Dissertations / Theses on the topic 'CO₂storage'
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1
Gundogan, Ozgur. "Geochemical modelling of CO₂ storage." Thesis, Heriot-Watt University, 2011. http://hdl.handle.net/10399/2505.
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The injection of CO2 into the reservoir acidifies the brine, which in turn drives mineral dissolution and precipitation processes. This thesis explores how far geochemical modelling can be applied to evaluate the CO2-brine-rock interactions during CO2 storage in North Sea saline formations. First, modelling requirements and the capabilities and limitations of the numerical codes used in this study (PHREEQC, GEM, TOUGHREACT and MoReS) were identified. Solubility of CO2 in brine by different models at conditions relevant to CO2 storage was compared. Batch modelling of three sandstone core samples from target CO2 storage formations was performed to compare the numerical codes and assess mineral trapping capacity of the formations. Finally, reactive transport modelling of Rannoch formation at reservoir scale was studied. The simulation results of GEM and MoReS were compared. It was shown that current codes can model geochemical reactions with acceptable simplifications and the choice of simulator is not critical for the model predictions. It was demonstrated how thermodynamic data and activity models can affect the modelling results. It was also found that the models are sensitive to relative mineral composition, grid discretization, permeability models, and kinetic parameters. Mineral trapping is comparable to solubility trapping in Rannoch formation.
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Lazaro, Vallejo Lorena. "Improved streamline-based simulation for CO₂ storage." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9546.
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CO2 Storage is one of the key technologies to mitigate climate change at a large scale and ensuring that the injected CO2 stays trapped underground is one of the main challenges. It is critical to develop fast and more physically accurate methods for CO2 storage simulations, otherwise computation times become prohibitive, especially when geological uncertainty is large, as in deep saline aquifers. Injection strategies and geological uncertainty have an impact on how much CO2 can be trapped as residual saturation. Fast and accurate simulators such as the one in this work are necessary to run the large number of simulations used in optimising CO2 sequestration. Our existing research streamline simulator has been extended with two improved thermodynamic models to maintain thermodynamic equilibrium along the streamlines. This minimises time-step size dependence and convergence errors. 1D simulation along the streamline was compared against analytical solution. Models were validated on 2D and 3D sections of the SPE 10th Comparative Model using water alternating gas (WAG) injection followed by chase brine. Results show that both new thermodynamic algorithms are faster (lower CPU cost) and have a faster convergence of results than the previous algorithm. Based on the validated model, we run 3D simulations for a single well strategy for the stage 2 CO2CRC Otway Project to test residual trapping. Simulation results were compared to TOUGH2 (finite-difference simulator) simulation results to study numerical dispersion, convergence of results and CPU times. Streamline simulations decreased computational time by a factor of five but results were not in agreement. Streamline simulations simulate advection processes accurately. However, there are other non-advective processes, such as diffusion, dispersion and buoyancy effects, which streamlines cannot simulate properly. This could cause the differences between streamline and TOUGH2 simulation results. Incompressibility was one of the main assumptions of the streamline-based simulator and this could pose some challenges when trying to simulate CO2 sequestration projects where injection strategy is complex. The CO2 streamline code was extended to add compressibility. Supercritical CO2 is slightly compressible so including compressibility in the streamline code is important to be able to model the physics more accurately. Streamlines can now end anywhere in the reservoir. Expansion or contraction of fluids can create source or sink cells which act as injection/production cells. Initially the pressure profile obtained numerically was compared to the analytical solution for radial single-phase flow and 1D simulations were run to study the effect of compressibility on the saturation profile. 2D simulations of a slightly compressible case on the SPE10 geological model were compared to ECLIPSE simulations, resulting in good matching. Then, the 3D Otway field case was re-simulated using the compressible code and results were compared to those obtained by TOUGH2 without obtaining a good agreement due to the complexity of the case. With most of the storage potential being in geological formations which are poorly characterised, monitoring will be a central part of any CO2 storage project. We have adapted a new approach for streamline-based history matching which exploits the analogy between the propagation of a wave front and the pressure front in the reservoir. This approach uses diffusive time-of-flight which determines the velocity at which pressure propagates as a function of static and fluid properties. This tool enables us to reconcile response data with static geological data at an earlier time, improving the management of the project. This approach has been applied to drawndown-buildup well test for a 2D synthetic case and a 3D real field case. Results for both cases were satisfactory, showing a clear improvement in the pressure matching after the 10th iteration in most cases.
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MacMinn, Christopher William. "Analytical modeling of CO₂ migration in saline aquifers for geological CO₂ storage." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45642.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 53-55).
Injection of carbon dioxide into geological formations for long-term storage is widely regarded as a promising tool for reducing global atmospheric CO₂ emissions. Given the environmental and health risks associated with leakage of CO₂ from such a storage site, it is critical to ensure that injected CO₂ remain trapped underground for the foreseeable future. Careful site selection and effective injection methods are the two primary means of addressing this concern, and an accurate understanding of the subsurface spreading and migration of the CO₂ plume during and after injection is essential for both purposes. It is well known that some CO₂ will be trapped in the pore space of the aquifer rock as the plume migrates and spreads; this phenomenon, known as capillary trapping, is an ideal mechanism for geological CO₂ storage because the trapped gas is immobile and distributed over a large area, greatly decreasing the risk of leakage and enhancing the effectiveness of slower, chemical trapping mechanisms. Here, we present an analytical model for the post-injection spreading of a plume of CO₂ in a saline aquifer, both with and without capillary trapping. We solve the governing equation both analytically and numerically, and a comparison of the results for two different initial plume shapes demonstrates the importance of accounting for the true initial plume shape when capillary-trapping effects are considered. We nd that the plume volume converges to a self-similar, power-law trend at late times for any initial shape, but that the plume volume at the onset of this late-time behavior depends strongly on the initial shape even for weakly trapping systems.
by Christopher William MacMinn.
S.M.
4
Goater, Aaron Lewis. "Multiphase flow simulation with applications for CO₂ storage." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9538.
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Geological storage of carbon dioxide (CO2) has potential to significantly reduce atmospheric emissions of greenhouse gases. However, challenges exist to the successful establishment of this process. These include estimating and understanding storage capacity as well as its economic viability. A large proportion of Europe’s potential storage capacity is to be found in large open aquifers. However, in times when the European carbon price is low, storage in depleted oil reservoirs may be required to make early commercial projects economically viable. Regulation will require that storage in these sites is well understood and it currently requires conformity of actual with modelled behaviour. In this thesis we consider two areas with direct implication for these issues. Firstly, we consider the effect of top-surface structure and heterogeneity upon the storage capacity of open aquifers. It is found that top-surface structure is more likely to decrease storage efficiency in models with low average reservoir dip and/or permeability. Heterogeneity is seen to reduce injectivity and reduce capacity in low permeability models but increase lateral spread of CO2 and storage efficiency in higher permeability cases. Both features can change storage capacity by more than a factor of two. Secondly, we undertake investigation into 1D solutions for three-phase flow problems representative of CO2 storage in depleted oil reservoirs. We begin by trying to determine rigorously the physical solution to three-phase flow problems that may have non-unique solutions using the third-order essentially non-oscillatory (ENO) numerical method. However, we demonstrate that ENO only produces first-order convergence in discontinuous solutions, which means rigorous analysis using our proposed methodology is not possible. We do, however, benchmark compositional three-phase, three-component ENO simulations against analytic solutions for the first time and demonstrate that ENO is still preferable to low-order numerical methods. Finally, we demonstrate the convergence of three-phase numerical solutions by comparing solutions with water-wet and oil-wet capillary pressure functions as the magnitude of the capillary pressure functions become small.
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Kim, Seunghee. "CO₂ geological storage: hydro-chemo-mechanically coupled phenomena and engineered injection." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/50110.
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Global energy consumption will increase in the next decades and it is expected to largely rely on fossil fuels. The use of fossil fuels is intimately related to CO₂ emissions and the potential for global warming. Geological CO₂ storage aims to mitigate the global warming problem by sequestering CO₂ underground. Coupled hydro-chemo-mechanical phenomena determine the successful operation and long term stability of CO₂ geological storage. This research explores various coupled phenomena, identifies different zones in the storage reservoir, and investigates their implications in CO₂ geological storage. Spatial patterns in mineral dissolution and precipitation are examined based on a comprehensive mass balance formulation. CO₂-dissolved fluid flow is modeled using a novel technique that couples laminar flow, advective and diffusive mass transport of species, mineral dissolution, and consequent pore changes to study the reactive fluid transport at the scale of a single rock fracture. The methodology is extended to the scale of a porous medium using pore network simulations to study both CO₂ reservoirs and caprocks. The two-phase flow problem between immiscible CO₂ and the formation fluid (water or brine) is investigated experimentally. Plug tests on shale and cement specimens are used to investigate CO₂ breakthrough pressure. Sealing strategies are explored to plug existing cracks and increase the CO₂ breakthrough pressure. Finally, CO₂-water-surfactant mixtures are evaluated to reduce the CO₂-water interfacial tension in view of enhanced sweep efficiency. Results can be used to identify optimal CO₂ injection and remediation strategies to maximize the efficiency of CO₂ injection and to attain long-term storage.
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Verdon, James P. "Microseismic monitoring and geomechanical modelling of CO₂ storage in subsurface reservoirs." Thesis, University of Bristol, 2011. http://hdl.handle.net/1983/eb611dda-5db8-4581-ae68-b422539a2b3b.
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Hesse, Marc Andre. "Mathematical modeling and multiscale simulation of CO₂ storage in saline aquifers /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Jayasekara, Manathum Nadeeshani Pushpamala. "Intelligent control of PV co-located storage for feeder capacity optimization." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/1415.
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Battery energy storage is identified as a strong enabler and a core element of the next generation grid. However, at present the widespread deployment of storage is constrained by the concerns that surround the techno-economic viability. This thesis addresses this issue through optimal integration of storage to improve the efficiency of the electricity grid. A holistic approach to optimal integration includes the development of methodologies for optimal siting, sizing and dispatch coordination of storage.
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Hänchen, Markus. "CO storage by aqueous mineral carbonation : olivine dissolution and precipitation of Mg-carbonates." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17459.
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Campbell, Brent D. "Geochemical investigation and quantification of potential CO₂ storage within the Arbuckle aquifer, Kansas." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/19086.
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Master of ScienceDepartment of Geology
Saugata Datta
With the ever-rising atmospheric concentrations of CO₂ there arises a need to either reduce emissions or develop technology to store or utilize the gas. Geologic carbon storage is a potential solution to this global problem. This work is a part of the U.S. Department of Energy small-scale pilot studies investigating different areas for carbon storage within North America, with Kansas being one of them. This project is investigating the feasibility for CO₂ storage within the hyper-saline Arbuckle aquifer in Kansas. The study incorporates the investigation of three wells that have been drilled to basement; one well used as a western calibration study (Cutter), and the other two as injection and monitoring wells (Wellington 1-28 and 1-32). Future injection will occur at the Wellington field within the Arbuckle aquifer at a depth of 4,900-5,050 ft. This current research transects the need to understand the lateral connectivity of the aquifers, with Cutter being the focus of this study. Three zones are of interest: the Mississippian pay zone, a potential baffle zone, and the Arbuckle injection zone. Cored rock analyses and analyzed formation water chemistry determined that at Wellington there exists a zone that separated the vertical hydrologic flow units within the Arbuckle. This potential low porosity baffle zone within the Arbuckle could help impede the vertical migration of the buoyant CO₂ gas after injection. Geochemical analysis from formation water within Cutter indicates no vertical separation of the hydrologic units and instead shows a well-mixed zone. The lateral distance between Cutter and Wellington is approximately 217 miles. A well-mixed zone would allow the CO₂ plume to migrate vertically and potentially into potable water sources. Formation brine from Cutter was co-injected with supercritical CO₂ into a cored rock from within the Arbuckle (7,098 ft.). Results show that the injected CO₂ preferentially preferred a flow pathway between the chert nodules and dolomite. Post reaction formation chemistry of the brine showed the greatest reactivity occurring with redox sensitive species. Reactivity of these species could indicate that they will only be reactive on the CO₂ plumes front, and show little to no reactivity within the plume.
