Yes / The process of capturing and storing carbon dioxide (CCS) was previously considered a crucial and time-sensitive approach for diminishing CO2 emissions originating from coal, oil, and gas sectors. Its implementation was seen necessary to address the detrimental effects of CO2 on the atmosphere and the ecosystem. This recognition was achieved by previous substantial study efforts. The carbon capture and storage (CCS) cycle concludes with the final stage of CO2 storage. This stage involves primarily the adsorption of CO2 in the ocean and the injection of CO2 into subsurface reservoir formations. Additionally, the process of CO2 reactivity with minerals in the reservoir formations leads to the formation of limestone through injectivities. Carbon capture and storage (CCS) is the final phase in the CCS cycle, mostly achieved by the use of marine and underground geological sequestration methods, along with mineral carbonation techniques. The introduction of supercritical CO2 into geological formations has the potential to alter the prevailing physical and chemical characteristics of the subsurface environment. This process can lead to modifications in the pore fluid pressure, temperature conditions, chemical reactivity, and stress distribution within the reservoir rock. The objective of this study is to enhance our existing understanding of CO2 injection and storage systems, with a specific focus on CO2 storage techniques and the associated issues faced during their implementation. Additionally, this research examines strategies for mitigating important uncertainties in carbon capture and storage (CCS) practises. Carbon capture and storage (CCS) facilities can be considered as integrated systems. However, in scientific research, these storage systems are often divided based on the physical and spatial scales relevant to the investigations. Utilising the chosen system as a boundary condition is a highly effective method for segregating the physics in a diverse range of physical applications. Regrettably, the used separation technique fails to effectively depict the behaviour of the broader significant system in the context of water and gas movement within porous media. The limited efficacy of the technique in capturing the behaviour of the broader relevant system can be attributed to the intricate nature of geological subsurface systems. As a result, various carbon capture and storage (CCS) technologies have emerged, each with distinct applications, associated prices, and social and environmental implications. The results of this study have the potential to enhance comprehension regarding the selection of an appropriate carbon capture and storage (CCS) application method. Moreover, these findings can contribute to the optimisation of greenhouse gas emissions and their associated environmental consequences. By promoting process sustainability, this research can address critical challenges related to global climate change, which are currently of utmost importance to humanity. Despite the significant advancements in this technology over the past decade, various concerns and ambiguities have been highlighted. Considerable emphasis was placed on the fundamental discoveries made in practical programmes related to the storage of CO2 thus far. The study has provided evidence that despite the extensive research and implementation of several CCS technologies thus far, the process of selecting an appropriate and widely accepted CCS technology remains challenging due to considerations related to its technological feasibility, economic viability, and societal and environmental acceptance.

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

Yes / Carbon capture and storage (CCS) has attracted renewed interest in the re-evaluation of the equations of state (EoS) for the prediction of thermodynamic properties. This study also evaluates EoS for Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK) and their capability to predict the thermodynamic properties of CO2-rich mixtures. The investigation was carried out using machine learning such as an artificial neural network (ANN) and a classified learner. A lower average absolute relative deviation (AARD) of 7.46% was obtained for the PR in comparison with SRK (AARD = 15.0%) for three components system of CO2 with N2 and CH4. Moreover, it was found to be 13.5% for PR and 19.50% for SRK in the five components’ (CO2 with N2, CH4, Ar, and O2) case. In addition, applying machine learning provided promise and valuable insight to deal with engineering problems. The implementation of machine learning in conjunction with EoS led to getting lower predictive AARD in contrast to EoS. An of AARD 2.81% was achieved for the three components and 12.2% for the respective five components mixture.

