground deformation, commonly observed in storage projects, carries useful information about processes occurring in the injection formation. The Krechba gas field at In Salah (Algeria) is one of the best-known sites for studying ground surface deformation during geological carbon storage. At this first industrial-scale on-shore CO2 demonstration project, satellite-based ground-deformation monitoring data of high quality are available and used to study the large-scale hydrological and geomechanical response of the system to injection. In this work, we carry out coupled fluid flow and geomechanical simulations to understand the uplift at three different CO2 injection wells (KB-501, KB-502, KB-503). Previous numerical studies focused on the KB-502 injection well, where a double-lobe uplift pattern has been observed in the ground-deformation data. The observed uplift patterns at KB-501 and KB-503 have single-lobe patterns, but they can also indicate a deep fracture zone mechanical response to the injection. The current study improves the previous modeling approach by introducing an injection reservoir and a fracture zone, both responding to a Mohr-Coulomb failure criterion. In addition, we model a stress-dependent permeability and bulk modulus, according to a dual continuum model. Mechanical and hydraulic properties are determined through inverse modeling by matching the simulated spatial and temporal evolution of uplift to InSAR observations as well as by matching simulated and measured pressures. The numerical simulations are in agreement with both spatial and temporal observations. The estimated values for the parameterized mechanical and hydraulic properties are in good agreement with previous numerical results. In addition, the formal joint inversion of hydrogeological and geomechanical data provides measures of the estimation uncertainty.

This paper provides an overview of the existing data and knowledge presented in recent literature about the potential leaking of CO2 from the deep subsurface storage reservoirs and the effects on groundwater quality. The objectives are to: 1) present data and discuss potential risks associated with the groundwater quality degradation due to CO2 gas and brine exposure; 2) identify the set of geochemical data required to develop models to assess and predict aquifer responses to CO2 and brine leakage; and 3) present a summary of the findings and reveal future trends in this important and expanding research area. The discussion is focused around aquifer responses to CO2 gas and brine exposure and the degree of impact; major hydrogeological and geochemical processes and site-specific properties known to control aquifer quality under CO2 exposure conditions; contributions from the deep reservoirs (plume characteristics and composition); and the possibility of establishment of a new network of reactions and processes affecting or controlling the overall mobility of major, minor, and trace elements and the fate of the elements released from sediments or transported with brine. This paper also includes a discussion on the development of conceptual and reduced order models (ROMs) to describe and predict aquifer responses and whether or not the release of metals following exposure to CO2 is harmful, which are an essential tool for CO2 sequestration related risk assessment. Future research needs in this area are also included at the end of the paper.

CO2-enhanced coalbed methane recovery, also known as CO2-ECBM, is a potential win-win approach for enhanced methane production while simultaneously sequestering injected anthropogenic CO2 to decrease CO2 emissions into the atmosphere. In this paper, CO2-ECBM is simulated using a coupled thermal–hydrological–mechanical (THM) numerical model that considers multiphase (gas and water) flow and solubility, multicomponent (CO2 and CH4) diffusion and adsorption, heat transfer and coal deformation. The coupled model is based on the TOUGH-FLAC simulator, which is applied here for the first time to model CO2-ECBM. The capacity of the simulator for modeling methane production is verified by a code-to-code comparison with the general-purpose finite-element solver COMSOL. Then, the TOUGH-FLAC simulator is applied in an isothermal simulation to study the variations in permeability evolution during a CO2-ECBM operation while considering four different stress-dependent permeability models that have been implemented into the simulator. Finally, the TOUGH-FLAC simulator is applied in non-isothermal simulations to model THM responses during a CO2-ECBM operation. The simulations show that the permeability evolution, mechanical stress, and deformation are all affected by changes in pressure, temperature and adsorption swelling, with adsorption swelling having the largest effect. The calculated stress changes do not induce any mechanical failure in the coal seam, except near the injection well in one case of a very unfavorable stress field.