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González, Martínez de Miguel Gerardo José. "A hydromechanically-based risk framework for CO₂ storage coupled to underground coal gasification." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2579.
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Most of the energy produced in the world comes from fossil fuels: coal, oil and gas. Amongst them, coal is the most abundant and widespread fossil fuel in the world. Underground Coal Gasi cation (UCG), an in situ method to extract the calori c value of the coal, has been known for a century but has had very limited implementation throughout the world, mainly due to the availability of cheap oil over that period. It is now gaining relevance in order to unlock vast resources of coal currently not exploitable by conventional mining. However, growing concern on increased levels of carbon dioxide concentration in the atmosphere is pointing out the necessity to reduce the use of fossil fuels. Since alternative sources of energy (e.g. nuclear and renewables) are not in a position to meet the constantly increasing demand in a short term, carbon capture and its geological sequestration (CCS) is considered the best remedial option. An environmental risk assessment framework has been developed for coupling UCG to CCS accounting for bene ts and cost from both global and local perspectives. A UCG site presents signi cant di erences from other typical CCS projected scenarios, most notably the injection of CO2 into a heavily fractured zone. A model which accounts for ow in fractures represented by dual-porosity ow (TOUGH2) is coupled to a geomechanical model (FLAC3D). The impact of this fractured zone in the CO2 injection pressure buildup and stress eld is evaluated. Furthermore the effect of stress-dependent fracture permeability is assessed with the hydro-mechanically i coupled compositional simulator GEM. Simulation results suggest that in such a scenario, CO2 injectivity and dissolution improve though con nement is compromised and commercial injection rates seem unattainable. The e ects of miscibility and relative permeability on pressure buildup implemented in semianalytical solutions are also evaluated. Albeit further research is required, a UCG operation may, therefore, not be able to accommodate the produced CO2 in the gasi ed cavity and its surroundings in a safe and economical fashion. Rigorous studies and management practices are needed to establish the requirements for secure long-term con nement of the carbon dioxide in such scenario.
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Langenfeld, Julie K. "Geospatial and Economic Viability of CO2 Storage in Fractured Shale." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1470171664.
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Bhaduri, Gaurav Ashok. "Catalytic enhancement of hydration of CO₂ using nickel nanoparticles for carbon capture and storage." Thesis, University of Newcastle upon Tyne, 2018. http://hdl.handle.net/10443/4135.
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The capture and storage of atmospheric CO2 as mineral carbonates, is one of the safest ways to combat global warming. The slow CO2 hydration rate is one limitation of the mineralization process. The current study presents the discovery of nickel nanoparticles (NiNPs) as a catalyst for enhancing the rate of CO2 hydration for mineralization carbon capture and storage. The NiNPs at an optimum concentration of 30 ppm, increased the saturation concentration by three folds as compared with deionized water alone. The mechanism of the reaction on NiNPs surface is also proposed. The kinetics of catalysis of CO2 hydration was additionally studied using stopped flow spectrophotometery and pH changes in buffer solution upon addition of saturated CO2 solution. To distinguish between physical gas-liquid transfer and catalysis, other inorganic nanoparticles (NiO and Fe2O3) have been studied. The effect of CO2 partial pressure on NiNPs catalysis was studied. Nickel nanowires (NiNWs) were synthesised and tested for catalysis of CO2 hydration. The photocatalytic activity of NiNPs was evaluated under artificial solar irradiation compared with that in the dark. The results suggest that the surface plasmonic resonance (SPR) of NiNPs enhances the rate of water dissociation on the NiNPs surface leading to higher rate of CO2 hydration under solar irradiation. The effect of temperature on the catalytic activity of NiNPs is evaluated. Optimum activity was observed at room temperature (20-30 °C). Application of NiNPs catalysis was investigated for CaCO3 precipitation and the rate of CO2 absorption in 50 wt% carbonate solutions. Vapour-liquid equilibrium studies of CO2-H2O in presence of nanoparticles (Ni, Fe2O3 and NiO) found that ii the presence of nanoparticles decreases the surface tension of DI water, responsible for the increase in CO2 saturation concentration. Additionally a novel method for mineralization of CO2 using gypsum and sodium chloride was developed including design of a customized reactor.
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Wu, Xiaoyu Ph D. Massachusetts Institute of Technology. "Membrane-supported hydrogen/syngas production using reactive H₂O/CO₂ splitting for energy storage." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111696.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 231-242).
Energy storage technologies are crucial for supporting the fast expansion of intermittent renewable energy at the grid scale. One such technology is the efficient and economic conversion of H₂O and CO₂ into fuels utilizing excess thermal energy at intermediate temperatures. This thesis explores fuel production using oxygen permeable membranes. La₀.₉Ca₀.₁FeO₃-[subscript [delta]] (LCF-91) perovskite is used to develop a framework for reactor design based on a careful assessment of fuel production rates on the membrane design and operating conditions. This material exhibits strong chemical stability but relatively low permeability. Hydrogen production from water splitting is investigated using CH4 to increase the chemical potential gradient across the membrane. Analysis shows that oxygen consumption on the sweep-side is the rate limiting step, and the addition of a nickel catalyst on a porous LCF-91 layer on that side raises the hydrogen production rate from water splitting by two orders of magnitude, reaching 0.37 [mu]mol/cm²"s. Raising the oxygen flux suppresses carbon deposition and achieves optimum syngas composition for gas-to-liquid. CO₂ splitting was also demonstrated on the same membrane material, with similar enhancement as fuel is introduced and porous layers are added on both sides, but at measurably lower rates than water splitting. Based on the experimental data, an oxygen flux model incorporating the surface kinetics and ion transport is developed, in which the oxygen direct-incorporation kinetics are used on the feed-side, and the Mars-van Krevelen (MvK) mechanism for fuel (H₂, CO or CH₄) oxidation reactions are applied on the sweep-side. The data show that H₂ has the lowest activation energy for oxidation among the three fuels, and hence, leads to the highest oxygen flux for H₂O/CO₂ splitting. Moreover, while the limiting step is always the fuel oxidation in water splitting, it changes from CO formation reactions on the feed-side to fuel oxidation reactions on the sweep-side as the temperature is raised in CO₂ A monolith membrane reactor model based on the reaction kinetics is developed for hydrogen and syngas production from water splitting and partial oxidation of methane, respectively. Results show that the efficiency is ~2% points higher than the conventional steam-methane reforming, when high-purity hydrogen (>99%) is produced. Sensitivity analysis shows that, for the best performance, it is critical to maintain high operating temperatures and high catalytic reactivity for methane oxidation.
by Xiaoyu Wu.
Ph. D.
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Kane, David. "CO₂ savings from micro-CHP : influence of operating regimes, demand variations and energy storage." Thesis, Heriot-Watt University, 2012. http://hdl.handle.net/10399/2607.
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A high temporal precision model was developed to assess the performance of thermal load following micro-CHP system design variants in detail for a number of design days. Carbon savings (relative to a base-case energy system) and prime mover lifetime drivers (thermal cycling and operating duration) were quantified. Novel performance metrics were defined, including Potential Thermal Supply Demand Ratio, and Effective Carbon Intensity of μCHP-Generated Electricity. Significant relative carbon savings were found for design variants with a PTSDR between 0.1-1.5, suggesting that it is a design selection parameter for thermal supply/demand matching. Alternative μCHP operating regimes, restricted seasonal operation, changing thermal demand, fuel and electricity grid carbon intensities, and energy storage (using batteries and hydrogen) were studied. It was found that annual relative carbon savings in excess of 23% were achievable for appropriately-sized design variants, with relatively high electrical efficiency, once a complex control strategy is applied. The control strategy also reduces thermal cycling for the μCHP design variant (versus the Thermal Load Following operating regime), hence increasing prime mover lifetime.
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Jablonski, Leanne M. "Reproductive response to elevated CO¦2, the roles of vegetative carbon storage, nitrogen and seed traits." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0008/NQ36986.pdf.
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Toukan, Ibrahim (Ibrahim Khaled). "Exploring the value proposition of integrating back-up saline storage into anthropogenic CO₂ supplied EOR operations." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78540.
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Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 83-85).
Enhanced oil recovery (EOR) through carbon dioxide (CO₂) sequestration from anthropogenic sources has been gaining attention in policy circles. In particular, it is viewed as a potential way to help accelerate the deployment of carbon capture and sequestration (CCS) technologies. The interest in the EOR-CCS model stems from the economic, geologic and regulatory benefits this model offers when compared to the waste-driven CCS model that utilizes saline aquifers for CO₂ storage. However, there are still some major challenges impeding the deployment of the EOR-CCS model; chief among these challenges is the mismatch between CO₂ supplies from anthropogenic sources and CO₂ demand from EOR operations. One potential way to address this challenge is through a CO₂ stacked storage system. A CO₂ stacked storage system utilizes brine formations adjacent to EOR oilfields for the purpose of storing any additional quantities of CO₂ the EOR operation cannot handle. The concept of a stacked storage system with focus on CO₂ supplies from coal-fired power plants was analyzed using a case study. A U.S. coal-fired power plant and a U.S. EOR oilfield were used to model a stacked storage system in order to determine the economic and technical viability of such a model. More specifically, this thesis has three main objectives. The first is to determine the overall cost of implementing the stacked storage system. The overall cost of the system came to approximately $90 per ton of CO₂ avoided.
by Ibrahim Toukan.
S.M.
18
Bacci, Giacomo. "An experimental and numerical investigation into permeability and injectivity changes during CO₂ storage in saline aquifers." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/7082.
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CO2 storage appears as one of the best solutions to effectively decrease carbon emissions into the atmosphere in the short to medium term. CO2 can be stored in different types of geological formations. Among the various storing options, deep saline aquifers have the greatest capacity. As supercritical CO2 is injected in the aquifers, a number of strongly coupled chemical and physical processes occur. Among these various mechanisms, dissolution and precipitation of minerals, in particular carbonates, and halite deposition due to vapourisation of water require particular attention as they can lead to significant reduction in injectivity. This research investigated the mechanisms involved in injectivity losses through experimental and theoretical methods. The impact on injectivity of permeability changes occurring at various distances from the wellbore was studied using an idealised 1-D CO2 injection well flow model. A new experimental set-up was used to investigate the effect on dissolution/precipitation mechanisms of the pressure and temperature changes that the fluid is subjected to as it advances from the wellbore. Additional CO2 core flooding experiments were conducted on limestone and sandstone cores saturated with saline water in order to study the effects of water vapourisation. These vapourisation experiments aimed to provide a relationship between porosity changes and resulting permeability variations representing the effect of salt precipitation due to vapourisation. Such relationship was used to obtain more accurate results from a 2-D radial CO2 injection well flow model studying the effect of salt precipitation on the field. Numerical modelling of the injection wellbore have shown that changes in the petrophysical properties of the reservoir several metres away from the wellbore can still have a significant impact on injectivity. As indicated by the experimental research carried out, pressure and temperature gradients that exist inside the reservoirs may lead to re-precipitation in the far field, however no significant permeability and porosity changes were detected to suggest major losses of injectivity due to these effects. The results of vapourisation experiments have shown that small reduction in porosity can induce significant impairments in permeability. Results of the 2-D model showed that without appropriate injection strategies the technical and economical feasibility of CO2 storage projects can be compromised due to this effect. The numerical study also highlighted the possibility of the progressive formation of a layer of halite scaling in the interface between host-rock and cap-rock which would work as an extra sealing protection in the near wellbore area.
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Szulczewski, Michael Lawrence. "Storage capacity and injection rate estimates for CO₂ sequestration in deep saline aquifers in the conterminous United States." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53087.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2009.Includes bibliographical references (p. 141-148).