[ES] Esta tesis está centrada en la combinación de diferentes tecnologías para mejorar las tecnologías emergentes de captura y almacenamiento de carbono (CSS) y la revalorización del CO2 capturado. La principal tecnología estudiada en esta tesis fueron las membranas de transporte de oxigeno (OTMs), las cuales pueden producir oxigeno puro de forma más flexible que las actuales tecnologías de producción de oxigeno, como la destilación criogénica de aire. La producción de oxigeno puro es crucial para desarrollar reactores de oxicombustión que podrían ser mas eficientes para la captura de CO2 que los reactores actuales de combustión con aire. Los estudios sobre OTMs se dividieron en dos temas principales: membranas de bifásicas estables en CO2 y membranas basadas en BSCF (Ba1-xSrxCo1-yFeyO3-¿). Por otro lado, para la revalorización del CO2 capturado, se estudio' la tecnología de looping químico basada en catalizador de oxido de cerio, que aprovecha las propiedades redox del catalizador a diferentes pO2 y altas temperaturas (entre 700- 1400 ¿C). En general, las principales etapas limitantes en OTMs son la transferencia de oxigeno a trave's de la membrana y las reacciones superficiales. Por eso, una mejora en las propiedades de la capa catalítica podri'a mejorar la permeacio'n total de oxigeno. El primer estudio sobre membranas bifásicas se centro' el estudio de capas catali'ticas con distintas proporciones de ambas fases. Para este estudio, se selecciono' el NFO-CTO (NiFe2O4/Ce0.8Tb0.2O2-¿) como composite. Este material ya ha sido estudiado en nuestro laboratorio, y mostró una gran estabilidad en atmósferas de CO2, pero con baja permeación de O2 en comparación con otros composites. Este estudio mostró resultados interesantes, y se combino' con medidas de espectroscopia de impedancia electroqui'mica (EIS), utilizadas habitualmente para estudiar electrodos para pilas de combustible de o'xido so'lido (SOFC) y pilas de electro'lisis de o'xido so'lido (SOEC). El segundo estudio sobre composites para OTMs se centro' en el aumento de la permeacio'n de oxi'geno con composites basados en espinela-fluorita. En este caso, el transporte de oxigeno esta' controlado, adema's de por la temperatura y el gradiente de pO2, por la conductividad ambipolar, en la que intervienen las conductividades eléctrica e io'nica. Asi', se cambio' la fase de NFO por la fase de CMO (Co2MnO4) que tiene mayor conductividad total que el NFO. El composite resultante (CMO-CTO) ha mostrado un mayor rendimiento que el material predecesor NFO-CTO. Como se ha mencionado anteriormente, el otro estudio sobre OTM se realizo' con membranas basadas en BSCF. En este estudio, la membrana capilar BSCF fue electrificada para aumentar la temperatura de la membrana por efecto Joule y como consecuencia un aumento en la permeación de oxigeno. Además, se estudió este efecto bajo deshidrogenacio'n oxidativa de etano, obteniéndose una mejora importante para las membranas BSCF electrificadas en comparación con las membranas BSCF no electrificadas. Estos estudios abren las puertas al uso de ellas con reactores a más baja temperatura. El último estudio se centra en la revalorización del CO2 mediante el reformado de metano por ciclos químicos. Los ciclos químicos están basados en las propiedades redox del catalizador y las dos etapas de reducción y oxidación del catalizador. La reducción del catalizador es realizada mediante temperatura y en condiciones inertes o con corrientes reductoras como por ejemplo en metano. Los estudios se centran en la reducción a través de metano que trabaja a temperaturas más bajas que para corrientes inertes y, ademas, proporciona corrientes de syngas (mezcla de CO y H2) en la etapa de reducción del catalizador, que mejora la eficiencia global del proceso. La revalorización del CO2 se realizaba en la etapa de oxidación del catalizador. La oxidación de estos catalizadores podría formarse con flujos de H2O y/o / [CA] Aquesta tesi està centrada en la combinació de diferents tecnologies per millorar les tecnologies emergents de captura i emmagatzematge de carboni (CSS) i la revalorització del CO2 capturat. La principal tecnologia estudiada en aquesta tesi van ser les membranes de transport d'oxigen (OTMs), les quals poden produir oxigen pur de manera més flexible que les actuals tecnologies de producció d'oxigen, com la destil·lació