Carbon capture and storage (CCS) in geological formations is considered as a promising option that could limit CO2 emissions from human activities into the atmosphere. However, there is a risk that pressure buildup inside the storage formation can induce slip along preexisting faults and create seismic event felt by the population. To prevent this to happen a geomechanical fault stability analysis should be performed, considering uncertainties of input parameters. In this paper, we investigate how the distribution of the coefficient of friction and the applied frictional law could influence the assessment of fault stability and the characteristics of potential injection-induced seismic events. Our modelling study is based on a hypothetical industrial-scale carbon sequestration project located in the Southern San Joaquin Basin in California, USA, where the stability on a major (25 km long) fault that bounds the sequestration site is assessed during 50 years of CO2 injection. We conduct nine simulations in which the distributions of the coefficients of static and dynamic friction are changed to simulate a hardening and softening phase before and during rupture. Our main findings are: (i) variations in friction along the fault have an important effect on the predicted seismic activity, with maximum magnitude ranging from 1.88 to 5.88 and number of seismic events ranging from 338 to 3272; (ii) the extreme values of the coefficient of friction (lowest and highest) present along the rupture area control how much stress is accumulated before rupture; and (iii) an argillaceous caprock can prevent the development of large magnitude seismic events but favor the occurrence of a large number of smaller events.

The rates of mineral dissolution reactions in porous media are difficult to predict, in part because of a lack of understanding of mineral reactive surface area in natural porous media. Common estimates of mineral reactive surface area used in reactive transport models for porous media are typically ad hoc and often based on average grain size, increased to account for surface roughness or decreased by several orders of magnitude to account for reduced surface reactivity of field as opposed to laboratory samples. In this study, accessible mineral surface areas are determined for a sample from the reservoir formation at the Nagaoka pilot CO2 injection site (Japan) using a multi-scale image analysis based on synchrotron X-ray microCT, SEM QEMSCAN, XRD, SANS, and FIB-SEM. This analysis not only accounts for accessibility of mineral surfaces to macro-pores, but also accessibility through connected micro-pores in smectite, the most abundant clay mineral in this sample. While the imaging analysis reveals that most of the micro- and macro-pores are well connected, some pore regions are unconnected and thus inaccessible to fluid flow and diffusion. To evaluate whether mineral accessible surface area accurately reflects reactive surface area a flow-through core experiment is performed and modeled at the continuum scale. The core experiment is performed under conditions replicating the pilot site and the evolution of effluent solutes in the aqueous phase is tracked. Various reactive surface area models are evaluated for their ability to capture the observed effluent chemistry, beginning with parameter values determined as a best fit to a disaggregated sediment experiment (Beckingham et al., 2016) described previously. Simulations that assume that all mineral surfaces are accessible (as in the disaggregated sediment experiment) over-predict the observed mineral reaction rates, suggesting that a reduction of RSA by a factor of 10–20 is required to match the core flood experimen

CO₂ sequestration is one of the critical areas of research throughout the world, as it is a major step to investigate non-fossil fuel energy sources. One of the biggest challenges in this field is designing and developing an effective methodology for modelling the CO₂ sequestration system, which depends on the proficiency of using different parameters and processes of CO₂ sequestration. The geochemical and geomechanical processes are the most significant components for establishing this system, which relies on adaptable utilising the effects of various parameters including pressure, temperature, salinity, impurities in the supercritical phase, and mechanical deformation. These parameters can considerably alter the behaviours of geochemical systems. Although the existing codes can address several challenges in the geochemical problems, these codes do not fully account for many of the above effects.Consequently, in this thesis, four integrated models (Model A, B1, B2 and C) are developed, with each model is building on the previous, for the purpose of investigating several factors previously not considered in the CO₂ sequestration geochemical model. Models A and B1 account for the explicit corrections of high pressure and salinity on the activity coefficient models and water activity; the effects of pressure and salinity on the chemical equilibrium and solubility constants; and the effect of pressure on mineral activities before and after the injection of CO₂. Model B2 also includes the effect of impurities such as sulphur dioxide (SO₂) in the supercritical phase. Model C also accounts for chemical-mechanical coupling, based on a new equation for coupling of mechanics on chemistry via the solid activity coefficient and chemical effects on the mechanics through the mineral dissolution.The proposed models are applied to analyse a limestone aquifer saturated with saline water, CO₂ sequestration in a limestone saline aquifer, CO₂/SO₂ sequestration in a limestone saline aq