A promising method to mitigate global warming is injecting CO₂ into deep saline aquifers. In order to ensure the safety of this method, it is necessary to understand how much CO₂ can be injected into an aquifer and at what rate. Since offsetting nationwide emissions requires storing very large quantities of CO₂, these properties must be understood at the large scale of geologic basins. In this work, we develop simple models of storage capacity and injection rate at the basin scale. We develop a storage capacity model that calculates how much CO₂ an aquifer can store based on how the plume of injected CO₂ migrates. We also develop an injection rate model that calculates the maximum rate at which CO₂ can be injected into an aquifer based on the pressure rise in the aquifer. We use these models to estimate storage capacities and maximum injection rates for a variety of reservoirs throughout the United States, and compare the results to predicted emissions from coal-burning power plants over the next twenty-five years and fifty years. Our results suggest that the United States has enough storage capacity to sequester all of the CO₂ emitted from coal-burning plants over the next 25 years. Furthermore, our results indicate that CO₂ can be sequestered at the same rate it is emitted for this time period without fracturing the aquifers. For emissions over the next 50 years, however, the results are less clear: while the United States will likely have enough capacity, maintaining sufficiently high injection rates could be problematic.
by Michael Lawrence Szulczewski.
S.M.
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Trittin, Tom [Verfasser]. ""NO SMOKING": CO 2-arme Stromerzeugung in einem nachhaltigen deutschen Energiesystem : ein Vergleich der CO 2-Vermeidungskosten von erneuerbaren Energiequellen und Carbon Capture and Storage / Tom Trittin." Flensburg : Zentrale Hochschulbibliothek Flensburg, 2012. http://d-nb.info/1037171071/34.
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Borén, Eleonora. "Off-gassing from thermally treated lignocellulosic biomass." Doctoral thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-141921.
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Off-gassing of hazardous compounds is, together with self-heating and dust explosions, the main safety hazards within large-scale biomass storage and handling. Formation of CO, CO2, and VOCs with concurrent O2 depletion can occur to hazardous levels in enclosed stored forest products. Several incidents of CO poisoning and suffocation of oxygen depletion have resulted in fatalities and injuries during cargo vessel discharge of forest products and in conjunction with wood pellet storage rooms and silos. Technologies for torrefaction and steam explosion for thermal treatment of biomass are under development and approaching commercialization, but their off-gassing behavior is essentially unknown. The overall objective of this thesis was to provide answers to one main question: “What is the off-gassing behaviour of thermally treated lignocellulosic biomass during storage?”. This was achieved by experimental studies and detailed analysis of off-gassing compounds sampled under realistic conditions, with special emphasis on the VOCs. Presented results show that off-gassing behavior is influenced by numerous factors, in the following ways. CO, CO2 and CH4 off-gassing levels from torrefied and stream-exploded biomass and pellets, and accompanying O2 depletion, are comparable to or lower than corresponding from untreated biomass. The treatments also cause major compositional shifts in VOCs; emissions of terpenes and native aldehydes decline, but levels of volatile cell wall degradation products (notably furans and aromatics) increase. The severity of the thermal treatment is also important; increases in torrefaction severity increase CO off-gassing from torrefied pine to levels comparable to emissions from conventional pellets, and increase O2 depletion for both torrefied chips and pellets. Both treatment temperature and duration also influence degradation rates and VOC composition. The product cooling technique is influential too; water spraying in addition to heat exchange increased CO2 and VOCs off-gassing from torrefied pine chips, as well as O2 depletion. Moreover, the composition of emitted gases co-varied with pellets’ moisture content; pellets of more severely treated material retained less moisture, regardless of their pre-conditioning moisture content. However, no co-variance was found between off-gassing and pelletization settings, the resulting pellet quality, or storage time of torrefied chips before pelletization. Pelletization of steam-exploded bark increased subsequent VOC off-gassing, and induced compositional shifts relative to emissions from unpelletized steam-exploded material. In addition, CO, CO2 and CH4 off-gassing, and O2 depletion, were positively correlated with the storage temperature of torrefied softwood. Similarly, CO and CH4 emissions from steam-exploded softwood increased with increases in storage temperature, and VOC off-gassing from both torrefied and steam-exploded softwood was more affected by storage temperature than by treatment severity. Levels of CO, CO2 and CH4 increased, while levels of O2 and most VOCs decreased, during storage of both torrefied and steam-exploded softwood.CO, CO2 and O2 levels were more affected by storage time than by treatment severity. Levels of VOCs were not significantly decreased or altered by nitrogen purging of storage spaces of steam-exploded or torrefied softwood, or controlled headspace gas exchange (intermittent ventilation) during storage of steam-exploded bark. In conclusion, rates of off-gassing of CO and CO2 from thermally treated biomass, and associated O2 depletion, are comparable to or lower than corresponding rates for untreated biomass. Thermal treatment induces shifts in both concentrations and profiles of VOCs. It is believed that the knowledge and insights gained provide refined foundations for future research and safe implementation of thermally treated fuels as energy carriers in renewable energy process chains.
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Kippie, Mu'azzam. "Improvements to a key contributor of frequency control : the co-ordination of guide vane operation in a pumped storage plant." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/13124.
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Includes bibliographical references.The South African grid has been experiencing small reserve margins from 2008 and this will continue until the new power stations are integrated onto the grid. This is a time where the frequency control performance has become an important indicator to see how the power plants are able to deal with the restoration of frequency specifically during peak times. A study was done to identify the systems/aspects which at the time contribute a considerable amount to frequency control or could affect frequency in the medium to long term. From this, the co-ordination of the guide vanes at pumped storage plants was selected. Pumped storage units exhibit a non-minimum phase characteristic which can negatively affect the frequency response on the grid. Attempts were made to improve this system’s contribution to frequency control. To achieve this, the main waterway, including surge tank and guide vanes of a pumped storage station were modelled in a thermal-hydraulic simulation environment. With the model it was possible to realise the reverse power phenomenon inherent in pumped storage plants. The model was validated with similar studies in the literature and pumped storage plant data. A selection of scenarios with various guide vane operation techniques were proposed to improve the performance of two connected units during load changes. Some of the techniques produced improvement in the reverse power characteristic while others produced deterioration in the performance due to coupling of the unit using a common penstock but enjoyed an improvement in the plant net output. The study showed that it is possible to reproduce the non-minimum phase characteristic of a pumped storage plant using thermal-hydraulic models, and that various control schemes can be tested using the model. This paves the way for more elaborate control scheme evaluations, including those that look at coordination of all the pumped storage plants on a network.
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Griffith, Craig Alexander. "Physical Characteristics of Caprock Formations used for Geological Storage of CO2 and the Impact of Uncertainty in Fracture Properties in CO2 Transport through Fractured Caprocks." Research Showcase @ CMU, 2012. http://repository.cmu.edu/dissertations/122.
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Capture and geological sequestration of CO2 from energy production is proposed to help mitigate climate change caused by anthropogenic emissions of CO2 and other greenhouse gases. Performance goals set by the US Department of Energy for CO2 storage permanence include retention of at least 99% of injected CO2 mass. Part of meeting these goals will be detailed assessments of each potential storage site’s geologic environment, especially properties of the storage reservoir(s) and caprock(s) that may affect permanence of CO2 storage.
The overall goals of this research were to examine the physical and lithologic characteristics of caprock formations considered for saline CO2 sequestration, and to investigate the impact of uncertainty in hydraulic properties of a fractured caprock on the ability to meet long-term CO2 storage goals. To accomplish these goals three specific objectives were pursued: 1) Review the current state of knowledge on the physical and lithologic characteristics of caprocks in areas considered for CO2 sequestration, and identify common features that may impact long-term CO2 storage. 2) Develop an integrated analytical model to investigate the influence of fracture hydraulic properties on the transport of CO2 through caprocks. 3) Investigate the impact of uncertainty in fracture aperture and density on predicting CO2 loss and caprock hydraulic fracture properties associated with meeting long-term storage goals.
Review of the caprock properties revealed that they were generally thick and exhibited low permeability. However, they were not continuous or uniform in lithology throughout the regions examined. Caprocks exhibited lateral facies changes, fractures, and spatial variability in thickness, permeability, porosity, and other physical properties that could affect CO2 storage. Fractures reported in caprock formations were not fully characterized and had unknown regional extent and interconnectivity.
An integrated analytical model was developed to estimate the limits of hydraulic fracture properties within a caprock that are consistent with storage performance criteria, and with observed ranges for aperture size and density within field studies on fracture networks. Results showed hydraulic fracture properties, consistent with performance objectives, to be low in comparison to reported measurements. In particular, 1) microfractures (e.g. 10-7 to 10-6 m range) yielded CO2 loss rates of concern given certain conditions. (2) Fracture permeability was in the nano- to micro-Darcy (μD) range (i.e. 10-21 – 10-18 m2), and 3) Fracture porosities were below 0.02 %.
For the third objective, a stochastic framework was applied to the integrated analytical model to examine the impact of uncertainty in caprock fracture aperture and density on predicting CO2 loss and hydraulic fracture properties meeting CO2 storage criteria. Major findings include: 1) combinations of parameters meeting the CO2 loss criteria were rare events and more data would be needed to characterize caprock fractures. 2) Fracture porosity was identified as a good diagnostic parameter for caprock screening. (3) Fracture permeability had the strongest association with CO2 loss, with a high probability (>90%) that caprocks which met performance goals had values < 10-17 m2. (4) Correlations between reservoir parameters and caprock fracture properties became stronger as the CO2 loss from the system became more constrained.
Overall, the results of this study showed that selected caprocks in the U.S, currently investigated for CO2 storage, exhibit significant variability in their structural, lithologic, and fluid transport characteristics. Pre-existing fractures can occur in caprocks, which is of interest for impact on long-term CO2 storage. Modeling results suggest a low tolerance for microfractures in overlying caprocks, where acceptable hydraulic fracture properties were low in comparison to reported measurements. In addition, the interdependence of the transport parameters showed that the storage reservoir and caprock fracture properties needed to be modeled together in order to assess the potential to meet CO2 storage criteria.
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Nooner, Scott L. "Gravity changes associated with underground injections of CO₂ at the Sleipner storage reservoir in the North Sea, and other marine geodetic studies /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2005. http://wwwlib.umi.com/cr/ucsd/fullcit?p3171110.
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Akyildiz, Hasan. "Hydrogen Storage In Magnesium Based Thin Film." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612652/index.pdf.
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ABSTRACT
HYDROGEN STORAGE IN MAGNESIUM BASED
THIN FILMS
Akyildiz, Hasan
Ph.D., Department of Metallurgical and Materials Engineering
Supervisor : Prof. Dr. Tayfur Öztü
rk Co-Supervisor : Prof. Dr. Macit Ö
zenbas October 2010, 146 pages A study was carried out for the production of Mg-based thin films which can absorb and desorb hydrogen near ambient conditions, with fast kinetics. For this purpose, two deposition units were constructed
one high vacuum (HV) and the other ultra high vacuum (UHV) deposition system. The HV system was based on a pyrex bell jar and had two independent evaporation sources. The unit was used to deposit films of Mg, Mg capped with Pd and Au-Pd as well as Mg-Cu both in co-deposited and multilayered form within a thickness range of 0.4 to 1.5 &mu
m. The films were crystalline with columnar grains having some degree of preferred orientation. In terms of hydrogen storage properties, Mg/Pd system yielded the most favorable results. These films could desorb hydrogen at temperatures not greater than 473 K. The study on crystalline thin films has further shown that there is a narrow temperature window for useful hydrogenation of thin films, the upper limit of which is determined by the intermetallic formation. The UHV deposition system had four independent evaporation sources and incorporated substrate cooling by circulating cooled nitrogen gas through the substrate holder. Thin films of Mg-Cu were produced in this unit via co-evaporation technique to provide concentrations of 5, 10 and 15 at. % Cu. The films were 250-300 nm thick, capped with a thin layer of Pd, i.e. 5-25 nm. The deposition was yielded nanocrystalline or amorphous Mg-Cu thin films depending on the substrate temperature. At 298 K, the films were crystalline, the structure being refined with the increase in Cu content. At 223 K, the films were amorphous, except for Mg:Cu=95:5. The hydrogen sorption of the films was followed by resistance measurements, with the samples heated isochronally, initially under hydrogen and then under vacuum. The resistance data have shown that hydrogen sorption behaviour of thin films was improved by size refinement, and further by amorphization. Among the films deposited, amorphous Mg:Cu=85:15 alloy could absorb hydrogen at room temperature and could desorb it at 223 K (50 º
C), with fast kinetics.