criogènica de l'aire. La producció d'oxigen pur és crucial per al desenvolupament de reactors d'oxicombustió que podrien ser més eficients per a la captura de CO2 que els reactors actuals de combustió amb aire. Els estudis sobre OTMs es van dividir en dos temes principals: membranes composites de dos fases estables en CO2 i membranes basades en BSCF (Ba1- xSrxCo1-yFeyO3-). D'altra banda, per a la revalorització del CO2 capturat, es va estudiar la tecnologia de looping químic basada en catalitzador d'òxid de ceri, que aprofita les propietats redox del catalitzador a diferents pO2 i altes temperatures (entre 700-1400 ºC). En general, les principals etapes limitants en OTMs són la transferència d'oxigen a través de la membrana i les reaccions superficials. Per això, una millora en les propietats de la capa catalítica podria millorar la permeació total d'oxigen. El primer estudi sobre membranes bifàsiques es va centrar en l'estudi de capes catalítiques amb diferents proporcions de ambdues fases. Per a aquest estudi, es va seleccionar el NFO-CTO (NiFe2O4/Ce0.8Tb0.2O2-δ) com a composite. Aquest material ja ha sigut estudiat en el nostre laboratori, i va mostrar una gran estabilitat en atmosferes de CO2, però amb baixa permeació d'O2 en comparació amb altres composites. Aquest estudi va mostrar resultats interessants, i es va combinar amb mesures d'espectroscòpia d'impedància electroquímica (EIS), utilitzades habitualment per estudiar elèctrodes per a piles de combustible d'òxid sòlid (SOFC) i piles d'electròlisi d'òxid sòlid (SOEC). El segon estudi sobre composites per a OTMs es va centrar en l'augment de la permeació d'oxigen amb composites basats en espinela-fluorita. En aquest cas, el transport d'oxigen està controlat, a més de per la temperatura i el gradient de pO2, per la conductivitat ambipolar, en la qual intervenen les conductivitats elèctrica i iònica. Així, es va canviar la fase de NFO per la fase de CMO (Co2MnO4) que té una major conductivitat total que el NFO. El composite resultant (CMO-CTO) ha mostrat un major rendiment que el material predecessor NFO-CTO. L'últim estudi es centra en la revalorització del CO2 mitjançant el reformat de metà per cicles químics. Els cicles químics estan basats en les propietats redox del catalitzador i les dues etapes de reducció i oxidació del catalitzador. La reducció del catalitzador és realitzada mitjançant temperatura i en condicions inertes o amb corrents reductores com per exemple en metà. Els estudis se centren en la reducció a través de metà que treballa a temperatures més baixes que per a corrents inertes i, a més, proporciona corrents de syngas (barreja de CO i H2) en l'etapa de reducció del catalitzador, que millora l'eficiència global del procés. La revalorització del CO2 es realitzava en l'etapa d'oxidació del catalitzador. L'oxidació d'aquests catalitzadors podria formar-se amb fluxos de H2O i/o CO2 a altes temperatures 700- 1000 ºC. El nostre estudi es centra en òxids de ceri dopats al 10% amb elements 19Chapter 0: Preamble trivalent, generalment lantànids. En aquest estudi es va correlacionar la velocitat de splitting del CO2 en l'etapa d'oxidació amb el volum de cel·la de l'estructura cristal·lina i la conductivitat total d'aquests materials. / [EN] This thesis is focused on the combination of different technologies to improve emerging technologies for carbon capture and storage (CSS) and the revalorization of the CO2 captured. The leading technology studied in this thesis was oxygen transport membranes (OTMs) that could produce pure oxygen more flexibly than the current oxygen production technologies like cryogenic air distillation. The production of pure oxygen is crucial for developing oxycombustion reactors that could be more efficient for carbon capture than traditional combustion reactors. The OTMs studies were divided into two main topics: dual-phase membranes with stable operation in CO2 and BSCF-based membranes (Ba1-xSrxCo1-yFeyO3-¿). For the revalorization of the captured CO2, the chemical looping technology based on a cerium oxide catalyst was studied, which takes advantage of the redox properties of the catalyst at different pO2 and high temperatures (between 700-1400 ¿C). In general, the principal limiting steps for OTMs were the bulk oxygen transfer and the surface exchange reactions. In this matter, the improvement in