Monitoring of the CO2 distribution at depth is imperative for onshore geological storage of CO2. Seismic methods are effective monitoring tools during and after the injection process, but are generally expensive and time consuming to perform. In this paper we perform a series of synthetic experiments in order to compare the seismic waveform inversion method with conventional seismic monitoring methods for time-lapse monitoring at CO2 geological storage sites. We mainly focus our study on seismic data sets with typical reflection acquisition geometries that is far offset limited. Two synthetic seismic data sets (consisting of one baseline and repeat) were generated by a third party 2D forward modeling code to compare the waveform inversion method with a conventional time-lapse procedure. The velocity models are based on a simplified structure of the Heletz site in Israel. The area into which CO2 is injected is on the order of a few hundred meters wide and a few 10 s of meters high. We compare the waveform inversion results and conventional time-lapse results to determine how sparse spatial sampling affects the results by increasing both the shot and receiver spacing. We test the waveform inversion method for a synthetic time-lapse data set with different inversion strategies. First, we invert each data set independently by using both phase and amplitude information. Then we invert them by using only phase information. We also test the influence of the starting model. Finally, we test the double difference inversion method which is equivalent to only inverting the difference between the baseline and repeat data sets. During the test a relative coarse starting model and higher starting frequency were used in order to better represent real seismic reflection data. Our results show that, under certain noise conditions, it may be possible to use a combination of sparse spatial sampling geometries and seismic waveform inversion to monitor the velocity changes caused by CO2, Följande post har en snarlik titel, men syfter möjligtvis till en annan post: http://uu.diva-portal.org/smash/record.jsf?pid=diva2:573803

The US DOE-funded National Risk Assessment Partnership (NRAP) has developed an integrated assessment model (NRAP-IAM-CS) that can be used to simulate carbon dioxide (CO2) injection, migration, and associated impacts at a geologic carbon storage site. The model, NRAP-IAM-CS, incorporates a system-modeling-based approach while taking into account the full subsurface system from the storage reservoir to groundwater aquifers and the atmosphere. The approach utilizes reduced order models (ROMs) that allow fast computations of entire system performance even for periods of hundreds to thousands of years. The ROMs are run in Monte Carlo mode allowing estimation of uncertainties of the entire system without requiring long computational times. The NRAP-IAM-CS incorporates ROMs that realistically represent several key processes and properties of storage reservoirs, wells, seals, and groundwater aquifers. Results from the NRAP-IAM-CS model are used to quantify risk profiles for selected parameter distributions of reservoir properties, seal properties, numbers of wells, well properties, thief zones, and groundwater aquifer properties. A series of examples is used to illustrate how the risk under different storage conditions evolves over time, both during injection, in the near-term post injection period, and over the long term. It is also shown how results from NRAP-IAM-CS can be used to investigate the importance of different parameters on risk of leakage and risk of groundwater contamination under different storage conditions.