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Lee, Changhoon Ph D. Massachusetts Institute of Technology. "The chemistry of transition metal complexes related to solar energy storage : H₂ production and small molecule (CO₂ and HX; X = Cl, Br) chemistry." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68545.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references.
The studies in this thesis have focused on the chemistry of transition metal complexes related to solar energy storage: electrochemical H₂ production, HX splitting and CO₂ activation mediated by transition metal complexes. Transition metal complexes, for example with macrocyclic ligands, can catalyze electrochemical proton reduction, a half reaction of water splitting to H₂/O₂ by electricity generated by sunlight. The strategy for designing efficient molecular catalysts were explored by introducing a Hangman scaffold into metallomacrocyles. The study exhibits synthesis and electrochemistry of metallomacrocyles, and an example of Hangman effect for electrochemical H2 production. Thermodynamically demanding HX splitting to H₂/X₂ by sunlight can be a promising method for solar energy storage. To date, most HX splitting chemistry was studied with metal complexes based on 2"d or 3 rd row transition metals. Hence, the usage of cheaper first row metals is an imperative to discover economically viable catalytic systems. HX chemistry of Ni complexes and photoelimination of H₂ from Ni hydride complexes, and photoactivation of Ni-Cl bonds were studied. CO₂ can be utilized as a carrier of H₂ by the syntheses of liquid fuels from CO₂ and H₂. The challenge of using CO₂ as a precursor for organic molecules is the activation of strong O=CO bonds. The reaction with metal complexes is one of the methods to break or weaken the bonds. The CO₂ chemistry of Ni complexes was explored, and generation of a new binding mode of CO₂ and activation of CO₂ to CO were studied.
by Changhoon Lee.
Ph.D.
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Auffray, Baptiste. "Impact du stockage de CO₂ dans les systèmes réservoirs carbonatés : interactions et transport d'éléments traces, effets sur les propriétés réservoirs." Thesis, Bordeaux 3, 2014. http://www.theses.fr/2014BOR30034.
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Depuis une dizaine d'années, une volonté internationale de réduction des émissions de gaz à effet de serre s'est développée, afin de limiter leur concentration dans l'atmosphère. Ainsi, il est envisagé de récupérer le CO₂ issu d'activités humaines fortement émettrices afin de le réinjecter dans le sous-sol à l'état supercritique. Hors du panache de CO₂ supercritique, ce gaz se dissout dans la saumure et l'acidifie. Deux phénomènes ont alors lieu. Ils constituent la base des études menées au cours de cette thèse : (i) le devenir des espèces chimiques mobilisées par la dissolution des minéraux, et (ii) les variations des propriétés d'écoulements induites par la réactivité de la roche encaissante. Pour étudier ces phénomènes, des expériences ont été menées sur les carbonates de Lavoux et de St-Emilion. Ces deux échantillons naturels ont été sélectionnés pour leur composition minérale modèle qui assure une forte réactivité dans le contexte de l'étude, et l'absence d'argile et de matière organique qui limite la complexité du système géochimique. Les expériences menées sont de deux types. En autoclave, la compétition entre dissolution et sorption des éléments traces est mise en avant et permet d'investiguer des conditions variant de celles de la surface (20°C – 1 atm) à celles d'un site de stockage (40°C – 90 bar de CO₂) en passant par des intermédiaires de pression (30 et 60 bar). Les effets de la salinité de la saumure, de la concentration initiale en cations divalents ainsi que de l'état de l'échantillon solide (poudre, plug) sont étudiés. D'autre part, un dispositif expérimental a été développé au cours de cette thèse. Il permet d'étudier les propriétés de diffusion d'éléments traces à travers une carotte dans des conditions représentatives de celles d'un réservoir de stockage de CO₂. Les résultats expérimentaux obtenus mettent en évidence à la fois l'impact de la dissolution sur la mobilisation des espèces chimiques, la compétition entre différents cations pour la sorption et les conséquences de cette sélectivité sur le transport et la disponibilité des espèces chimiques. L'étude pétrophysique des échantillons réagis met en évidence une augmentation de la porosité, et une tendance à l'uniformisation du réseau de pore. Les données obtenues dans les expériences en batch permettent d'obtenir par simulation les paramètres de sorption du système pour les différents éléments traces, en fonction des conditions de pression. Grâce à ces différents résultats, la surveillance de sites de stockage géologique de CO₂ est possible dans différentes formations, et permet un suivi à la fois des flux des espèces chimiques et des propriétés d'écoulementOver the last decade, an international will to reduce the emissions of greenhouse gases in the atmosphere developed, in order to limit their atmospheric concentration. Thus, to deal with the large amounts of CO₂ produced by human activities, this gas is to be injected under supercritical state in the underground. Outside the CO₂ plume, this gas dissolves within brine and acidifies it. Two phenomena occurs then. They are the main subject of this work: (i) the fate of chemical species mobilized by mineral dissolution, and (ii) the evolution of flooding properties induced by mineral reactivity. To study those phenomena, experiments were carried out on the Lavoux and the Saint-Emilion carbonates. Those two natural samples were selected because their mineralogical composition ensures a high reactivity and limits the complexity of the geochemical system, as they contain neither clays nor organic matter. Two types of experiments were carried out. Competition between dissolution and sorption was studied in batch reactors, from conditions similar to those of the surface (20°C – 1 atm) to those of a storage site (40°C – 90 bar of CO₂), passing by intermediate pressures (30 and 60 bar). The parameters investigated are salinity, initial concentration of divalent cations, and the state of solid samples (powder, core). On the other hand, an experimental setting was developed during the thesis project. It allows the study of trace elements diffusion through a core in CO₂ geological storage conditions. The experimental results evidence the impact of dissolution on chemical species mobilization, competition between those species regarding sorption and consequences of this selectivity on transport and availability of those chemical species. The petrophysical study of reacted samples evidence a porosity increase and the homogenization of the porous network. The data resulting from the batch experiments are used as input data for simulations, in order to estimate sorption parameters of trace elements in the systems investigated. Thanks to those results, the monitoring of CO₂ geological storage sites is possible within several different geological formations, and allows to track both flux of chemical species and flooding properties evolution
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Ren, Yu. "Applications of ordered mesoporous metal oxides : energy storage, adsorption, and catalysis." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/1705.
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The experimental data and results demonstrated here illustrate the preparation and application of mesoporous metal oxides in energy storage, adsorption, and catalysis. First, a new method of controlling the pore size and wall thickness of mesoporous silica was developed by controlling the calcination temperature. A series of such silica were used as hard templates to prepare the mesoporous metal oxide Co₃O₄. Using other methods, such as varying the silica template hydrothermal treatment temperature, using colloid silica, varying the materials ratio etc., a series of mesoporous β-MnO₂ with different pore size and wall thickness were prepared. By using these materials it has been possible to explore the influence of pore size and wall thickness on the rate of lithium intercalation into mesoporous electrode. There is intense interest in lithium intercalation into titanates due to their potential advantages (safety, rate) replacing graphite for new generation Li-ion battery. After the preparation of an ordered 3D mesoporous anatase the lithium intercalation as anode material has been investigated. To the best of our knowledge, there are no reports of ordered crystalline mesoporous metal oxides with microporous walls. Here, for the first time, the preparation and characterization of three dimensional ordered crystalline mesoporous α-MnO₂ with microporous wall was described, in which K+ and KIT-6 mesoporous silica act to template the micropores and mesopores, respectively. It was used as a cathode material for Li-ion battery. Its adsorption behavior and magnetic property was also surveyed. Following this we described the preparation and characterization of mesoporous CuO and reduced Cu[subscript(x)]O, and demonstrated their application in NO adsorption and delivery. Finally a series of crystalline mesoporous metal oxides were prepared and evaluated as catalysts for the CO oxidation.
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Nuutinen, Antti, and Giovanni Graziano. "Towards Flexible Cogeneration: Techno-economic Optimization of Advanced Combined Cycle Combined Heat and Power Plants integrated with Heat Pumps and Thermal Energy Storage." Thesis, KTH, Energiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-235820.
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The liberalization of electricity markets and a growing penetration of renewables is changing operation of electrical grids. The boundary conditions for the operation of conventional power plants are changing and, as such, an improved understanding of the varying loads and prices on the electricity grid is required to assess the performance of emerging combined cycle gas turbine (CCGT) concepts and to further optimize their design for these new markets in the pursuit of increasing their profitability, especially when considering combined heat and power (CHP). To increase the flexibility of CCGT-CHP plants, three new plant layouts have been investigated by integrating different storage concepts and heat pumps in key sections of the traditional plant layout. The present study analyses the influence that market has on determining the optimum CCGT-CHP plant layout that maximizes profits (in terms of plant configuration, sizing and operation strategies) for a given location nearby Turin, Italy, for which hourly electricity and heat prices, as well as meteorological data, have been gathered. A multi-parameter approach for design and operation was followed using KTH’s and EPS’ techno-economic modeling tool DYESOPT. Results are shown by means of a comparative analysis between optimal plants found for each layout and the state-of-the art CCGT-CHP. It is shown that a plant configuration in which a cold storage unit is integrated together with a heat pump at the inlet of the gas turbine unit increases the net present value of the plant by approximately 0.3% when compared against conventional plant layouts. Using the same concept with a heat pump alone can improve lifetime profitability by 1.6%. A layout where district heating supply water is preheated with a combination of a heat pump with hot thermal tank increases plant profitability by up to 0.5%. This work has been performed as part of the PUMP-HEAT project, an EU Horizon 2020 research project in which KTH collaborates with other 13 stakeholders including industry and research institutions. The results will directly influence future work of the project.
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Rauchfuß, Hardy. "Untersuchung von Konzepten zur CO2-Abtrennung in Kombikraftwerken mit integrierter Wirbelschichtvergasung." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2013. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-114409.
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Im Rahmen dieser Arbeit werden Konzepte für Gasaufbereitung in Kombikraftwerken mit integrierter Wirbelschichtvergasung und CO2-Abtrennung untersucht (IGCC-CCS). Dabei stehen die Konvertierung von Kohlenmonoxid (CO-Shift) und die Einbindung dieses Prozeß-schrittes in ein IGCC-CCS-Kraftwerk im Mittelpunkt. Ziel der Arbeit ist die energetische und wirtschaftliche Bewertung von Konzepten zur CO2-Abtrennung für ein ab 2015 baubares, grundlastfähiges IGCC-CCS-Kraftwerk der 800-MW-Klasse. Dazu werden neben den bekannten konventionellen, mehrstufigen Konzepten der Rohgas- und Reingas-Shift weitere alternative Ansätze zur Steigerung des Anlagenwirkungsgrades sowie zur Senkung der spezifischen CO2-Emission verfolgt. Die Ergebnisse der mit Hilfe von ASPEN Plus und EBSILON Professional durchgeführten Prozesssimulationen werden im Vergleich zu Dampfkraftwerken neuester Bauart wirtschaftlich bewertet.
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Rhino, Kévins. "Caractérisation, quantification et modélisation des processus de transfert et des interactions CO₂-eau-roche en milieu poreux non saturé en contexte de forage lors d'un stockage géologique." Thesis, Bordeaux 3, 2017. http://www.theses.fr/2017BOR30040/document.