the behaviour of the catalytic layer could achieve better oxygen permeation. The first study for dual- phase membranes was focused on the role of the different dual-phase ratios in the behaviour as a catalytic layer in OTMs. For this study, NFO-CTO (NiFe2O4/Ce0.8Tb0.2O2-¿) was selected as dual-phase material. This material was previously studied and showed high stability under CO2 environments but with poor oxygen flux compared with other dual-phase materials. The study considered for the present Thesis showed interesting results, and it was combined with electrochemical impedance spectroscopy (EIS) measurements, commonly used to study electrodes for solid oxide fuel cells (SOFC) and solid oxide electrolysis cells (SOEC). The second study in dual-phase materials for OTMs focused on the increase in oxygen permeation for spinel-fluorite-based materials. In this matter, the bulk oxygen transports are controlled, apart from the temperature and the pO2 gradient, by the ambipolar conductivity, where the electrical and the ionic conductivities are involved. So, the NFO phase was changed for the CMO phase (Co2MnO4), which has higher total conductivity than the NFO. The resultant dual- phase material (CMO-CTO) performed better than the predecessor NFO-CTO material. As mentioned previously, the other study on OTMs focused on BSCF-based membranes. In this study, the BSCF capillary membrane was electrified in order to increase the membrane temperature via the Joule effect and, as a consequence, an increase in the oxygen permeation. In addition, this effect under oxidative dehydrogenation of ethane was studied, obtaining an essential improvement for electrified BSCF membranes compared with non-electrified BSCF membranes. These studies have opened new gates to operate these membranes at lower reactor temperatures. Finally, the last study was focused on CO2 upcycling via chemical looping methane reforming. Chemical looping is based on the redox properties of the catalyst in two principal steps, reduction and oxidation of the catalyst. The catalyst reduction is performed with temperature in inert conditions or with reducing streams like methane. We were focused on the reduction via methane that works at lower temperatures than inert streams and could provide syngas streams (a mixture of CO and H2) that improve global efficiency. The revalorization of the CO2 was performed in the other step, the oxidation part of the cycle. The oxidation of those catalysts could be formed with H2O and/or CO2 streams at high temperatures of 700-1000 ¿C. Our study was focused on 10% doped cerium oxide with trivalent elements. In this study, the CO2 splitting on the oxidation step was correlated with the crystal structure parameters and the total conductivity of these materials. / Laqdiem Marín, M. (2024). Development of high temperature MIEC catalytic reactors for energy conversion and storage aplications [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/204871

Det ständigt växande behovet av att minska CO2-utsläpp har lett till en ökad tonvikt på teknik för avskiljning av koldioxid från rökgas. MEA (monoetanolamin) anses vara riktmärket för lösningsmedel för att fånga in koldioxid på grund av dess höga absorptionshastighet. MEA är dock benäget att brytas ner, bilda giftiga biprodukter och dess regenerering har ett högt energibehov. Ett annat lösningsmedel med liknande teknisk mognad är vattenlösning med kaliumkarbonat (K2CO3) som används i den så kallade hot-potash carbonate (HPC)-processen. Emellertid är absorptionshastigheten i K2CO3-lösningen låg i jämförelse med MEA, vilket kräver tillsats av hastighetspromotorer för att öka absorptionshastigheten. Denna avhandling undersöker effekten av olika hastighetspromotorer på absorptionshastigheten av kaliumkarbonat. För detta utfördes absorptionsexperiment i laboratorieskala i en autoklavreaktor av rostfritt stål under kontrollerade förhållanden. Olika promotorer har undersökts, nämligen de organiska promotorerna glycin, piperazin och MEA, och de oorganiska promotorerna borsyra och vanadinpentoxid. Promotorkoncentrationen varierades mellan 3 vikt% till 7 vikt% samtidigt som koncentrationen av K2CO3 hölls konstant vid 25 vikt%. Driftförhållandena såsom det initiala partialtrycket av CO2 och temperaturen var respektiva 5 bar och 50 °C. De oorganiska promotorerna studerades enskilt