Our limited understanding of mineral reactive surface area contributes to significant uncertainties in quantitative simulations of reactive chemical transport in subsurface processes. Continuum formulations for reactive transport typically use a number of different approximations for reactive surface area, including geometric, specific, and effective surface area. In this study, reactive surface area estimates are developed and evaluated for their ability to predict dissolution rates in a well-stirred flow-through reactor experiment using disaggregated samples from the Nagaoka pilot CO2 injection site (Japan). The disaggregated samples are reacted with CO2 acidified synthetic brine under conditions approximating the field conditions and the evolution of solute concentrations in the reactor effluent is tracked over time. The experiments, carried out in fluid-dominated conditions at a pH of 3.2 for 650 h, resulted in substantial dissolution of the sample and release of a disproportionately large fraction of the divalent cations. Traditional reactive surface area estimation methods, including an adjusted geometric surface area and a BET-based surface area, are compared to a newly developed image-based method. Continuum reactive transport modeling is used to determine which of the reactive surface area models provides the best match with the effluent chemistry from the well-stirred reactor. The modeling incorporates laboratory derived mineral dissolution rates reported in the literature and the initial modal mineralogy of the Nagaoka sediment was determined from scanning electron microscopy (SEM) characterization. The closest match with the observed steady-state effluent concentrations was obtained using specific surface area estimates from the image-based approach supplemented by literature-derived BET measurements. To capture the evolving effluent chemistry, particularly over the first 300 h of the experiment, it was also necessary to account for the grain size distri

Two experimental small-scale cells have been constructed in the field to better understand passive mineral carbonation under natural atmospheric conditions in the ultramafic milling wastes of Thetford Mines (Québec, Canada). The magnesium-rich milling wastes mainly consist of poorly sorted grains and fibers of lizardite and chrysotile, with smaller amounts of antigorite, brucite and magnetite. These wastes could serve as significant and long-term CO2 sinks but the mechanisms and rates of mineral carbonation are not well understood. In this paper, the design of the experimental cells along with observations on gas composition, gas pressure, soil temperature, volumetric water content and mineral composition are presented with the objective to better understand the mineral carbonation processes under natural conditions and to propose a conceptual model for mineral carbonation at the field cell scale. Low CO2 concentrations (5–50 ppm) measured in the experimental cells and the presence of hydromagnesite suggest that natural and passive mineral carbonation is a significant process occurring in the magnesium-rich wastes (4 kg/m3/year of sequestrated CO2). In the proposed conceptual model, atmospheric CO2 (∼400 ppm) dissolves in the hygroscopic water of the piles, where weathering of magnesium silicates forms magnesium carbonates. Water saturation in the cells is relatively stable over time and varies between 0.4 and 0.65, which is higher than optimal saturation values proposed in the literature, reducing CO2 transport in the unsaturated zone. Gas-phase CO2 concentrations along with gas flow rate measurements in the cells suggest that the reaction is most active close to the surface and that diffusion of CO2 is the dominant transport mechanism in the wastes. Although the carbonation reaction is exothermic, no evidence of thermal convection has been observed in the experimental cells. This conceptual model will serve to support a reactive transport model in order to quantif

Injection of CO2 at depth will cause the acidification of groundwater. As a preliminary study for the potential use of MgO as an alternative to Portland cement in injection wells, MgO carbonation has been studied by means of stirred batch experiments under subcritic (pCO(2) of 10 and 50 bar and T of 25, 70 and 90 degrees C) and supercritic (pCO(2) of 74 bar and T of 70 and 90 degrees C) CO2 conditions.; Magnesium oxide reacts with CO2-containing and Ca-rich water nearly equilibrated with respect to calcite. MgO quickly hydrates to brucite (Mg(OH)(2)) which dissolves causing the precipitation of magnesium carbonate phases. Precipitation of these secondary phases (magnesite and/or metastable phases such as nesquehonite (MgCO3 3H(2)O) or hydromagnesite (Mg-5(CO3)(4)(OH)(2) 4(H2O)) depends on pCO(2), temperature and solid/water content. In a constant solid/water ratio, the precipitation of the non-hydrated Mg carbonate is favored by increasing temperature and pCO(2).; The experimental variation of Mg and Ca concentrations and pH over time at the different temperatures and pCO(2) has been simulated using the CrunchFlow reactive transport code. Simulations reproduce the experimental evolution of the aqueous concentrations and indicate a decrease in porosity when increasing temperature and pCO(2). This decrease in porosity would be beneficial for the sealing properties of the cement. These results have been used in the simulation of an application case with a deep borehole surrounded by MgO cement at 90 degrees C., Peer Reviewed, Postprint (author's final draft)