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Le stockage géologique du carbone est l’une des techniques les plus prometteuses pour réduire le taux de CO₂ dans l’atmosphère. La séquestration géologique possède la capacité et la longévité potentielles pour diminuer les émissions de CO₂ vers l’atmosphère. Dans le cadre d’injections à l’échelle industrielle, les réservoirs carbonatés peuvent faire partie des sites aptes à stocker du CO₂. Toutefois, ces injections à grandes profondeurs sont sujettes à des risques de fuites du piège géologique lui-même ou des infrastructures liés à l’exploitation du site de stockage. Ainsi, il existe principalement deux types de fuite : brutale et diffuse. Dans les deux cas, elles sont susceptibles d’entrainer des risques pour l’environnement et de mettre en danger les populations. Il est ainsi nécessaire de développer des outils capables de prévenir une fuite de CO₂ quel que soit son type. Par ailleurs, il est particulièrement indispensable de comprendre les mécanismes de transport réactif qui rentrent en jeu lors de l’arrivée de cette fuite en contexte de proche surface (zone vadose) et ainsi d’essayer d’étudier comment cette fuite peut s’amortir. Ces travaux de thèse traitent donc de la caractérisation, de la quantification et de la modélisation des processus de transferts et des interactions CO₂-H₂O-CaCO₃ dans la zone vadose en contexte de fuite à partir d’un puits de forage. Cette problématique a été d’abord abordée par une approche expérimentale sur un site pilote à Saint-Emilion. Puis, les interactions CO₂-H₂O-CaCO₃ ont été étudiées au travers d’une approche expérimentale à l’échelle de la carotte en laboratoire. L’approche expérimentale a conduit à la réalisation de deux fuites dans la zone vadose du site pilote : une fuite diffuse et une fuite ultra diffuse. Elles furent réalisées dans la continuité des expériences qui avaient déjà eu lieu auparavant. Une comparaison de l’ensemble des fuites a montré la nécessité d’utiliser des gaz nobles comme précurseurs de l’arrivée en surface du CO₂. Selon le type de fuite, l’hélium peut servir de précurseur temporel du CO₂, tandis que le krypton prévient de l’étendue du panache de gaz durant la fuite. Plus la pression d’injection du CO₂ est importante et plus le gaz migre par advection. Par ailleurs, une pression d’injection importante favorise l’existence de passage préférentiel dans la zone vadose. L’utilisation d’isotopes tels que ceux de l’hélium et du carbone permet de mettre en évidence la présence locale de phases aqueuses dans le massif et de déterminer l’origine biologique ou anthropique du CO₂. Les expériences à l’échelle de la carotte permettent d’estimer le pouvoir tampon des calcaires oligocènes en fonction du faciès de la roche. La perméabilité et la porosité de celle-ci conditionnent la dissolution des calcaires. De même, la réactivité des carbonates en contexte de fuite dépend du pH de la phase aqueuse, du débit qui traverse le réseau poreux, de la saturation en eau et des caractéristiques pétro-physiques des carbonatesCarbon storage is one of the most encouraging methods to decrease CO₂ concentration into the atmosphere. Carbon storage provides the longevity and the capacity needed to decrease CO₂ emissions toward the atmosphere. When dealing with storage on an industrial scale, carbonated reservoirs can be among the most suitable storage sites. However, these high depth injections are subject to leakage risks from the geologic trap itself or from the framework created by the establishment of the site. Two main types of leakage exist: brutal and diffusive leakage. In both cases, they are likely to endanger the environment and the population. Therefore, it is essential to develop tools that are able to anticipate any types of CO₂ leakage. Furthermore, it is also necessary to understand the reactive transport mechanism that take place when the leakage arrives in the shallow subsurface (vadose zone)and to see how the leakage can be buffered. This work deals with the characterization, the quantification and the modelling of transfer processes and CO₂-H₂O-CaCO₃ interactions into the vadose zone in a context of a leakage from a drilling well. This issue was first dealt through field experiment on the site of Saint Emilion. Then, the CO₂-H₂O-CaCO₃ interactions were studied through an experimental approach in laboratory. Two leakage experiments were performed on the site: a diffusive leakage and an ultra-diffusive leakage. They were performed as a sequel of former experiments carried on the pilot site. A comparison of all the leakage experiments revealed the necessity to use noble gases as precursor of the CO₂ arrival at the surface. Depending of the type of the leakage, helium can be a temporal precursor while krypton can anticipate the spread of the CO₂ gas plume. The higher the injection pressure, the more the gas migrates through advective flux. Moreover, a high injection pressure favors the existence of preferential paths in the vadose zone. The use of helium and carbon isotopes makes it possible to reveal the presence of a local aqueous phase within the porous media and to identify the origin of CO₂. The core scale experiments lead to the estimation of the buffering power of Oligocene limestone according to the rock facies. The permeability and the porosity influence the dissolution of the limestone. The reactivity of carbonates during a leakage depends on the pH of the aqueous phase, the flow rate that goes through the porous media, the water saturation and petrophysical characteristics of the carbonates
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Miocic, Johannes Marijan. "A study of natural CO₂ reservoirs : mechanisms and pathways for leakage and implications for geologically stored CO₂." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/17881.
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Carbon Capture and Storage (CCS) is a suite of technologies available to directly reduce carbon dioxide (CO2) emissions to the atmosphere from fossil fuelled power plants and large industrial point sources. For a safe deployment of CCS it is important that CO2 injected into deep geological formations does not migrate out of the storage site. Characterising and understanding possible migration mechanisms and pathways along which migration may occur is therefore crucial to ensure secure engineered storage of anthropogenic CO2. In this thesis naturally occurring CO2 accumulations in the subsurface are studied as analogue sites for engineered storage sites with respect to CO2 migration pathways and mechanisms that ensure the retention of CO2 in the subsurface. Geological data of natural CO2 reservoirs world-wide has been compiled from published literature and analysed. Results show that faults are the main pathways for migration of CO2 from subsurface reservoirs to the surface and that the state and density of CO2, pressure of the reservoir, and thickness of the caprock influence the successful retention of CO2. Gaseous, low density CO2, overpressured reservoirs, and thin caprocks are characteristics of insecure storage sites. Two natural CO2 reservoirs have been studied in detail with respect to their fault seal properties. This includes the first study of how fault rock seals behave in CO2 reservoirs. It has been shown that the bounding fault of the Fizzy Field reservoir in the southern North Sea can with hold the amount of CO2 trapped in the reservoir at current time. A initially higher gas column would have led to across fault migration of CO2 as the fault rock seals would not have been able to withhold higher pressures. Depending on the present day stress regime the fault could be close to failure. At the natural CO2 reservoir of St. Johns Dome, Arizona, migration of CO2 to the surface has been occurring for at least the last 500 ka. Fault seal analysis shows that this migration is related to the fault rock composition and the orientation of the bounding fault in the present day stress field. Using the U-Th disequilibrium method the ages of travertine deposits of the St. Johns Dome area have been determined. The results illustrate that along one fault CO2 migration took place for at least 480 ka and that individual travertine mounds have had long lifespans of up to ~350 ka. Age and uranium isotope trends along the fault have been interpreted as signs of a shrinking CO2 reservoir. The amount of CO2 calculated to have migrated out of the St. Johns Dome is up to 113 Gt. Calculated rates span from 5 t/yr to 30,000 t/yr and indicate that at the worst case large amounts of CO2 can migrate rapidly from the subsurface reservoir along faults to the surface. This thesis highlights the importance of faults as fluid pathways for vertical migration of CO2. It has been also shown that they can act as baffles for CO2 migration and that whether a fault acts as pathway or baffle for CO2 can be predicted using fault seal analysis. However, further work is needed in order to minimise the uncertainties of fault seal analysis for CO2 reservoirs.
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Hendren, William Robert. "Optical and magneto-optical studies of ultrathin Co/Pt and Co/Au layered structures." Thesis, Queen's University Belfast, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295392.
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Petit, Anélia. "Processus physico-chimiques et impacts des fuites de CO₂ sur les hydrosystèmes proches surface lors d’un stockage géologique : approches expérimentales in-situ et en laboratoire." Thesis, Bordeaux 3, 2020. http://www.theses.fr/2020BOR30032.
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Le CO₂ est l’un des principaux gaz à effet de serre qui participe activement au réchauffement du système climatique. La capture et le stockage géologique du carbone permettent de limiter les impacts des augmentations de concentration en CO₂ dans l’atmosphère. La principale qualité d’un site de stockage est de présenter une probabilité de fuite minimale. Il est donc essentiel de développer des outils de surveillance afin d’évaluer leur importance et de prévoir des actions correctives. Ce travail de thèse a pour objectif d’étudier les processus physicochimiques et les impacts d’une fuite de CO₂ sur les hydrosystèmes proches surface (zone vadose (ZV) et nappe) dans un système carbonaté réservoir d’âge Oligocène situé au sein du bassin aquitain. Cette étude a suivi : i) une approche expérimentale sur le site pilote de Saint-Emilion (Gironde, France) où une injection de CO₂ a eu lieu dans l’aquifère à partir d’un puits de forage ; ii) une approche en laboratoire à l’échelle de la carotte afin d’étudier les interactions du système CO₂-H₂O-CaCO₃. Ce travail apporte une démarche expérimentale nouvelle en couplant des méthodes géochimiques et géophysiques sur les deux échelles d’investigation. La ligne de base, réalisée à travers la ZV l’année précédant l’expérience d’injection, a étudié l’évolution naturelle du CO₂ lors d’un cycle hydrogéologique. Après l’injection dans la nappe et au regard de nos résultats, la conductivité électrique (σ), le pH, les concentrations en Ca²⁺, HCO₃- et CO₂ se sont avérés être de bons indicateurs, suffisamment sensibles et réactifs, pouvant être utilisés sur un site de stockage de CO₂ afin de suivre toutes perturbations physicochimiques. Des simulations numériques ont permis de mieux appréhender les processus de réaction et de transport. Les expériences à l’échelle de la carotte ont quantifié l’influence des effets du CO₂ sur le comportement électrique de la roche carbonatée. Une meilleure définition de la relation entre les concentrations en CO₂, la σ et le pH permet de passer de l’échelle de la carotte à l’échelle du site pilote et vice versa. L’ensemble des résultats de ce travail de thèse met en avant l’importance de la caractérisation de l’hétérogénéité pétrophysique du réservoir. Il est également essentiel d’établir une ligne de base, permettant de distinguer les variations naturelles en CO₂ de celles induites par une fuite. Le couplage des observations sur le terrain et des démonstrations en laboratoire permet d’augmenter les chances de détection d’une fuite de CO₂ sur un site de stockage géologiqueCO₂ is one of the main greenhouse gases that actively contributes to the global warming. The carbon capture and geological storage can limit the impacts of increases in CO₂ concentration in the atmosphere. The main quality of a storage site is to present a minimum probability of leakage. Therefore, it is essential to develop monitoring tools in order to assess their importance and plan corrective actions. The objective of this thesis is to study the physicochemical processes and the impacts of a CO₂ leak on near-surface hydrosystems (vadose zone (VZ) and aquifer) in a carbonate reservoir system of Oligocene age located within the Aquitaine basin. This study followed: i) an experimental approach at the Saint-Emilion pilot site (Gironde, France) where CO₂ injection took place into the aquifer from a borehole; ii) a core-scale laboratory approach to study the interactions of the CO₂-H₂O-CaCO₃ system. This work brings a new experimental approach by coupling geochemical and geophysical methods on the two scales of investigation. The baseline, carried out through the VZ the year before the injection experiment, studied the natural evolution of CO₂ during a hydrogeological cycle. After injection into the aquifer and according to our results, the electrical conductivity (σ), the pH, the concentrations of Ca²⁺, HCO₃- and CO₂ turned out to be good indicators, sufficiently sensitive and reactive, which can be used on a CO₂ storage site to monitor any physicochemical disturbances. Numerical simulations have made it possible to better understand the reaction and transport processes. Core-scale experiments quantified the influence of CO₂ effects on the electrical behavior of carbonate rock. Better definition of the relationship between the concentrations of CO₂, σ and pH makes it possible to pass from the core scale to the pilot site scale and vice versa. All the results of this thesis work highlight the importance of characterizing the petrophysical heterogeneity of the reservoir. It is also essential to establish a baseline, making it possible to distinguish natural variations in CO₂ from those induced by a leak. Coupling field observations and laboratory demonstrations increases the chances of detecting a CO₂ leak at a geological storage site
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Bachaud, Pierre. "Stockage du CO₂ dans les aquifères profonds : Etude en conditions réelles des propriétés de confinement des roches de couverture et de leur altération." Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL084N/document.