såväl som i blandningar med K2CO3 för att studera effekten av varje promotor. De organiska promotorerna visade en signifikant förbättring av absorptionshastigheten jämfört med icke promoterad K2CO3. När det gäller de oorganiska promotorerna visade vanadinpentoxid jämförbara resultat med organiska promotorer med endast 3 vikt%. Ökad tillsatts av borsyra minskade absorptionshastigheten av lösningen promoterad av vanadin. Den experimentellt uppmätta absorptionshastigheten är anpassad till en enkel absorptionsmodell från vilken en skenbar absorptionshastighet för de främjade lösningsmedlen härleddes / The ever-growing need to reduce CO2 emissions has led to an increased emphasis on carbon capture technologies. MEA (monoethanolamine) is considered the benchmark solvent for CO2 capture due to its high rate of absorption. However, MEA is prone to degradation, forms toxic side products and its regeneration has a high energy demand. Another solvent with similar technological maturity is aqueous potassium carbonate (K2CO3) that is used in the so-called hot-potash carbonate (HPC) process. However, the rate of absorption in aqueous K2CO3 is low in comparison to MEA calling for the addition of rate promoters to enhance the absorption rate.  This thesis investigates the effect of different rate promoters on the absorption rate of potassium carbonate. For this, absorption experiments on the laboratory scale were conducted in a stainless-steel autoclave reactor under controlled conditions. Various promoters have been explored, namely the organic promoters glycine, piperazine, and MEA, and the inorganic promoters boric acid and vanadium pentoxide. The promoter concentration was varied between 3 wt% to 7 wt% while keeping the concentration of K2CO3 constant at 25 wt%. The operating conditions, such as the initial partial pressure of CO2 and the temperature were 5 bar and 50°C, respectively. The inorganic promoters were studied alone as well as in blends with K2CO3 to understand the effect of each promoter. The organic promoters demonstrated a significant enhancement of the absorption rate compared to unpromoted K2CO3. Regarding the inorganic promoters, vanadium pentoxide showed comparable results to organic promoters with only 3 wt%. When looking at the results of vanadium and boric acid, increasing concentration of boric acid resulted in a decrease in the absorption rate. The experimentally measured absorption rate are fitted to a simple absorption model from which an apparent absorption rate for the promoted solvents was derived.

The objective of this study is to conduct a critical evaluation of the environmental law framework applicable to carbon capture and storage (hereafter CCS) in South Africa. The discussion begins by confirming that CCS has a place in environmental law as a mitigation measure. The inclusion of CCS in the clean development mechanism could incentivise the development of environmental law frameworks for CCS in South Africa. Implementation of CCS is gradual, with only eight large scale integrated CCS projects having been established around the world. An appreciation of key scientific concepts is helpful for an understanding of the CCS process. The CCS project life cycle and related impacts on the environment provide a context for discussion of the legal requirements accompanying the CCS life cycle. The Constitution of the Republic of South Africa, 1996 and the National Environmental Management Act 107 of 1998 constitute appropriate framework legislation for CCS. Decision 3/CMP.1, Modalities and procedures for a clean development mechanism as defined in Article 12 of the Kyoto Protocol adopted by the Conference of the Parties serving as the Meeting of the Parties to the Kyoto Protocol held at Montreal from 28 November to 10 December 2001 March 2006 provides international legal requirements accompanying the project life cycle against which the South African legal framework is examined. Some provisions of additional South African laws and policies will be applicable to CCS depending on the nature of the specific CCS project, but specific regulations may have to be developed for South Africa. Policy documents have been gradually bringing clarity to the way forward in arriving at a legal framework for CCS, and by reference to existing local legislation and international guidance, an environmental law framework for CCS can be developed for South Africa. / LLM (Environmental Law and Governance), North-West University, Potchefstroom Campus, 2014