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Une solution prometteuse pour diminuer les émissions anthropogéniques de gaz à effet de serre consiste à injecter une partie des rejets industriels de CO2 dans des formations souterraines. Celles-ci comportent un réservoir entouré de roches de couverture, qui constituent la première barrière à la migration des fluides. La caractérisation de leurs propriétés de confinement et de leur évolution en présence de CO2 est donc un élément clé de la sécurité d’un site de stockage. Le travail présenté propose une méthodologie, appliquée ici à des roches carbonatées du bassin parisien, permettant de mesurer les paramètres de transport de roches de couverture et les conséquences d’un vieillissement en conditions représentatives de celles d’un stockage en aquifère profond. La pression de percée, le coefficient de diffusion des produits de dissolution du CO2, et la perméabilité, paramètres contrôlant les principaux mécanismes de fuite, ont été mesurés avant et après altération des matériaux par réaction avec une saumure saturée en CO2 dans des conditions thermodynamiques typiques d’un réservoir (environ 80°C et 100 bar). Les résultats obtenus ont révélé un bon comportement global des roches, mais également une forte diminution du potentiel de confinement en présence de défauts structurels initiaux (fractures rebouchées, pores de grand diamètre...). Une simulation numérique décrivant les évolutions de la formation rocheuse non-fissurée sur une durée de 1000 ans a été réalisée en s’appuyant sur des paramètres mesurés directement ou obtenus par modélisation des essais d’altération. Elle a montré que les transformations engendrées par le stockage de CO2 sous une roche de couverture homogène restent très limitées spatialementA promising solution to reduce anthropogenic emissions of greenhouse effect gases consists in the injection and long-term storage of a part of the industrial carbon dioxide discharges in underground formations. These formations must be composed of a reservoir surrounded by tight caprocks, which represent the first barrier preventing fluids migration. The characterization of their confining properties and of their evolution in presence of CO2 is thus a key element regarding a storage site security. This work presents a methodology allowing the measurement of caprocks transport parameters and the consequences of an alteration under representative conditions of deep aquifers storage. This methodology was applied to carbonate rocks from the Paris basin. The breakthrough pressure, the diffusion coefficient of CO2 dissolution products, and the permeability, controlling parameters of leakage mechanisms, were measured before and after alteration of the materials by reaction with a CO2-saturated brine under reservoir thermodynamic conditions (about 80°C and 100 bar). Results revealed a satisfactory global behaviour under these aggressive conditions, but also a strong diminution of the confinement potential in presence of initial structural faults (sealed fractures, large-diameter pores…) forming higher-permeability zones. A numeric simulation describing the evolution of a homogeneous rock formation during 1000 years was also realized based on parameters directly measured or obtained by modelling of the alteration experiments. It showed that the transformations brought by the CO2 storage under a rock formation with no initial faults remain very localized spatially
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Ngo, Tri Dat. "Mise à l’échelle d’un écoulement diphasique avec gravité dans un milieu géologique hétérogène : application au cas de la séquestration du CO₂." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS005/document.
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Ce travail de thèse porte sur la modélisation mathématique et la simulation numérique de la migration par gravité et capillarité du CO₂ supercritique injecté dans un site de séquestration géologique hétérogène. Les simulations sont réalisées à l'aide du code DuMux. Particulièrement, on s'intéresse à la mise à l'échelle, de l'échelle de la cellule à l'échelle du réservoir, d'un modèle d'écoulement diphasique CO₂ -saumure, au sein d'un milieu stratifié périodique constitué d'un réseau de barrières peu perméables horizontales, continues ou discontinues. La mise à l'échelle est effectuée par la méthode asymptotique à double échelle. Dans un premier temps, on considère le cas d'une colonne verticale parfaitement stratifiée. Un modèle homogénéisé est développé puis validé par simulation numérique pour différentes valeurs du nombre capillaire et du flux incident de CO₂ . La méthode d'homogénéisation est appliquée au cas d'un écoulement dans un milieu bidimensionnel constitué de strates discontinues. Par l'effet de gravité, le CO₂ s'accumule sous les strates peu perméables, ce qui conduit à un problème mathématique local non standard. Cette stratification est modélisée à l'aide de l'approche des courants de gravité. L'approche est étendue au cas des strates semi-perméables et en prenant en compte la capillarité. Le modèle mis à l'échelle est comparé à des simulations numériques effectuées pour différents types de strates, avec ou sans pression capillaire, et sa limite de validité est discutée pour chacun de ces cas. La dernière partie de la thèse est dédiée à l'étude des performances du code DuMux pour simuler par calcul parallèle l'injection et la migration de CO₂ dans des milieux hétérogènes tridimensionnels (milieu périodique stratifié, milieu fluviatile et milieu réservoir SPE10)This work deals with the mathematical modeling and the numerical simulation of the migration under gravity and capillarity effects of the supercritical CO₂ injected into a geological heterogeneous sequestration site. The simulations are performed with the code DuMux. Particularly, we consider the upscaling, from the cell scale to the reservoir scale, of a two-phase (CO₂ -brine) flow model within a periodic stratified medium made up of horizontal low permeability barriers, continuous or discontinuous. The upscaling is done by the two-scale asymptotic method. First, we consider perfectly layered media. An homogenized model is developed and validated by numerical simulation for different values of capillary number and the incident flux of CO₂ . The homogenization method is then applied to the case of a two-dimensional medium made up of discontinuous layers. Due to the gravity effect, the CO₂ accumulates under the low permeability layers, which leads to a non-standard local mathematical problem. This stratification is modeled using the gravity current approach. This approach is then extended to the case of semi-permeable stratas taking into account the capillarity. The upscaled model is compared with numerical simulations for different types of layers, with or without capillary pressure, and its limit of validity is discussed in each of these cases. The final part of this thesis is devoted to the study of the parallel computing performances of the code DuMux to simulate the injection and migration of CO₂ in three-dimensional heterogeneous media (layered periodic media, fluvial media and reservoir model SPE 10)
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Roberts, Jennifer Jean. "Natural CO₂ fluids in Italy : implications for the leakage of geologically stored CO₂." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/11805.
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A principle concern for engineered CO2 storage is long-term security. Surface leakage (‘seepage’) of injected CO2 to the surface is economically and environmentally undesirable. Italy is a region of intense natural CO2 degassing; 308 CO2 seeps are catalogued which exhibit different surface characteristics, and a number CO2 rich reservoirs were discovered when drilling for hydrocarbons. These seeps and reservoirs provide excellent natural analogues for seeps that might arise from breached carbon stores. This thesis explores the geological controls on the crustal plumbing of CO2 fluids to model the processes governing CO2 seep locations and distribution, and characteristics; and their consequences on human health risk. Risk of human death from accidental CO2 poisoning at all seep types is low (10-8 yr-1) and several factors influence risk of human mortality. Seeps distribute on two spatial scales; on a local scale (<5 km) seeps are clustered and aligned with subsidiary geologic structures, while on large scales seep clusters are discrete, and align with regional structures. Within clusters, seep locations are influenced by fault maturity, the presence of lithological boundaries and seep manifestation, which is determined by the flow properties of the outcropping lithology and local topography. Sealing and seeping CO2 reservoirs are identified, and their geological characteristics compared. Italian reservoirs successfully retain large CO2 columns at a range of reservoir conditions. Reservoirs which have hydrostatic pressure conditions in the overburden, determined from well logs, are located close to surface CO2 seeps and recent extensional faults. Where there is significant overpressure above hydrostatic in the overburden, there are no seeps present above the reservoir structure. Overpressure of reservoir fluids may enhance fluid flow rates but is not a necessary condition for CO₂ leakage. Geothermal conditions influences the style of leakage at depths and towards the surface. Total CO2 degassing from dry Italian CO2 seeps is 3.5 ± 0.5 Mt(CO2)yr-1. It would take thousands of years for the effectiveness of a commercial scale store to be significantly reduced if it leaks to form a single seep with the mean flux rates modeled in Italy. If a seep cluster develops, the storage effectiveness will reduce more rapidly, and could negate engineered CO₂ storage as a climate mitigation strategy. The research presented in this thesis contributes to a body of knowledge which directly informs site selection procedure for carbon storage and maximise the long term storage potential for CCS. Thorough scientific understanding of the geological processes governing fluid escape is crucial to assure the scientific, political and public communities that safe, long-term carbon storage can be realised as an effective climate mitigation technology.
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Zaharieva, Roussislava. "Ab initio studies of equations of state and chemical reactions of reactive structural materials." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42784.
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The motivations for the research issues addressed in this thesis are based on the needs of the aerospace structural analysis and the design community. The specific focus is related to the characterization and shock induced chemical reactions of multi-functional structural-energetic materials that are also know as the reactive structural materials and their reaction capabilities.
Usually motivation for selection of aerospace structural materials is to realize required strength characteristics and favorable strength to weight ratios. The term strength implies resistance to loads experienced during the service life of the structure, including resistance to fatigue loads, corrosion and other extreme conditions. Thus, basically the structural materials are single function materials that resist loads experienced during the service life of the structure. However, it is desirable to select materials that are capable of offering more than one basic function of strength. Very often, the second function is the capability to provide functions of sensing and actuation. In this thesis, the second function is different. The second function is the energetic characteristics. Thus, the choice of dual functions of the material are the structural characteristics and energetic characteristics. These materials are also known by other names such as the reactive material structures or dual functional structural energetic materials. Specifically the selected reactive materials include mixtures of selected metals and metal oxides that are also known as thermite mixtures, reacting intermetallic combinations and oxidizing materials. There are several techniques that are available to synthesize these structural energetic materials or reactive material structures and new synthesis techniques constitute an open research area.
The focus of this thesis, however, is the characterization of chemical reactions of reactive material structures that involve two or more solids (or condensed matter). The subject of studies of the shock or thermally induced chemical reactions of the two solids comprising these reactive materials, from first principles, is a relatively new field of study. The published literature on ab initio principles or quantum mechanics based approach contains the ab initio or ab initio-molecular dynamics studies in related fields of a solid and a gas. One such study in the literature involves a gas and a solid. This is an investigation of the adsorption of gasses such as carbon monoxide (CO) on Tungsten. The motivation for these studies is to synthesize alternate or synthetic fuel technology by Fischer-Tropsch process.
In this thesis these studies are first to establish the procedure for solid-solid reaction and then to extend that to consider the effects of mechanical strain and temperature on the binding energy and chemisorptions of CO on tungsten. Then in this thesis, similar studies are also conducted on the effect of mechanical strain and temperature on the binding energies of Titanium and hydrogen. The motivations are again to understand the method and extend the method to such solid-solid reactions. A second motivation is to seek strained conditions that favor hydrogen storage and strain conditions that release hydrogen easily when needed.
Following the establishment of ab initio and ab initio studies of chemical reactions between a solid and a gas, the next step of research is to study thermally induced chemical reaction between two solids (Ni+Al).
Thus, specific new studies of the thesis are as follows:
1. Ab initio Studies of Binding energies associated with chemisorption of (a) CO on W surfaces (111, and 100) at elevated temperatures and strains and (b) adsorption of hydrogen in titanium base.
2. Equations of state of mixtures of reactive material structures from ab initio methods
3. Ab initio studies of the reaction initiation, transition states and reaction products of intermetallic mixtures of (Ni+Al) at elevated temperatures and strains.
4. Press-cure synthesis of Nano-nickel and nano-aluminum based reactive material structures and DTA tests to study experimentally initiation of chemical reactions, due to thermal energy input.
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Syckor, Jens. "Dropbox & Co, alles schon ge-cloud?" Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-153998.