The objective of this study is to conduct a critical evaluation of the environmental law framework applicable to carbon capture and storage (hereafter CCS) in South Africa. The discussion begins by confirming that CCS has a place in environmental law as a mitigation measure. The inclusion of CCS in the clean development mechanism could incentivise the development of environmental law frameworks for CCS in South Africa. Implementation of CCS is gradual, with only eight large scale integrated CCS projects having been established around the world. An appreciation of key scientific concepts is helpful for an understanding of the CCS process. The CCS project life cycle and related impacts on the environment provide a context for discussion of the legal requirements accompanying the CCS life cycle. The Constitution of the Republic of South Africa, 1996 and the National Environmental Management Act 107 of 1998 constitute appropriate framework legislation for CCS. Decision 3/CMP.1, Modalities and procedures for a clean development mechanism as defined in Article 12 of the Kyoto Protocol adopted by the Conference of the Parties serving as the Meeting of the Parties to the Kyoto Protocol held at Montreal from 28 November to 10 December 2001 March 2006 provides international legal requirements accompanying the project life cycle against which the South African legal framework is examined. Some provisions of additional South African laws and policies will be applicable to CCS depending on the nature of the specific CCS project, but specific regulations may have to be developed for South Africa. Policy documents have been gradually bringing clarity to the way forward in arriving at a legal framework for CCS, and by reference to existing local legislation and international guidance, an environmental law framework for CCS can be developed for South Africa. / LLM (Environmental Law and Governance), North-West University, Potchefstroom Campus, 2014

Thesis (MScEng)--Stellenbosch University. / ENGLISH ABSTRACT: Carbon dioxide (CO2) is classified as the main greenhouse gas (GHG) contributing to global warming. Estimates by the Intergovernmental Panel on Climate Change (IPCC) suggest that CO2 emissions must be reduced by between 50 to 85% by 2050 to avoid irreversible impacts. Carbon capture and storage (CCS) strategies can be applied to de-carbonize the emissions from fossil-fueled power plants. Compared to other CCS techniques, post-combustion capture (PCC) is most likely to be implemented effectively as a retrofit option to existing power plants. At present however CCS is not yet commercially viable. The main challenge with CCS is to reduce the inherent energy penalty of the CO2 separation stage on the host plant. Seventy-five to eighty percent of the total cost of CCS is associated with the separation stage. There are several technologies available for separating CO2 from power plant flue gas streams. Reactive absorption with aqueous amine solutions has the ability to treat low concentration, low pressure and large flux flue gas streams in industrial-scale applications. It is most likely to be the first technology employed commercially in the implementation of CCS. The energy required for solvent regeneration however, is high for the standard solvent used in reactive absorption processes, i.e. MEA. This leads to a reduction in thermal efficiency of the host plant of up to 15%. Alternative solvent formulations are being evaluated in an attempt to reduce the energy intensity of the regeneration process. The main objective of this study was to establish a novel, simplified thermodynamic method for solvent screening. Partial solubility parameters (PSPs) were identified as the potential basis for such a method. The major limitation of this approach is that the model doesn’t account for effects from chemical reaction(s) between materials, e.g. CO2 reacting with aqueous alkanolamine solutions; considering only the effects from dissolution. The EquiSolv software system was developed based on PSP theory. The Hansen 3-set PSP approach was used to describe the equilibrium behaviour of CO2 absorbing in task specific solvents. The Hansen theory was expanded to a 4-set approach to account for contributions from electrostatic interactions between materials. The EquiSolv program was used successfully to screen large sets of solvent data (up to 400 million formulations) in the search for suitable alternative solvent formulations for CO2 absorption. The secondary objective of this study was to evaluate the ability of the proposed PSP model to accurately predict suitable alternative solvents for CO2 absorption through preliminary experimental work. A series of CO2 absorption experiments were conducted to evaluate the absorption performance of predicted alternative solvent formulations. The predicted alternative solvent formulations exhibited a significant improvement in absorption performance (up to a 97% increase in the measured absorption capacity) compared to conventional solvent formulations. Statistical analysis of the experimental results has shown that there is a statistically significant concordant relationship between the predicted and measured rankings for the absorption performance of the predicted solvent formulations. Based on this it was concluded that PSP theory can be used to accurately predict the equilibrium behaviour of CO2 absorbing in task specific solvents. Recently ionic liquids (ILs) have been identified as potential alternatives to alkanolamine solutions conventionally used for CO2 absorption. Absorption experiments were conducted as a preliminary assessment of the absorption performance of ILs. Results have shown ILs to have significantly improved performance compared to conventional alkanolamine solvents; up to a 96% increase in the measured absorption capacity compared to conventional solvents. Future work should focus on developing task specific ionic liquids (TSILs) in an attempt to reduce the energy intensity of solvent regeneration in CO2 absorption processes. / AFRIKAANSE OPSOMMING: Koolsuurgas (CO2) word geklassifiseer as die vernaamste kweekhuis gas (GHG) wat bydra to globale verwarming. Beramings deur die Interregeringspaneel oor Klimaatsverandering (IPKV) toon aan dat CO2 emissies teen 2050 verminder moet word met tussen 50 en 85% om onomkeerbare invloede te vermy. Verskeie koolstof opvangs en bergings (KOB) strategieë kan toegepas word ten einde die koolstof dioksied konsentrasie in die emissies van kragstasies wat fossielbrandstowwe gebruik, te verminder. Naverbranding opvangs (NVO) is die mees aangewese KOB tegniek wat effektief toegepas kan word op bestaande kragstasies. Tans is KOB egter nog nie kommersieël lewensvatbaarvatbaar nie. Die hoof uitdaging wat KOB in die gesig staar is om die energie boete inherent aan die CO2 skeidingstap te verminder. Tussen vyf-en-sewentig en tagtig persent van die totale koste van KOB is gekoppel aan die skeidingstap. Daar is verskeie metodes beskikbaar vir die skeiding van CO2 uit die uitlaatgasse van kragstasies. Reaktiewe absorpsie met waterige oplossings van amiene kan gebruik word om lae konsentrasie, lae druk en hoë vloei uitlaatgasstrome in industriële toepassings te behandel. Dit is hoogs waarskynlik die eerste tegnologie wat kommersieël aangewend sal word in die toepassing van KOB. Die oplosmiddel wat normalweg vir reaktiewe absorpsie gebruik word (d.w.s. MEA) benodig egter ‘n groot hoeveelheid energie vir regenerasie. Dit lei tot ‘n afname in die termiese doeltreffendheid van die voeder aanleg van tot 15%. Alternatiewe oplosmiddelstelsels word tans ondersoek in ‘n poging om the energie intensiteit van die regenerasieproses te verminder. Die hoof doelwit van hierdie studie was om ‘n nuwe, ongekompliseerde termodinamiese metode te vestig vir die keuring van alternatiewe oplosmiddels. Parsiële oplosbaarheidsparameters (POPs) is geïdentifiseer as ‘n moontlike grondslag vir so ‘n metode. Die model beskryf egter slegs die ontbindings gedrag van materiale. Die effekte van chemise reaksie(s) tussen materiale, bv. die tussen CO2 en waterige oplossings van alkanolamiene, word nie in ag geneem nie. Die POP teorie het gedien as grondslag vir die ontwerp van die EquiSolv sagteware stelsel. Die Hansen stel van drie POPs is gebruik om die ewewigsgedrag te beskryf van CO2 wat absorbeer in doelgerig-ontwerpte oplosmiddels. Die Hansen teorie is verder uitgebrei na ‘n stel van vier POPs om die bydrae van elektrostatiese wisselwerking tussen materiale in ag te neem. Die EquiSolv program is verskeie