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Cloudspeicherdienste sind zu einem Standard für den Austausch großer Datenmengen in virtuellen Gemeinschaften geworden, sowohl im privaten Umfeld als auch im öffentlichen Bereich. Einfache Bedienbarkeit sowie nahtlose Integration in Applikationen, Betriebssystemen und Endgeräten sind wesentliche Bausteine dieses Siegeszuges.
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Nouailletas, Olivier. "Comportement d'une discontinuité dans un géomatériau sous sollicitation chemo-mécanique : expérimentations et modélisations." Thèse, Université de Sherbrooke, 2014. http://savoirs.usherbrooke.ca/handle/11143/110.
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Résumé : Ces travaux de thèse s'intéressent à l'étude du comportement d'une discontinuité dans un géomatériau sous sollicitations chemo-mécaniques à l'échelle du laboratoire. Des essais de traction-compression cyclique étudient la refermeture d'une fissure. Ils indiquent que les déformations inélastiques seraient gouvernées en partie par les frottements générés lors du ré-emboîtement des lèvres de la discontinuité, non correspondantes du fait des contraintes internes. Des joints rocheux altérés chimiquement sous sollicitation tangentielle sont étudiés au travers d'essais de cisaillement direct : le comportement des joints dégradés est profondément modifié du fait de la diminution des propriétés mécaniques du matériau de part et d'autre de la discontinuité et de l'accentuation de la non-correspondance des profils rugueux. Le comportement d'une discontinuité est modélisée par le couplage d'un modèle élasto-plastique endommageable continu avec une résolution discrète du problème de contact/frottement (code calcul aux éléments finis Cast3M). Les résultats numériques confirment les phénomènes constatés expérimentalement.//Abstract: To probate the technology of CO[indice inférieur 2] geological storage, the integrity of the site must be assure over time. This industruial problematic involves the study of the mechanical properties alteration of geomaterials in the presence of CO[indice inférieur 2]. The scenario at the origin of this thesis illustrates the possibility of a CO[indice inférieur 2] leakage on a fault located in the caprock. This geological problem is complicated by the many parameters to consider: in situ temperature and pressure, scale effect, heterogeneities of the geomaterial, geofluide composition, chemical reactions ... These works focus on the behavior of a discontinuity in a geomaterial solicited chemomechanically at the laboratory scale. They were realised in cotutelle between SIAME laboratory at the University of Pau and Pays de l'Adour (France) and the laboratory of rock mechanics and engineering geology from the University of Sherbrooke (Quebec, Canada). The first part of the experimental program was defined to characterize the reclosing of a crack under cyclic uniaxial stress. The second experimental campaign has studied the shear behavior of a rock joint chemically degraded. The data obtained were used to model the behavior of a discontinuity by the finite element method. The mechanical behavior of a crack under normal stress is assessed with cyclic tension-compression tests. Stress curve showed hysteresis during opening and closing cycles of a discontinuity in concrete, it indicated inelastic deformations The analysis of displacement field by image correlation indicated that theses deformations were partially governed by the friction generated during the closing of the discontinuity lips. Frictional phenomena are due to asperities mismatching induced by the internal stresses in the concrete. The shear behavior of a rock joint chemically damaged was studied through direct shear tests. Rough surfaces were immersed in acid solution during 6 hours at constant pH. Digitalization of these surfaces befor and after immesion, with a lase profilometer, indicates little modifications of the geometry induced by dissolution of material. Results of tests pointed out significant modifications for altered joints illustred by a of the peak shear strength and an increased of contractancy. They are induced by: 1) the mismatch enhancement of the rough profiles of the discontinuity and, 2) the degradation of the mechanical properties of the material on both sides of the discontinuity due to the chemical attack. Numerical contribution of the thesis lies in modeling the behavior of a discontinuity by the coupling of an continuous elastic-plastic damaged model with a discrete resolution of the contact/friction problem. The model is developed with the finite element code Cast3M. Geometries lips discontinuities are modeled directly from the roughness profiles from experimental scans. The numerical results correctly represent the friction phenomena observed experimentally. Finally, a model of the shear test altered joints is performed by coupling the mechanical model with chemical damage model.
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Sathitsuksanoh, Noppadon Tatarchuk Bruce J. "Sequestration of CO₂ by chemically reactive aqueous K₂CO₃ in high efficiency adsorbents using microfibrous media entrapped support particulates." Auburn, Ala., 2007. http://repo.lib.auburn.edu/2006%20Fall/Theses/SATHITSUKSANOH_NOPPADON_5.pdf.
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Trompelt, Michael. "Untersuchung von Möglichkeiten zur Wirkungsgradsteigerung von braunkohlegefeuerten IGCC-Kraftwerken mit CO2-Abtrennung." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2015. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-158214.
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Mit der Arbeit werden braunkohlegefeuerte IGCC-CCS-Kraftwerke gesamtheitlich beschrieben, deren Potenziale erarbeitet und mit ASPEN Plus™ sowie EBSILON® Professional simulativ abgebildet. Es kann gezeigt werden, dass ausgehend von Basiskonzepten braunkohlegefeuerter IGCC-CCS-Kraftwerke mit verschiedenen Potenzialen zum gegenwärtigen Stand der Technik sowie dem im Jahr 2025 Wirkungsgradsteigerungen sowie prozesstechnische Vereinfachungen möglich sind. Als Potenziale werden dabei verringerte Braunkohletrocknung, konservativere Annahmen der technologischen Auslegung als auch Modifizierungen der CO-Konvertierung, sowie für das Jahr 2025 konservative Annahmen und innovative Potenziale untersucht. Ausgangspunkt bildet eine Analyse von bestehenden und zukünftig erwarteten Prozesskomponenten braunkohlegefeuerter IGCC-CCS-Kraftwerke unter Berücksichtigung von drei unterschiedlichen Vergasungsverfahren (nach Siemens, nach Shell und dem HTW-Verfahren).
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Occhineri, Lorenzo. "Technical and economic assessments of CO2 capture processes in power plants." Thesis, Mälardalen University, School of Sustainable Development of Society and Technology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-4705.
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Nouailletas, Olivier. "Comportement d'une discontinuit?? dans un g??omat??riau sous sollicitation chemo-m??canique : exp??rimentations et mod??lisations." Thèse, Universit?? de Sherbrooke, 2014. http://savoirs.usherbrooke.ca/handle/11143/110.
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R??sum?? : Ces travaux de th??se s'int??ressent ?? l'??tude du comportement d'une discontinuit?? dans un g??omat??riau sous sollicitations chemo-m??caniques ?? l'??chelle du laboratoire. Des essais de traction-compression cyclique ??tudient la refermeture d'une fissure. Ils indiquent que les d??formations in??lastiques seraient gouvern??es en partie par les frottements g??n??r??s lors du r??-embo??tement des l??vres de la discontinuit??, non correspondantes du fait des contraintes internes. Des joints rocheux alt??r??s chimiquement sous sollicitation tangentielle sont ??tudi??s au travers d'essais de cisaillement direct : le comportement des joints d??grad??s est profond??ment modifi?? du fait de la diminution des propri??t??s m??caniques du mat??riau de part et d'autre de la discontinuit?? et de l'accentuation de la non-correspondance des profils rugueux. Le comportement d'une discontinuit?? est mod??lis??e par le couplage d'un mod??le ??lasto-plastique endommageable continu avec une r??solution discr??te du probl??me de contact/frottement (code calcul aux ??l??ments finis Cast3M). Les r??sultats num??riques confirment les ph??nom??nes constat??s exp??rimentalement.//Abstract: To probate the technology of CO[indice inf??rieur 2] geological storage, the integrity of the site must be assure over time. This industruial problematic involves the study of the mechanical properties alteration of geomaterials in the presence of CO[indice inf??rieur 2]. The scenario at the origin of this thesis illustrates the possibility of a CO[indice inf??rieur 2] leakage on a fault located in the caprock. This geological problem is complicated by the many parameters to consider: in situ temperature and pressure, scale effect, heterogeneities of the geomaterial, geofluide composition, chemical reactions ... These works focus on the behavior of a discontinuity in a geomaterial solicited chemomechanically at the laboratory scale. They were realised in cotutelle between SIAME laboratory at the University of Pau and Pays de l'Adour (France) and the laboratory of rock mechanics and engineering geology from the University of Sherbrooke (Quebec, Canada). The first part of the experimental program was defined to characterize the reclosing of a crack under cyclic uniaxial stress. The second experimental campaign has studied the shear behavior of a rock joint chemically degraded. The data obtained were used to model the behavior of a discontinuity by the finite element method. The mechanical behavior of a crack under normal stress is assessed with cyclic tension-compression tests. Stress curve showed hysteresis during opening and closing cycles of a discontinuity in concrete, it indicated inelastic deformations The analysis of displacement field by image correlation indicated that theses deformations were partially governed by the friction generated during the closing of the discontinuity lips. Frictional phenomena are due to asperities mismatching induced by the internal stresses in the concrete. The shear behavior of a rock joint chemically damaged was studied through direct shear tests. Rough surfaces were immersed in acid solution during 6 hours at constant pH. Digitalization of these surfaces befor and after immesion, with a lase profilometer, indicates little modifications of the geometry induced by dissolution of material. Results of tests pointed out significant modifications for altered joints illustred by a of the peak shear strength and an increased of contractancy. They are induced by: 1) the mismatch enhancement of the rough profiles of the discontinuity and, 2) the degradation of the mechanical properties of the material on both sides of the discontinuity due to the chemical attack. Numerical contribution of the thesis lies in modeling the behavior of a discontinuity by the coupling of an continuous elastic-plastic damaged model with a discrete resolution of the contact/friction problem. The model is developed with the finite element code Cast3M. Geometries lips discontinuities are modeled directly from the roughness profiles from experimental scans. The numerical results correctly represent the friction phenomena observed experimentally. Finally, a model of the shear test altered joints is performed by coupling the mechanical model with chemical damage model.
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Rieger, Mathias. "Advanced modeling and simulation of integrated gasification combined cycle power plants with CO2-capture." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2014. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-150522.
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The objective of this thesis is to provide an extensive description of the correlations in some of the most crucial sub-processes for hard coal fired IGCC with carbon capture (CC-IGCC). For this purpose, process simulation models are developed for four industrial gasification processes, the CO-shift cycle, the acid gas removal unit, the sulfur recovery process, the gas turbine, the water-/steam cycle and the air separation unit (ASU). Process simulations clarify the influence of certain boundary conditions on plant operation, performance and economics. Based on that, a comparative benchmark of CC-IGCC concepts is conducted. Furthermore, the influence of integration between the gas turbine and the ASU is analyzed in detail. The generated findings are used to develop an advanced plant configuration with improved economics. Nevertheless, IGCC power plants with carbon capture are not found to be an economically efficient power generation technology at present day boundary conditions.
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Ylänne, H. (Henni). "Herbivory control over tundra carbon storage under climate change." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526215105.
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Abstract Air temperatures in high-latitude regions are anticipated to rise by several degrees by the end of the century and result in substantial northward shifts of species. These changes will likely affect the source and sink dynamics of greenhouse gases and possibly lead to a net carbon release from high-latitude soils to the atmosphere. However, regional differences in carbon cycling depend highly on the vegetation community composition, which may be controlled by the abundance of herbivores. I investigated whether mammalian herbivores, mainly reindeer and rodents, alter ecosystem carbon storage through their impacts on vegetation and on dominant plant functional traits. I combined observations of recent changes in ecosystem carbon with experimental field manipulations of both herbivory and climate change and measured carbon storage in vegetation and soil, the uptake and release of carbon dioxide, microbial activity and compared these to plant community composition. Results of my PhD thesis show that under ambient conditions, the impacts of herbivory on both above- and belowground carbon storage ranged from positive to negative. Herbivory altered dominant plant functional traits and these were fairly good predictors of the changes in soil carbon. When combined with experimental warming, herbivory continued to exert control on the dominant plant functional traits but the strong effects of warming on ecosystem carbon storage mostly concealed the impact of herbivory. Interestingly, herbivory–nutrient interactions that were not linked to dominant functional traits determined the consequences of warming on soil carbon. Taken together, I show clear and site-specific impacts of herbivores on vegetation and ecosystem carbon storage and the processes that govern them. Therefore, I suggest that an improved understanding of the role of herbivory in the global carbon cycle could improve estimations of global carbon–climate feedbacksTiivistelmä Vuosisadan loppuun mennessä arktisten alueiden lämpötilan odotetaan nousevan usealla asteella ja johtavan lajien siirtymiseen yhä pohjoisemmaksi. Nämä muutokset todennäköisesti muuttavat pohjoisten ekosysteemien kykyä vapauttaa ja sitoa ilmakehän hiiltä ja saattavat johtaa siihen, että yhä enemmän hiiltä vapautuu tundramailta ilmakehään. Kuitenkin paikallisesti hiilenkierto on riippuvainen kasviyhteisöstä ja erityisesti kasvien funktionaalisista ominaisuuksista. Väitöskirjassani tutkin, voivatko herbivorit, pääasiassa porot sekä jyrsijät, muokata hiilenkiertoa muuttamalla kasvillisuutta. Tutkimuksissani seurasin kuinka alueen laidunnushistoria on muokannut hiilivarastoja ja hiilenkiertoa tällä hetkellä ja pyrin arvioimaan herbivorien vaikutusta lämpenevässä ilmastossa kokeiden avulla, joissa manipuloidaan sekä herbivoriaa että lämpötilaa tai ravinteiden saatavuutta. Tulokseni perustuvat arvioihin hiilen varastoista, hiilidioksidin vapautumisesta ja sitoutumisesta sekä mikrobien aktiivisuudesta, joita vertaan kasviyhteisöön. Tulokseni osoittavat, että herbivoria voi joko lisätä tai vähentää ekosysteemin hiilivarastoja sekä maan päällä että maan alla. Muutokset hiilivarastoissa selittyivät varsin hyvin herbivorien tuottamilla kasvillisuusmuutoksilla ja valtalajien funktionaalisilla ominaisuuksilla. Herbivoria muokkasi kasviyhteisöä myös kokeellisen lämmityksen yhteydessä, mutta lämmityksen välittömät vaikutukset hiilivarastoihin peittivät suureksi osaksi alleen herbivorian vaikutukset. Kuitenkin herbivorian ja lannoituksen kasvillisuusmuutoksista riippumattomat yhdysvaikutukset määrittivät lämpenemisen seuraukset maan hiileen. Kaiken kaikkiaan, tutkimukseni osoittaa, että herbivorit voivat paikkakohtaisesti muokata kasvillisuutta, ekosysteemin hiilivarastoja sekä hiilenkierron prosesseja. Näiden tulosten myötä ehdotan, että parempi ymmärrys herbivorian vaikutuksista maailmanlaajuisesti voisi parantaa nykyisiä ennusteita siitä, kuinka ilmaston lämpeneminen muuttaa hiilenkiertoa
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Hunter, Kelsey A. "CO2-Enhanced Water Recovery through Integrated CO2 Injection and Brine Extraction in the Rock Springs Uplift Formation in Southwest, WY." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1511816662671574.
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Sagerfors, Jörgen. "Land-atmosphere exchange of CO₂, water and energy at a boreal minerotrophic mire /." Umeå : Dept. of Forest Ecology and Management, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/200704.pdf.
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Hoffmann, Jean-Francois. "Stockage thermique pour centrale solaire thermodynamique à concentration mettant en oeuvre des matériaux céramiques naturels ou recyclés." Thesis, Perpignan, 2015. http://www.theses.fr/2015PERP0033/document.
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Par rapport aux ressources énergétiques fossiles combustibles, l’énergie solaire présente des caractéristiques inhérentes à la nature même de la ressource. Ce constat met en évidence la nécessité de système de stockage d’énergie. Ce travail de thèse consiste à étudier un stockage thermique pour une centrale solaire à concentration, ainsi que ses deux composants essentiels : le fluide de transfert et les matériaux de garnissage solides. La compréhension du système de stockage thermocline sur lit de roche est réalisée grâce à une approche expérimentale et numérique. Une alternative innovante sur le choix du fluide de transfert consiste à utiliser des huiles végétales. Concernant le garnissage, un matériau à géométrie contrôlée est développé à partir d’un coproduit issu de la sidérurgie. L’originalité de cette association pour le stockage thermique permet d’allier performance, disponibilité des matériaux en quantité industrielle tout en réduisant l’impact environnemental et financierCompare to fossil fuel energy resources, solar energy presents the inherent characteristic given by the very nature of the resource (intermittent availability). This observation highlights the need for thermal energy storage system. This doctoral thesis studies thermal energy storage for concentrating solar power plant, as well as its two essential components: the heat transfer fluid and the thermal energy storage materials. The analysis of the thermocline storage system with filler materials is achieved through experimental and numerical approaches. An innovative alternative for the heat transfer fluid consists to use vegetable oils, which offers comparable thermal properties and operating behavior to conventional thermal fluid. Regarding thermal energy storage materials, many natural and recycled materials can be used. A storage material with controlled geometry is developed from steel industry co-product. The originality of this combination for thermal energy storage combines performance, materials availability at industrial scale while reducing environmental and financial impact
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Al-Zaidi, Ebraheam Saheb Azeaz. "Experimental studies on displacements of CO₂ in sandstone core samples." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33183.
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CO2 sequestration is a promising strategy to reduce the emissions of CO2 concentration in the atmosphere, to enhance hydrocarbon production, and/or to extract geothermal heat. The target formations can be deep saline aquifers, abandoned or depleted hydrocarbon reservoirs, and/or coal bed seams or even deep oceanic waters. Thus, the potential formations for CO2 sequestration and EOR (enhanced oil recovery) projects can vary broadly in pressure and temperature conditions from deep and cold where CO2 can exist in a liquid state to shallow and warm where CO2 can exist in a gaseous state, and to deep and hot where CO2 can exist in a supercritical state. The injection, transport and displacement of CO2 in these formations involves the flow of CO2 in subsurface rocks which already contain water and/or oil, i.e. multiphase flow occurs. Deepening our understanding about multiphase flow characteristics will help us building models that can predict multiphase flow behaviour, designing sequestration and EOR programmes, and selecting appropriate formations for CO2 sequestration more accurately. However, multiphase flow in porous media is a complex process and mainly governed by the interfacial interactions between the injected CO2, formation water, and formation rock in host formation (e.g. interfacial tension, wettability, capillarity, and mass transfer across the interface), and by the capillary , viscous, buoyant, gravity, diffusive, and inertial forces; some of these forces can be neglected based on the rock-fluid properties and the configuration of the model investigated. The most influential forces are the capillary ones as they are responsible for the entrapment of about 70% of the total oil in place, which is left behind primary and secondary production processes. During CO2 injection in subsurface formations, at early stages, most of the injected CO2 (as a non-wetting phase) will displace the formation water/oil (as a wetting phase) in a drainage immiscible displacement. Later, the formation water/oil will push back the injected CO2 in an imbibition displacement. Generally, the main concern for most of the CO2 sequestration projects is the storage capacity and the security of the target formations, which directly influenced by the dynamic of CO2 flow within these formations. Any change in the state of the injected CO2 as well as the subsurface conditions (e.g. pressure, temperature, injection rate and its duration), properties of the injected and present fluids (e.g. brine composition and concentration, and viscosity and density), and properties of the rock formation (e.g. mineral composition, pore size distribution, porosity, permeability, and wettability) will have a direct impact on the interfacial interactions, capillary forces and viscous forces, which, in turn, will have a direct influence on the injection, displacement, migration, storage capacity and integrity of CO2. Nevertheless, despite their high importance, investigations have widely overlooked the impact of CO2 the phase as well as the operational conditions on multiphase characteristics during CO2 geo-sequestration and CO2 enhanced oil recovery processes. In this PhD project, unsteady-state drainage and imbibition investigations have been performed under a gaseous, liquid, or supercritical CO2 condition to evaluate the significance of the effects that a number of important parameters (namely CO2 phase, fluid pressure, temperature, salinity, and CO2 injection rate) can have on the multiphase flow characteristics (such as differential pressure profile, production profile, displacement efficiency, and endpoint CO2 effective (relative) permeability). The study sheds more light on the impact of capillary and viscous forces on multiphase flow characteristics and shows the conditions when capillary or viscous forces dominate the flow. Up to date, there has been no such experimental data presented in the literature on the potential effects of these parameters on the multiphase flow characteristics when CO2 is injected into a gaseous, liquid, or supercritical state. The first main part of this research deals with gaseous, liquid, and supercritical CO2- water/brine drainage displacements. These displacements have been conducted by injecting CO2 into a water or brine-saturated sandstone core sample under either a gaseous, liquid or supercritical state. The results reveal a moderate to considerable impact of the fluid pressure, temperature, salinity and injection rate on the differential pressure profile, production profile, displacement efficiency, and endpoint CO2 effective (relative) permeability). The results show that the extent and the trend of the impact depend significantly on the state of the injected CO2. For gaseous CO2-water drainage displacements, the results showed that the extent of the impact of the experimental temperature and CO2 injection rate on multiphase flow characteristics, i.e. the differential pressure profile, production profile (i.e. cumulative produced volumes), endpoint relative permeability of CO2 (KrCO2) and residual water saturation (Swr) is a function of the associated fluid pressure. This indicates that for formations where CO2 can exist in a gaseous state, fluid pressure has more influence on multiphase flow characteristics in comparison to other parameters investigated. Overall, the increase in fluid pressure (40-70 bar), temperature (29-45 °C), and CO2 injection rate (0.1-2 ml/min) caused an increase in the differential pressure. The increase in differential pressure with increasing fluid pressure and injection rate indicate that viscous forces dominate the multi-phase flow. Nevertheless, increasing the differential pressure with temperature indicates that capillary forces dominate the multi-phase flow as viscous forces are expected to decrease with this increasing temperature. Capillary forces have a direct impact on the entry pressure and capillary number. Therefore, reducing the impact of capillary forces with increasing pressure and injection rate can ease the upward migration of CO2 (thereby, affecting the storage capacity and integrity of the sequestered CO2) and enhance displacement efficiency. On the other hand, increasing the impact of the capillary force with increasing temperature can result in a more secure storage of CO2 and a reduction in the displacement efficiency. Nevertheless, the change in pressure and temperature can also have a direct impact on storage capacity and security of CO2 due to their impact on density and hence on buoyancy forces. Thus, in order to decide the extent of change in storage capacity and security of CO2 with the change in the above-investigated parameters, a qualitative study is required to determine the size of the change in both capillary forces and buoyancy forces. The data showed a significant influence of the capillary forces on the pressure and production profiles. The capillary forces produced high oscillations in the pressure and production profiles while the increase in viscous forces impeded the appearance of these oscillations. The appearance and frequency of these oscillations depend on the fluid pressure, temperature, and CO2 injection rate but to different extents. The appearance of the oscillations can increase CO2 residual saturation due to the re-imbibition process accompanied with these oscillations, thereby increasing storage capacity and integrity of the injected CO2. The differential pressure required to open the blocked flow channels during these oscillations can be useful in calculating the largest effective pore diameters and hence the sealing efficiency of the rock. Swr was in ranges of 0.38-0.42 while KrCO2 was found to be less than 0.25 under our experimental conditions. Increasing fluid pressure, temperature, and CO2 injection rate resulted in an increase in the KrCO2, displacement efficiency (i.e. a reduction in the Swr), and cumulative produced volumes. For liquid CO2-water drainage displacements, the increase in fluid pressure (60-70 bar), CO2 injection rate (0.4-1ml/min) and salinity (1% NaCl, 5% NaCl, and 1% CaCl2) generated an increase in the differential pressure; the highest increase occurred with increasing the injection rate and the lowest with increasing the salinity. On the other hand, on the whole, increasing temperature (20-29 °C) led to a reduction in the differential pressure apart from the gradual increase occurred at the end of flooding.