kere met groot sukses gebruik vir die sifting van groot stelle data (soveel as 400 miljoen formulasies) in die soektog na alternatiewe oplosmiddels vir CO2 absorpsie. Die sekondêre doelwit van die studie was om die vermoë van die voorgestelde POP model om geskikte alternatiewe oplosmiddels vir CO2 absorpsie akkuraat te voorspel, te ondersoek deur voorlopige eksperimentele werk. ‘n Reeks CO2 absorpsie eksperimente is gedoen ten einde die absorpsie werkverrigting van die voorspelde alternatiewe oplosmidels te ondersoek. ‘n Verbetering in absorpsie werkverrigting van tot 97% is gevind vir die voorspelde oplosmiddels vergeleke met die van oplosmiddels wat tipies in die industrie gebruik word. Statistiese ontleding van die eksperimentele resultate het getoon dat daar ‘n beduidende ooreenstemming tussen die voorspelde en gemete rangskikking van die voorspelde oplosmiddels se werkverrigting bestaan. Dus kan POP teorie gebruik word om die absorpsie van CO2 in doelgerig-ontwerpte oplosmiddels akkuraat te beskryf. Ioniese vloeistowwe (IVs) is onlangs geïdentifiseer as moontlike alternatiewe oplosmidels vir die alkanolamien oplossings wat normaalweg gebruik word vir CO2 absorpsie. Absorpsie eksperimente is gedoen ten einde ‘n voorlopige raming van die absorpsie werkverrigting van IVs te bekom. Daar is bevind dat IVs ‘n beduidende verbetering in werkverrigting toon in vergelyking met die alkanolamien oplosmiddels wat normaalweg gebruik word. ‘n Verbetering in absorpsie werkverrigting van tot 96% is gevind vir die voorspelde IV-bevattende oplosmiddels vergeleke met die van oplosmiddels wat tipies in die industrie gebruik word. Die fokus van toekomstige navorsing moet val op die ontwikkeling van doelgemaakte ioniese vloeistowwe (DGIVs) in ‘n poging om die energie intensiteit van oplosmiddel regenerasie in CO2 absorpsie prosesse te verminder.

This dissertation presents a fibre-optic sensing approach to provide continuous measurements of CO2 concentration at discrete points under typical conditions of geological CO2 storage. Carbon capture and storage is considered to have potential for a large-scale reduction in CO2 emissions in a relatively short period of time while other solutions to replace fossil fuels are being investigated. One significant drawback of carbon capture and storage is the possibility of long-term CO2 leakage. Therefore, the development of reliable technology for monitoring, verification, and accounting of geological CO2 storage is critical to fulfill safety regulations and achieve public acceptance. The major limitations of current technology include relatively low resolutions, high costs, and the lack of continuous monitoring for long periods of time. To address these limitations, two types of fibre-optic sensors are investigated, namely long period gratings and Mach-Zehnder interferometers. The sensing principle for CO2 detection is based on the sensitivity of these sensors to the refractive index of the medium that surrounds the fibre. Fibre-optic sensors are attractive for downhole applications due to the possibility of fabricating inexpensive high resolution devices that are able to operate in harsh environments over long periods of time. This dissertation focuses on increasing the refractive index sensitivity of long period gratings and Mach-Zehnder interferometers by applying coatings that have a high refractive index. The dip-coating method is used to coat long period gratings with polystyrene, and the sensitivity at low refractive indices is increased by tuning coating thickness. The results show that long period gratings coated with polystyrene are able to detect CO2 in gaseous and aqueous media. This work reports the first measurement of CO2 dissolution in water at high pressure with a fibre-optic sensor. Additionally, atomic layer deposition is investigated to coat long period gratings and Mach-Zehnder interferometers with hafnium oxide. The study of this coating technique aims to address the main limitation of the dip-coating method: the challenge to achieve precise control over coating thickness. The results show that atomic layer deposition is suitable to maximize the sensitivity of long period gratings and Mach-Zehnder interferometers at a target refractive index. / Graduate / 0548 / 0752 / 0799 / luismelo@uvic.ca

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